No seriously, carb issues. **UPDATED** two months later

[802 305]

Hey everybody, new to posting here but i've been poring over the forum for a few weeks now trying to figure her out. Just got a 91' gs500e from a dealership in st. petersburg, fl. My first bike. Loved it like crazy for 150 miles, until the lower end took a crap and i had an uncomfortable ride home on one cylinder (suprised it got me there). After around three weeks of waiting, my new (2001) motor arrived and was installed. Note: I have the pre-2001 carbs with only two stages. Not too much of a problem though, right?

I have a foam filter (newly cleaned and oiled) in the stock airbox, and what appears to be the Cobra exhaust (S version i think? with snout).
Heres the problem: the bike will start up fine, and idle ok. however, when I take it out, randomly and without warning, the bike will sputter, surge, and then die as I engage the clutch. Almost feels like its running out of gas. If i leave it alone for a bit, it will start, but only with mid-to heavy choke use, and dies immediately when i disengage the choke. Once i get it running, i can disengage the choke sometimes, but the problem returns with no warning and seemingly at random. I'm so tired of getting stranded!  

Now i have heard that the bike runs lean stock, and although the Cobra doesn't NEED rejetting, it could make matters worse (leaner). Bad enough to cause me to stall out? Unfortunately work has led me away from the bike until next week, but I plan on ordering some new mods to hopefully solve the problem.

1. New K-N clamp on filter (will leave more room to route fuel lines and to ensure nothing is pinched, and will take care of any possible vaccuum issues of the airbox/carb)
2. Rejet-but how aggressively? 40/140? Im stck here, seen so many numbers my head is spinning.

Really appreciate the help folks, not trying to be lazy but i've had trouble finding the rejet specs with this specific configuration. This bike is a blast to ride, light and flickable, and good lookin. Just gotta get it good running. Oh and also pop on decell. Thanks!

[jeremy_nash]

pop on decel is fairly normal with an aftermarket exhaust.  sounds like you may be in the market for a carb clean and rejet.

[802 305]

Thanks; I have also heard pop on decell is a symptom of running lean. Also note, it's just a slip-on.
I agree about the cleaning and rejet, anyone have ideas of the size mains i might want to run? I want to try and order some now so when I get back home I can start experimenting with it. Does anyone know if when you order from bikebandit or other websites and they come in packs of 4, is it $12-$14 PER jet or for the 4 pack. Hopefully i can get two or three sizes. thanks

[The Buddha]

Your lower end crapped out and you rode on 1 cyl ...
OK then you replaced the motor ...

OK with a 2001 ...

Sheesh, replace the motor again, clearly you have that part down pat.

Bottom end dead motors do not let you get home on 1 cyl.

Bikes that have bad crank triggers let you run home on 1 cyl.
I'd bet your motor was fine, needed a crank trigger ... 100 bucks new, 20-40 used from gstwin.
OK now you're classically starving for fuel.
More than likely its due to stuff beign clogged, or a vacuum line having a hole in it.

You can rejet, but I would clean out the whole fuel system ... and I actually recomend you diagnose it all properly with gstwin's help and fix it.

Do not use modifiying it as a way to repair.

Yea it can be rejetted, and I would recomend a 125 mains, 40 pilots, 1 washer and 3 turns set up. I sell a jet pack for 25 made to your set up, and its still going to need your fuel issue properly addressed.

With K&N I would run 150 mians along wiht that pipe you have.

Really, look for rust in the tank, leaks in the vacuum line, rip in diaphragm, clogs in the lines etc etc

Your old motor was fine, hopefully you didn't throw it out.

Cool.
Buddha.

[802 305]

Wow Buddha once again you come through with classically vital advice. Good thing i didn't throw out the motor - but I will have words with the mechanics who told me I needed a wholly new motor ($850) when i only paid $1k for the bike. 

Still gonna get the K&N so I have lots of room to run new fuel lines, I think the airbox might have been pinching them, and they were probably old/clogged. and also rejet based off your specs - maybe get your kit. The diaphragms looked good when I checked them, and i did drain the tank showing alot of rust. But I will re-check everything in the fuel system; the tank, replace the lines, and clean the petcock somehow when I get home.
Thank you thank you! 

And just so we're clear: leanness wouldn't cause the bike to die out completely? It has a flat spot in the first 1/4 of throttle, 1.5-3.5rpm or so.This issue has persisted with the old and new motor.
However, the stalling only occured with the new motor.

Alot of really helpful info on this site, not to mention helpful people. Really appreciate the help.

[The Buddha]

Well what crank trigger are you running. If you're running the old one in the new motor I'd then think its not that ... but dead bottom ends dont let motors really run on even 1 cyl. From the first sign of trouble - a clicky noise form the lower end, to stuck and dead and never to even turn over is under 10 miles ... If you stop at the clicking you can save it if you're lucky by putting new bearings, but most people are not lucky ,,, and it always seizes, eats a rod bearing, bangs the crank up, bends a rod and possibly shoves it through the case.

Anyway, K&N and pipe = 150 mains, 40, 1 washer 3 turns.

The thing has to flow as well as it can, else you will starve ... and vacuum ... cant have that let air in.

