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Knocking on Decel

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Alright I just cant seem to solve this problem. I have 94 cr250 bottom end with a 00 cylinder. Has a wiseco piston and seems to run just fine but when I rev the engine it bangs/knocks on decel. I'm running the 00 pwk carb with I think 45p and 178m on 3rd clip. I'm going to try the 48p but it shouldnt make that much of a difference. Anything I'm missing here guys? BTW I'm at sea level and run 91octane

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anyone?

Give the 48 a try but I think a 50 will be the best bet for you. How many AS turns out are you?

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banging/knocking like in the pipe? if so maybe air leak where pipe connects to cylinder?

banging/knocking like engine mechanical noise? check that crank main bearings OK by pushing up & down on flywheel, there should be no play. con rod bearings? piston hitting head? (did you measure squish?)

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Sounds like it could be detonation to me. Try running higher octane and see if it goes away.

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Well I put in new factory crank bearings and seals. I run 91 octane so maybe I'll try some race gas to see if it does anything. I dont think its the pipe manking noise, this is all on decel and sometimes just idling, on the pipe it runs hard and strong, no pinging or knocking. I tried messing with the timing and it did nothing. I also put in the 48p and it didnt do anything if anything it made it worse. It runs strong but this just bugs me and i cant figure it out.

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Im in the process of timing the bike but it seems my Snap on timing gun wont work because the rpm guage is way off, is there a certain timing gun that I need to time the bike?

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check your piston to head clearance, that usually happens on de accel,its the piston just barely tapping the head.Since you are running a newer cylinder you may have clearance issues, maybe not but worth a try

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