Running on one cylinder... Honest opinions

So I got a "Bobber" late last month from a guy that said he bought it and didnt ride it much. He said that he ran a compression test and all cylinders were within spec gave me some bullshit numbers but I dont remember anymore. He said the carbs have been cleaned and synced recently as well. Well I just got it back from the shop today after putting a new voltage reg, tci, stator, and a whole new minimum wiring harness. Well it still doesnt run it will run in neutral but will only let me ride it in gear for about a mile and then it dies and wont start or run in gear again for quite a while. It WILL start and run forever in neutral. The shop also told me the bike is only running on one cylinder the rest are all so full of oil it fouls the plugs and its spitting oil from my exhaust. I belive this is most likely because it has pods and straight headers and had never been re jetted. I just bought a used set of carbs off ebay for $50 bucks but its pointless to rebuild re jet and sync with a bad motor. SO... my question is what should I do in this situation??? part it out, sell it whole, or take the time and spend the money to fix it? I live in a apartment with minimal space for anything. All I need is some honest opinions???

 

Really, you should start with a compression test - I'm sure there is a "Sticky" somewhere. At least this should help you decide if it is worth spending more money.

I don't think I would take a bike back to that shop!

The fuel problem could be related to a vacuum being formed in the gas tank - try taking the cap off and listening for a hiss.

My old XJ600 had 48000 miles on it so these engines are built to last and will tolerate quite a bit of neglect - unfortunately, it sounds like you have one in need of TLC!

 

I will give it a shot and I dont know how to do a compression test but I will look into it.

 

+1 on the compression check. That is a first step to decide if its worth fixing.
I am not an expert on these bikes (yet), but I would suggest you take a look at the side stand switch. These bikes won't run in gear with the side stand down. There is a switch that detects the side stand position and if its loose or making intermittent contact, it might explain the shutting down mysteriously while riding.

 

The results of Compression Testing will let you know what condition your condition is in.
You can perform the Test yourself.
You need a Compression Test gauge.
(Some AutoZone Stores let you use theirs if you leave a License or Deposit)

You need a Fully Charged Battery
Pull all the Plugs
Un-Plug the "Black Box"
The Throttles will need to be Wide Open.

Google:
Compression Test and learn what the results will indicate.

 

KumanK a compression test is very easy to do - trust me on this one.

Go to the auto parts store and get a compression tester $20 (they also rent them). The one I picked up had 12mm, 14mm, & 16mm adapters. Almost certain on your bike it's 14mm. Unplug the TCI harness, pull your plugs, screw in the compression adapter, open the throttle all the way and crank it over about 4 or 5 times or until the needle doesn't rise anymore, record your numbers for each cylinder.

I know you are getting frustrated and tired of this, but don't let it get you down. Either it can be fixed (most likely) or you can recoup your money by patiently selling what you can.

Did you ever put any sort of muffler or pipe on your headers? Unfortunately I believe you are suffering from what happens when someone sets out to modify these bikes (not you) and doesn't do it the right way. If you change intake, exhaust, wiring, suspension, etc. it MUST be done correctly and there isn't much wiggle room there.

That bike shop is a joke. Don't go back to them and give them any more of your money. Your bike CAN NOT run on 1 cylinder-it just won't do it. Try disconnecting 3 of your plug wires when you've got it running and see what happens. They are lying to you-and they are clueless.

Modifying a bike like yours requires compensating for EVERY change that's been made. You have more air entering your carbs, much less exhaust backpressure and who knows what else is different that is throwing it all haywire.

Your best route now is determine the TRUE condition of your motor, then if you decide to fix it - one by one compensate for the changes. Like for example you need some exhaust backpressure because that's the way these engines were designed and you can't just modify the design away. Hope this helps you.

 

ony be careful about the loaner compression gauges I got 3 babck to back loaners and they were all crap. if you get crazy low numbers its most likley a bad whacked out gauge. I got one from harbour frieght for 19.00.
and yeah it would not run on one cylinder they are idiots.
Also yes your engine is 14mm in the plug hole, pug number BP7ES the "B" denotes 14mm
Far as the pods-- good luck with that if it were mine Id find an airbox and mod a cover out of diamond pate to fit the bobber look-but thats just me
get the gas out of the oil fast though like yesterday

 

I had my engine shut down on my 82 650 Maxim, turned out to be the kickstand safety switch. If you have oil coming from your mufflers you may have stuck or broken oil control rings. This may not be reflected in a comp test, because oil control rings do little for compression.

