Just did a complete top end rebuild on an 80 185. Replaced the head with one from Ebay as the original one was shot. Cam lobes ground down to almost nothing as well as rocker arms shot. So I just replaced the whole head assembly to start fresh with good parts. I check valves and guides. Looked good but I did lap the valves just a bit. Replaced valve guide seals, etc, etc. Checked the cylinder and piston. Cylinder walls looked good, no scratches, grooves or glazing. Piston also looked good, skirts, etc. Top of piston was very clean also. So I put the piston and cylinder back together, didn't hone or change rings though. Put everything back together. Started it up and it smoked pretty good and was spitting a black oil type of stuff out of the exhaust. Not a steady stream but once you shut it off, you could see the film on stuff. I did put fresh oil in during the rebuild and had used the good old assembly lube to put things back together. Only has a few hours of run time since rebuild so oil is still clean. But looks like it is using oil as it was low. Back in the old days (the 70's), I rebuilt more 70's, 90's etc single cylinder and twin cylinder Honda's than I can remember. So I've been there, done that many times. Before I tear this thing down again, Is there anything that I could have missed or should check (besides rings and that). The bike did smoke before the rebuild only much worse than now. Since rebuild it runs very strong ans starts on the first pull. BTW, the plug is not fouling and looks clean, no oily stuff on it.

Suggestions anyone??? Thanks

 

Just a thought....If it was smoking prior to rebld and was ran a good bit, then there is oil in the pipe and it will smoke until it's burnt out or you clean it out.

 

Hmmm, Interesting thought. I will check that. I have a piece of straight pipe I can temporarily put in and see what happens. If that's the case and the muffler, etc does have oil in it from before, how in the heck would you be able to clean that out.

Thanks for your tip!! I will see what happens.

 

Did the oil ring get put in upside down?

 

Nope. I never pulled the rings off.

 

You can wash the oil out with gas. Make sure you let it dry VERY well before re-install...

 

My two cents worth
Seen this on cars with chrome molly rings
When you removed the piston from the cylinder
and inspected all was cool So you decide to reuse piston and rings
Ok
But while piston out of cyl rings get rotated on piston
So when reassembled rings are not in same orientation as they have been for some 20 years
At this time best way to describe
Square peg in round hole
So what you probably need to do is reseat the rings to the cyl or basicly now make the rings fit their now new enviroment (no I am not going green)
So go to the grocery store
Get some Bon Ami Cleanser
This has Pumis which will act like when you ysed valve lapping compound to seat valves
But
Remove air cleaner
Fire up engine
Dust the Bon Ami in cyl
and Yes this will hone cyl and seat rings
you may have to give this a go a couple times
But it works on automotive engines and boats to seat rings with same issue
single cyl just smaller scale same issue

But don't get carried away a little goes a long way
Then change oil after ride about 10 minutes
Just a thought
but worth a try
Worst you would have to do is remove head and cyl and rerring
Thanks
Ray