carb #2 no change with propane test

So before I start with my new found problem, let me start off by admitting that I have not yet checked valve clearances. I know....I know...shame on me, I'm just a little intimidated by the complexity of it all. Kind of silly coming from a guy that read the thread on cleaning carbs about a million times and dug right in. However here's what I ma encountering. My bike runs great after a running sync, then a few days later it's popping and running funny. I re-sync and it's good for a few days. Today I had the funny idea that maybe I had a vacuum leak and was sucking air so I did the propane test and had no leaks. I then pulled the rubber boots off the nipples for doing the running sync. I did this one intake at a time. When I got to carb number 2 and I applied propane to the nipple it didn't change my RPM's at all. I can feel it sucking on my finger when I put it over the port but I don't get a rise in RPM's what so ever. Any thoughts?

 

That cylinder is probably not firing.

But you shouldn't be pulling those nipples off while it's running.

 

I'd check the plugs, check for spark, see if the pipe is getting hot on that cylinder. (and check your VC's but you already know that!)

 

You really want a "thought?"

CHECK THE BLOODY VALVES. It AIN'T rocket science; it' a part of normal maintenance that you need to do every 5000 miles as long as you own the bike. (I'm assuming you want to actually ride it.)

What else do we need to say fercryinoutloud? I believe I already spoke to this in a reply to an earlier post of yours.

A lot of work went into these, ya know. I don't know how much plainer it can be:

Valve adjustment: http://xjbikes.com/Forums/viewtopic/t=14827.html

Part Deux, how to use the tool and the zip tie trick: http://xjbikes.com/Forums/viewtopic/t=29209.html

As has been covered over and over and over, you won't get a good sync with out of spec valves. Why do you keep trying?

Just soldier up and check the blasted valves already. Geez.

Wanna bet me $5 for every tight valve? I offered the same bet to another member recently, I woulda got $30 if he'd gone for it.

 

I have a little over 120 psi compression on that cylinder, the header gets hot as hell, I have good spark from the plug, it's gapped correctly, everything looks good I simply am not getting any increase in RPM;s when I allow propane to enter through the sync port. Any other thoughts?

 

I give up. Go ahead and blow up your 9K miles motor.

Unbelievable.

 

Brothers and sisters here at the church of XJ bikes we know one thing to be as true as the sun rising in the east. You have to check those valves and make sure they are in spec. If not that bike will never, run the way it should. Now I know you are saying Brother Doc, that can't be my bike pulls like an ox, and runs great. I say to you I know it does, but in the end you are slowly killing that motor. And it will give you every thing it has up until the day a valve finally burns up.

Now I can tell you as a new XJ owner myself, the thought of playing with the guts of the motor was something I didn't want to to. But with some help from other members of our little community, and a great step by step how to I found my self doing it. In fact it only took a few hours on a Saturday to do this.

The maker, Yamaha has told us in the book of XJ and so have others who have copied and improved on the original book, that every 5K miles you have to check the valve clearances. Now brother's and sister's let me tell you these bikes are getting some age on them, and many of us bought our XJ's from some nice guy for a good price and he told us all the work had been done on the bike. I can tell you most likely that nice person lied to you! I know it is hard to believe, and you may have asked someone who knows about motorcycles, and they may have said no you don't need to do this valve checking thing. They do not know about your special machine. If your bike has over 5K on it you need to check them. There is a fine how to to show you how to do this. It is right here http://xjbikes.com/Forums/viewtopic/t=14827.html

Now brother's and sister's let us all count our miles and think if it has been 5 or more thousand miles and if so you know what you have to do! If you choose not to, we are a forgiving lot, but all of our help may not get that bike running just right.

My self I noticed the first start how much better my bike sounded after putting the correct shims and getting my valves in spec. It runs much better and I have not done step two the carb, clean, rebuild and synch. But that is another sermon.

 

Testify Brother Doc! Amen!