 

wow lots of great info guys I really appreciate it, I will go down and buy a compression tester and check that out hopefully it will turn out better than what I expected and be a simple fix without having to pull the motor and all that fun stuff. The PO obviously neglected the bike maintenance wise, and even more obviously he didnt take the time to research proper mods and spend anytime on this site. Thanks again for the help I will let you guys know what I come up with.

 

Even if you need a valve job or even to do rings/pistons, etc; you don't need to pull the motor.

It's NOT going to be a "simple" fix; the more important question is "how much will it COST and is it worth it?"

The first step to answering that is a compression test.

 

So I did a compression test and cylinder 1, 2, and 3 are pushing 150 and cylinder 4 is pushing 145. But 2, 3, and 4 plugs are coverd in oil. Cylinder 1 is white with almost a orangeish brown tint.

 

So cylinder 1 is running lean, and the others are running way too rich. Since 1 is clearly working, that would mean that 5 is firing somehow, though not well, since it is so oily. 2 and 4 may or may not be firing. Get an extra new spark plug and do a test.....pull each spark plug wire, one at a time, hook it to the extra plug, lean the plug against the engine where there is bare metal to touch the bottom outside of the plug. Hit the start button and see if there's spark at each plugwire.

1 and 3, 2 and 4. If one of these combos doesn't fire, that's probably a bad coil. Easy to replace.

If all 4 have spark, good. Pull the carb rack and do a rebuild. NOT hard to do. Just take your time and do a lot of reading HERE and ask questions HERE. WE are a whole lot smarter and knowledgeable about these bikes than your "shop" is.

Make sure to drain the crankcase oil and put in fresh, along with a new filter. I bet your oil smells like gas down in there too.

The stalling after 1 mi seems to fit that....it would be an "overheating due to thinned oil" condition.

If if were the sidestand switch you wouldn't be able to consistently get that far. It would me more sporatic, or immediate.

It IS possible that there are other relays interfering.... check back through recent threads--there was one where someone said to pull the "gray/red" (?) wire off of the tci and that would bypass all the safety circuits. Just a thought, I've never tried that, but like I said....it was a recent post here on the forums.

Good luck, DON"T get discouraged. We've had worse cases than your's. Your's is easy (relatively). Just hang in there. It's gonna all be worth it when you're riding down the road and able to say "I built this MYSELF".


Dave F

 

Those compression numbers are good news! Just an FYI, I know harbor freight isnt considered the best but they do sell compression checkers for around 15.

 

I'd like to start off with this reply motivated the hell out of me... I will go buy a new plug tomorrow and do that test.

The PO had straight headers and pods so its weird that they would be running rich? Someone said that the oil rings may be blown and that wouldnt reflect much on the compression of each cylinder so thats what I am thinking at this point.

I am in the process of cleaning, rebuilding, and re jetting a spare set of carbs now so that will eliminate that problem once its all done and mounted.

Im going to look into the overheating issue more, the "shop" that had it said they changed my oil as well, maybe and just maybe they were dumb enough to only partially fill the crank case and the lack of oil is causing an overheating issue, which would be a extremely easy fix.

It cant be a sidestand switch because it is a limited wiring harness with only the essentials, so the sidestand and neutral switch arent wired in, the prong on the TCI is not connected to anything so thats ruled out. And the coils are the only part in the elcetrical system that hasnt been replaced.

I was really thinking it was the carbs or some kind of fuel problem but hopefully it is an overheating issue. Is there a certain temp that the bike will just shut off? It only dies when I pull the clutch in and coast from what I have experienced (havent pushed it hard enough to tell).

And I cant wait for the day that I can druise with no worries and have the pride of knowing my work has really paid off.

I tell my dad all the time who rides a Harley Dyna series that my bike runs on blood, sweat, and tears...

 

OK, but good compression numbers don't mean valves that are anywhere close to spec, just that they're not damaged. THAT'S the next step before carburetor muckage occurs.

I highly doubt your "oil rings are blown" if anything is "blown" it's more likely you need some valve stem seals. If the plugs are truly oily that's a more common cause than ring issues. AND easier to fix by a long shot.

 

Rich would be fuel.

I beleive you mentioned oil. Two very dif probs.

R your plugs fouled with fuel or oil?

 

soot and fuel can appear to be oil, check it out. Use your finger tool

 

it seemed like oil but I will check it out again today... and fitz what are the steps to checking if the valves are the problem?

