Top end rebuild (Stuttering, Elec. Issues Prior) (Pic heavy)

cut 1/2 inch off the end of the hose, and put it back on with a clamp.....you could have a small vacuum leak, and that is the popping noise that you hear (lean pop) .....I feel you are close to fixing all of your problems.

Kenneth

 

Re-checked all the vacuum hoses.

Checked breather hose

Put on new wiring harness

Got another new, better battery

Found a stock air filter

Nothing. No change.


I am so close to parting this out.

 

Backfiring thru intake = burned valve or a cam that is severely out of time.

Why not put a vac/pressure gauge on that #1 intake (might need a T-fitting) and watch what happens in real-time, see if you can isolate anything.

Would also put the vac/pressure gauge on the other intakes to do a comparison.

Assuming that there's not a mini-turbocharger hidden somewhere, you shouldn't have positive pressure in the intake system.

 

Nooooooo

I love this bike.... love this thread..... hate that there's no solid answer yet...

Have had this feeling/instance on mine too but like I said, a wiggle of my spark plug wire's and it's gone away... **knock on wood**


Have you tried capturing it on vid??? Is it sporadic enough you can't do it??


If you do scrap the bike, I got a parts list for ya, hahaha

 

OH THE EMOTIONAL ROLLER COASTER I AM ON

I made the decision that I will not part it out. At this point, there has been too much time and money put into it that I need to give it a rest for a while. But along the same lines, there has been so much time, money, and effort put into it that I just can't part it out! Why would I even consider it!

Through all the trials and tribs, I could be so close to the answer. I'm not going to give up on that chance, even if the bike sits for a while.

The plan for now: Keep my eye open for another bike.

There are always Seca II's on the market in my neck of the woods. One or two of them are always parts bikes, too. Before too long I might snag one and combine parts. Mine is in really good shape, brand new tires, no modifications. If it turns out to be engine related, slap the engine from the parts bike into my frame, and then rebuild my engine. A good running project/parts bike would get me a working mode of transportation, and give me the no pressure time to rebuild my engine...just start from the bottom up, really.

This whole time the XJ has been down (or the majority of the time, really), I've been borrowing a '95 Ninja EX500 from a buddy of mine. It has some get up and go. Fairly comfortable. More pressure on the wrists because of the stance. I've probably put close to 2k miles on it lol.

But I just sit on the XJ...there is no other bike like it, really. It balances so well. The posture feels good on the back and hands. The foot position in comfortable. Even putzing around on it during my lunch break at work while diagnosing and testing -- I know know it needs to be road worthy. I've ridden a ton of bikes...nothing feels and handles as well as a Seca II.

I have tried to get some video. Audio is the issue. Being able to hear the stutter while there's tons of wind noise. I have an idea or two which I'll try tomorrow.

The next things to try on it are take-my-time things. Like rebuilding this extra rack of carbs I have completely. Splitting the rack and replacing throttle shaft seals, investigating the enrichment plungers, ect. The only other thing besides that is splitting the case and making sure I haven't spun a bearing or something. Its just every time I think of what it could be, it contradicts what I've already found out, and then I start to think of something else but realize I already checked that a thousand times, and so on and so forth.

I'm in the mindset that this needs to be fixed RIGHT NOW, because at the moment it's my only transportation. I was in the process of rebuilding the engine on my Chevy K1500, when some joker -- get ready for this -- stole the transmission. Yep, you heard me right. I ended up just having to scrap the truck because well, I was minus a transmission, and it got vandalized pretty good before that. Shortly after, I bough this XJ. You guys helped me get it running one year ago, and it ran SUPER for a year. Then I hopped on it and rode to Pennsylvania and that's where it went hoolllddd onn thheeerree missteeerrr lol. I think the best thing for me right now (like I already said) is to find another bike, and then take my sweet time on this one. Trying to rush and figure out what's wrong with it might have me missing some important steps.

Sorry for the long post lol.

Edit afterthought: I sure as heck don't want people to think any of the procedures or methods in this thread aren't useful because I haven't had any positive outcome yet. It's just that wherever this issue is coming from, I've haven't touched there yet. It's in an unknown region. The stuff I've learned about bikes, engines, new techniques, and tricks about this bike in particular -- oh man, throw all the parts in a bucket and I'll put one together from scratch. Sure it's not running yet, but what I've learned in this process almost...almost justifies it borking. At the end of the day I can feel good about that.