 

Check the valve clearances. These XJ's are odd machines and it all starts with the valve clearances. You can synch the carbs to the cows some home but if the vavles aren't right it isn't going to work. OH are you and I see no mention of a YICS tool either, so if you are not blocking off that port your synchs are not gonna work.

We here are not trying to be dicks but we are telling you from experience that the valves is where you start. Hell, it basically is what the shop manuals all say.

 

I understand that I need to get the valve clearances checked ASAP......I have every intention of getting it done tomorrow. I'm going to use the zip-tie method and bang it all out in a couple of hours (I hope) I was simply looking for an explination as to why the propane wasn't having an effect on that cylinder? Is the intake valve clearance so tight that the propane isn't making it's way into the cylinder? How is the manifold getting so hot? It will only reach the same temp as the others if it's firing....correct?

 

If you lived within 100 miles of me, I'd come over and spend the hour and check your valves for you - just so you could see how frigging easy it is.

 

One note you may want to have a set of metric micrometers when I check mine two of them were either installed upside down or the etching had worn off and I had to measure them to find out what size they were

It could very well be that the valves are not opening all the way. It may be firing and running but not enough propane is getting in to the cylinder to really have an effect.

 

More like not closing all the way, but that's not the point.

The point is, you START there. Because until that's done, there are no talking points, no theories. WHO KNOWS what weird vacuum-signal behaviour you'll get with a valve that's not fully closed. An intake valve that's not sealing properly will blow back into the carb on every compression stroke. What's THAT do to your sync? To the effects of propane? I can't tell you, but it won't be right, or necessarily logical.

You don't have a YICS motor (if it's original) so don't fret that. But you won't "bang it out in a couple of hours" if you need 6 or 8 shims in sizes you don't have.

Get your valves in spec, and run a compression test. Then report back. Heck, report back after you check the valves. Due to XJ LAW #2, nobody can say "I told you so."

Not that we would...

 

Just a random guess based on the fact you say there is no increase in RPM on one cylinder, but you say there is spark and compression.

1. sync is so far out that carb is not letting in any air at all. Introducing more fuel (propane) make no difference due to a non combustible mixture. Do you use a YICS tool when syncing?

2. cylinder is flooding or so rich that the cylinder is not firing - adding propane wont make a change.

Worried about checking valve clearances? Don't be, checking them is a simple job - adjusting them is more involved. In the long run it will save you time, and it will get the valve clearance evangelists off your case.

 

Adjusting the valves is more involved? Maybe I did it wrong. I pulled the old ones replaced with with the new ones and checked to insure they were in spec... Buttoned bike back up -fired it up runs much better and sounds much better...

 

The pure, and simple truth.

It is harder to get the carbs properly cleaned, and floats set than to get the valve clearances in spec!!!

With step by step instructions available. What is the malfunction?

Ghost

 

ADJUSTING the valves IS more involved than checking them, you have to do more than what you would have to do to just check them. Thats pretty obvious. Hes not saying its the difference between changing the oil, and rebuilding an engine, hes just saying you have to do a little bit more. I understand the emphasis on checking them but theres no need to be a smart ass about it to someone trying to help the person youre emphasizing this to.

 

RDR, you came in late. OP was trying to talk himself out of the need to check OR adjust. Bike has 9K miles, he doesn't/didn't seem to feel the need.

Yes, there is more involved in pulling shims and swapping them than just reading the clearances with a feeler gauge.

The thing is, as soon as he checks them, he's gonna REALIZE the need for adjustment. We were discussing the prevailing fear of even LOOKING at them.

