Valve clearance question

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pleasefixitup

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When moving the motor to check clearances, when I am at TDC on the left side, I am having HUGE clearances. My dad says something isn't right, it doesn't happen on the right side. There is a lot of room between the rocker arm and valve stem. It does get tight later when the piston goes through its stroke but after it's loose as a goose.

The book and internet make this look really simple but my bike hasn't moved in 8 years and I'm not sure how out of spec it is.

Thanks.
 
Check compression is there ANY on that side? put some air in the plug hole with the piston on TDC where does it go? If you are SOOL you have bent valves. If you are real lucky a dumbass PO misadjusted the valves, set em and fire it up. A third possibility is described in this thread. http://www.xs650.com/forum/showthread.php?t=11693

Pull the carbs and exhaust see what you can see.
 
The motor runs but is loud.
The compression feels good, I will test it.
The valves move fine, I don't think any are bent.

Its only at one point in the stroke that the valve clearance is so high.
I do see carbon build up!
 
I could be checking clearances at the wrong stroke, I think I'm having issues finding the compression stroke for a particular cylinder.

I think the P.O. misadjusted them--but I'm scared he rode the bike with them that way.

I have excessive clearance at one side only, I checked my cam chain adjustment and it's flush except for one small "pop" out of the guide during the stroke.

I'm confused why I have so much clearance on only one side!!!!
 
The valve stems are completely covered with carbon, it looks like it would stop the valve from fully seating. The head of the valve looks ok, same with the seat--but the entire area of the exhaust valves is covered in carbon.
 
The exhaust always are carbon covered, all we are concerned about is the thin ring where the valve touches the valve seat when closed. The stems are fine, never hurts to hit them with a bit of rust buster between the springs.

Here are some pics from a hot rod 750'd engine with leg bursting compression.

madness 010 (2).jpg

madness 009 (2).jpg

madness 011 (2).JPG

madness 014.jpg
 
pleasefixitup said:
I just checked and the right side tappet isn't hitting the center of the valve stem. It's just a little off.
Click to expand...

That's not a big deal see it all the time.

madness 016a.jpg madness 017r.jpg
Couple of shots from that pro built engine. One is not ideal but not unusual either.

Just set your clearances, see what it runs and sounds like.
You are kinda new to whole 4 stroke engine thing? The cam pushes the lifter up which pushes the valve down. The only time there is supposed to be clearance is on the compression stroke. The clearance is measured at TDC. remove the LH round alternator cover, rotate the engine with the 17mm nut until the the mark on the rotor aligns with the T line on the timing marks. On one side both valves will be loose, measure and set those two. Then rotate the crank one full revolution until the rotor mark aligns with the T again now set the other two valves.
 
that is what I was doing but the amount of clearance was HUGE. it's like a few 16ths.

I'll take pictures tomorrow.

I'm thinking the valves are not seating right.

Yes, I am new to the four strokes. I remember building them in high school and I did build my 88 bmw but it's a car with computers controlling everything.

It's so much clearance that it's like the valve isn't coming all the way up.
 
Another possibility that may make sense is if the previous owner incorrectly set the valve lash for all 4 valves while at right cylinder TDC. A way to confirm this is to check the left cylinder valve lash while at right cylinder TDC. If the clearances are found to be closer to normal, then this scenario is likely...
 
If the valves were not closing all the way, you would have no compression on that one cylinder. The bike would run on only one cylinder, the other one. You said it ran pretty good, just noisy. I'm thinking the valves are just set wrong.

To determine when the cylinder is at TDC on its compression stroke, watch the valves on that cylinder open and close as you rotate the engine by hand via the 17mm nut on the crank. Watch for the intake valve to open and close, then the exhaust valve, then the intake again. After the intake opens and closes again, start watching the rotor mark to align it with the TDC mark. Do that BEFORE the exhaust opens again and you will be at TDC on the compression stroke for that cylinder.
 
so after the intake opens twice, find the mark on the stator and I'm at TDC?

I think they were adjusted per the wrong cylinders.

I am new to motorcycles, so I'm getting used to all of this stuff--but I love learning about it.
 
Yes, TDC on the compression stroke, which is what you want for valve setting. During the course of its 4 strokes, each cylinder actually reaches TDC twice. Once is on the compression stroke and then again on the exhaust stroke. You want it on the compression stroke for valve setting. Something else you have to realize is that even though the two pistons on these bikes move up and down together, they're not on the same stroke. While one side is coming up to TDC on its compression stroke, the other side will be doing so on its exhaust stroke. That's why you can't set the valves on both cylinders at once, at the same TDC setting. It requires another full revolution to bring the other cylinder to TDC on its compression stroke. The one you just set will now be at TDC on its exhaust stroke.
 
I still am having all this excess play. I don't know where or why it's happening because my valves are seated and they are moving.......


Bike runs...

What could make one side have all the play.
 
sometimes we don't catch everything you do or don't know how to do. Have you loosened the locknuts and set the clearance using a feeler gauge?
 
https://sites.google.com/a/umn.edu/xs650-repair/our-bike/exhaust

search "3/16" or "rocker arm" on that page.

It talks about so much carbon being on the valve stem that there is about 3/16in play.

I am having this issue of "play"

I just used a gun kit to clean the valve seats. Ok, that was a great idea!

I cleaned up so much crap and I feel confident about how they're seating.

I sprayed pb blaster in the valve springs and on the valve stem.

I set clearances but is there any point when the motor is moving that one side of the motors would have 3/16 inch play at the rockers?
 
No TDC where you set the gap, is the point of greatest clearance. It is the center of the "base circle" on the cam, after that the ramp that opens the valve reduces clearance until the valve starts to open.
 

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