Gs450 1984 run on 1 cylinder....

[Guest]

Hi,

At first sorry for my english!!! I had this trouble for all the summer and don't find why...... My left cylinder run perfectly but the right one look like he don't want explosion....When I put my hand on the exhaust, left is hot and right is cold. At first we (me and my uncle that work in mechanic for year but he live far away....) found that the head was having some leak after a compression test and other test. So he rebuilt the valve and the head for me and I put everything back in place but still have the same trouble...

The next thing I try is to invert my coil and my spark plug. But the problem was still the right cylinder. The left one was running perfectly.

And then the bike start to make intake back fire and some time there some white smoke that is getting out of the carb from the cylinder. My uncle said to me that i don't have enough fuel and that's why there some intake back fire. So i make a second clean up of my carb and I have fuel...

When I put my hand in front of the carb, the bike look like having less difficulty to start and my hand is wet of gaz

That's the best indication that I have. I have fuel, fire, air, good compression, good valve ajustement. Did I forgot something?

Somebody have a idea?

Thank you

[tom203]

So you inverted the coils and still the right cylinder refuses to work - this means the coil and plug are good, but maybe the ignitor ( metal box about the size of cigarette pack) is not firing the right ignition coil. Check your signal generator coils and the wiring up to the ignitor and from there to ignition coils.
the signal coils are on right end of crankshaft behind a small cover.

[Gorminrider]

vbabin, when you remove the left hand plug and "ground" it, does it spark? If not, carry on with electrical as above.

If it sparks ok, your uncle is right and the left side is lean. There are several possibilities to cause lean fuel issues.

Your rubber and o-rings at the intake manifold may be in poor condition and may leaking air. You may not see a crack, but sometimes, putting a heavy oil on them may seal it temporarily. There are other ways too.
Also, there is a vacuum port on the left carb connected to the fuel tap. Check that for leaks or, if it is not the original tap, make sure this port is plugged.
Plus,on the same manifold rubber, there are vacuum ports for synchronisation on both carbs-the screws must be there..
You say you have gas. If you loosen the bottom bolt on your carb, some gas must flow out. If not, you must find out why one carb has gas and not the other. A float may be stuck or the CV diaphraghm may be old and cracked etc etc etc. inside the carb.

So,when you "cleaned the carbs" , how good a job did you do? It should include Pulling the main jets if you have not and clean them very well. My bike ran on one cylinder until I did a thorough job.

Go Here:

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

and find some info how to do this.

And introduce yourself (with a picture of your bike !) here

http://www.thegsresources.com/_forum/forumdisplay.php?101-GS-Owners

[vbabin]

Thank You, for your quick answer!!!! I never check the ignitor because i was having fire so i tough that was not an electrical problem....

The problem was the signal. I was having no voltage at the exit of the ignitor for the right cylinder. Is at that moment i understand something. The spark and the signal is two different wire and that's why we can have fire but no explosion if we don't have the signal. There some water that entered in the ignitor box and when i take a look under the ''electrical plate'' there was some rust and now i'm pretty sure is when i wash it last time.......

Gorminrider

For the carb, yes the main jet and my diaphragm are find. I was having problem with the main jet when I bought the bike, so that was the first job i did on the bike and he was running find after that!! I'll try to find a new ignitor box and i will give you some news!

Thanks both!!!

[vbabin]

The other side of the ignitor box i was not able to see

[Gorminrider]

aha! Good find, vbabin! I hope you have solved it! That's a new one for me!-I never wash my bike with a hose--just a sponge and bucket.

[vbabin]

Still have some trouble.... I have a better spark but still run on one cylinder... Is there somebody know the specs (resistance) that i'm supposed to have on the pickup coil? And on the coil/second coil?

In my manual shop there's nothing....

[Gorminrider]

vbabin, each signal generator (pickup coil?) is 60-80 ohms.

I find this in the Clymer publisher's manual for 400-450 twins, page 179. You can get this manual here->

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

[vbabin]

Thank you for the for the link Gorminrider! So my pick up coil wasn't good anymore, i found some use that was ok. Also i have fire in both cylinder, the ignitor box the guy give me the first time wasn't good so he give me another one and everything is find know.

But..... The bike start pretty well and my idle is good but when i give some gaz, the bike dont go over 4000 rpm.... I don't understand because i'm able to see the ''spray'' of gaz in the carb, so there's not a lack of gaz