 

Guud call man...

I hope for you.... I really do...

I love the seca.... such a smooth bike, different, I get old and young rider's that are intrigued by it all day long.

Take a break, go ride, think inside that helmet of yours and see what might occur...

Don't part it, I was kidding of course... all your parts are so pretty damn straight I'd take em but don't do it!!!

 

I don't think the problem is something you haven't touched yet.

I think the problem is somewhere there, right in front of you, being masked by an assumption.

What have you "crossed off the list" because you're assuming it has to be fine?

I'm only asking because I've assumed myself into a corner more times than I can count. "Oh, it can't be that because..."

Let's go back over the whole thing: The bike ran fine before the trip.

What happened on the trip that stands out in your mind? Did the problem come on suddenly, gradually, or not surface until you got home and then rode the bike after?

Describe the "stuttering" more thoroughly, please.

It's not mechanical is it, like maybe you wore all the teeth off the front sprocket?

C'mon, man--- remember Sherlock Holmes. What has been "falsely eliminated" as a possible cause? It's right in front of us, I can smell it...

 

LEFT FIELD HUNCH!

HUMOR ME! Unplug the safety relay and take it for a ride.

 

opcorn

 

Milk Duds

 

Nahhh, I'd eat them too fast...


Maybe some sunflower seeds?

 

Have you checked the spark plug caps? Check inside for corrosion....I still believe that it somthing simple.

Kenneth

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Grab a drink...

Since you all are here with your favorite munchies (I prefer Cracker Jack) and are ready for story time, I suppose that's it's only fitting to start from the beginning. Maybe recalling the PA trip from the point the XJ started acting ridonkulous will help me see what could have possibly gone wrong as well.

tl;dr, maybe. But I need to get this out of my brain and put it in words.

My brother and I left our hotel about an hour before the wedding started. It was only a 20-30 minute ride from Chambersburg to Gettysburg, but being unfamiliar with the area we wanted to be able to find the church with time to spare. As planned, we arrive at the church half-hour early, and at this point I am out of gas. Like no gas. Like switched to reserve three miles back out of gas. Since we knew where the church was, we decided to go on a hunt for a gas station before the wedding started. Ok, right here is the first time I noticed something different: When I started the XJ at the church, it wasn't that instant start and idle that usually occurs. It stumbled to a start, kind of bobbed a little, and then idled ok. It sounded way different, too. It wasn't that crisp clean sounding engine and exhaust, it was muffled and muddied, like the sound when your plugs are fouled. Hold your nose and go "wahhhhhhhhhhhhhhhhgnnnnnnn". That's what it sounds like, lol. Also there was no throttle response in neutral. It didn't rev real fast and come back to idle like a properly running engine does. It climbed slower, and it took a second or two for the RPM to come back down to idle.

So I'm thinking that all this has to do with the fact I has no gas, and I'm probably running on fumes. Or maybe Chacal was right and it is demon possessed since it started acting up while in a church parking lot. Anyways, I just need to find a gas station, and go from there. Turns out that Gettysburg, PA has no gas stations. None. If it did, we didn't find any because we rode up and down the city for 25 minutes and did not find one. That's science, kids. It was kind of frustrating because of that fact and knowing that I could run out of gas any second. With 5 minutes before the wedding starts, we head back to the church. Fast forward an hour, two people are married, they run through bubbles since no one throws rice because of exploding birds or some bulls**t like that. We get back on our bikes and try to find a gas station on the way to the reception. The XJ is still running the same. Crummy, no power, sounds sick. Three miles out of town we find a gas station, and not just any gas station, a pump first then pay no credit cards accepted gas station. It had the oldest ghetto pumps I had seen in a while. However, this fill up was such a relief. I would have paid that man $100 instead of $12 for that motion lotion and that feeling knowing I wasn't going to konque out on the side of the road in the middle of Gettysburg, where a canon ball gone awry from a mock war is about to fly across a hundred-acre misty field of grass and take me the F out.

