I was warming up the motor to change oil last night, and noticed that the left side was not getting hot. In the 1000 miles I have ridden, I hadn't noticed this issue. What I had noticed was that my fuel mileage is less than most, and my idle is never over 1500 rpm, choke or not. Bike runs great at anything over 4k rpm except for a slight surging at about 5k and part throttle cruise (60mph). Was going to try bigger jets, just to see if that gets better. But I think the dead cylinder at idle has been a problem since I bought it. Not that Dgyver sold me a lemon or anything. Would have bought it even if I knew. Just sitting there idling it sounds fine, and I just have to use a RWD (Right Wrist Damper) opening the throttle when moving from a stop. So I don't think D knew there was an issue either. For all I know the problem may have cropped up while sitting in the garage waiting for the rain to stop - if it's a carb problem..... Hate messing with carbs.
So I have pulled the plugs to see. Here is a picture of the plugs after idling for a few minutes. The left one is wet with fuel.
(http://www.familyjones.org/paul/idle.jpg)
Here is a picture of the plugs after a 10-15 minute ride and shutting the engine off at 4k rpm and coasting into the driveway.
(http://www.familyjones.org/paul/4000.jpg)
So I have checked coil resistances (Ignition coils and signal generator coils) and all are good. Swapped ignition coils and plugs. Looked at the signal generator coils and made the gaps equal.
So as for ignition, the only thing left is the ignitor I think. Anything else as far as ignition?
So what about carbs? What shall I be looking for? Did I mention I hate messing with carbs? But I don't want to spend $150 on an ignitor box if it's just a hunch.
Recycling info posted here, rather than personal knowledge in detail, but if you have spark at all, it's not the ignitor. If the problem does not follow the coil, it's not even the spark.
Easy first thing to check on carbs is float height, using a small clear tube on the drain - centerstand the bike so it's level, fuel level should be equal to the joint between the bowls and the tops of the carbs, +/- 1mm.
Yeah, that sounds easy enough. Do you know what size tube?
1/8 inch works for me. Aquarium airline tubing (don't ever use with fish again, or they will be dead fish) might work in a pinch, I just got 2 feet of 1/8 inch fuel line (chainsaw or hobby shop should have it), which is enough to run all the way into a gas can when doing a flow test or draining the whole bowl.
You may want to check compression in both sides. Synchronizing your carbs can also fix this problem.
My bike wasn't that bad but it would always start on one cylinder and the other would not kick in for a bit. I ran Seafoam through it for maybe 4-5 tanks, pulled the carbs, they were really clean, re-jetted and whomp! that engine roared to life like it never had. I was completely missing an air mixture screw on the left carb, the PO had drilled the plugs and opened up one side and messed with the jets because they were nicked up, but all jets were stock.
I'm basically just noting that re-jetting the carbs can only help the bike overall. I think finding that missing screw and replacing it is what solved the dead/late coming on line cylinder problem for me, not that that is your problem. I had one plug more fouled as well.
Left cyl maybe vacuum line problems. Only at idle ... definetly vacuum related IMHO ... but also carb balance can be an issue.
Cool.
Buddha.
Oh, BTW if it runs at all, its not the ignitor.
Left cyl misbehaving other than vacuum leak can be due to a bad auxillary ground. but of course that wont usually get better past idle.
If it runs well you can also forget about crank trigger issues.
Sorry buddy - that leaves carbs. Or maybe an exhaust leak ... unlikely ... plugs also unlikely, though they do look a bit ashy ...
I dunno why people hate carbs ... OK fine I do know ... they are a freaking geeks paradise. Small changes, huge effect, easy to totally overshoot and create almost the same damn problem you had but entirely from the other side. Yea ... like having a all powerful chauffeur who only speaks russian. :mad:
Cool.
Buddha.
Ok, I had time to check fuel level in the bowls. It is indeed high on the left: at least 2mm, probably more. Right side is 1mm (maybe less) low.
