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Post by dangerousal on Dec 4, 2017 17:29:48 GMT 1
Hi all..I have what I think is a big standard ypvs engine ...I do not know what bore it's on as I have not had the top end apart yet...I was wondering if anyone has any info on overstroked...and what route they took in getting it built and running....crank, pistons, rods, bore and barrel spacers, porting work and carburetion...any pointers would be greatly received...Al
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Post by oldelsieboy on Dec 4, 2017 18:55:33 GMT 1
Hi all..I have what I think is a big standard ypvs engine ...I do not know what bore it's on as I have not had the top end apart yet...I was wondering if anyone has any info on overstroked...and what route they took in getting it built and running....crank, pistons, rods, bore and barrel spacers, porting work and carburetion...any pointers would be greatly received...Al Speak to Martin @ Mad Biker Designs he should be able to talk you through all of the various options. www.mb-designs.co.uk/page5.phpOEB |
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Post by 4l04ever on Dec 4, 2017 23:33:47 GMT 1
Cranks are available in +4mm +7mm +10mm +16mm ++++
Various manufacturers and prices.
+4mm fits standard YPVS casings.
+7mm and +10mm require trenching of the cases. Bigger may need serious modifications or aftermarket billet casings
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Post by Mr Kipling on Dec 7, 2017 17:56:05 GMT 1
Anything over 68mm bore size starts too get a bit vibey n needs more attention with the cooling side of things...
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Post by peddrotzr on Dec 7, 2017 18:09:52 GMT 1
Anything over 68mm bore size starts too get a bit vibey n needs more attention with the cooling side of things... Sorry but, I have built several big-bore motors for customer's 485 & 535, plus my own TZR535 none of them vibrate, & all are reliable, they just need to be built properly. |
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Post by Mr Kipling on Dec 7, 2017 18:28:30 GMT 1
Sadly due to there design all motors vibrate period 350 motors vibrate more than the 250,s due to the crank not being re balanced from the factory this gets more noticeable as bore size n crankshaft increases , I,m not saying too any point uncomfortable or unreliable but it happens due to the law of physics..
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Post by bare on Dec 15, 2017 18:44:58 GMT 1
No vibes seems as a bit of an exaggeration. Our engines were developed/derived from 250s which are fairly smooth. Certainly compared to a 350.
Unless one can get Much bigger crank counterweights in there (tricky to do :-) the Engine will vibrate.
Only issue is how much is tolerable
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