Honda Twins banner

1 - 9 of 9 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter · #1 ·
It's been a while, but I am digging in to my Bike again. I had a good amount of smoke coming out of my right side exhaust, so I took the top end of the engine to an engine guy. He took one look at it and said I need the cylinders bored, a hone wouldn't do it. He thought a 70.75-71mm would do the trick. I have spent the last hour scouring the internet for oversized pistons but haven't seen anything. Wondering if anyone has any experience with this.

Thanks
 

·
Registered
Joined
·
13,085 Posts
It may - I'm not versed in the SOHC 400/450 series, but one of the knowledgeable members will be along to answer that soon. You can always go to cmsnl.com, look up both bikes and check the part numbers for parts to compare... many times over their history, parts will fit multiple bikes and the part number comparisons will confirm that
 

·
Premium Member
Joined
·
24,208 Posts
The cylinders for the 400 are all pretty much the same. The early versions, 78/79, had an extra oil galley in the base that needs to be plugged on late engines.
1978/79 engines used a domed piston, 1980/81 used a reduced dome. The early pistons can be used with an early head. eBay seller Cruzin Image has the early pistons
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #6 ·
Thanks longdistancerider. I placed an order from cruzinimage, I went with the CB400's based on the picture because looking at the CM's on their site they looked different than the ones I took out (flat head in picture)...maybe just the wrong picture but maybe not. Hopefully all works out, really want to get this on the road this summer!
 

·
Registered
Joined
·
1,573 Posts
I have a good cm 400 cylinder if it works out that you need one. I bought it for my cb 400 cleaned it up and honed the cylinders for stock pistons. I found a good cb400 cylinder so dont need the cm400.

Bill
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #8 ·
Thanks Bill. I Will keep that in mind. Because I am going up in size on the cylinders do I need to find a oversized head gasket or will the standard size work
 

·
Registered
Joined
·
2,475 Posts
As long as you are not going to a much larger overbore (like over 1.0mm) you will be fine to use the stock gasket.
TOOLS
 
1 - 9 of 9 Posts
Top