Jump to content
Sign in to follow this  

valve noise?

Recommended Posts

A month ago I bought a 1985 Honda XL 250R. 12000 miles. The previous owner said he had a new piston and rings installed.

The bike runs fine. A few bad threads and some small oil leaks but nothing major. Good power across the RPM range but, is has a serious taping which I assume is a valve. Working with a gage I checked the clearance using the following numbers .05MM (.002) intake and .08MM (.003) exhaust.

The exhaust valves seemed very close so I made no adjustment. I did adjust the intake as they seemed a bit loose. After restart, I still have the same tapping. For a test I removed all play from both intake and exhaust. Now set at zero. Restart and the tapping is still there so the problem is not the valve lash. I then set the valves back to the specs of .002I and .003E.

I wondered if it could be detonation from 85 octane fuel but it's more of a tap then any ping I have ever heard. While the engine is running if I press the compression release lever in with my finger to engage it, I get another similar tap which is in harmony with the original tapping I am trying to get rid of. So it makes me think it is related to a valve.

Now I am wondering if I have a bent valve or what?

Any experts have any ideas?

Share this post


Link to post
Share on other sites

Oh haven yes detonation aka ping noies from low 85 octane will causes that with high compression piston which is a stock 10.2:1 on that bike you should run 93 high octane fuel.

Keep mind that all soild lift will have some tapping noise

Share this post


Link to post
Share on other sites

To the person who move this thread, thanks. I was looking for an engine forum but didn't see one. It's clearly not an injection/jet issue.

Yesterday I did refill the tank with 93 octane fuel. I didn't realize the compression ration was so high. I will need to run it a bit and see if it has any effect but as I said before it just doesn't sound like ping.

I guess I need to find another similar engine and hear how it sounds for comparison.

To fix the oil leaks and some of the destroyed threads I will need to remove the head. When I get around to those tasks I will get a good look at what is in there.

Thanks.

Share this post


Link to post
Share on other sites

Take a close look at the play of the cam chain,when bad enough it can sound like a tapping. Peak into a cam cap at the cam then turn the crank very slightly at TDC back and forth.

Share this post


Link to post
Share on other sites

Thanks, that's a great tip. I was wondering if there was a possibility that some component of the valve/cam system could be in play.

I will check it out.

Share this post


Link to post
Share on other sites

I had a tap sound I could not adjust out as well. what I found was a badly worn rocker arm, it did not destroy the cam, I was able to polish it, but the rocker needed replaced.

no matter how I adjusted it stayed noisy.

I suggest pulling the rocker cover and looking at the cam and rockers

Share this post


Link to post
Share on other sites

I hate to say it but I have owned 4 XL bikes and i know that tapping you are talking about... I am willing to bet it is the cam chain. I know it sounds like tapping and not slapping but like I said I know exactly what you are talking about. No biggie though, cam chain isint that bad to replace you just have to be patient :smashpc:

Share this post


Link to post
Share on other sites

Yes, after tightening up the valves to the point of burning them there is no question it's ware in some part of the cam/chain/rockerarm system. I just put the valves back to spec for now. I wonder if the bottom of the rocker arm bar might have excessive ware. I have seen that in the past due to low oil flow

I will plan on a top end rebuild. It's a 1985 bike so hopefully parts will not be to difficult to find. Does any one know the compatibility of valve train part going up to, let's say 1990?

Thanks for the great hints everyone.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...