GStwin.com GS500 Message Forum

As for Trey, I think he's dead.

History: He had bad PO. Recently, put in LeFe battery and MosFet regulator. That went OK. Did a SeaFoam to all bikes. Junior is super! Trey was OK for a while. Then checked oil. A little low. added some. Now is at the "F" on the stick, so maybe a half a cup too much. Not too much that I would  think it would cause any problems.

For a while, he has been getting harder to start the longer he sits. Seem as if the carbs were either flooding (due to bad carbs) or draining (due to a slow fuel leak).

There was fuel showing around the intake boots to the carbs, so there was excess fuel from somewhere. Looking in the airbox, I saw fuel all over the carb air intake.

Hadn't been run for a week so he needed some attention. No power. None at all. He would rev just fine in neutral. When running, even at 6k RPM in 2nd gear hard to go 20 mph.

Probably Trey was ready to go bad and some say SeaFoaming simply sped up his demise (not a complaint, it just sped up the clock).

Today we adjusted his carbs. They looked pretty clean and the needles were good, but replaced them and the seats, anyway. Then everything was wet with fuel. Intake and output of the carbs. Put on the extra set of carbs (from running bike and we didn't do anything to them just as a control in case we screwed up the other carbs) and still runs like before. Backfiring through air box, clicking of valves or something. So maybe his valves suddenly went bad? No power. Then once in a while there is power for a few seconds (running around the block as a test). Probably intake valves are sticky. What else would cause backfiring through carbs & airbox? If intake valve stuck open and the plug fires, wouldn't that be the only way you would get a backfire through the airbox? Then the metallic ping, could that be the valve closing suddenly when the plug fires?

Thinking of sending one set of carbs to PJ Motorsports in Oregon to be professionally adjusted - that would eliminate that as a variable. They charge $100+parts and take about a week. I really doubt the carbs are the main problem. I'm thinking it is the valves or something worse.

So could the valves suddenly attention and the top end need work?

I'm thinking that it does. The occasional tink of metal (valves snapping shut?) and the backfiring through the air box would indicate the intake valves are not closing before the plug fires. That's my guess.

While I'm an expert on electricity, I do admit I am new at carbs and valves (in my family, we did not work on cars so I do not have that background).

Should I (1)do another heavy SeaFoam dose or (2)take the top end off and check things or (3)part out Trey......and spend my time on the new bike build?

Is Trey dead? Is there hope?

While I am no carb expert either I do understand engines. As you already know, you will need air for intake, fuel, combustion & spark for power. If I read your thread correctly it sound like you maybe getting fuel in the oil? You may try a cylinder leak down test to see if you have bad rings causing blow-by into the oil case. That test will also let you see if the valves & seats are good as well that could be forcing fuel back through the carbs into the airbox when the compression stroke is formed. Other than that sounds like it's time to rebuild your carbs and do a video inspection while you're at it. lol.

You can rent a cylinder leak down tool from any auto store. Take the spark plug out and screw in the leak down tester. Make sure the piston is on BDC, use a little compressed air to fill up the cylinder and read the gauge. Let it sit for awhile and if your gauge is still at the same psi you're good. if the psi is less you have leakage from either the rings or the valves & seats.

Please reaf & refer to the instruction booket when renting because I'm sure I left a couple of safety steps out and do not need to get flamed by others. I am giving you the general rundown.

Good luck and let us know how it goes.

Old bike = possibly bad ignition module. I've had similar symptoms - backfire, power loss, no run, etc - with bad modules.

If you're confident that the carbs are OK (if you took them apart and cleaned them, they are likely OK though the presence of fuel concerns me) then start checking the electrical system for issues, esp if you have a spare bike to trade parts from. Start at the pickups and work back.

Typically, backfiring is a timing issue, not a carb issue. The intermittent symptoms also sound electrical in nature (a skipped tooth on the cams would not be intermittent.)

If that doesn't work, pull the head cover and look at the valves... though I doubt you've issues there. Check chain, sprocket... or anything amiss.

