Topic: 1975 CB400F Crankshaft/Case Questions

[ttr400]

This is common on the 400's that i have done over the years.
The gold colour is i think Aludine coating. not sure why Honda did this, Aludine coatings can be done on aluminium surfaces to give extra protection or as a base/primer prior to painting.

I doubt you have mismatched cases, but easy to check if the engine is apart. bolt the cases together and mic the bores. but if it's been running for years then i don't think you have anything to worry about.

Kevin

[CB400JAY]

This is common on the 400's that i have done over the years.
The gold colour is i think Aludine coating. not sure why Honda did this, Aludine coatings can be done on aluminium surfaces to give extra protection or as a base/primer prior to painting.

I doubt you have mismatched cases, but easy to check if the engine is apart. bolt the cases together and mic the bores. but if it's been running for years then i don't think you have anything to worry about.

Kevin

Thanks so much for the explanation.  Makes a lot of sense.  I didn't know that only the top case was painted at the factory. What made me think the cases were mismatched was the color and the lack of dowel pins.  Everything looks good and I am sure that all is OK and the cases were in fact matched. As this is a very early example maybe that explains the lack of dowel pins?  I will be a installing one of your cam chain tensioner horseshoes.  Nice work!!

[bryanj]

Should all have dowel pins to locate for machining, fit pins and mate casings the see if one half is offset to the other at the bearing locations, if there is a feelable step with your fingernail they are mismatched cases

[754]

 If they  are mismatched,  and the case is not closing at the join line, next step would be ...remove dowels to allow it to line up..

[CB400JAY]

I installed a new set of dowel pins and plastiguaged the crank.  Everything is fine, no issues.

[754]

And transmission bearings fit bad cases squeeze together by hand, correct ?