81 gs450 running on half engine

[josariet]

I just got a 1981 gs450t from my buddy. He said it doesn't run right but you can have it. I has new plugs, plug wires, coils, and a new spark generator on the way.

The problem is that the right side runs fine but the left side comes and goes. If I rev it up, it blows smoke out the left side tailpipe and runs great, when its not blowing smoke out it runs horribly. Putting my hand behind the muffler when its blowing smoke coated my hand with fuel.

I looked at the spark plugs, and the one in the bad engine was black and covered in oil/gas.

If I take the plug wire off the left side it shocks me but the engine still runs. If i take it off the right side it dies.

What makes it come and go, when reved up it blows extra fuel out and runs great.

Thanks for any help.

[almarconi]

I wouldn't draw any conclusions yet until you get the valves adjusted and clean the carbs. Once you do that, install the parts you ordered and go from there.

In the meantime, get a service manual so you have something to reference.

Check out basscliff's site, lots of helpful information

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

[Charlie G]

I'm not much of a mechanic but it sounds like the left carb is giving you too much fuel and flooding out or the spark to the left plug isn't consistant. Firing once in a while and blowing out raw fuel the rest of the time. I'm sure someone will come along with more.

Charlie G

[josariet]

how to I stop it from getting to much fuel. Isn't there an air/fuel mixture screw? would that do the trick

[Rein]

There is a AFM screw on top of the carb, on the engine side. It's the little circle next to the dome. It's covered by a little cap. You'll need to carefully drill a hole and use a screw to pull off the cap.

[Killer2600]

how to I stop it from getting to much fuel. Isn't there an air/fuel mixture screw? would that do the trick

Depends on the cause, if the spark is intermittent it'll always look rich; same if air flow is restricted. Is the petcock connected to the left side (bad side) carb, if so your petcock's diaphram may be leaking. In any case the fuel mixture screw isn't the fix unless someone adjusted it and f'ed it up and left it that way which isn't very likely.

[Charlie G]

On my 80 450e the vacum line from the petcock attaches to the left carb. My Petcock diaphram was shot ( the aluminium backing plate shattered) and was starving the engine randomly of fuel. If it is torn it may flood out the left carb. See if there is a hose from the petcock to the left carb.

Charlie G

[josariet]

On my 80 450e the vacum line from the petcock attaches to the left carb. My Petcock diaphram was shot ( the aluminium backing plate shattered) and was starving the engine randomly of fuel. If it is torn it may flood out the left carb. See if there is a hose from the petcock to the left carb.

Charlie G

There is a second hose running from the petcock to the carb. This one goes from the back of the petcock(opposite the valve handle) to the carb just in front of the choke handle. If the petcock is left on the on position when the bike isn't running it leaks continously. How do I check this or do i just buy a new petcock. I've noticed that if I leave the petcock just cracked open (nearly closed) that the bike will run much better.

[josariet]

so another update....if i take the vaccum line off, fuel pours out of it for a moment then stops and the bike runs correctly...i'm assuming that there is something wrong with the petcock that is letting fuel go though the vaccum line and flooding the left cylindar. Is the possible? What do I do about it, where do I find a new petcock?

[kparkfan]

time for a new petcock. try z1 for a new one

[Charlie G]

I agree with kparkfan. Buy a new one. I ordered one for my specific bike through a local dealer, but there are a number of on line retailers. Z1 has been recomended by various people here at GSR. Pretty easy to do. PM me if you need more info on doing this.




cg

[dearnhardt7]

half engine

I just went through same problem on my 85 gs450l...turned out to be the CDI box...put another one on and it runs GR8.

[josariet]

just an update. Got a new petcock from ebay (50 bucks) and it started the first crank and runs perfectly now.

Another question, I have highway pegs and I was wondering if there is anyway to put forward controls (brakes and clutch) on it.

[Charlie G]

I think it's kool you got her running. Congrats. I don't know about the controls your speaking of.

cg

[snark]

just an update. Got a new petcock from ebay (50 bucks) and it started the first crank and runs perfectly now.

Another question, I have highway pegs and I was wondering if there is anyway to put forward controls (brakes and clutch) on it.

This place has a universal kit.

http://www.tcbroschoppers.com/