[hr] so I just finished changing the headgasket on my buddys f2. taking it apart and putting back together went real smooth. got the timing marks lined up perfect. it starts and runs but sounds as if the timing is off. it also sounds like the timing chain has some slop in it. we took the cam cover off and double checked the timing. it's perfect. the #4 cylinder also doesn't seem to be firing. the #1-#3 cylinder exhaust pipes are hot. the #4 is not. it's getting spark.

I'm at a complete loss here and it's really starting to **** me off. anyone got any ideas.[/align]

 

Check compression. Any chance you bent the #4 valves when setting the timing? Why did you replace the head gasket in the first place?

 

it's got spark, got fuel, got compression. how could I have a bent a valve? we set the cams in just as the book states and the timing lined up perfect. after we started it up it sounded like a timing problem. Immediatly took the cam cover off and checked the timing....it's still right on the money. The way it's acting it seems like the only thing that could be wrong is a stuck or bent valve.

 

Getting spark, good compression, but no hot header? I'd look into seeing if fuel is going through that carb. Is it possible that you disconnected a line or caused an air leak when you removed all that stuff?

 

If the engine was rotated too much without the cam chain hooked up, you could have rotated the engine to the point where a piston hit an open valve. Enough force could have bent the valve. Very common on DOHC or OHC engines. You say that you have compression, but how much in each cylinder? Do a compression test with a gauge, and see how much compression you have. If your valve is bent, you won't have any compression on that cylinder. I agree with the above post too, check your fuel. The carbs are vacuum operated, so you'll need a vacuum gun (MityVac) to apply vacuum to the carbs with the bike not running. Then you can turn the throttle to see if fuel is coming out of the carb. You can rent these tools at Autozone.

 

Well I guess that would explain some of the noise coming from that side. So I have a spare motor sitting around, can I use the valve out of it to replace the bent ones or do I NEED to buy new ones?

 

No, you can use those valves. Just inspect the valve seats on the head and make sure they're ok.

 

I would for sure check the compression first before you pull the head back off, just to be sure that's the problem.

 

And if you do replace the valve, make sure you read up on proper procedure. IIRC, it's not quite as simple as just pulling old one out and sliding new one in.

 

Ok.....so I finally got the thing taken back apart. Obviously a bent valve, actually two. So now my question is can I reuse the headgasket that I just bought?