Need help with compression problem...

I'll see what I can do and get back to you.....thanks

Post edited by: FreeKZ650, at: 2007/09/21 19:30

FreeKZ650 wrote:

The bike has 39K on it. What do I need to do to check valve clearance? I want to make sure I do this right. I have alot of plans for this bike so I dont want to start with hacking something....

Checking clearances is the relatively easy part.

Am guessing under-bucket shim needs replacing (intake and/or exhaust on low cylinder) and would urge serious homework before undertaking, including factory service manual and advice from the pros (not me) on this site.

RetroRiceRocketRider wrote:

Not a KZ650 cheap, but FREE? (are you seeing this BadKaw?...lol!)
Lucky you!

you four r's are a bad, bad man!
:laugh: :side: :woohoo: :lol: :silly: :laugh: :woohoo: :silly:

Had some more time on the bike today. I put a small amount of oil in the low cylinder and re-checked the compression and it did NOT increase the compression. I bought a battery today so I could start it up and see how she acted. First thing I noticed was there was no fuel flowing through the petcock. The petcock was filled with bad gas so once that was cleaned out she flowed no problem. Next problem was gas started dumping out of the #3 carb overflow. Pulled all float bowls and needles and now getting ready to clean the carbs. Thats as far as I am at the moment.

So far so good .
But don't neglect correcting valve clearances in low cylinder :ohmy: .
Because running too tight valves risks burning the valves and seats $$$$$ .

Rooting for you!

Before you start it up, change the oil and filter! If it had old gas in it the oil is surely even older and ineffective as a lubricant. I don't know if the dirt bikes you mentioned were 2 strokes, but 4 strokes need good oil or they can go belly-up very quickly. Oil & filter is cheap / engine is expensive. You don't want to kill this bike by being in a hurry to run it. Ed

Yep...oil and filter are allready changed.

Got the carbs cleaned up and back on, no fuel overflow. Gave her a couple of kicks, nothing. Checked for spark, nothing. Now the previous owner has installed Accel coils and wires and I checked for power at the coils and no power. Besides a manual, which is on order, is there anywhere I can access a wiring diagram so I can troubleshoot this tonight?

Ok, I dont know if this is stock but it has an electronic ignition box that had a bad connection. Now I have spark..... I cant seem to get it to start by kicking it over. The starter whines but doesnt engage.... not really sure what to do now.

You may want to try kickstarting. That will leave more battery power for the ignition system as the starter motor won't be drawing current. I've found that to work well for me when my battery has run a little low. Here's a wiring diagram for KZ650C2 ('78 Custom). Move your cursor around in the lower righthand corner of the diagram until you see a little box with some arrows. Click on that and the diagram will expand. Ed


diagrams.kz650.info/wiring/images/KZ650-B2,C2.jpg

With fuel, air, and spark, in the proper amounts and at the proper time, it will start, so you must be lacking one of those.

Down and dirty way to solve the problem:

Apply the choke (pull up if lever type choke), kick it over 5 or 6 times then pull the plugs to see if they are wet. If the plugs are wet with gas then it's getting fuel, if the plugs are dry you have a fuel problem.

Spark timing can be assumed to be correct as the timing is not adjustable. If you have the plug wires crossed then it will backfire and let you know it.

The starter spinning is probably due to a bad (or sticking) starter clutch, get it running first then decide if you want to deal with fixing it.

So check the plugs and see if they are wet with gas, then tell us the results.

I appreciate all the fast response's and the help. I hope you guys dont mind but I have a couple more questions.

Ok, my starter is good. If you pull the starter out and add power it spins just fine. When installed, it doesnt engage, so am I to assume that there is a problem in the case itself.

Also, I got all the little issues worked out and she kicked over and started up. I let her warm up to operating temp and re-checked the compression. All cylinders including the one that was low are all at 140. The bike wont run without the choke on. I know nothing about carbs so what do you recommend for tuning these? Also, on the carb under the petcock there is a rubber line coming off of mine with a bolt blocking it off almost like a vacuum hose. Where does this hose attach or what is it for?

Other than that....she sounds real good. No noise except a nasty resonating sound out of the exhaust at certain RPM's. Its close.....and Im happy. In it for $35.00 so far.....

The starter clutch is inside the motor behind the crank on the secondary shaft. The easiest way to fix/replace it is to pull the motor out and flip it over. I have heard of people dropping the oil pan and replacing the starter clutch while the motor was in the bike, but I think I'll pass on doing it that way.