Spare parts? Does a parts whore have spare parts?
I'll try the ignition module.
2 sets of csrbs and similar issue, so doubt it is the carbs.
Either ignition control or valves.
Or it is just cold and Trey doesn't like 40* weather.

Update: ICU: not the problem. Swapped and no change. Seems to be running on the right cylinder. Changed left coil- no change. Changed left plug: no change.

Unplug left - no change. Unplug right: dies. So that means left cylinder not working.

Interesting: unplug right and try to start with full choke and it will eventually start up with only the left cylinder. So what gives? Left cylinder going out or left left side valves? Intake not opening?

I guess when I have a warm day, take the top cover off and see what the valves and ships are up to? Re-check a set of carbs and see if the carbs are screwed up?

I'm thinking of sending off a set of carbs to PJ Motorsports in Oregon to be professionally fix up a set. I think the set we worked on got really screwed up and the spare set, which we didn't work on, may have a poorly function left side.

check your inlet shims probably to tight .

When you say you changed the needles and seats...you mean new ones or ones out of other old carbs...?Replace the float needles etc with new if you haven't. Physically clean the carbs-take them off the bike and clean all the orifices/jets/air passages etc.
Check the floats to make sure they float.Verify/correct float height if needed. Fuel leaking out an intake boot...stuck/bad float is what I immediately think.  The intakes boots look cracked (since you mentioned them..)?They new?-that can be a BIG air leak.They can look ok and be bad...(buy new if they are needed).

Ethanol/additives in gas and bikes sitting  sucks for carbs...

If you can get the engine warm enough- What's the compression on both cylinders? (look at the valve clearances before you warm it up).

Did you check the signal generator....? You said you swapped plugs and coils...New plugs??...get spark but no fire on left cylinder?with the air filter out- shoot some gumout (EDIT) CARB (/EDIT) cleaner into the airbox towards the right carb inlet and try to start the bike....see if it fires off on both cylinders for a second ...
Good luck.

Like Jared said and is easyenough to do, run a compression check on both cylinders and compare the readings. You did check the spark output and ensure that there was spark going to the plug correct???

After the compression test is done it will either be rings or valve. If you are getting spark & fuel into the right cylinder it sounds like you have no compression in that cylinder.

Pull the plugs and give it a quick finger in the hole compression check, if you get a loud pop from both cylinders the problem is not valves.  Only takes a minute or two and it's always a good starting point.

+1

low compression can lead you to think it's an electrics/fuel problem initially. instead of a thud thud thud vrooom like on normal startup it will thaw up thawup thawup and not fire nicely. check the valve clearances after you do a compression test.

i'll remember the sound my drz made forever, when the rings gave up.

Check compression, of course. Make sure you have enough.

Bike is running on one cylinder, with the left picking up intermittently... this still sounds electrical . So we've probably ruled out the ICU... methinks you have another wiring issue somewhere between the pickups and the ICU. Have you pulled your right side inspection cover to see what's happening in there? Trace back the wires to the ICU and make sure everything's solid. Then, the pulse up to the coils from the ICU. Check it with a small 12V bulb or noid light (used to test fuel injector pulse.)

The only problem I've had causing my 02 GS to run on one cylinder is the plug wire coming loose in the coil, should be bonded in tight.  adidasguy has already checked this by switching coils above.

Other GS'ers here have had the problem caused by both carb problems and in a couple of cases a bad pickup coil.  Maybe time for a parts whore to swich the pickup assembly with a known good one.

The way I learned it 64 years ago working in a garage was to check compression and then spark and finally carbs in that order when you have no idea what's wrong with a vehicle.  Cars have changed a lot since then but the GS500 has not.   :icon_lol:

Damn GSJack,

Quote,"The way I learned it 64 years ago workig in a garage"  :o

How old are you????

I think I've seen a video you did on youtube and you don't look over 64 + 5 or 7 years of childhood making around 70 to 72

Did you check the battery to see if you are having an abnormal voltage drop? Also check around the starter solenoid harness... That is where the majority of my problems came from (the main power harness goes thru here and mine started to melt so connections because intermittent).. I pulled the entire harness and wired both the battery positive and the positive coming off the rectifer to an inline fuse and wired that directly to the positive post of the battery. All the starter solenoid does now is star tht ebike off the switch, nothing else runs thru there... 
You can also do a voltage check on the coils themselves to make sure the connection is good and also that your CDI isn't bad... If you have 2 meters i would check both LH and RH coil.. i believe LH reads inverse of RH (electronic tach taps off RH) and make sure they are the same...