 

I doubt it's oil if the compression is that good. Of course, I'M not there to look at the bike in person.

Do a forum search on how to check valve clearances. It is NOT difficult, just take your time, work carefully, and record all your numbers so you can do the correct math.

I HIGHLY HIGHLY (I'll add one more HIGHLY) recommend that you get the XJCD. That will give you all the info you need for everything.

Now here's a question....I haven't seen what your odometer reading is. Have you posted the miles? If so I missed it. If you're a hig-mileage bike, then you definitely want to check the clearances. If its a low mileage bike, it's not quite as critical......yet.

Keep reporting everything you do, and we'll get you through it!

Dave Fox

 

I have no idea what the mileage is, when I bought the bike it had no odometer, so in that case I must treat it like it is a high mileage bike either way!

I want to purchase the CD what does it cost and where do I get it?


anyone know exactly how much oil the bike needs...?

 

Don't want to jump in Dave's way here cause he's got you covered. Good man so listen to him and he'll guide you home.
Takes about 2.7 quarts
What I do is this: from dry with new oil filter fill with 2.5 quarts of MOTORCYCLE oil, I use castrol 20/50 4T
run the bike a minute and shut it down
with the bike on the CENTER STAND check the oil window and SOWLY fill little at a time--- LITTLE AT A TIME--unti there is only a little bubble left at the top
more on why the litte bubble later.
for the CD go to the general lounge and there is a "STICKY" thread about it

 

I bought my XJ650 book On-line. Bought my XJ900 also online as CD. Takes 2.5 liters oi lwithout filter & takes 2.8 liter oil with filter change. Also shows High & low on the side cover (right side).

 

On your clutch cover where you put the oil in is a stamped quantity. On my XJ550 it says 2200 cm3 (as in centimeter cubed) which is the same as 2.2L or 2.32 Quarts. Your 750 will take more.

You have a sight glass on that side of your oil reservoir. It will likely need to be cleaned-I used some solvent and q-tips. When you fill it put in slightly less than the printed amount, run the bike then wait 3 minutes, add until there is just a small bubble at the top of that glass.

Fuel on your plugs mixed with soot will look just like oil. You can tell the difference by the viscosity. And fuel mixed with soot coming out of your pipes could be mistaken for oil by the "clueless mechanics."

One other thing since you don't know the mileage, why not add other info to your signature. Like the current modifications on the bike. If you can I would also take some pics of the things in question-your plugs, your headers, your pods etc-Just so we know what you have.

 

I put the oil in and it doesnt want to start for some reason... its probably my plugs they are so fouled I doubt the have any life in them, but I am getting some new ones tomorrow. The black is in fact fuel. SO in that case what could be the cause? I will update my signature to fill you guys in....

 

carbs carbs carbs, are they CLEAN? your rich
hows your valve clearences? numbers? gotta start there-- cant tune without valves being in spec and clean
also you should do like MercuryMan said and add your bike and all mods to your signature. can we see the mods? Start a gallery

 

sorry didnt see that, please excuse me I see the mods now. Ill put the crayons down and stop eating them

 

Yes my next step will be buying the XJCD and checking my valve clearances...
my carbs are pretty dirty and probably worthless but I am rebuilding and jetting a spare set I picked up on ebay. What all will I need to check the valve clearences? Feeler gauge, valve cover gasket...? anything else?

 

a shim tool. motion pro makes one and you can get those from chacal. less than 20.00.
if you are rich then it will probably tune out once youre clean and in spec.
Big fitz has a GREAT how to on the valve clearence

 

will I need new valve seals...? also is there anything I should replace while I have it torn apart?

 

No not for clearences, you WILL need shims but you cant get them untill after you see what you have. PM me for a phone number

 

I don't expect you to need valve seals unless you're blowing a lot of blue smoke. Since you didn't mention that, I doubt you need it.

Get the right airbox and get rid of the pods
Get the right exhaust and mufflers

You CAN tune the bike wiithout doing shims. You will get it running a whole lot better. KEEP IN MIND....if you DO go that route, you will need to re-tune when you finally DO do the shims. Since you have stuff apart, now is the time to do it. I think you already know that.

Quick question.....did you sniff the crankcase through the oil filler hole yet? Smell like just oil? Good. Smell like gas? Gotta drain it and get that gas out so it doesn't run too hot. Running too hot with too much gas in the crankcase = KABOOOOOOMM!! and I DON'T think you want that.

