In need of brain storming from everyone

[Anonymous]

The large diameter line on the petcock goes to a fuel fitting between #2 and #3 carb. This fuel fitting is aaprox level with the top of the float bowl.
The hose on the petcock that goes to the fitting on the side of #3 carb is a vacum line to operate the petcock diaphram.

Earl

Got it. Learn something new every day, right?

[earlfor]

I learn a few tidbits every day on the site. :-) :-)

Earl

Got it. Learn something new every day, right?

[Anonymous]

Ok earl, new question.

I got the piece I needed for my compression tester and I have started checking the compression on cylinders 1 & 2 however, I think I might be doing this wrong. Tell me if this is right.

I took out plug #1 and screwed in the tester into the #1 cylinder. I then started the bike. Now here are the results. The needle on my gauge hardly moved unless I rev the motor. I get the same results on cylinder #2 also.

The 120 compression mentioned earlier, is that when the bike is idling or at a higher rpm.? I have it set to idle with the choke off at 1500 rpm's. At what rpm's should I be checking compression at?

Thanks.

P.S. The plug in cylinder #1 is still fouling up with black soot, but only on cylinder #1. The others still look new.

[Anonymous]

Compression should be check on a warm engine at wide open throttle.

It should not be check running.

Start the bike take it for a ride.
Now disable the ignition (pulling the positive wires off the ignition coils should do it).
Remove the plug you want to test. Screw in the gauge. Crank the engine over a maximum of 4 times with the choke off and the throttle held wide open.
Repeat this for the other cylinder.
You should have less than 10% difference between cylinder.
If you have money start looking for problems.

Thanks,
Gavin

[Anonymous]

What condition is the battery in? How new are the spark plugs? Electrical problems are often diagnosed as carb problems. IMHO, Yamahas are designed by engineers from hell.

[Anonymous]

Ok, I read some other post on how to do the compression check. Took out all four plugs, put my tester in plug #1 opened thottle all the way and hit the start button. Did the same on the other three. Here are my results going left to right (if sitting on the bike).

#1 = 91; #2 = 90; #3 = 92; #4 = 90

So if they should all be around 120, then I got problems then, right?

Is it just fouled valves or is it bad induction tubes/gaskets?

[Anonymous]

What condition is the battery in? How new are the spark plugs? Electrical problems are often diagnosed as carb problems. IMHO, Yamahas are designed by engineers from hell.

Battery and plugs are brand new.

[earlfor]

All you compression readings are close to the same, so my inclination is that is is not valves because if you had a burned or open valve, there would be no compression. I think you have worn rings. How many miles are there on the bike? To confirm that it is a ring problem. repeat the compression test but this time just before you screw the compression fitting, put about 1/2 teaspoon of oil into the cylinder through the spark plug hole. Your compression should increase because the oil will seal the rings. If it makes no difference, then it isnt a ring problem. Let me know.

Earl



quote="JGonier"]Ok, I read some other post on how to do the compression check. Took out all four plugs, put my tester in plug #1 opened thottle all the way and hit the start button. Did the same on the other three. Here are my results going left to right (if sitting on the bike).

#1 = 91; #2 = 90; #3 = 92; #4 = 90

So if they should all be around 120, then I got problems then, right?

Is it just fouled valves or is it bad induction tubes/gaskets?[/quote]

[Anonymous]

The bike only has 20,xxx miles on it. I will do a wet compression test next (tomorrow most likely) and post the results of that test. I will also try spraying some started fluid around the induction tubes while the bike is running to see if there are leaks there or not. Will let you know what happens.

[TheNose]

My Clymer manual says:

Make sure the engine is warm

Remove all the spark plugs.

Make sure the choke is off.

Connect the guage to one cylinder.

Hold trottle completely open.

Crank until guage does not increase anymore.

[Anonymous]

Ok, I have done the wet compression test and my numbers stayed about the same (i.e. +/- 2 psi). I have also moved the fouled number 1 plug and switched it with the number 4. The results of this confusses me. The number 1 plug that was fouling real bad in cylinder #1 is now burning just fine in cylinder #4 and the good plug from #4 put into #1 is also burning just fine. So what makes the one plug foul in #1 but does not do the same when different plug put in #1?

Anyhow, the bike runs good now. Still a little sluggish when first getting on the throttle, but my bike has the same problem which has been contributed to my induction tubes/gaskets, I am assuming this bike is suffering from the same issue (stored nine years).

Anyhow, this guy who owns the bike is a cheap S.O.B who ain't paying my nothing to get this running and complains when I tell him I needs parts to do it, so I think I am done working on this bike. It runs/drives good and and thats all he wanted anyhow.

Thanks for everyones help. Especially Earl. I wish I had someone like this that lives close to me to not only help me out, but that I can watch and learn first hand from. While this forum is the best, having someone by your side is even better.