petcock or carb problems

[KitKat]

So heres the deal

I recently purchased an 1982 gs300L with under 8k from craigslist. It ran great in first and second gear, but would start bogging down in the higher gears.

First of all, i changed the oil. Then to try and solve the problem, i set the petcock to prime before starting the bike. The petcock was almost jammed shut in the on position which indicates that the PO never used prime, but i managed to wrench it into prime, and now its easier to move. Before i ran the bike i set it back to on. The bike ran great.

Next day, the bike would bog down again this time, in first gear and second gear itself. It would do fine in the lower rpms, but as soon as you gave it some throttle it sounds like it was starved for fuel. I tried running the bike soley on prime, but that didn't do anything, i also tried fiddling with the clutch during those times when it would bog down, but same thing.

so i then put some SeaFoam in the tank and let it idle for about 10 min. Then i put it in gear (never used prime this day). The bike ran perfectly!. Put it in my garage for the night

Next morning, theres a big gas/oil (i dont know what) spill under the bike that came from the overflow ,that is connected the the airbox, close to the carbs.

The bike still seemed to be starved for fuel, so i took of the tank, drained it. Drained the carbs. Then bought new supreme gas and filled it up. after letting it sit a bit in prime so it could fill up, switched over to on, and still bogged down. Put a little sea foam in it and let it idle for 10 min. Drove it and it still bogged down.

So right now im letting it soak in the sea foam. Also, there has been white smoke coming out of the left exhaust, but i believe thats the seaFoam because before i started that, it wouldnt do it. The bike idles perfect. When you give it gas while idling, it will rev up to a certain point, then the rpm's wont increase past a certain point.

So at this point i believe that it is a petcock or carb issue. I am thinking about rebuilding the petcock first.

Any suggestions/concurrence/other ideas of what it could be? Also, how, and is it hard, to rebuild a vaccuum line petcock, i've only rebuilt a manual one before.

Please help, this problem is quite frustrating.

Also, as soon as you start the bike and let it sit for a sec, then start driving it it drives and accelerates perfectly, just after like 30 sec of driving it, it starts bogging. This is the same every time i start the bike

(hope that helps you visualize my problem).

Thanks

[Larry D]

Buy a new petcock, the rebuilds are hit and miss. And clean and rebuild your carbs. I'm pretty sure you can get a set of new orings for your bike here.

http://www.cycleorings.com/

And follow the carb rebuild series here.

http://www.thegsresources.com/gs_carbrebuild.htm

You also want to adjust your valves. The adjust tutorial can be found on Cliff's site.

http://members.dslextreme.com/users/bikecliff/

[rphillips]

If your bike does the same on "pri" or "on", the petcock shouldn't be the problem. When it starts bogging down, try giving it some choke & see if it runs better.

[KitKat]

i have already tried giving it some choke and it has stayed the same.

Also, since its an 82 i just want to make sure, its VM carbs right?

and since its a 300L is it a 4-valve? - buecause i only have 2 carbs?

or is it 8? because i cant find a 4-valve guide on bikecliff's site, onlyt 8 and 16, so im guessing mines 8, correct me if im wrong please

I havn't really done a lot of works with valves before.

Thanks

[kparkfan]

you should have cv carbs on yours. it is a 4 valve

[KitKat]

are there any 4-valve adjustment guides that ayn1 knows of?

[MacGyver]

So right now im letting it soak in the sea foam. Also, there has been white smoke coming out of the left exhaust, but i believe thats the seaFoam because before i started that, it wouldnt do it. The bike idles perfect. When you give it gas while idling, it will rev up to a certain point, then the rpm's wont increase past a certain point.

Thanks

I would suggest a carburetor problem, especially since it you cannot get it to properly respond to throttle when idling. You should be able to red line the engine in neutral. Not recommended, but you should be able to do that. Having just been through a carb rebuild, I would theorize that you have dirt in your needle valves, floats, (pool of gas you experienced) and quite likely some stuck in your main jets. A carb clean/rebuild will take care of that.

Seafoam will only do so much, I would say it is better at dealing with residue rather than pieces of stuff and the engine will usually run poorly and smoke for a while. The local bike shop recommended a ten minute run, wait a day, and then run/drive through as much of the tank of gas as you can. In my case, there was nothing Seafoam could do. (http://www.thegsresources.com/_forum...d.php?t=141950)

Your symptom sounds similar to what a fellow KLR rider experienced when his main jet got plugged up by a piece of sand.

[KitKat]

i think your right,

but whats the deal with it running fine and perfectly and revving in idle perfectly for the first couple seconds after i start it, then it starts going down, and this happens every time i start it, is it possibly the lack of proper fuel from the petcock?

Thanks

[MacGyver]

i think your right,

but whats the deal with it running fine and perfectly and revving in idle perfectly for the first couple seconds after i start it, then it starts going down, and this happens every time i start it, is it possibly the lack of proper fuel from the petcock?

Thanks

Possibly, but unless you have a spare tank around, you cannot properly test that theory. You can get some other fuel line hose and connect it to the petcock. Put the other end in a gas can and set the petcock to prime, the fuel should drain out at a reasonable stream of pee like rate. If this happens and running the engine while on prime makes no difference, it is unlikely it is a fuel flow issue - from the tank that is. The fuel tubes in the carbs could be clogged, mine had a lot of junk in the needle valve screens.

I wish I could say it was something simple like "x", but my personal experience dictates otherwise. In my case the ultimate culprit was a stuck starter/choke plunger, but I also suffered from:

• Valve adjustment required - tight on cylinder #2
• Wrong plugs (previous owner installed)
• Carburetor clean/rebuild - 25 years of use/gunk
• Intake leaks - worn out clamps and possibly o-rings
• Carburetor sync/balancing - mmmm, smooth
• Pilot/idle mixture screw adjustment - smooth consistent idle

Even if I fixed the starter/choke plunger issue right away, the remainder of the issues could have caused similar problems, especially the last three.

I doubt you will find a specific valve adjustment guide for your engine, but the process is similar on many bike engines, not just the GS line. Checking the valves is typically easy, adjusting them varies and may require shims.

[KitKat]

also, the bike once sitting overnight, is leaking gas out of the overflow( i think its an overflow). The pipe is located on the airbox, right after the airbox connects to the carbs, on the bottom of the airbox.

What could be a possible reason for that?

I have never experienced this before

[hampshirehog]

also, the bike once sitting overnight, is leaking gas out of the overflow( i think its an overflow). The pipe is located on the airbox, right after the airbox connects to the carbs, on the bottom of the airbox.

What could be a possible reason for that?

I have never experienced this before

Sounds like your petcock is letting fuel through (unless you're leaving it on prime) and possibly your needle valves or carb floats (or float levels) are faulty.

[KitKat]

does any1 have the specs for the carbs,

there mikunis,

im plannign to run through the petcock and possibly the carbs today

[Larry D]

Yep......you do !!!! Re-read post #2.

[KitKat]

oh ok, thank you larry!

Also, i have never had a four stroke bike besides this one before, so i have no other shims, so i think ill hold off on the valve adjustment because i wouldn't be able to replace the shims if needed

[KitKat]

does any1 else have any other ideas on what might be causing this problem???