Many problems with Engine

[bladebj]

i dont know if this has ever been mentioned or not i didnt read every post but how are the intake boots on the motor?  and have you try to run the bike on prime instead of on or res.?

intake boots are checked and good and there is no problem with the fuel in the carb. fuel comes to carb without a problem and float levels are good. thanks.

you can not synch the carbs with the bike running on one cylinder
you have to have the bike running fair before you can have it running good

ok that was my misunderstood   ok thanks

[HPP8140]

The 2002 GS I bought a week ago has a thud sound below 2-3k

There is a thud, then the rpm briefly drops less than 100rpm. Seems sporadic.

Does this sound like cam knock or starter clutch bolts?

Can't believe this!! Now this bike is probably out of commission along with my 95, which this was supposed to replace.

[The Buddha]

The 2002 GS I bought a week ago has a thud sound below 2-3k

There is a thud, then the rpm briefly drops less than 100rpm. Seems sporadic.

Does this sound like cam knock or starter clutch bolts?

Can't believe this!! Now this bike is probably out of commission along with my 95, which this was supposed to replace.

Dude - you decided to drag a 5 yr old thread back to life - OK fine, this is GSTwin after all, where threads never die ...

How much of a thud - and below 2k when accelerating ? steady or decelerating.
And Who the Fruck rides a GS below 2k rpm ...

Cool.
Buddha.

[HPP8140]

Below 2k meaning, at idle in traffic, but goes away if I rev above 3k or so.

At the moment, it's a small thud, seems like it's coming from left, lower side. When it happens the rpm briefly drops a little.

Sounds like something hitting, but I can't tell if the thud is also the engine stalling for that brief moment.

[The Buddha]

Misfire type ? That may be the Carber-nator.

The left side has alter-ma-nator, start-ernator and the whatchamcall it ... the goats generata-manator.

I am inclined to think you're losing that cyl every once in a while ... maybe carb ...
Left carb has the vacuum fitting ...
See if you can create that noise by spraying wd40.

Cool.
Buddha.

[bombsquad83]

My bike did this a couple times 2 years ago when it was decending in revs with the clutch pulled in.  It would happen around 2k and sounded like a thud as you said.  I think it was just a misfire from bad mixture.  You might want to adjust your pilot screws to change your mixture at idle/low rpm.

[BockinBboy]

Ok, so I just caught that there is same post in thread as well... I'll quote below what I typed/linked in other thread.  It sounds like Buddha and Bomb are on the same track I am with your issue.

HPP, your issue seems like lean misfire.  I had it on my '04 when everything was stock.

Here is the link to the first thread I originally saw it come up on here, but there have been a couple since. So check that out.

http://gstwins.com/gsboard/index.php?topic=66633.msg801720#msg801720



- Bboy

- Bboy

[bombsquad83]

Ok, so I just caught that there is same post in thread as well... I'll quote below what I typed/linked in other thread.  It sounds like Buddha and Bomb are on the same track I am with your issue.

HPP, your issue seems like lean misfire.  I had it on my '04 when everything was stock.

Here is the link to the first thread I originally saw it come up on here, but there have been a couple since. So check that out.

http://gstwins.com/gsboard/index.php?topic=66633.msg801720#msg801720



- Bboy

- Bboy

Yep!  That makes 3 of us!

[HPP8140]

Nice, I have a few things to check that don't automatically mean motor is toast haha. Can't thank you all enough.

The PO mentioned cleaning the carbs. The plugs are stark white. I know they run lean, but that's whitest I've seen plugs on all my GS500's

[HPP8140]

I don't have a service manual for the 2002 3 circuit carbs.

What is the float height range?

Buddha, are you still doing carbs?

[The Buddha]

I don't have a service manual for the 2002 3 circuit carbs.

What is the float height range?

Buddha, are you still doing carbs?

Buddha is the carb-er-ma-nator.
OK you caught me. I am doing carbs. You can just clean the suckers and rejet.

Float height - top of the bowl. If its lean and ashy white, its the idle reading right ? Yea you can lean misfire or spark knock yourself into those thuds.

Cool.
Buddha.

[HPP8140]

Looks like the mixture screws have been tampered with.

Buddha,

1. what do you mean by is the idle reading right? It idles ok...doesn't hang.

2. what is stock for the mixture screws? which way is rich and lean? which way should I turn to fix this issue?

3. the float height is difficult to set on these 3 circuit carbs. The floats sink easily when I turn the carbs over. My 95 held it's position better and the float needle spring was longer. Is this normal for the 3 circuit carbs? Are the float needles interchangeable? Any tips on setting the float height?

Thanks.

[attachment deleted by admin]

[The Buddha]

Read the whole sentence man -
If its lean and ashy white, its the idle reading right ? = Your plug reading was after you had it @ idle a few sec ??

Air screws - unscrew to be richer. 2.5 is stock, you're likely @ 3+ - dont bother going back to stock, turn it out 1/4 turn. See if it gets better. Or fine, screw it all the way to lightly seated counting the turns as you do, then out the same number + 1/4.
Floats - top of the bowl, for now Just check it, dont change it unless one carb id different. If its the left carb, change that to the same as other one.
Dont put any older parts in an 01-02 carb. They look like they may fit, but in reality, no.

Cool.
Buddha.

[HPP8140]

I found and fixed the following issues as I pulled the bike apart. The previous owner said he cleaned the carbs, changed spark plugs, and calls himself a retired US marine mechanic.

1. float bowls were installed backwards.

2. The screw that holds the float on the right carb was loose, screwed in half-way, causing the float assembly to move around.

3. The ON and Out to carb petcock hoses are switched. http://gstwins.com/gsboard/index.php?topic=67287.msg815239#msg815239

4. Verified the jets and mixture screws.

Stock jets: 17.5, 60, 127.5

Mixture screws:
Left: 3-1/4 turns out
Right: 3 turns out

I set them both to 3-1/4 and turned them an extra 1/4 out.

Also replaced the spark plugs.

I have ridden ~150 miles without issue.

Thanks for all the help.

[HPP8140]

Grrrrr...it did it again leaving work.  What a waste of money.

Could it be a sticky exhaust valve? I checked the valves when I first brought the bike home and the left exhaust valve was extremely tight...dropped down 3 sizes to get clearance. The bucket still turns freely.

[HPP8140]

Did some more testing. I can reproduce the misfire by holding throttle between 1500-2000 rpm

[bombsquad83]

Is it possible that your floats are actually set too high (fuel level too low)?  This would affect your mixture down low quite a bit.  The fact that the screw was loose on the one float just makes me concerned that the height was messed with...  As always, check with the clear tube from the carb drain with the petcock on prime.

If that's right on (should be level with float bowl gasket), then try another quarter turn out.

It's also possible that your intake valves are tight and you are experiencing a backfire through the carbs.

[HPP8140]

Float level was correct around 13mm.

It rather seems the opposite....engine runs lumpy, boggy, rich from 1500-2000.

First, let me correct the fuel hose routing, then check everything again.

[The Buddha]

Float level was correct around 13mm.

It rather seems the opposite....engine runs lumpy, boggy, rich from 1500-2000.

First, let me correct the fuel hose routing, then check everything again.

Who rides this thing between 1500 and 2000. I set it to idle @1700. 3k minimum.
Rich @1500 but OK @ idle ?
Cool.
Buddha.

[bombsquad83]

Yeah...never ride below 3000 rpm.  Just slip the clutch up to that point.  I thought you were talking about misfires with the clutch pulled in or revving slowly in neutral.