I bought this machine for my son and had problems with hard starting. After chasing all the obvious things, I finally clued in to low compression as the reason. Upon checking the intake & exhaust valve clearances, I found the intake valve to be tight, no clearance at all. I adjusted both valves and life was good, the machine ran well. As time went on, it became hard starting again and eventually would not start. I checked the intake valve again and found no clearance. As the summer progressed, I have had to adjust (loosen) the valve numerous times to the point now where I have no adjustment left.

I am assuming that the valve seat is worn to the point that the valve is pushing into the cylinder head. Can the head be rebuilt at this point, or am I looking at a complete cylinder head?

Thanks.

 

hey welcome to the forums!

you should be able to just lap in the new valves.

but just dont run it any more to prevent any major damage from pulling the valves comletley thru.

hth

 

Thanks for the reply 230. So I am assuming that the valve is what has worn and not the seat in the head?

 

I am doing that very job on my 250 right now. I thought I might have to replace the seat but it cleaned up good with a little valve lapping compound. I'll be going back together with it today or tomorrow. All I had to do was replace the intake valve and I did the exhaust to while I was apart. For me the worst part about the job was taking off the exhaust. I am putting a new K&N filter on when I go back together so I don't have to do this again.

 

Ever tightening valves indicate either a sunked seat as you mentione, or a stretched valve (although its usally the exhaust that does it).

Take it apart, clean it all up examine the seats, and replace them both while you have them out. I like to leak test the valves before installation. A quick and diry way to do it is install the new valve and spring after lapping, tip it up so the intake/exhaust port is facing up (depending on which you're doing) and fill it full of water. Then watch for any leaks.

 

well, it is possible. but generally the seats are very soild and problem-free in these suzuki heads.

 

I just got mine back together today. It seems to run better now since when I bought it last fall. except that it does have a little noise that was not there before when the engine is decelerating from a rev. I think it is in the cam chain, not sure. I'll pull the cylinder head cover tomorrow and double check everything I can from there. I'll try and drive it at least 10 miles or more by sometime next week and post how it's running.

once again all i replaced was the intake and exhaust valve, and the head gasket. Exhaust was only $45ish more and i figured while I was there I might as well. I put a little valve grinding compound on the new valves and cleaned up the seats and then put everything back together. The valve seats seemed to have no excessive wear.

hope this helps. the most time consuming part of the job is not the head but taking off the exhaust and heat shields to get the head off. I did do it with out removing a fender, but that was only because i had some bolts that could not be removed without destroying them and I did not have access to a grinder to do that.

Post up, Since I've just done this I'll try and be as much help as possible.

 

From my past experience, these engines don't have a valve seat regression problem. However, in your case, I would replace both as a matter of course, set up clearance slightly loose and go from there.

 

So I have been driving mine off and on the past week and seem satisfied so far. Definatly more power as wheelies are easier. No problems so far. I'd double check the valve after you get everything back togather afer a hour or two of opperation. I guess it set itself on mine a little. If I had it to do again I would have spent the money and replaced the seats just for peace of mind. But being that it is summer I did not want to be down any longer than necessary I did not do them. Anyway good luck.