petrol

Joined
Jun 3, 2001
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#1
hi i own a 1998 XR250 and i took it in to get a new cam chain fitted. any how they found that the inlet valves had mushroomed and was unable to adjust the tapets as the inlet valves had pulled through the seats.I read some were that this was the result of poor fuel. at the moment it is running on SUPER and was wondering if we could run it on premiun unleaded?
thank you any more help would be great:) :)
 
Joined
Aug 22, 2000
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#2
Nope, this time it's probably not a problem with the fuel.

Since you're also replacing the timing chain - I'd say sustained high RPM riding is probably the culprit.

Replace the valves with stainless ones (intake and exhaust). this will keep the problem from happening as frequently. Have the shop do a 3-angle valve grind when they install the new valves.

Also, have them check the small end of the rod for excessive pin tip. This would be anything over .004" on either side. The small end of the rod is one of the first things damaged in a high rpm Honda RFVC engine.

Lastly, before you run it again, you might think about gearing it up a bit and short shifting. It should last longer if you do.