The gas is paid for and I saddle myself up, hit the start button, and it does the same bobble of a depressing start like before. Same muddied sound coming out of the exhaust. Crap. We rode about 20 miles to the reception, and the XJ ran the same. Now I'm thinking that it could be the plugs, or the tank was so low that it sucked some rust particles through and into my carbs. No big, I'll investigate when we get back to the hotel. Fast forward two hours. Lots of dancing (none done by me, I just socialize with the other non-dancers), some champagne drinking, photo shoots, best man speeches. We say our goodbyes. My brother and I make out way down to our bikes still in our suits, put on some jeans and jackets over our suits, and begin the (from this geographical location) hour long ride back to Chambersburg. It's close to 1 am at this point. We are both tired and are only concentrating on getting back safely. The XJ is running kind of the same, no throttle response, same muddied exhaust sounds, except now it had developed an annoying vibration around 4.5K RPM. Needless to say we are wiped out when we get back to the hotel.

Too bright and early the next morning, I decide to try changing the spark plugs. It just so happens that I brought my tools, extra plugs, and a plug gapper. Aren't I smart? Actually, it was probably one of you who told me to do that lol. The new plugs are gapped and torqued in. I fire up the bike and the exact same thing. Throttle response like an 18-wheeler. The exhaust sounds like someone shoved a rag in both pipes. Still has that darn vibration when I rev it in neutral and hold it at 5K RPM. So about now, I'm thinking something happened with the carbs. An air jet or something got clogged because the plugs were black and sooty. Or maybe, just maybe the idle mixture screws vibrated out some? Nope, they were still where I had set them before the trip. Nothing I could check at that point would tell me what changed or how I could fix it. But the XJ still rode okay, didn't have any certain spots in the RPM where it cut out. I could make it 700 miles to home. Ahh home. This was one of those times you really miss home.

Fast forward three or four fill ups. We're somewhere in Virginia (I think). Lots of choppers, none of which had a rider that was wearing a helmet. Which really sucked, because you can't help but feel like a complete n00blet when they smirk at you for wearing protective gear. Oh well. We stay the night and the next morning, I pull the plugs and check them again. Black. Black and sooty. Black and sooty as the hearts of the chopper riders who smirk at you for wearing protective gear. Black and sooty as the brains of those chopper riders who smirk at you for wearing protective gear. Black and sooty as the faces of those chopper riders who smirk at you for wearing protective gear because the filth of the street flies up in their face all day. I wire brush the blackness and sootiness off the plugs, put them back in, and head to Advance Auto Parts which I had seen on the way in the day before. They're the only non-online place that I know of that carries the plugs I use, NGK CR8-E. While I'm there, I talk with the guy behind the counter for a little while. While he was talking, I spied some Seafoam around the corner. Maybe some Seafoam would help in some way if I put some in each fill up on the way back to Georgia.

Extremely too bright and early the next morning, the new gapped plugs go in, and so does a splash of Seafoam at the gas station. The XJ is running the same. We're cruising down the highway, and I can't get the XJ to go faster than 70. Wide open throttle, just 70mph. No coughing, stuttering, bogging of any kind, it just seemed to have a top speed of 70. Which really wasn't good, because it took a while to get there, too. And when you're trying to merge onto the highway and not get squished by the 10 18-wheelers that are flying up behind you at a hundred and ten, well, you'll go through some underwear. And we had just stopped for a refresher and I'm not about to delay our trip over some poopy underwear. At this point, the XJ develops a hesitation in acceleration. Where you give it gas real quick and it bogs for a half second, then starts accelerating. Running rich? Cranky diaphragms? Not sure which end of the spectrum I should be worried about. Can't do anything about it now.

Fast forward 200 miles. Lots of bugs on the visor, cool breezes, mountain passes, we are home in Georgia. Two days later, I go with a buddy to meet up with a buddy. He's riding a Honda CM400T, I'm on the Seca II. It's still running the same as before. After riding for about 30 minutes, it starts to get real slow and starts bogging on acceleration. Ok, now it's definitely time for some after trip investigation. The next day, I break down the carbs. Nothing out of the ordinary. Everything is still pretty clean, but I still give it the complete treatment. All passages and jets cleaned, diaphragms have no tears, they go clunk, float levels are all nominal while checked dry. The rack goes back on, new plugs go in. It fires up a lot faster than before, no stumbling to a start. Next I check the floats properly (as in, clear tube method, because no matter how much you want to argue, dry setting the floats is not proper) and they're all within spec although a little on the high side. But still within spec. It sounds better, idles better, but doesn't ride better. Still bogs down under a heavy load.

