Quote from: Phil B on May 12, 2012, 06:03:05 PM

Quote from: adidasguy on May 11, 2012, 06:50:17 PM
Is there anything the West Seattle GS500 Club can not do? In 6 hours we built a new engine from parts of 4 different engines. It works!

Junior is ALIVE!

Muahahah.. frankenGS !

Nice!!


.. wish there was a gs club like that in the LA area.. sniff...

thats what i called my first gs ( of 4) called it frankenbike

Quote from: yamahonkawazuki on May 14, 2012, 12:58:47 AM
dig thru trans. problem lies there i believe, check the shifter dogs. ( shifter forks among other things, something in there is amiss

You missed a few postings. It is the counter balance bearing.
Engine ran fine. Tran shifted through all gears just fine.
This used to be a counter balance bearing:

Hey Addidasguy... where did you get that Suzuki "S" emblem for the contact cover?  Looks great.

from chuck81.

I don't know if he has any more. Contact him and see his for sale threads on them.

I love it! He has the matching one for the left side. 

#5206

Well, he's been doing fine.
There is an issue of run away throttle when hot. Slipping the clutch would being it back down.
So I decided it is finally time to fix it. He didn't do it before the engine swap. The carbs were not touched in the engine swap.

When hot, a blip of the throttle and it goes up to 5k RPM. Slip the clutch (or block the air box when on center stand -- on center stand so slipping clutch would do nothing because rear wheel not on the ground) and it comes back down.

I knew the manifold o-rings were hard as a rock. I replaced them last night.
That didn't seem to help much - just a little.

I can spray starter fluid all over as well as WD-40 and they do nothing at all. So, no air leaks anywhere.
I did notice the left side was running really rich. Plug had lots of carbon on it. Right side looked good. To rule out petcock vacuum line as a source of excess fuel or air leak, I pinched it off (Using  a Motion Pro test tank, bypassing the petcock.). No change.

One thing I did notice when looking into the air box (filter removed) was the right slide bounced up & down. The left slide was steady. In a run-away situation, both slides were down - not stuck up.

Seals on the caps looked ON. Removed caps and diaphragms looked OK as well.

Sort of at a loss. Removed carbs and they looked OK. Mixture screws were out like 4-1/2 turns. That seems excessive.

I have to add again that I did not have the problem until the engines were swapped after the bearing went out.

What I plan to try:
1. Mixture screws back to 3-1/2 turns
2. Swap slides & diaphragms to see if one is bad. If issues swap between sides, then there is the problem.
3. Maybe put in new jets since I have spares, it can't hurt.
4. Maybe put a rebuild kit in both sides - again that can't hurt.

I suppose a valve adjustment would be in order. The engine was built up and valves checked when assembled. They may have seated in and now need adjustment.

When right plug pulled, engine dies. When left plug pulled, engine slows down a little.

Any other ideas for a run-away throttle? It is not a "hanging" - it really does run away some times.

I have a spare set of carbs that were rebuilt months ago. They don't work so I have to re-check them. They were never used as carbs were not Trey's problem when he was running on one cylinder. But I should get this spare set working anyway.

For fun I could put on newer 3-jet carbs and see what happens. I do have some of those on the shelf. Its not like I am without a running bike.

Any thoughts on a run-away throttle when there are no longer any air leaks (manifold o-rings replaced) and only happens when bike is hot?

Sounds like an intermittent vacuum leak on the left side.  Try capping off the vacuum tube port completely with one of those caps from the carb sync ports.  If nothing else, at least it could rule it out. 

I don't think your slides or diaphragms should be a problem since you didn't take your carbs apart when you swapped, but I suppose it doesn't hurt to swap them.  The mixture screws do seem to be too far out.  That could be due to the need for more fuel at idle due to the vacuum leak.

#5207

It only happens when hot then happens a lot. Replacing the manifold o-rings helped (they were hard and flat).  Spraying crap in that area did kill the engine before replacing them. I would guess dying from being too rich with junk leaking in.

It might be good to re-torque the head bolts when checking the valves. It is a newly assembled engine. Something is opening up when hot.