I'm going to check carb balance and check for leaks before taking them apart. But I am curious about how a vacuum leak would cause my problem? Leak in the top of the diaphragm cover maybe? Manually operated petcock by the way.
Quoteall powerful chauffeur who only speaks russian
:laugh: :icon_confused:
Thanks everyone for your input!
The vacuum leak is like in the manifold or somewhere ... at idle the bike only takes in a small amount of fuel, the vacuum is very strong and a tiny air gap can relatively have a huge effect. However as you rev up, so much air and fuel is flying through your carb, that small whiff of air cant do much to keep it from firing.
If the air is getting into the top cap, that is a huge problem, it wont ever let the slide rise, it will not run past 2K ... aka ... not your problem. However remember that little O ring under the top, isn't part of the top, its a part of the vacuum ... lose that and it will affect idle ... and not touch higher revs.
Cool.
Buddha.
Well, I did find a vacuum leak. That changed things a little bit: Choke now has some effect. Also, there is just a little more power off-idle so creeping in traffic and parking lots is a little easier.
When I had the carbs apart, I tweaked the float tang a little bit. Trying to sight the floats at 14mm is just about impossible, but I did my best. Well, went too far with the left one, fuel height was too low. So I made myself a 14mm block so I could do it right. Well, 14mm is Horse Puckey! Fuel level way too low! Wouldn't even run when it got warmed up.
I worked on them some more last night and got the right one set, no problem. But the left was a pain. Too high, too low, too high.... So touchy! Finally got it right and rode it to work this morning. Runs pretty bad. Rode home for lunch and check fuel height: 25mm high! :o OK, now I know there is a problem with the float needle or seat o-ring. Sure enough, the float seat just about fell out. O-ring is flat, and maybe even cracked. Float needles are good.
Well, I've got the carbs out once again, so I decided to check the pilot jets. Left one clogged. I've got it soaking in carb cleaner, but I'm not betting it will come clean. Anyone think an ultrasonic cleaner will get it?
So Buddha, what size are the o-rings for float valve seats and float assembly? How much for a 40 pilot jet if I can't get this one clear?
40 pilots and O rings $20 ... no idea what size they are. Set of 4 X 2 $10, $2 shipping, $8 a pair of pilots ... you want 1 pilot :mad: ... no, they are 2 ...
Cool.
Buddha.
Much better now! :)
Got the pilot jet cleared, and replaced o-rings. Runs much better. Both cylinders running at idle. Smooth power from about 2.5k all the way up. No 5k-6k surging at part throttle either. :dunno_white: I had hanging idle at times, too, and it seems to be gone.
Now the only thing that might be wrong is that the throttle is like a switch when going from closed to open and open to closed. If I'm idling in gear with clutch engaged and want to accelerate just a little bit I look like an idiot! :laugh: Got to watch it braking hard and downshifting too. Twice today the rear tire chirped when I engaged the clutch in 2nd gear before turning left. Hmmmmm..... Slipper clutch???
Thanks every one for your help!
Its like that at all rpm ... sorry man, that's a first ... GS500 chirping its tire when you open throttle ...
Maybe dgyver bored and stroked and put high compression cams and pistons in it, and you're just not man enough to ride it ... :laugh:
Maybe you should ride a bicycle instead ... :laugh:
Anyway, check your chain and heck check if you splashed oit on your tire, else just ride the thing, its got power, and I dont see how its a bad thing. Just learn to handle it. Or put a better rear tire and what not to match with that front end.
Cool.
Buddha.
Yeah, I'm a wuss. Can't handle it :icon_lol:
Guess I wasn't clear: tire chirp on DECEL. Throttle closed, moving ~40 mph, engage 2nd gear with front end loaded a bit. No problem with the rear tire, it matches the front Metzler M1
Oh, I'm not complaining either. I just mean it is so much different now that the jets are clean and fuel level is right. Gotta learn to handle it!
Niiiice ... you drop it in 2nd at 40 mph ...
why, you didn't put it in 1st at 80 ???
I think you're trying to break the dgyver's bike ... :2guns:
Cool.
Buddha.