This is where I venture into the valves. A place I had not ventured before. I'm expecting the clearances to be horendous, because I had never messed with em, and I don't know if the PO had ever messed with them, and I don't know if the PO before him had ever messed with them, and for all I know they're the same shims that Mr. John Q. Yamaha put in the motor when it was built. To my surprise, there were only two valves out of spec, and even then, one shim off. Huh! After calling the five motorcycle repair shops in my area, I find out that they're all idiots who don't swap out shims. That's if the person I talked to knew what I was talking about. There was one fellow who said he's sell me one for $20. Did he have it in stock? Nope, he'd probably order from Bike Bandit and mark up the price five bucks. Well, I can do that. And I did. A week later, I have my two shims, pop them in, and fire the XJ up. Sounds a little better, only a little better, but still hesitated and bogged a little under acceleration. After a day or two of riding with this bog, it starts the stutter. As it's warming up, it stutters like the cylinders are fighting against each other at 4.5K + RPM. When it's all the way warmed up, it stutters under ANY acceleration.

At this point, I'm pretty sure that's when I made this thread. Start from page one if you want to get caught up lol.

Today, I did a good bit of riding/diagnosing on it. Got alot of good video with decent sound, so you can hear the stuttering. Unfortunately, my internet sucks a krayt dragon nut, and the video has been uploading the whole time I've been typing this. But it was the same today. Still. 5K RPM stutter, fully warmed up, unrideable. You cruise at 30mph, 3rd gear, 5K RPM, and give it some gas, it just feels and sounds like the engine is popping popcorn and you just lose speed, even while trying to accelerate. I don't think I've described it like that yet -- you lose speed while you're giving it gas and trying to accelerate like a motor gnome magically advanced the timing 30 degrees.

Safety relay -- for the sidestand switch? Must consult manual for location.

Yes, I replaced the coils and got new caps for all four.

Video finished uploading, now I can hit submit. This is probably the best audio I'm going to get. It's easier to hear the stuttering in the "chain angle" -- the "under bike" mount, not so much. But keep in mind, this is only the audio. When it stutters, it does it violently. You can't experience that with just watching the video.

[flash=560,349]http://www.youtube.com/v/Z3TyxuWpeDY.swf[/flash]

2:41 is the spot where you can hear the stutter in the exhaust the best

At 3:00 going up that hill, it almost didn't have enough power to get up there.

 

Very neat drive-chain cam............

 

I watched your video 3 times, and does sound like a miss, with popping from the exhaust, however, the "under bike" video almost sounds like something in the driveline....maybe I'm hearing road noise......I think your problem is still in the ignition system. I wish I was closer to ride the bike.

Kenneth

 

Same thing my bike does... atleast by the sound... and yes, grabbing your nose and going WAAGHHHHHHHHHHHHHHHHHHHHHHHHHHnnnnnn!!!! is a great equivalant to the sound it makes......

Great cam....


Unfortunately I can offer no help but am halfway through my bag of popcorn.... do I get a free refill since I bought a Large??

 

I should say same thing my bike does but for much shorter periods of time, and so far a wiggle of the spark plug wire... #1 on the left side, and it goes right away...

First time I noticed as well was the first time I got down to reserve...

Makes me wonder if the fuel pump is the issue.... sucking air when it's low or something..... I don't know but again....

opcorn

 

have you tried Bigfitz,s idea of unpluging the safety relay? Also, when you put the stock air filter back in, did you re-colour tune and re-sync the carbs?

 

I think your missing a Shim or a Thrust washer.

It seems like the NOISE accompanies the DRIVE CHAIN Vibrating excessively.
(Not running true. You can see the evidence of this near the END of the Video.)

Although the Drive Sprocket's Securing Nut is tight on the Shaft, ... an Alignment Shim or Thrust Washer appear to be:
Missing. (Needed; not present)
Extra. (Aftermarket Sprocket; Spacer~Shim -- Not deleted.
Backward. (Drive Sprocket shouldered for alignment. Installed backward?)

Some other issue causing the Chain to Vibrate rather than run true.
Warped Sprocket
Rear Sprocket not fully seated.
Rear Sprocket warped.
Rear Sprocket loose.
Worn Rear Wheel Bearings

Wrong Sprockets.

What-ever is the fault is causing the Drive Chain to Vibrate excessively on the run from the Rear Sprocket to the Drive Sprocket.

The Vibration is excessive.
Could lead to the Chain "Jumping" the Sprocket.