I only add this part because of a recent issue with the Katana and loss of power.. Turns out I had a fuel line kink. It started to restrict fuel flow and I started to drop cylinders. On some turns it must have jared the line the right way and it opened up a little and would restore power... Just another thing to possibly look at...

- Check to see you have left side spark first.
- If no spark, swap out lead with one you know is working.
- Add correct milk as required

Michael

Quote from: ghostrider_23 on December 05, 2011, 10:04:07 AM
Damn GSJack,
How old are you????

Looking forward to riding my 02 GS on my 80th birthday next summer.   :thumb:

Swapped ICU
Swapped coil
Swapped plug
Do have spark (ouch!)
Did quickie valve clearance check (was cold in the 30's and late at night) 0.04-0.05 so within spec (0.03-0.08) but on the tight side. Will do a more proper check when in the 40's

Didn't do thumb compression check yet.  Valve bucket does go up and down smoothly as engine rotated, so I don't think the valve is stuck (could be damaged). Will check mixture screws, though unlikely 2 sets of carbs would both be lean on the left side (but possible).

Here's the odd one:
Unplug left wire, runs the same.
Unplug right, dies
Put on full choke with only left plug and runs the same as no choke with only right plug.

Gas is good. Had to fill up after only 100 miles when testing and running around the block. Problem came on slowly over a couple weeks where it would get harder to start unless full choke.

Will do more testing and go over the suggestions for what I have not checked when it gets above 40.

Left valve could be bent and still look fine going up and down (Mine did  :2guns:). Do the compression check with your finger that GSJack has suggested.

Adidas is going to try everything first and then do the compression test last. lol :icon_idea:

I'm did the electrical first, as I know electrical the best and electrical things are a piece of cake for me.
Now moving on the the mechanical.
I knew Trey had a bad PO and never had a valve adjustment. So went checking valves, since I was going to do that anyway and was next on my to-do list.
Not necessarily doing things in a backwards order, but going through things first that I know needed to be done and were going to get fixed first. 
If I find compression is the problem, that IS on the list as there are gaskets with minor leaks and the whole top end WILL be taken off this winter for a complete overhaul.
Hope this makes sense --- doing easy things first on the list to see if he will run, before weather warms up (or I get a heater in the bike cave) and do the complete engine overhaul.
If warm this weekend or some evening, the finger test will be done along with a proper valve clearance check.
Bent or bad valve would not surprise me as it came on slowly over a 3 week period. A valve burning or bending could reach the current state in 50 miles of riding.
I'll pull the carbs (now only takes about 1 minute to remove them, 2 minutes to put back on), because I remember seeing the intake valves looked different and will take pictures. Tempted to insert a camera in the spark plug hole and see what the top of the inside of the cylinder looks like - that's the video nerdiness in me.

As an added note - I really want to get on to the bike build so the easier I can fix Trey to run a few months before the tear down, the better.

UPDATE
OK - went to 36* bike cave (needs a heater!). Every other turn of the engine the ffffffffffffttt on each side with thumb over spark plug hole feels the same.

More update
Brought original carbs inside to replace the screws with SS ones, just because I was bored tonight and it is 34* outside. Found the mixture screws were 4 turns out. That won;t explain his current problem with the left cylinder, but could explain all the gas in the carb air intake and dripping from the airbox boots (which were not properly connected so all the extra air leaking in might explain why the PO cranked up the mixture. Don't you love bad PO's?)

Adidas,

How is it going???

Sad to see someone that helps others out so much on this forum having trouble.

Hope you discover the problem soon

With it under 40*, things are slow. Hoping for warmer weather - at least the upper 40's.

Thumb compression test done and seems OK. With 3 bikes and the build, I figured a compression tester was in order. Should be here tomorrow. Will do real compression test and re-check valve clearances again.