I have lots of options:
1. Carefully check and replace some parts in existing carbs
2. Figure out why the spare set of rebuilt carbs do not work
3. Take carbs out of Trey and fix Trey later. His carbs are great.
4. Try another spare set of carbs
5. Try 04+ carbs as I have some taken off of running bikes.
6. Possible a defective carb sync cap - they're old, originals so I'll replace them and do a carb sync.

The carbs have been sprayed down like crazy with no effect (after o-rings on manifolds replaced) I now have a very well WD40 lubricated outside of the engine and carbs.

sounds a lot like the enrichment system has a problem? go over the sliders and stuff and see if they are leaking or sticking or whatever? just a guess

#5209

Tonight we swapped carbs. No change.
Carb boots with new o-rings no change.
Spraying the crap out of everything everywhere - no change.
Did valve adjustment. Left side was tight on exhaust and loose on intake. Right side OK.

So we've ruled out carbs, vacuum leaks, plugs, valve shims.

Only other discovery was compression: 100psi on left. 115 psi on right.  Both are low.

Not sure what to do. I think I may adjust things to run as best as possible - which he does run well. Then wait until winter to redo piston rings and check the valves in the head. Possible there is a bad valve or something else. It is the engine we built from 4 engines in 6 hours. So maybe the jugs need honing and the pistons could use new rings.

Unless there are some good theories of what's causing the run away throttle, I'll live with it until winter.

Remember that we've ruled out carbs (replaced them) and any vacuum leaks.

Quote from: adidasguy on May 14, 2012, 10:11:31 AM

Quote from: yamahonkawazuki on May 14, 2012, 12:58:47 AM
dig thru trans. problem lies there i believe, check the shifter dogs. ( shifter forks among other things, something in there is amiss

oye spun bearing for  the lose Eh?, we blew up a backpack blower @ pawnshop. for giggles. it was ugly. and no one would buy it, hell no one would take it, so i got it to ventilate the crankcase , fire = good ratings as a youtuber once said

You missed a few postings. It is the counter balance bearing.
Engine ran fine. Tran shifted through all gears just fine.
This used to be a counter balance bearing:

#5212

Not sure why you quoted that old posting with no new comments.

Anyway, that was history. New motor was built.

Now back to the problem...

1. Not carbs (swapped a spare set)
2. Not vacuum leak (sprayed the sheit out of everything)
3. Intake manifold o-rings were replaced as those were bad (flat and hard)
4. Not gas
5. Not spark plugs
6. Carb slides are not sticking up - they drop down freely
7. Valve shims are OK and were re-checked.
8. Throttle cable has ample play and the carbs close down -- that is evereything springs back closed when throttle released.

Engine can do run away throttle when hot. ONLY when hot.
Could something heat up then open up when hot?
Could something get sticky when hot? However, slipping the clutch drops the RPM's down then they stay until the throttle twisted.

Other notes: did not do it with old engine using same carbs and everything else. I am thinking it is somehow related to something in the engine - but no idea what.

Only thing not absolutely correct is low compression: 100 on the left and 115 on the right.

What would close down or something when the clutch is slipped to drag the engine back down to 1300 rpm and then stay there?

There aren't a lot of parts to these GS500's. So I'm really trying to understand what can cause this before ripping into anything again.

Quote from: adidasguy on August 01, 2012, 02:42:40 PM
#5207

It only happens when hot then happens a lot. Replacing the manifold o-rings helped (they were hard and flat).  Spraying crap in that area did kill the engine before replacing them. I would guess dying from being too rich with junk leaking in.

It might be good to re-torque the head bolts when checking the valves. It is a newly assembled engine. Something is opening up when hot.

I have lots of options:
1. Carefully check and replace some parts in existing carbs
2. Figure out why the spare set of rebuilt carbs do not work
3. Take carbs out of Trey and fix Trey later. His carbs are great.
4. Try another spare set of carbs
5. Try 04+ carbs as I have some taken off of running bikes.
6. Possible a defective carb sync cap - they're old, originals so I'll replace them and do a carb sync.

