P200 Engine
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Member
1981 Vespa P200E
Joined: 31 Jan 2019
Posts: 13
Location: Southern California
Fri Sep 06, 2019 11:09 pm quote
Any experience with building P200 motor with crankcases that have un matching stamped numbers? If so what was result, did it leak, hold compression... thoughts please, Thanks.
Addicted
GL, PK, PE200
Joined: 24 Apr 2012
Posts: 661
Location: Deep in the heart of Texas
Sat Sep 07, 2019 5:43 am quote
Many have done it and able to hold compression and not leak. The problems comes later if the two halves dont align the crank properly. May not able to tell when install but if incorrect the misalign crank can cause problems at some time in the future.
Member
1981 Vespa P200E
Joined: 31 Jan 2019
Posts: 13
Location: Southern California
Sat Sep 07, 2019 6:19 am quote
This is what Iím hearing from other forums... that the two cases are machined together so by mismatching them that leaves the possibilities of layshaft, crankshaft and driveshaft not running straight and would be a no bueno... which makes perfect sense to me... others have said theyíve pulled it off.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1560
Location: Veria, Greece
Sat Sep 07, 2019 7:35 am quote
I had built a mismatched motor on a friendís Cosa I, cause he wanted his electric starter back (old big half, had a damaged rotary from a small screw he lost down the carbís throat) from his first damaged motor. We couldnít find a decent complete set so we decided to risk it. That was 4 years ago. Itís still going strong with almost 36k Kms on itís back so far. We only do the usual maintenance (engine oil, spark plug, etc.). Cases were 328 & 843. Coincidentally they matched perfect on the cylinder surface although I gave them a lapping just to be sure...
Molto Verboso
Joined: 26 Oct 2015
Posts: 1635

Sat Sep 07, 2019 8:33 am quote
I've also done it before for a friend. I didn't notice any ill effects. Unlike SaFis, I didn't match the cylinder surface, but it would have been a real good idea.
Molto Verboso
1979 P150X, 1983 P200E, 1987 T5, 1996 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 1560
Location: Veria, Greece
Sat Sep 07, 2019 8:41 am quote
David, I commented on your FB post. Those aint the numbers you need to worry of. Check the cylinder sealing surface like the photo in my comment...
Hooked
P200e
Joined: 13 Feb 2017
Posts: 101
Location: Eureka, Ca
Tue Sep 10, 2019 8:00 pm quote
I've got mismatched cases on my p200. I've put 4,000 miles on it in the last couple of years. There is a very slight step (.002") between the two cases where the cylinder mounts. I just cut a piece of shimstock and it's been fine.

Most of the bearings are balls, i can't believe a tiny bit out of alignment is critical
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