Cool.
Buddha.

[802 305]

Well here's what I know: bike died, I got it towed to dealership where I had bought the bike a week and 150 miles earlier. I bought the motor off ebay, and they outsourced the motor installation free. I'm assuming everything in the motor is from 2001, but you know what happens when you assume. 
What you're saying makes sense, I don't think anything would have been able to run if the bottom end were shot. However it didn't make sense at the time  I didn't include much info about the old motor issue because with the completely new motor it wasn't neccessary, but at the same time half the motor shat out so did the clutch. The clutch lever had no tension, and the techs said it was shot as well. Thus, a replacement meade sense to me rather than sort out several different problems. I now plan on keeping the motor around for spare parts and tinkering, or in case I might need a random part (or someone from the site).
I got the bike back, took it home, then for another ride and the current problem cropped up. Does feel like fuel starvation but since it runs for many miles and dies randomly I was stumped. However, when I get home I will go through the whole fuel system, new lines, clean petcock, and rejet for leanness and just in case they are clogged.

Thanks again

[The Buddha]

Cable losing tension isn't how a clutch dies either. That can be how the cable dies ...

I dunno about trigger swaps, I've not run old harness and new trigger ... 01's got electronic tach isn't it ? anyone know for sure. Maybe they swapped that also ? Is the electrical stuff under the right side round cover there on the old motor ?

Cool.
Buddha.

[802 305]

Well the same mechanics who told me I needed an entirely new motor said the clutch was shot so go figure...
But the damage has been done, I have a 2001 motor which works well and has less than half the miles of the other one. Still has the analog tach I think.

Anyway, like I said damage is done i have this motor, now it's just the fuel or carb issue to deal with. Anyone else got a hunch? Still won't be home til the weekend to replace/check things but cleaning and replacement of lines sounds like a start.

Products to use for cleaning the tank/petcock out?

[802 305]

For anybody who's having similar problems:

UPDATE:
So i've learned quite a bit at this point, only two months later. Made some adjustments to the bike, WOW what a difference.

1. Ditched the airbox and got a lunchbox, K&N that is.
2. Total carb rebuild/clean and rejet to 145, 1 washer, haven't messed with mix screw - COULD NOT get that damn pilot screw out, it's seized to hell.
3. New fuel lines
4. tank clean

Bike runs much better, with pretty smooth power delivery. Still has issues around 4-5k RPM, where the tach moves wildly between 4-5. Still pops on decel.
Had an issue with it dying randomly, and finally pulled my head out of my butt. WATER. IN THE TANK. Emptied it, washed it out with a hose, poured in some alcohol, let that out, and put in fresh fuel with Seafoam. good stuff.
No problems except for chain issues, which I am currently resolving.

[JerGStwinguy]

"Your lower end crapped out and you rode on 1 cyl ...
OK then you replaced the motor ...

OK with a 2001 ...

Sheesh, replace the motor again, clearly you have that part down pat.

Bottom end dead motors do not let you get home on 1 cyl.

Bikes that have bad crank triggers let you run home on 1 cyl.
I'd bet your motor was fine, needed a crank trigger ... 100 bucks new, 20-40 used from gstwin.
OK now you're classically starving for fuel.
More than likely its due to stuff beign clogged, or a vacuum line having a hole in it.

You can rejet, but I would clean out the whole fuel system ... and I actually recomend you diagnose it all properly with gstwin's help and fix it.

Do not use modifiying it as a way to repair.

Yea it can be rejetted, and I would recomend a 125 mains, 40 pilots, 1 washer and 3 turns set up. I sell a jet pack for 25 made to your set up, and its still going to need your fuel issue properly addressed.

With K&N I would run 150 mians along wiht that pipe you have.

Really, look for rust in the tank, leaks in the vacuum line, rip in diaphragm, clogs in the lines etc etc

Your old motor was fine, hopefully you didn't throw it out.

Cool.
Buddha."

I have had my carbs rebuilt by a local zook shop 3 times and sync'd once and I get the bike home it runs well after a week of setting with fresh fuel it only runs on one cylinder.  Valves adjusted, new fuel lines, new vacuum lines, new petcock, also went back to the original air filter and box from a K&N. I am at my wits end and don't want the shop to replace parts any more.  Any new ideas?


Jerry

[Ken in Regina]

Jerry,

It sounds like you're having fuel system issues. Some sort of crud in the fuel system. Might be rust in the tank and particles are plugging the jets.

Some people have reported that with the mandatory ethanol in the pump gas now they are having the same sort of issues you report after their bike sits for awhile without running. But most of those reports are after sitting for at least two or three weeks.

...ken...

[JerGStwinguy]

everything is new, Tank, lines petcock.  This is the rebuild after CharGStwingirl got into her accident in Dec 07.  Has not run right since.  Definitely fuel issues.  Carbs have been brought pack to stock.  I think the only thing left is the diaphrams.

[skirecs]

I put 150s on mine with pod air filters and exhaust and it was too rich, power would decline at full throttle

i took my stock 125s and popped them on the lathe and drilled them to 1.39-1.40 something, and its pretty good, level powerband, just a tiny dip at 5 or 6 thousand, but thats expected