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Marks on Stroker Piston

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Just had my 485 top end rebuilt and found some marks on the piston..

The bore is unmarked... just the piston on the intake side..Not sure what they are caused from ..

I haven't seen this from normal wear before ..any thoughts on the cause?

Intake side

044.jpg

Exhaust side looks ok

045.jpg

046-1.jpg

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what does the cylinder look like. you were definatley having ring seal issues. the scuff looks like foreign material or a oiling issue or possibly a cylinder out of round.

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The cylinder looks perfect..Can't show pics as it's now reassembled..

Torqued the head to 45 fl lb this time .with 3 piece gasket and as an experiment used some grey bond on the head gasket..

I have sent Kevin an email about ordering the 94 mm kit for next rebuild..

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you were definatley having ring seal issues.QUOTE]

Are you saying Craigo is having ring sealing issues because he has scuffs on his piston or is there something that is telling you this:worthy:?

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Any thoughts about why the poor ring seal....Do you think it's about running too much compression..? or maybe the 1 compression ring deal ?

I have been getting some audible detonation, but the top of the piston doesn't indicate that..

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Thank You for confirming ...

So when I go to a 94mm bore with the +5mm crank will I need to use a cylinder spacer for the 3 ring piston ? and if so can you supply one?...

Please pass on relevant "bits required list" to Kevin ....Thanks Mate...

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Thank You for confirming ...

So when I go to a 94mm bore with the +5mm crank will I need to use a cylinder spacer for the 3 ring piston ? and if so can you supply one?...

Please pass on relevant "bits required list" to Kevin ....Thanks Mate...

Yes the cylinder spacer is required for use of the 3 ring piston and 5mm stroker crank.... you also MUST degree the cams.

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Yes the cylinder spacer is required for use of the 3 ring piston and 5mm stroker crank.... you also MUST degree the cams.

Yeah...I thought that would be the case.....just fitted the adjustable cam gears I got from Eddie on this rebuild...

retarded the IN. cam and advanced the EX for some more mid range....

I Am keen to ride it but I can't see myself back on the bikes for at least a couple of weeks..

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Thank You for confirming ...

So when I go to a 94mm bore with the +5mm crank will I need to use a cylinder spacer for the 3 ring piston ? and if so can you supply one?...

Please pass on relevant "bits required list" to Kevin ....Thanks Mate...

ok,i will.

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worn,which happens in much less time with a 2 ring piston vs a 3 ring piston.

I am hearing you...This piston has done only 6,500kms (4,000 miles)..:bonk:

I use 15/50 full syn oil with changes @1000kms....

The piston itself has minimal wear (apart from the damage from foreign material ?) but as Eddie said, the rings are cactus....

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