 

Have you checked? The video does seem to indicate that the driveline needs some attention.

However I don't think that's the problem.

I've been channeling Sherlock Holmes again.

We've thoroughly examined the fuel, intake and carburetors, and you've rebuilt the "air pump" (the top end of the motor.)

What HAVEN'T we thought of or discussed; at all?

........

the EXHAUST SYSTEM. Ever put a potato in an exhaust pipe (or have mud dauber wasps build a nest in your muffler?)

WHAT IF: The bike originally started running a bit "flat" because it was nearly out of gas.

BUT THEN, while you were in the church, somebody's unattended 3-year old very carefully and industriously filled your muffler (or mufflers) up with pebbles from the parking lot? I've raised five kids; and they've done it to me at least twice.

Did you have the mufflers off when doing the upper end rebuild?

If not pebbles, maybe you've had a baffle come loose or there's some sort of other obstruction in the exhaust system (like a wasp's nest?) Worth a look...

BUT

I still want to know what happens when you unplug the safety relay;

AND

You need to have a look at your front sprocket (although I don't believe it's related to your problem.)

 

Stay tuned -- I'll be checking all this stuff today and will return with a thorough report

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Still trying to find time to do this today, but let's do some thinking in the meantime:

Unfortunately all I did was slap the air filter and try to ride the bike. I couldn't do any tuning because I had to give the air filter back (someone let me borrow it). However, I went ahead and bought an OEM filter and when it shows up, I'll colortune and sync.

That's definitely something I would not have noticed. I did replace both the chain and sprockets before the trip, so there's a possibility something could be amiss down there. New thrust washer, too. We'll find out when I pull off the chain and front sprocket.

You're right, my mind tells me based on the stuttering miles I've put on this XJ that the problem is fuel/air related -- but driveline is one of those things we have not considered.

The headers and mufflers were both off when doing the head rebuild. There was no sound of anything loose in there (rocks, debris, baffles, or otherwise). I'll get a flashlight in there to see what I can see.

As far as any other things we haven't though of or discussed...Thinking out loud:

Electrical? Everything has been replaced. Lets work up the food chain:

Spark plugs ---> boots ---> coils ---> wiring harness/fuses ---> pickup coil ---> CDI

Stator ---> reg/rect ---> battery

Safety relay is missing from that list, going to check.

----------------------------

Fuel/air? What I've touched:

Compression is good ---> rebuilt head w/new gasket ---> lapped valves ---> stem seals ---> valve clearances in check ---> timing is correct ---> chain tensioner is functional

Intakes and o-rings ---> carb boots ---> correct jets ---> float levels correct ---> no tears/rips in diaphragms ---> they go clunk ---> emulsion tubes in good shape ---> fuel pump and lines ---> petcock and vacuum tube ---> tank and cap air inlet

Carb to airbox boots ---> air filter

As you suggested Fitz, throttle shaft seals are not in that list. Plus, the airbox is two-peice and there's a gasket/seal between them. Perhaps that seal is disintegrating. Also, as Mr.Etobicoke suggested, I did not try and sync/tune with the OEM air filter.

UPDATE:

Ok, there are two relays on here. The right one is the flasher, the left one I'm assuming is the safety relay. I can find it on the parts fiches but can't find anything that tells it's purpose. Not even in the manual. Well I'mma gank it and see what happens.



The side stand area is pretty nasty. The switch back there could probably use some cleaning.



UPDATE: The bike doesn't start without the relay on the left

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Driveline check:


Nothing out of the ordinary at first, but there was a little play in the sprocket. I hammered the lock washer back, and the nut just spun off with no socket...Looks like the lock washer did it's job. That explains the chain vibes, I bet.


I didn't put it on backwards, lol


No unusual wear


No damage to the spindle


While I'm waiting for a new lock washer, I'm going to finish up these carbs. Might even try to score another parts rack off ebay since I've got two racks, but only one complete set of internals.

 

I love getting emails about this topic.... everytime it's like christmas...

I open it up hoping for the best present ever, the solution


Only to be disappointed by a pair of socks.....

I think it's something to do w/ the fuel system going to reserve and back... I really do

Thinking about it today at work... your problem came up when you switched it... I noticed it when I was switching back and forth, since then I've nailed my mpg and haven't had to use my reserve on my rides. Just plan to stop when I know I'm 5miles or less til reserve....