Case in point.......this past summer I was contacted by a fellow who had trouble with his bike: Couldn't go more than 2mi and the bike would stall out. He'd have to trailer the bike home or walk it to somewhere til it was cold. Then he could ride it most of the way home. I went to help him. The smell in the crankcase was as strong as the gas tank. I told him he had gas in the crank case, etc......... He said it couldn't be there. Yeah, ok. I took 2.25 gal of liquid out of the crankcase. It was so full it was backed right up into the airbox via the breather tube and the filter was soaked. He said he had a fellow already clean the carbs and didn't need to be done. Ok, fine, I left them alone. I put fresh oil and filter in for him.

Long story finally shortened.....that was June, he rode it the rest of the summer and into Oct. without ANY incident.

Without seeing your bike, yours sounds similar, except you do have jetting issues due to the pods, and cleaning issues, and adjusting the valve shim clearances will alleviate many other potential issues.

Again, keep us posted!

Dave Fox

 

Just to check your valves you only need a feeler gauge, the allen wrench to remove the valve cover, screwdriver (or impact driver) to remove the ignition cover (left front) and a 19mm wrench to turn the crankshaft.

You might need a new VC gasket, new VC bolt donuts, & new ignition cover gasket. When I did mine the gaskets were all fairly new and intact, same with my donuts. If you must ride then I would have these on hand just in case. I am replacing mine this winter so I know they will be good. Also I changed my stripped screws on the ignition cover for matching allen bolts (same mm as valve cover-available at Lowe's for $1.89)

There is a write-up on here from Bigfitz that walks you right through the process, and it is really easy and very important to engine health.

+1 to Hogfiddles advice about your intake and exhaust. At the very least you need something besides just headers. And if you keep the pods your tuning window is much smaller, and so you must tinker and be good at it.

Since that is fuel on your plugs it is possible that the po did re-jet your carbs and either got it wrong or there are other carb issues. It's always a process of elimination but you'll get there, and once there you'll practically be a certified motorcycle mechanic, at least on these related issues.

 

Ok so I need to...

1. Drain my oil and refill plus a new filter.

2. Check my valve clearance. Then shim if necessary.

3. Check my coils with a spare plug.

4. Finish rebuilding and rejetting my carbs.

5. Hope and pray that this thing purrs...

I do plan on fabricating some pipes in the near future and also making a PVC manifold with two UNI filters and just rejetting to them

 

Wow, you're starting to sound like an xj-mechanic now.

Dave F

 

Your on the right tract.

These guy's know the're stuff and wont lead you wrong.

One more thing that can't be stated enough.......

NO Short Cuts

 

to quote from comment on page 1, they're all, unfortunately, "in need of TLC!"

 

Yea that seems to be about right from what I have read NigeW...

Yea especially with carbs, I know that going in... I am a Heavy Equipment mechanic for the Marine Corps.

 

If you go through the bike and put everything right, the only ongoing "TLC" required is normal maintenance. Valve clearances need to be checked every 5000 miles, the oil changed every 2500 or so, and other basic things like spark plugs and air filters attended to regularly. The bike will only require constant attention if you don't go through and reverse the effects of the years of neglected maintenance.

Carbs don't need constant attention once they've been properly dealt with. Nor will the rest of the bike if you do it right.

 

Thats where I am now, I am rebuilding and re jetting the carbs. Checking my valve clearences and swapping out the plugs. Changing my rear shoes, and then riding.

 

Ok so I just ordered my new jets from Chacal. #126 main and #42 Pilot. almost done with the rebuild. This may be a stupid question but again go easy on me Im a rookie at this whole thing. What kind of syncing will be necessary? will a bench sync do (because that looked pretty simple from the write-up in the info overload) or will more extensive syncing be required?

 

Bench synch puts you in the ballpark, but you will be setting all four up exactly the same-each cylinder has unique properties (not drastically different but different just the same ), so a running synch is required to "catch the ball" to use a baseball metaphor. You will then be matching each cylinder to the other three and creating equal power strokes-so you eliminate those unique properties from the equation.

If you've ever heard an engine go from only benched to running synched you will understand the difference. One sounds like a room of people arguing and the other like Elvis singing "Hunk of Burning Love", ok so not really but you get my point. It's a big difference in the smoothness and power response.

So yes you will want to take it further, but first things first-get your carbs done, floats dry set, wet set, mixture right, valves right, then running synch.

