1977 Yamaha IT175 Engine Cases

[mnein]

Question on a rebuild of the title bike - is it acceptable/immoral to mix engine cases (i.e. use cases from two different engines) or are they machined and intended to be used as a set? IT 175 cases are vertically split, and on mine one case side has major kickstart shaft and pocket damage. Thanks!

[m in sc]

they are not line bored at the factory contrary to popular belief. so should be just fine. i've done it on other motors, including vert split ones.     

[mnein]

Thank you M in SC!

[RDnuTZ]

I have had mixed success with this on my Vintage Yamaha dirt bikes. Have multiple 1975 MX400B and 1 that ran perfect in races but had a broken mount for countershaft cover from a previous chain hit. Swapped on a Left center case from a parts donor basket case motor and the bike developed an air leak I could never track down that causes unpredictable WOT- usually on race starts- FUN times! I'm swapping back on the case with broken mount tab when I get time.

Also had a project 1987 YZ490 that had notorious kick start backlash case damage. Swapped on a new right center case from a YZ465 bought on Ebay that fit/ran perfectly. I opt for complete set of matching whenever possible nowadays.

YMMV

[mnein]

Thanks RDnutz for your contribution. If my fantasy of putting a bushing in the kickstart hole pans out I may be able to use these cases, otherwise I'm at the mercy of ebay. Yamaha must have had a thing for kickstart shaft/pocket damage, every shaft I see on ebay has damage. BTW, you like your big bore 2 strokes I see!