[dspych]

So I ran into a bit of a problem adjusting my valve clearance. I was able set all of the valves to .03 mm clearance except for the left intake. I cannot get my feeler gauge in there no matter the position of the adjuster. Any thoughts? Any reason that I could set all of the other valve clearances except for that one? I even tried a thin piece of foil and it wouldn't clear. I am at a loss.

 

[66Sprint]

The left cylinder was at TDC on the compression stroke...Correct?....(You ARE gauging between the tappet and the cam, not at the valve aren't you?)
If so, you could have a worn tappet, although the exhaust sides tend to go first....

 

[Odin]

I have the exact same problem, except its the right intake I could not adjust. still don't know what to do.

 

[450roo]

have you checked to see if you have a sticky valve? If you do there will be low compression on that cylinder.

 

[dspych]

I have been checking clearance between the Cam and the tappet, and I have also been doing it at TDC for that cylinder. Also, I do not think that a worn tappet is the issue, as I have zero clearance; if it was worn, I believe that there would be too much clearance. My only thought is that the valve may be coming up too high, and it is pressing up against the tappet, forcing it against the cam at all times. Not sure if this is the case, and also not sure how to remedy the problem if this is the case.

 

[tbpmusic]

I have been checking clearance between the Cam and the tappet, and I have also been doing it at TDC for that cylinder. Also, I do not think that a worn tappet is the issue, as I have zero clearance; if it was worn, I believe that there would be too much clearance. My only thought is that the valve may be coming up too high, and it is pressing up against the tappet, forcing it against the cam at all times. Not sure if this is the case, and also not sure how to remedy the problem if this is the case.

Did you have new valve seats cut??

An old remedy from lawn mower days was to actually grind down the end of the valve. Never seen or heard of it being done on a Honda twin, though.

Are you sure you're on compression stroke??

 

[dspych]

No new valve seats were cut, and I am at LT when the timing marks are not lined up...the motor tries to "run by" at this point, so I am confident it is TDC on the compression stroke...

I am going to work on it now, and see if the tappet is not seated correctly on the shaft, or something weird like that...

 

[MNellis]

No new valve seats were cut, and I am at LT when the timing marks are not lined up...the motor tries to "run by" at this point, so I am confident it is TDC on the compression stroke...

I am going to work on it now, and see if the tappet is not seated correctly on the shaft, or something weird like that...

It could just as easy try to "run by" even if the LT is lined up but on the exhaust stroke since the right side will be on the compression stroke and trying to do the same thing. We're just trying to confirm things here. The best way is to watch the exhaust valve compress as you rotate the crank and the look for the LT as the exhaust valve starts it way back up.

 

[66Sprint]

I find it easier to watch the Left intake and set to the first TDC after it closes.....

 

[MNellis]

I find it easier to watch the Left intake and set to the first TDC after it closes.....

I agree except if the tank is on it's a lot tougher to get the valve cover off the intake side than it is the exhaust side.

 

[dspych]

Well, I have tried it both on the compression stroke at LT (when the timing marks on the cams DO NOT line up), and then one rotation from that, and neither have clearance. I can guarantee that there is no clearance at any point throughout the the whole stroke, as I tested every ten or so degrees for two whole rotations. I have pulled the engine out of the bike and am going to remove the head tomorrow to see if I put something together weird. I will let you know what I find.

 

[66Sprint]

The tappets wear concave so it can be difficult or nearly impossible to fit the feeler if the clearance is too small or the excentric is in the "wrong' half rotation....

 

[tbpmusic]

"dspych", I need to apologize to you - I just ran into the same thing on a customer 450 today.
Can't get any clearance in the right intake.
In this case though, the tappets and valves are all brand new, but we had new valve seats cut - so looks like the machinist may have taken it down a bit too far.
I'll have to disassemble - I'll try a new tappet shaft, but I don't think that will do the trick, gut feeling.
I may end up grinding a bit off the end of the valve.

First time I've run into this in over 40 years of working on 450's - just goes to show 'ya (or me, specifically) that it pays to stay humble.
No matter how much you think you might know, or how experienced you might be, that there's always something to learn.

Now I know this doesn't help your problem, but thought you'd like to know that you're not crazy, and that I can sometimes be short-fused and dismissive- my apologies, I guess it's part of getting old.......

 

[luketrash]

I ran into this problem because I didn't read far enough down in the service manual in my case.

I'm dealing with the CB350 rather than a 450, but it sounds similar.

At the LT mark I had the left intake and exhaust valves and right exhaust valves loose (move around by finger) but I couldn't figure out why the right intake valve was tight.

I had to read the service manual again to see that you set valve clearance for the right side of the engine by turning the engine over counterclockwise to the L mark after you've done the left side (duh). At that point it frees up both right side valves.

I might be stating the obvious here, but it was a brain fart on my part. If one of the valves is tight, put a wrench on the engine and slowly turn it to find the point at which the camshaft has released the rocker to the loosest it will go. Ignore the marks on the rotor since it's just a test to see if you really do have damage/wear to the valve seat to the degree that the valve is constantly in contact with the rocker.

 

[luketrash]

It was just a suggestion to find out if the valve ever does come loose. The cam chain could be off or something. I wouldn't use it as a way to set the valve clearance, but more as an investigative step.

 

[dspych]

So, I know that this is old and dead, and no one is probably still reading this, but I did end up disassembling over the summer, and comparing the valves, one was considerably longer than the other! It was an easy fix to knock it down with sandpaper on a piece of glass to bring it within spec. I reassembled and had no problems getting the correct clearance. I hope this helps if someone else has a similar problem.

 

[Znabb]

Thats strange. Did you measure how much difference there was between the valves?

 

[dspych]

I did a rough measure. It was probably around half a millimeter. It was weird to be sure. I certainly didn't think that I would need to measure the valves to make sure they were within tolerance before I put them in! Oh well, I guess thats what I get for buying non-Honda parts.

 

[tbpmusic]

....It was probably around half a millimeter. .....

That's all it would take.... glad you got it dealt with.

 

[nigelrharris03]

A cautionary note to us all not to chuck away the old part before checking the new against it.
Still at least the problem is resolved which is a bonus, and you can enjoy riding again.