 

This all using the clear tube method right?

 

You can just do the trial and error wet set (clear tube method) with the carbs level in both planes with gas on one carb. Once it's right you can set the other 3 using it's measurement to the carb body. Or you can trial and error set each carb using the clear tube method-it just takes a little longer for the drain and fill and set cycles.

There are several write-ups that take you through this process here and elsewhere and it's pretty much the same process for just about any carb. If you can find one that matches your carbs use that. Just be aware that a small adjustment to the "tang" can change the level a lot, and take enough time to orient yourself about which way you need to go with the level and which tweak will get you there. It will be less frustrating that way. Also since your working with gas, be careful.

 

well that sounds like its gonna be interesting, looks like I have some more reading to do.

 

Here's some reading for you to start with. The first link you have to work through and find the useful info, the other is all useful (or almost), and I believe those are the same carbs you should have.

http://xjbikes.com/Forums/viewtopic/p=215078.html

http://xjbikes.com/Forums/viewtopic/t=9 ... eight.html

I imagine you're feeling like I was before I did this the first time. It seems like it's going to be hard. Well it was a little tricky getting my carbs level in both planes (side to side & front to back), but I finally used some scrap wood and screwed together a quick little jig to hold them more like a manger for the the bottoms. After that it wasn't hard just time consuming. I overadjusted the first time I bent the tang but I took many pictures using a digicam so I could relate what I was doing to what happened and only missed it bad the first time. So don't worry you can handle it.

 

The "clear tube method" refers to setting and verifying the float levels. Even if you use the "matching" technique, they all need to be individually verified using fuel and the clear tube method.

For the running vacuum sync, you will need to block your YICS using either a correct YICS "tool" or you can use an oily rag wound into a rope. I emphasize "correct" because a lot of the DIY plans on the 'web and tools on eBay do NOT properly seal the YICS system off the way it needs to be. The oily rag works better than an incorrectly configured tool.

Then you will need some form of manometer (comparative vacuum gauge) to perform the sync. This can be a "two-bottle" system using baby bottles, tubing and ATV, or a 6' long (yes, feet) hunk of clear tubing zip-tied to a yardstick. Or you can use one vacuum gauge; a pair of vacuum gauges; FOUR vacuum gauges; or a tube-type 4-stick purpose manufactured manometer, like a Morgan CarbTune. You need some way of "comparing" the vacuum signal from the carbs; it can be accomplished many different ways. Unfortunately, the more money you spend on your manometer solution, the quicker and easier the process becomes.

 

Thanks for the info Fitz, I will most likely use the oily rag and the two baby bottle method because I most likely have all the materials laying around. Other than six feet of clear tubing that is. Do you know of a write up or diagram on how to set this up and utilize it?

 

If you own a Vacuum Gauge; you can Vac-Sync the Rack and get them all at the same drag without much fuss.

You need:
Gauge
Hose
Aquarium Air Valves 4-Valve Gang
White China Marker
(4) Vacuum Restricting Hose Unions*

(Carb Cleaner Spray Tubes Epoxied in Hose Unions*

Cut (4) - 2" Sections of Hose to slip on the Manifolds
Insert a RESTRICTING Union in each 2" Section
Attach Hoses to each RESTRICTING Union and run to Aquarium Valves
Run Hose from Valve to Gauge.
(An additional Restricting Union inserted between the Valves and Gauge may be necessary,)

Run cooling fans, ventilation precautions.
Lube the Sync screws.
Close the valves and war her up a bit.
Open the 3-Valve ... Read the Gauge.
The Needle fluctuates with the Intake Cycle.
Mark the Face of the Gauge using the China Marker at the ZENITH of Measured Vacuum.
MAINTAIN CONSTANT RPMS during SYNC.
Shut - 3
Open - 4 <--> Match 4 -to- 3
Close.
Read - 2 (Mark) Close.
Read - 1 <--> Match 1 -to-2. Close all.
Read - 2 <--> Match 2 -t0-3 (1's married to 2 and adjusts w/ 2)

Double check.
Tweak as needed.

 

Thanks alot Rick this will help out alot!

 

Harsh Solvents may damage the "Window" of your Vacuum Gauge if you use it to remove the China Marker.

Tissue dampened with WD-40 will do the trick.
Prepping the Gauge with Scotch Tape works.

Making "Arrows" out of the Sticky-strip of Post-it Notes works.