Will put back set of carbs with mixture at 2.5 turns (found it was a 4! Eeeeek!) and photograph the valves from the carb inputs and see if there is any obvious damage as they open and close. Found these older carbs are real easy to take on and off. 2 cables, 2 hoses and the 4 metal bands. Getting the air box seated is simple if you reach into the air box to push the rubber boots to the outside of the carbs as you push them together. (PO had the air box on wrong with air leaks and squished rubber boots).

A 1/2 gal. hanging shop fuel tank coming to make testing without the tank much easier.

I'm proceeding from the outside in - easy to hard - so the top end won't come off until deemed necessary. I only want him running OK until warmer weather at which time he will get a much needed tear down of the engine to replace all the gaskets. The PO bought a full set of gaskets - he just never put them on - and gave them to me.

I'll update as I proceed in the next few days. I am taking time to study everything since I need to know where everything goes for the bike builds. Trey was intended as a learning bike - so I guess I'm learning.

Holy Shazam I forgot you were way up north on the west side of town lol

I hate working in cold weather, my brain begins to slow down and when you hit your knuckles on something it seems to hurt 10x more than normal.

Still you do have a bike cave while us little ppl work outside.

Ok so electrically your fine, so that means you have a leak of some description somewhere. The compression tester will tell you of its your piston rings or your valves. Read up on doing the test it's been a while since I've done one but the Haynes or clymer will be able to tell you what and how to do. An oil can is handy to squirt the oil in the plug holes when your doing the test. Good luck.

The fact that the left cylinder runs OK with choke but not without indicates a carb problem to me. Blocked idle jet? (I know you swapped carbs.......).

You have spark and you have compression (finger test). That leaves fuel.
From your description it sounds like the left side is running super lean, just enough to run on full choke.
You swapped carbs and problem remains.
My guess is you have a vacuum leak, most likely the left hand carb boot. Remove and inspect, swap them around and see if the fault follows.
Flooding carburettor is also a worry. I'd be checking float levels using the clear tube method.
That's my 2/c hope it helps :)

Quote from: mitch79 on December 07, 2011, 05:37:58 AM
You have spark and you have compression (finger test). That leaves fuel.
From your description it sounds like the left side is running super lean, just enough to run on full choke.
You swapped carbs and problem remains.
My guess is you have a vacuum leak, most likely the left hand carb boot. Remove and inspect, swap them around and see if the fault follows.
Flooding carburettor is also a worry. I'd be checking float levels using the clear tube method.
That's my 2/c hope it helps :)

X2, keep going, were in this together..
:cheers:

Got a MotionPro compression meter in today.
Although engine was cold, 140psi left and 145psi right.
They both held the pressure for 20 seconds or so until I released the pressure and disconnected the meter. I know engine is supposed to be hot, but the fact that both had high compression I think means the engine is OK.
Now to put carbs back on adjusted correctly and to check for strong spark.
Quite possible there is spark, but weak due to a wiring issue. I did swap CDI's, coils and plugs.
Oh, I got a spark tester. I'll go see what that does! :icon_razz:

Ok...

Good compression and spark...

Have you physically removed the pilot jets etc from the carbs and cleaned out all the orifices in the carb bodies etc. yet?

Take one carb bowl off at a time-You already replaced the needle valve/seats yes? Pull the pilot jet out and see if you can see through it. If you can...blow some carb cleaner through it  just to make sure it's clean. If you can't-- take a wire brush and pluck a bristle out (brass..not steel..) and poke through the crud (don't use a drill bit..)  then blast it out til it's clean and reinstall it. Pull the main jet off and make sure it's clean -take the  top of the carb off  pull the jet needle etc out/ diaphragm too. Clean out the little orifices/air passages in the carb body (shoot carb cleaner through them..use a little compressed air to blow the cleaner etc out ( eye protection is a good idea..).
Check the diaphragm for any holes etc while it's out...Clean the needle jet if it's cruddy... Put everything back where it goes ( remember the little oring on the carb top..) after it's all clean.


