Surging issues after carb rebuild..

[nikux]

Completely frustrated.. need help..

About 2 months back I rebuild my card with new float needle, float seat, float gasket and o-rings from http://www.partsnmore.com/parts/suzuki/gs500e/?filters[category]=carb&filters[fitting]=custom (my earlier float needle and oring were completely worn out). After the rebuild have not been able to get the bike running in good condition since then. Have tried a bunch of little things but the problem does not seem to go away. The primary problem seems to be surging (after I open the throttle 1/4, it revs a lot without much power output).. sometimes the power catches up with the throttle, but I just can take it over 50-60mph).

After reading some posts, seemed to me a lean condition - to confirm, I put some duct take on the air filter to restrict the air, and if I cover the air filter about half, it starts bogging (seems to be very jerky).

Tried to look at the spark plugs, but was not able to make any conclusions from it.
The float height is almost in speck (using extra tube the level seems to be 1mm over the float gasket).
Also tried to raise the jet needle by just lowering the plastic doughnut on the needle by about 2mm.. the bike seems to run a bit better but still surges.

Not sure how to diagnose or what to try next - its GS500E'99 with stock air box. I had re-jetted it about four years back, so dont remember the current mains and pilot number. The air mixture is 3 turns out.

How can it suddenly start surging after a rebuild?

[ben2go]

Have you had a valve adjustment?This is critical to make sure the carbs are getting proper vacuum through them.Have the carbs been balanced or sync'd?Both terms mean the same thing.What exhaust and air filter do you have?Blocking the air filter cause more issues than it solves.From what you describe,it sounds like the carbs are partially plugged inside some where.There are hidden passages inside the carbs that can not be seen.

[nikux]

Thanks for the response ben2go...

I did the valve adjustment about 1000miles back.. things were in speck back then.

The carbs have not been synced for a while. Does that really make a difference for rich/lean conditions?

I have stock exhaust and airbox with after market uni air filter.

So you suggest that I do another rebuild, but make sure I clean every small little hole I can get to? Given that performance is a bit better with the jet needle extra 2mm out I also think somehow its not able to pull enough gas from the floats...

[The Buddha]

Valves going tight will act up 5 seconds after starting, they would want to stall without much throttle, and it would likely get OK ~5 mins after starting if you keep it running for that long.
OK surging and bogging when you block the air filter ...

OK you have an adjustable needle ? You'd have to find the numbers on the mains and get yourself a good baseline, DJ kit is a lot of trouble because they dont sell you 1 step up or down or even talk to you in a way that makes sense ... Say you got 128 in it, you feel it needs a wee bit richer, they dont have a 130, your next option is 136 if I recall. Its one of those ... "say you cant find a chicken to eat ... OK so here is this tiger"

Anyway Synch also is irrelevant, synch makes it vibrate more or less @ idle pretty much, you wont have this issue.

Cleaning is also useful, but given that you put new O rings and gaskets in it it may be just clean enough. I am guessing you're just 1-2 jet sizes lean.

Surging @ 1/4 throttle is a classic needle range and you're lean there. Pull it up some. However if you cant get past 50-60 - is there a tiny rip in the diaphragm ? Lean bikes make plenty of power to get to past 80 ... lean bikes run hotter and sorta accelerate wear but they make power just fine. Of course depends on how lean you are though.
Cool.
Buddha.

[nikux]

Hmm.. so opened up the carbs again.. couldnt see any thing obvious that I missed last time - seems clean, holes seems unblocked, diaphragm seems to have no hole..

The mains are 122.5 with 40 pilots, will try going up to 125/127.5 with a #4 washer... Buddha do you have them?

[ben2go]

Hmm.. so opened up the carbs again.. couldnt see any thing obvious that I missed last time - seems clean, holes seems unblocked, diaphragm seems to have no hole..

The mains are 122.5 with 40 pilots, will try going up to 125/127.5 with a #4 washer... Buddha do you have them?

Have you checked for a vacuum leak around the intake boots?PM Buddha.He will respond faster.

[nikux]

@ben2go  - yes I tried with spraying wd40 around the intake boots with the engine running... did not see any perceived difference.

... so I replaced 122.5 with 125 and added a thin metal washer in the needles. The response is much better now.. although its still a bit lean (still surges at high rpm at 70mph)... will try going to 127 or maybe add another washer... which one to try first any suggestions?

[ben2go]

@ben2go  - yes I tried with spraying wd40 around the intake boots with the engine running... did not see any perceived difference.

... so I replaced 122.5 with 125 and added a thin metal washer in the needles. The response is much better now.. although its still a bit lean (still surges at high rpm at 70mph)... will try going to 127 or maybe add another washer... which one to try first any suggestions?

Have you checked your float level?It may need to be raised 1mm.

[nikux]

....guess what... after trying to tweak a little bit, I just decided to take the motorcycle to a mechanic.. he was a nice guy (national city motorcycle, san diego - mike) and he was appreciative that I work on the motorcycle on my own. He told me he would be happy to ride it for 10mins to see if he can figure out the reason for lean condition (at no charge)... he starts and is back in 1 min with the solution - my clutch did not have any play meaning it was slightly pulled in even at rest.... a simple big but that made me go 

[xunedeinx]

That makes sense.

Mine has too much play I think.