But, the flash I had was the last time I had this problem... I had switched to reserve, drove the .7 miles to the gas station, gotten gas, and when I went to pull away it started to bog down/stutter...

With my fix.... a tap of the #1 spark plug, pull in the clutch and give it a lil gas, it seems to clear up...

but now thinking about it.. i wonder if it's more like the inside leaf that is only being sucked up when it has been on reserve... IDK

like I said, Damn pair of socks!!!

 

If you can't find the safety relay...just unplug the side stand switch and bypass the wiring harness there. It will be interesting to see how the bike runs with the front sprocket tight. What spark plugs are you using?

Kenneth

 

Come get your socks!

Haha I know what you mean Koi...the Christmas solution is coming, don't worry

Yea I'm curious what will happen with a correctly fastened driveline. Although I'm still convinced the stuttering is fuel/air related. One thing at a time I suppose.

Spark plugs -- NGK CR8-E

 

Stuttering is definitely fuel/air/spark related.... though i'm saying fuel more then air/spark.... just my intuition though I can't see how we've missed it so far...

anywho... damn you and your socks....

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

You don't like them?

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

No,,,, these are more my style




8O

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Dang Koi, you must have been working out!

ANYWAYS

Forgot to mention: sidestand relay unplugged, bypassed at the harness, there was change. That was the last electrical thing to diagnose.

Last night I got the XJ home from work, which is about 20 miles. Couldn't really start pulling things off while it's at work.

Inbound:

OEM air filter
Throttle shaft seals
Lock washer for sprocket

 

Quick tip, from looking at the pics: When you re-fit the countershaft sprocket, lube the splines with a nice high-temp grease. Running it "dry" like that will accelerate wear on the splines, as you can see by the red dust.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Come get your socks

Thanks for the tip, Fitz. I was curious where all that rust dust came from.

While waiting for the parts to show, I wanted to make sure the carbs were in tip top shape. Taking into consideration this is literally the 10th time I've taken them apart this year, I still found some things that were not to my liking.

Check out the o-ring on the valve seat. It wasn't like this last time I got my carb on.


The o-ring on the idle mixture screw isn't disintegrating, but it's kind of flat. Not sure if it's supposed to be like that.


The is the main jet tube. There's a little tiny o-ring that goes on the end of the jet, and presses up against the holey mistifier tube. As you can see, it's time for a new set.


Going to soda blast this rack today. It's the one I've been using to diagnose with while I'm rebuilding the original rack.



Either I didn't catch this stuff before, or something caused it recently. Regardless, it's something else that needs to be done properly before I can even hope to get the bike running right.

 

Don't soda blast the insides of the carbs unless you're breaking the rack. You don't want to drive soda dust into the throttle shaft seals from the inside.

The inside of that jet tube is pretty interesting...

and no, the o-rings on the idle mixture screws aren't supposed to be flat like that.

 

So, just throwing out there the latest stutter on my bike...

Went out for a ride the other night with some friends, had ran 135 miles on the first tank ((5-10 short of reserve)) and then 139 miles on the 2nd tank ((1-5 miles til reserve)) On the third tank of gas we went to dinner, no problems, ran fine..

And oh by the way, I replaced the stupid chrome fgt looking screaming gayh pipes with a set of stock exhaust I got off ebay.. run's smoother but there's a bigger gap in the middle of the power band around 6500rpm... anyway not the point

I was riding home after dinner, probably 38 miles into the tank of gas and was attempting to get on it a lil bit to cut through some slower cars, well when I romped on it, 5th gear, but was being lazy and not downshifting to 4th so it was a lower rpm, 5-5500? I got the bog/stutter/1/2 an engine feel.

Immediately got off it, reached down to trusty #1 spark plug, tap tap wiggle wiggle, no worky... Sh*t....

So I downshifted into 4th, still boggy, pulled in the clutch, revved it, smoothed out and never bogged again....

for the remaining 5 miles I thought about it and previous times and I can say the romping on it in a higher gear might be a reoccurance but I don't remember, never thought about that part of the situation til this last time...

Not saying it helps at all... when I got home it was running fine, I was full and tired, so when I got up in the next morning and put it on the stand, did some checks.. of course I couldn't find that big red arrow pointing to the answer...

Going to pull it apart in a few days before a major ride on the 28th to the redwoods... will take pics and show you how ugly my bike is internally compared to your clean lil princess....

