Blow by or bad valve guide?

[jensen]

Hi,

As there's oil in the muffler, something goes wrong. open it up and inspect (best way), well, I think everyone can think of that. Make sure that the oil level is right and that it's not overfilled.

A quick check (better with someone driving behind you), start accelerating fast, and keep an eye on the mufflers, if they smoke will accelerating it's probably the rings, after accelerating, close the throttle for a short period (preferably at high revs like 8000 rpm) and open it up quickly after a while (when reaching 5000 rpm for example, if it smokes while starting to accelerate now , it are the valves.

The idea is that, if the valves are the problem, oil is sucked in while closing the gas due to the vacuum, and it will not burn directly, but starts burning while opening the throttle again.

When the rings are bad, the engine will smoke during hard acceleration over a long period.

As mentioned, it's better that someone else is riding behind you, but be careful.

there are more possibility's why the an engine is smoking, it could be a bad head gasket (leaking oil into the head while shutting the throttle),

Jensen

[Jethro]

You have a good point RW. And thanks Jensen for the tip on the smoking exhaust. Aside from this issue I also have some bad gaskets and a strange clacky kind of sound coming from the head (is this normal for these old bikes?) so I think I might remove it and disassemble the top end for further inspection. I'm new to these old Honda bikes so I am very thankful for this forum. Thanks again for the input everyone.

Jethro

[rustywrench]

Jethro,
Certainly loose rocker arms can produce some extra noise but there are some conditions involving advance springs, neoprene things and worn advance mechanisms that can/do produce excess noise. All these things I have yet to deal with myself but my turn is coming like a freight train. My advice is use the search feature here and read,read,read. RW

[Spargett]

Jethro, this is getting slightly off topic, but I had the ticking noise due to the neoprene being worn off on my cam sprocket's advancers. Here's what it sounded like.

[rustywrench]

Spargett,
Thank you for adding that link. That gives us a pretty clear idea what clack sounds like. I do know that before I tore this 67 down, it sounded like an old treadle singer sewing machine. Oh,,,,,,,,that may be a little before your time and now I'm dating myself. Anyhow it was pretty noisy. Thanks again.
RW

[Jethro]

Well looks like I have some head work to do here. Thanks for the link Spargett and thanks for the advice RW; I find myself on here more and more often.

Jethro

[jensen]

Hi,

Maybe not worth mentioning, but most information in what state the engine is, is found while disassembling. Check very carefully and take pictures of every step you take, thinks that appears to be normal could be strange after all. Working on an engine which is not working properly will mostly reveal the reason while disassembling,

Jensen