Valve clearance -- DOHC -- Sanity check??

[DanMach]

So I've checked the valve clearance on my DOHC xs400 and was kind of shocked.

The problem I was having is that it was backfiring and refusing to start. This was about a month ago and while I cleaned the carbs right away I also wanted to adjust the valves. I finally found the time and energy to do so.

So I pulled everything apart, lifted the valve cover off the engine, and set to measuring the clearance. I went by the manual which said to position the cam lobe pointing away from the valve and then measure it using feeling gauges.

I came up with these[Left/Right is from sitting on the bike looking down at the engine]:

Left Exhaust - .09mm
Right Exhaust - .08mm
Left Intake - .11mm
Right Intake - .10mm

I have checked these three times and had my brother also check them.

The manual leasts these as the acceptable clearances:

Intake: .11 - .15mm
Exhaust: .16 - .20mm

So you can see that the intake is just on the inside of that range, but the exhaust is far more off. Is this considered a normal range for something to be off? I've never done anything with valve adjustments before and I don't know if .07mm is normal, or possibly an indication of something else??

Thanks in advance everyone

 

[drewpy]

its the valves seating (recess) into the head.

re-adjust them and check again 500 miles later. if they have closed up again, the valve seats need looking at.

 

[DanMach]

Awesome, thanks!!

 

[DanMach]

Grrr!! I cannot get this frigen tool to work. I've tried it a dozen times and the valve never stays depressed. I can't see into it clearly enough to gauge what its doing either.

This is driving me nuts.

 

[lhaolpa]

Do you have a manual?The manual shows clearly how to adjust them. The valves are adjusted by changing shims.The tool is placed to hold the lifter,under the shims to release the shim for changing.You have to turn the cam the proper direction or risk breaking the lobe or cam.If you don,t have the manual,download it from this site.Don't try to change shims without the right info and tools.The manual can be found in the tech pages or in the links section. Some unlearned owner must have adjusted the valves too tightly so that it wouldn't sound so loud,not knowing that that would burn the valves and make them leak. lha

 

[DanMach]

Yes I have the manual, and yes I know how to do it. The issue is not in the procedure but the tool. If you google the tool you will see other people having similar complaints about it being very difficult to get into the 'sweet spot'.

That is the issue I am having and I was hoping someone could illuminate the issue for me and provide a solution.

The risk is in breaking the head, not the cam or the valve. The tool attaches to the head and if you turn the cam into the tool the tool will exert pressure onto the head and crack it. Which is also mentioned in the manual. I am not trying to change the shims without the proper tools or manual. I have both. Which is why I said "Grrr!! I cannot get this frigen tool to work.".

Thank you for the input though.

Cheers.

 

[lhaolpa]

I didn't have any problems,just followed instructions,and worked carefully.I've done the same thing on DOHC cars with shims. lha

 

[DanMach]

Well I figured it out, it is really easy once you figure it out. Admitelly, its something I'm sure a lot of people didn't need to 'figure out'.

Anyways, for historical sake:

The tool will be very close to the cam(as in virtually touching it, but not the cam lobe.). Also, if the tool is moving at all when you move the cams you need to tighten it down. On the right side there are two metal.. shafts? There maybe spacers? Not sure what there function is, but I had to use them, longer hex bolts, and a washer to get the tool to stay in place on that side.

Thanks all!