I have been having issues with my bike since spring, I have cleaned the carbs after every 130-150 miles as she starts to get funny then.  I have to start messing with idle screw and she won't idle with out choke 1/2 on and kind of hesitates when running.  every time I clean the carbs and she runs great even though they are not dirty, last time i put an inline fuel filter on and sure enough after 130mile , yesterday she is all screwed up again.  i am running stock everything on a 1992 model.  at a loss of ideas i decided to pull the valve cover off and check them for the 1st time since she has 10000 miles and i only had since 9000 miles, not sure if they where ever checked.  Intake valves are too tight, less than .03 mm and exhaust where loose at .1mm.  so place to get shims right now but is this the reason for running like shaat after 100 miles or so??  Carbs are clean and fuel filter is clean so i know the carbs are ok, the only thing that is jerry rigged is the little O ring onthe one carb was lost and the prior owner cut a small peice of rubber to mimick the O ring, could that be the reason also, i never thought it to be the culprit since everytime i clean the carbs she runs like a champ, its been 4 time now this season and i would love for it to be the last!!!!  Please help

open up the intake valves just a bit, leave the exhaust valve clearances. exhaust can be run a bit loose as yours are now, but you should open up your intakes.  as for the carb o-ring piece that is "custom" you should take the right piece and go to an autoparts or hobby store. they should be able to match the o-ring you need for little to no money.

but, i dont think that's the problem. just to ask, after every 130-150 miles, and you refill the tank. the problem continues?

yes the tank is topped off each time and every other time i pull the carbs off to clean them even though they are not dirty it runs like a champ again.  I was hoping the intake valves being tight was or is the culprit but i am at a loss.  I have checked for vacum leaks by spraying wd-40 and the overflow tube from the tank is clear as well.  it gets worse cause now it wont run unless on choke 1/2 way when the weekend before it was running well.   

let me ask again..

you hit 130 to 150 miles, the bike starts to bog, then you get more gas and try to continue riding? or do you hit the 130-150 mark and it bogs, so you take it home and pull the carbs again? then, when carbs are reinstalled you get new gas and it runs fine?

also: have you checked float heights?

because i am trying to see how far i go in between problems i have been keeping the tank topped off before i go out.  Also even before i rip off the carbs i top off the tank it still runs horrible.  also i can see from the fuel filter that the ample gas as it is full so i can rule out no gas. 

so it constantly starts faltering after 130-150 miles? and more gas doesnt help the issue, even if you run on prime?

you could possibly try to clean the carbs and reinstall, with fresh gas, and check the plugs after 100 miles to see the condition. then, when the problems start, try pulling the plugs again to see if they've changed?

anyone have any ideas??

Fuel lines wrong way round,so you have no reserve?
Combo Jay.

If you're riding 130 miles in a single session, then the bike may be developing a heat related electrical fault.

Ignition failures can mimic carb problems and are not always so complete and sudden that they are obvious.

I would suggest the next time it happens do not clean the crabs....instead start checking different things. Make sure your fuel lines are not blocked. Maybe bypass the petcock see if that makes a difference. Your going to have to go through a systematic diagnosis and check different things. I wonder if its an ignition problem. I would check the spark plugs and see if their firing correctly.

When it starts to happen have you let the bike sit over night to cool down completely before you pulled the carbs...??

The more detail you can give the better odds of an workable answer.

I'll add you said you cleaned the carb but when was the last time they were rebuilt....new gaskets, floats, o-rings needle valves etc....I'm wondering if something is sticking in the carbs...Have you check the diaphragms for cracks or wear?

Next time it goes sour on Ya, take carb cleaner and spray around your carb mount gaskets to see if she magically improves for a minute or so.  Sounds like you are sucking air around an old gasket.

prs

quetion, if it where an old gasket wouldn't it do that all the time??  this is runs good then 130 miles or so starts to act up.  i am in the process of adjsting the valves to be within clearance in the intake and the exhuast was ok.  the stock jets are still in but they don't go bad do they??  the diaphrams are good and i have not rebuilt the carbs but everything appears good.  i don't ride 100 miles in a single session, usually 2 or 3 50 mile rides before issues

Your revelation about the home-made o-ring and old  gaskets got me thinking:  Some materials' properties change when they are in contact with certain solvents.  They can become softer or swell.  Maybe your cleaning procedure allows an o-ring or gasket to expand and seal, but over time it would shrink and leak.

I think your getting too hung up on the fact the bike runs good for 150 miles then runs bad. Rebuild the carbs with new parts (about $50) and then at least you can rule out homemade o-rings and old gaskets. I don't think you going to find a magic answer that points to your problem. I'm guessing you will have to do this the old fashioned way and rule out one system at a time until you discover the problem.

is there a carb rebuild kit available for 92 or would I need to buy all individual parts seperately

Yes they are available...pretty sure its the same parts from 1989-2000

I got my last kit from here http://www.crc2onlinecatalog.com/carb_kits.htm

You'll have to scroll down to get to the Suzuki parts.

There are a lot of places that sell rebuild kits. Its basically o-rings, gaskets and float valves. You may want to look at your needle valves and make sure they aren't worn or bent or corroded.

If nothing else at least you know your carbs are in good shape.

I did have another thought....check you tanks real well....maybe even drain it and check the screen on the tank petcock. I wonder if there is some random debris floating around and is getting stuck and choking fuel the floating free when you pull to tank off the clean the carbs.....just a random thought.  

thanks, i'll check that out!!  As for the tank, it was just lined with a KBS coating and the petcok screen is clean so I don't that is the culprit. 

Paulcet's post sounded interesting to me.  Improper O-ring size?? Maybe when the O-ring warms up, it shrinks and no longer provides a good seal.  My engineering teacher told me if there is one thing I get out of his class is that O-rings shrink with temperature.

Quote from: Allen on July 18, 2010, 03:44:12 AM
Paulcet's post sounded interesting to me.  Improper O-ring size?? Maybe when the O-ring warms up, it shrinks and no longer provides a good seal.  My engineering teacher told me if there is one thing I get out of his class is that O-rings shrink with temperature.

Yeah just ask NASA