 

I agree. My next maint. item is VC check, hopefully in the next week, done my me.
And I'm the kinda guy that stopped doing my own car repair when I started to earn enough to pay a mechanic (crappy and untrustworthy as they might sometimes be) because I was sick of going to the library, photocopying the Chilton's page I needed, going back home, ramping a couple of tires on the curb for clearance, sliding on a piece of dirty cardboard under the 14 year old corolla, and trying to figger out what I was looking at under all that caked, burnt oil, then taking the bus to Napa to get the parts and fix it, cross my fingers. Then a couple days later, finally getting to dig that crap from under what was left of fingernails.
It must have been the force of doing it all myself from living paycheck to paycheck that I still wont change my own 4Runner's oil, but I look at my bike everyday and want to remove a cover to see WTF is under there. And fitz, your how-to made it look like my wife could do it and still keep her manicure in tact.

 

On a separate note, would this feeler gauge be worth a hoot?

http://www.amazon.com/25025-26-Blade-Ma ... pd_cp_hi_0

Budget is always an issue for me. I got kids and mortgage.

 

I read the whole thing, like I said, I understand the bludgeoning of the op. Fibre was just throwing an observation, with a little bit of encouragement, and it gets a response like that.

 

Not really. It has the same issues most primarily American gauges have, in that the metrics are "equivalents" so there's a lot of goofy math once you start "stacking" blades.

The job is much easier with a gauge with metric blades, (and goofy American equivalents.)

The most common "Primarily" metric gauge is K-D Tools' #2274; widely available. Some Sears stores even stock them, or find one online. Don't pay more than $7 or $8. Some of the prices I see on the web are insane.

 

So....."Mr. Denial" finally found the time to pull the valve cover off the bike and check the shims. I need to talk to Chacal and order up some replacements. My exhaust vavles all looked within normal limits. My intake valves where a mess. They where all really tight with the exception of one that was within the limits listed in bigfitz writeup. I ran to Harbor Freight and got myself a metric feeler gauge set to make it less confusing trying to convert from standard to metric. I won't be able to order the shims until friday so the bike is out of service until then. Oh and bigfitz, if you go back through the posts above, you'll see that not once did I deny that my valve shim clearances where the problem, I was simply trying to figure out the mechanics behind the issue. I'm a paramedic and I believe that if you don't fully understand the inner workings of something, you shouldn't be messing with it. Would you want a medical professional giving you a medication if they didn't fully understand how it worked and interacted with your body? I'm taking the same apporach with my bike. No need to drag me through the mud in other posts on this site. That being said, thanks for all the help.

 

Brothers and sisters, he has seen the light. The maker will smile on to him, his motor will purr and his carbs will be less stressed! Now, as he walks to the valley of carb cleaning, bench synching, float setting, and final synch and color tuning he can know for sure, that with the valves in spec he work, his long hours of toil will not be in vain!

 

My apologies. It seemed like the point was to figure out all the reasons it wasn't necessary.

What's really frustrating is when new old-bike owners get bad "professional" advice from a supposedly reputable shop. The Yamaha XJ series weren't/aren't the only bikes in the world with shim-adjusted valves; but they ARE slightly different than most other bikes. The maintenance requirements are relatively unique to the marque, and apparently "making stuff up" is more common than actually knowing what the F they're talking about.

I wasn't dragging you thru the mud. And I'm genuinely glad you finally took the advice and saved your low-mileage motor from certain disaster. Good catch.

Be sure to ask questions if you have any issues with the adjustment process; and be sure you adjust your cam chain since you have the igniton cover off anyway.

 

baahahaha

 

Don't do it yourself!!!! H*ll thats what life is all about!!!!! OH the joy of getting in there and fixing your own TOYS, there no satisfaction like it!! Fitz when the day comes and I have to pay someone to fix my toys come shoot me and bury me in the back bush!!!

 

Well, now that I have a toy - of course. That was my point. I let someone else repair the commuters, because the wife isn't about to take the bus to get to work, or to get the kid to daycare, while I have the truck half taken apart for a week.

But while the bike is in pieces - just for sh*ts and giggles sometimes - I need the commuter to get me to the parts store, or liquor store :wink: , in a pinch.