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Interesting. Sucks you're having issues, though.

Gah!

Here's where mine stands. I got completely new o-rings and throttle shaft seals for the whole thang, and it idled better, sounded better, but still stuttered. Don't have the new air filter yet. But there are not-good noises coming from under the valve cover. I need to pop the cover and double check everything. Might even take the head off again.

I'm just keeping my open for a parts bike, really.

These are the little main jet o-rings. Old on top, new on bottom.


I used the back end of a small drill bit to press them in


O-rings for the valve seats


New idle mixture assemblies


Old on top, new on bottom


And then for some reason my XJ decided to molt? Maybe it will come out bigger and stronger as a XJ900. The way I had my tank in "storage" while wrenching caused some motion lotion to reconfigure the color. What's next.

 

Before you go yanking the head, just triple-check the cam timing and then the valve clearances; and run another compression test.

 

How did this conclude... I've just read the entire thread -- no resolution to-date?

Thanks

 

I am equally interested in knowing what happened.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Ahh, I've been meaning to update this thread. Turns out (to no big surprise) it was carb related, more specifically the throttle shaft seals. Those suckers would allow air to sneak in when the engine was drawing the right amount -- half throttle.

By the time I figured it out, I had three racks of XJ600 carbs in the garage and I would use the same internals (jets, diaphragms, ect...) in each set, but only one set I tried actually worked. The other two sets that didn't work had throttle shaft seals more shriveled and crusty that a raisin crossed with a hobo.

However, I should make a new thread for this particular XJ, because it has been getting a complete rebuild...

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

THANK YOU!! So good to know from a PREVENTATIVE perspective as I am doing some rebuild and tear down work this winter

Thank you!! p.s. looks great keep up the good work and post as you go.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Good deal. That's a better way too look at it too -- preventative. Then you can avoid ten page threads that conclude with something you should have checked in the very first place. :lol:

Honestly though, I learned so much from this whole thing and if someone else got something from it, superb.

Starting a new thread for the rebuild.

 

Throttle shaft seals can really fool you. Quite often you won't be able to detect any sort of vacuum leak, because they're only leaking when the shaft is at certain degrees of rotation, not constantly.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

For that reason, I think I'm going to strip the rack again this winter and replace mine. They were new a year ago, but I have a bad feeling I used petroleum-based lube when installing instead of the stuff I got from Chacal.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

I agree, sign me up for doing the carbs realllly soon.
Not to mention the soda blasting..

 

So I just read this ENTIRE thread. Started about two hours ago, and just finished. At the end of page 9 I was about to suggest removing the mufflers and checking that you didn't have a plugged exhaust header.. it seemed like the only thing that hadn't been checked, double checked, and completely eliminated.

Glad to hear you finally figured it out! Congrats on learning your bike inside and out, and thank you for sharing the journey with the community here! I think I have learned a great deal from your discussion and repair that will help me in the future if (knock on wood) I ever run into such a problem with my own XJ.

Speaking of your problems, I should probably pull apart and rebuild my carbs soon, including gasket replacements...

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

I am going to be re-doing my carbs in the winter months here, and definitely want to ensure everything is good from a preventative perspective.

I've done some looking, and "throttle shaft seals" turned up inconclusive as to exactly what part of the carbs these are. If you could explain, or show a pic of where these seals are so I can examine mine, that would be appreciated.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

They're on the outside of each carb body, one on either side of the butterfly shaft. They're covered up by a c-clip and a washer.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

AHA! Thanks for the image, Andrew.

The far right circle in the image with the C-clip is typically slightly moist with fuel on my bike, and drips slightly onto the pan below the carbs.

I am DEFINITELY going to be re-working my throttle shaft seals.

Thanks again for the perfect image.

 

It seems like a more invasive procedure -- which it IS -- but if you can handle normal carb cleaning dis/reassembly, you can do the shaft seals.

Just work slowly, carefully. Make sure you look and see how the shaft springs are coiled and how everything works. It will help with putting it back together.

Also keep everything organized on your workspace so you don't mix up which bits go on which side of which carb and yadda yadda squared.

 

Im definitely up for the challenge, but where do I get the replacement seals?

Any other bits I should be replacing/examining while I'm in the carbs? I replaced the float bowl gasket, O-rings, float needle & seat this spring.