Suggestions GS1000GT runs poorly under load.

[bobasoozoo]

I'm still messing with the GS1000GT.

engine is noisy once it warms up. I hear a little timing chain noise. a little valve noise, and what sounds like premature ignition. This at 1100 RPM. at 2000, it sounds OK. iexcept for same chain-valve noise which seems to be normal levels. get a slight pop in exhaust maybe avery 10 seconds or so at 1100. goes away at slightly higher RPM.


Timing is retarded about 3 degrees.
the popping and other noise was a little bit worse with static time 'by the marks'.
weights advance around 2500-3000 RPM
revs nicely to 7000
I watched the advance and it's smooth. and the timing is not jumping around.

When I ride, she seems to pull OK until about the same 2500-3000 RPM range at which point it feels like the ignition is not doing it's job. could be wrong but that's what it feels like to me.

I have good charge on the battery. the voltage at the coils is good. the coils, plug wires, and caps are within spec. the plugs are new ad properly gapped. the carbs are clean throughout. the low speed emulsion jet is a little oversized but she runs good at low RPM.

carbs are bench synced. i'm suspicious that sync could be the problem. because she runs well with no load. is this a safe assumption?

there are no airleaks between carbs and head as tested by spraying a bit of carb cleaner and ether around each carb. the airbox boots are not great but again she runs fine with no load. safe assumption again?

I'm going to check compression today and try a set of one step up main jets. she's not running well enough for color test on plugs. at least I would not want to ride for enough time with her running the way she is.

I have not checked the ignition sensors or ignitor but again would not expect load to make a difference here. Am I wrong?

Anyway, suggestions welcome. If you've had and solved the same prolblem, please lcomment.

I am going to try some 103 octane gas and see if there's a difference.

Thanks,

-Bob

[duaneage]

Put the timing back where it belongs first. Do not waste time with 103 octane gas as it will not fix this problem. I think you have a fuel flow problem. Dirty screen in the tank, clogged fuel filter, pinched fuel line, or the vent tubes hoses are bent and closed off.

This is a classic lean out cpondition caused by fuel starvation. If the carbs are clean, have the needles been moved? IF the bike is stock make sure everythng is indeed setup as stock.

[bobasoozoo]

This bike was not running at all when I got her.

Float bowls are full, fill fast, and the level is set to spec.
Petcock is not right as fuel flows freely without vacumn.
Hose is not kinked.
No screens on float needle valves.

I thought lean too but the carb kt I bought had number 200 pilot jets. The old ones were 180 as per the manual.
The new air pilots were the same size.

Perhaps I don't understand, but shouldn't it run richer than stock with this setup?
If not, I'll go back to figuring out why she's lean.

I cleaned all the orifices-ports-channels on the carbs.
Two of the pilot screws are cemented in place and have had the heads chewed up by previous owner. I got the other two out and have new ones set to 2.5 turns thinking that should be plenty rich with the bigger pilot juts. If we should be rich with bigger pilots and are still lean, that only leaves those pilot needles.

I just checked and plugs are white on the tip of the ground electrode and have just a touch of medium grey on the ceramic supporting the hot electrode. This is same for carbs with old and with new needle jets. pretty strong suggestion that she's lean.

-Bob

[duaneage]

Definately lean.
I know you say there are no vacuum leaks. Are you SURE???

Do you have a mercury manometer, also known as a carb sync?

If you do, hook it up and see what kind of vacuum your pulling. If your not getting a strong signal something is up.

[bobasoozoo]

Thanks.

I checked for leaks with a bit of carb cleaner around the spots I thought one might occur. I don't have a 4 channel manometer. Only an old automotive type vacumn guage.

I had asked about the pilot jet. My carb kit came with 200s and the manual specifies 180. I'm 3.5 turns out on the pilot screw with the 200. I just loked at the manual to see if I could figure if bigger meant leaner or richer. It looks like bigger means richer so something is defintly still amiss.

In looking at the diagram and reading the text, "the fuel from float chamber is first passed through main jet and metered by pilot jet...", it hit me that I did not see or clean any port behind the main jets when I cleaned up these really nasty carbs. Every hole in the main jet emulsion tubes was plugged! I'm thinking that the orifice might be restricting the fuel flow to the pilot jets.

I don't have time to pull the float bowls and look before my trip, but just in case, could you tell me just where this orifice is. Do I hav to pull the main jet emulsion tubes? How far in there is it?

Thanks,

-Bob