Put the float in a bowl of water and check it for holes.. if it's all good put it all back together as it came out - Check your Float level (Clymer manual shows you how...pretty easy) and adjust as necessary. Close it up and do the other carb.

One last suggestion...just for piece of mind- put fresh spark plugs in it. I've had  plugs look fine and not work well.
Hard to Diagnose from 3000 miles away.

Butter my butt and call me a biscuit.

I feel like a rubber nosed woodpecker in a petrified forest.

I swear I couldn't find my own butt with two hands and a search warrant.

Well HE'S ALIVE!

Read on.....

First, thanks to everyone for their suggestions.  :bowdown: You guys are smarter than a tree full of owls! I did a lot, bought lots of tools and learned a lot. Now that he's running again, I can clean him up and wait until spring for the full tear down of the engine.

Again, thanks to everyone.  After solving it, all this seems like a trick question on a game show.

so......  I did the compression test. All was OK. Tried out the Motion Pro spark tester. Both sides sparked really well. Though with the spark plugs testing a few days ago, it was intermittent but I chalked that up to a bad ground on the painted engine block (hint hint!). Connected up the Motion Pro shop 1/2 gal tank so I could start the engine. Yea, it was cold but somehow I was on a roll and had fun using the new tools.

So next I put the plugs back in. They were marked left and right so I reversed them (I often do things like that for testing and giggles). Started it up after a few cranks (thank god for LiFe batteries - that sucker is still cranking after all this testing!  :icon_lol: ).

Tried the usual test and pulled the left plug wire and guess what? The engine died! WTF! The left side was bad. Started back up. Pulled the right. WTF! No change! Well, grab another plug for the right.

HE WORKS!  :woohoo:

What are the odds of 2 out of 4 nearly new plugs going bad?  :technical:

That's right - 2 out of 4 nearly new plugs went bad. I don't think anyone would have guessed that. Spark (though a little intermittent) when watching the plug out of block with the bike running. Makes me feel like I couldn't pour rain out of a boot if the instructions were written on the heel.  :dunno_black:

Saturday I will go back through all the suggestions and work to get everything on Trey working right. Carbs will be correctly adjusted. All hoses checked and tightened. And then it should fix the hanging idle. Yes, he does that but he LIVES! Hanging idle should be easy once properly adjusted carbs are on him. Needs new throttle cable, too. Though to be honest about that, he always had a slight hanging idle when warmed up. Time to fix that!

So tie me to a pig and roll me in the mud  :cheers:

so what brand of spark plugs were they .ive always had excellant results with what the manual recomends.

Just our common every day NKG  DPR8EA-9
Its a fluke. Probably will never happen again.
Went to check the plug numbers and started him up again with no choke and what gas was left in the carbs.
Kinda makes me feel as sharp as mashed potatoes.  :icon_rolleyes:

Then..... I DID put on the new SS chain guard to take a picture. Could that be all he needed? Just some love and attention?

I bet even Buddha wouldn't have guessed 2 out of 4 bad spark plugs  :flipoff: and then intermittent. That still makes it puzzling that the left cylinder with a bad plug worked with the choke on. Is that a weak spark symptom? Seems we have a mystery to solve  :embarassed:

Realistically, how often does a spark plug go bad (ok, let's say marginally defective)? and not in a burnt out way, but internally defective?

I asked if you put new plugs in in my first reply (thought you had)....   Then suggested it ^^^^ there.

Glad it's running now.

Why tear down the engine..(gaskets leaking??) ...you have 145 compression cold...Warm the engine and do a real compression check and see what you have.

Adidas,

That's why we're here. One person has only so much knowledge, but a collection of people is like a virgin male in a whore house and a pocket full of money. lol OK, I am not as good as you are on the metaphors and I do appreciate your input:

I feel like a rubber nosed woodpecker in a petrified forest.

I swear I couldn't find my own butt with two hands and a search warrant.

Made me laugh so hard I almost spilled my coffee :laugh:

On a serious note, glad to hear he's running and you learned alot while doing so.

Are you still planning on coming to Florida???

Still planning for Feb or march.