The carbs have been sprayed down like crazy with no effect (after o-rings on manifolds replaced) I now have a very well WD40 lubricated outside of the engine and carbs.

ok when hot check voltage output from electronics ( ignition etc)  also i know youve doen this my friend, btu do it again,, take cares completely apart. all plastics and rubbers out. and dunk them ovrenight in carb cleaner. checkmix adjustment, as well as idle speed. i wish i were there, id solve it, in one hour and 3 beers.

could carb bodies be cracked somehow?

#5215

Nope. 2 sets of carbs. Same symptoms. One set was original set from Junior. Problem happened with a change of motor.

Could there be valve problems with the change in head?
Could a head have valve problems which show up when the engine is hot?
Could a valve or the head have a crack ( albeit small) that opens up when hot?

This is a head scratcher. Some things come to mind, but at this point I an grabbing at straws here:

An easy check would be exhaust bolts and/or exhaust manifold gaskets loose or not in order?

The most obvious thing here is compression is low. That tells me that there are worn out rings or valve problems. What about the head gasket?  Could the head be warped against the bottom half?  I think that you replaced the head. I'd start there. Do you still have your scope camera?  That may help.

#5231

Since carbs and exhaust were the same (and all tightened down) it seems there could be the issue with the head or pistons due to the low compression. It was a used head and used jugs (with matching pistons from same engine).

I will re-tighten the head bolts. They may have worked lose or just the crush washers crushed down so it gets lose when hot.

I can do a compression test when cold and when hot. If readings are the same, then it would seem nothing in the head is opening up or closing down when it gets hot.

I will do a valve adjustment again just to be sure.

I will check the plugs and lean him down. Left was very rich for some reason.

I will replace the petcock as there were a couple drops of gas in the vacuum line - just in case. HOWEVER I did clamp off the vacuum line and run with a MotionPro shop tank so that would rule out gas getting into the left carb through the petcock vacuum line (which would account for it being rich - if that were the cause).

Everything has been sprayed to hell and back - no vacuum leaks anywhere.

I might put Juniors original head back on after hosing it down with cleaner to get any metal dust off of it from the initial bearing disaster.

What is odd is the symptoms:

COLD: runs OK
WARM to very warm: Still OK
HOT: Throttle hangs. Slipping clutch beings it back down.

Remember that 2 sets of carbs have exactly the same issues so that would tend to rule out the carbs.

I was thinking more about this.  Could it be the head gasket?  That would cause low compression and possibly vacuum leak leading to a hanging idle.  You could try spraying WD-40 around the head gasket area when it hangs.

I've never heard of this happening before.  I'm just speculating from a logical process of elimination.

EDIT: Looks like jester had also though head gasket as a possibility.

That's where I'm heading.
I have totally eliminated the carb issue.
as for low compression, it does match on both cylinders. A little over 120 each. A leak on one side would affect one side. however, the slow leak probably would not impact the sudden pumping of air when doing a compression test. It would affect a leak down test.

A leak on one side would make one side go lean. I do hear that hiss or pfffffttt from the right side. It sounds like under the valve cover, at the  right intake.

I'm willing to give a spray around the head gasket area before removing the head. Possible there is a degrading spot. It was fine, and slowly gets worse with time.

If you end up taking the head off, I would remove the valves from the questionable side.
Then check them for even the slightest bend, and also check the valve guides.

You've probably taken valves out before, but just incase... its so easy, even without a stupid compression tool.

Get a long socket that fits nicely around the top of the valve. (bucket off)
Then you can either simply push down on it until the pins come off, or if its giving trouble that way, smack the top of the socket with a hammer. (but not enough to break anything and Be Careful!)

I've done it both ways without a single problem.

To go back in.
Put the parts back in.
Line up the pins in the middle and push down (by hand) with the same socket until they go back into place.
Need to place something below the valve to keep it from dropping out btw.

One of the members here has a video on youtube, thats how I leanred how to do it that way.

But im sure you know how or have the proper valve compression tool.
So im just wasting text, i dont care 

Haven't removed valves yet. I don't think valves are the issue. Something weird about timing like being 1/2 a link off.