2 bad spark plugs: (http://i1206.photobucket.com/albums/bb442/adidasguy/Videos/tiphat.gif) Tie me to an anthill and fill my ears with jelley! (http://i1206.photobucket.com/albums/bb442/adidasguy/Videos/head_hurts_kr.gif)

Quote from: Jared on December 09, 2011, 05:44:31 AM
I asked if you put new plugs in in my first reply (thought you had)....   Then suggested it ^^^^ there.

Glad it's running now.

Why tear down the engine..(gaskets leaking??) ...you have 145 compression cold...Warm the engine and do a real compression check and see what you have.

I did replace plugs per your suggestion. So one in that pair was also bad. Didn't pull plug wires until the second set was in. WTF! Bad plug in each set. Going to toss all 4 and put in fresh ones. Then found the mixture was 4 turns out. Going back to 2-1/2 turns and go from there.
Trey is marking his territory. So needs to have top taken off to replace gaskets. Might be just the cam tensioner. Have gasket and a new one coming. Otherwise it looks like the bottom of the jugs. Only a drip or two so no emergency.

oh nice congrats. when the bike is stubborn you just have to be stubborn right back at it and eventually one of you will win.

Plugs.  I think i suggested that first as well...

Congrats man.

i think i was the first to think it was plugs! :bs:

glad he's back up and running. now get that huger on the new chain guard and give us a photo :thumb:

I DID swap plugs! WTF! 2 bad plugs! Never would have though that AND both bad plugs put in the left side? What are the odds?
Plugs weren't fouled or had any signs of a problem. The defect was internal inside the plug. That's what made it confusing. Points on the plug looked just fine.

Then it WOULD run on the left cylinder with full choke. So that would imply the plug was good. Seems it had a weak spark? Running that way would make most of us think it was not the spark plug itself. How could one cylinder run with a broken spark plug?  :dunno_black:

lol, was just joking.. said it cause everyone seemed to have known it was the plugs haha. pay me no mind, except for getting a photo of chain guard with the huger attached. that i would like get my peepers on

Photoed the chain guard on Trey (see the WTSell section).
Hugger this weekend on Junior and Suzi as I have to drill the holes for the hugger, and wanted to get Trey working first.

I guess when it comes to spark plugs, I got as much sense as an empty change jar. (http://i1206.photobucket.com/albums/bb442/adidasguy/Videos/chduh.gif) But it worked with the choke on  :dunno_black: go figure?

"I got checks left. How come there's no money in my account for them?"
"Where's the ANY KEY ?"
"My computer stopped working.....OK....I'll open the window to see if it is plugged in. We're having a power outage at the moment."

(I know you're all giving me a hard time - its fun!)
I added a poll just for giggles  :icon_lol:

Funny poll. Voted for spandex.

Plugs can be bad new (bad batch) or the box they came in could have been dropped.  Goofy luck. Chalk it up to a learning experience.

Have fun with the rebuild.

You were lots of help there Scotty. Thanks for chiming in.

You can vote for 4 items.

Quote from: adidasguy on December 09, 2011, 04:06:25 PM
You can vote for 4 items.

Yeah, but only the spandex option is worth voting for  ;) :thumb:

Here in the fuel IV and carb sync. Not the origianl carbs. They will go on next week after the 37 jets are replaced with 40's.
He runs. Sputters a little - more like harder firing of one cylinder periodically. Not to worry, the carbs are the spare set thrown on for testing. He'll be even better when his cleaned up original carbs get back on. Also got 2 new plugs for him. Took him for a ride. Probably will run better after all the oil and craps burns out of everywhere.
(http://i1206.photobucket.com/albums/bb442/adidasguy/GS500/trey_on_IV.jpg)

Put 40 pilots in his original carbs. Replaced mains just so they were new. Adjusted and put on.
Now Trey runs better than ever! No hanging idle or any gaps in power.
Changed airbox for one that didn't have the boots all munched up. So no air leaks (WD40 tested!).
No gas leaks with change of o-ring in tank petcock.
Maybe a valve adjustment soon.
Trey will be good until warmer weather to do a complete replacement of all gaskets so he no longer marks his territory. Its only a drop or two and looks worse than it really is.