Valve Maintenance Question

[Meista007]

I was running my bike (1979 Special) on the freeway and when I stopped it had developed a top end engine tick. When finding someone to fix it failed the bike got put on a shelf but motivation has returned and I'm fixing it myself.

My plan is to check the valves and make the enhancement to a automatic cam chain tensioner.

So last night I pulled the valve cover off with the intention of checking my valves to ensure they were still within spec but I ran into a problem. My Haynes manual has the spec clearance as .0004-.0016 but I can't find feeler gauges that are that thin. The thinnest I could find was .0015 and while that is right at the top end I would rather aim for the middle.

I need to know if I'm looking at the wrong numbers, going the wrong places to buy tools or just plain crazy. Can you get feelers that small? Should I go to a Yamaha dealer?

[jetmechmarty]

First, the Yamaha dealer doesn't want to see you or your bike, unless you're buying a new one.


Exhaust valve clearance (cold):
0.008 to 0.010 in.

Intake valve clearance (cold):
0.006 to 0.008 in

[donebysunday]

Valve Maintenance Question

Snap On was the last place I looked and found what I needed but there must others.

[jetmechmarty]

Page VII Quick Reference Data in the Clymer book has valve clearance specs. They match the Factory Service Manual.

The metric specs are given and may make things easier for making adjustments if you have metric feeler gauges.

The specs given are pre 1980. As has been hashed out on this forum, the early spec is acceptable for the later bikes.

[Meista007]

That's the book I have...I must be looking at the wrong numbers because the ones posted are much closer to what I would expect.

I wonder what numbers I was looking at.

[jetmechmarty]

That's the book I have...I must be looking at the wrong numbers because the ones posted are much closer to what I would expect.

I wonder what numbers I was looking at.

I suspect you were looking at valve stem clearance in the engine overhaul section.

[TopCatGr58]

Miesta,

Marty has given you some good info, but you said that it was ticking after a highway run. The way these engines wear is that the valves slowly beat the valve seat INTO the head, this actually REDUCES the valve lash clearance, and they won't make as much noise because the valve/bucket/shim is closer to the cam.

However folks have reported that the top end is rather noisy to begin with, and can get a little more when the cam chain tensioner gets slack, then the cam chain can slap as it's running across the top bridge between the cams.

Checking and setting the cam valve shim lash is good, and setting it really to the larger setting will allow you to go longer between the need to check/change the shims, but the top end will be a little noisier. Also the performance might be a little off, but I don't think you would be able to perceive the actual difference running at the max spec vs the min spec.

If you wouldn't mind telling us WHEN it was that you parked it, how many years or decades ago it was?

T.C.

[Meista007]

Thanks for all the info!
From researching on the site I thought the 2 main things I needed to check was the valves and the cam chain. I'm doing a full restoration again now and figured it would be best to open it up and check everything. I was only confused because I was looking at the wrong numbers (dumb mistake) and couldn't find feelers small enough to use.

I restored the bike the first time when I was 21 but didn't have all the money I needed to do everything. The bike broke about 5 years ago and I was in the middle of building my house and had no time to dig into it. With other bikes to ride and not a lot of free time she has been sitting under a cover in the back of my garage. While spring cleaning the garage I pulled the cover off and the itch was back…so she is out and on the bike stand all apart and getting ready to hit the road again.

This bike was my dads, he bought it in 1980 slightly used and it sat for about 12 years before I restored it the first time. It will be nice to have it back on the road and I appreciate the help.

[jetmechmarty]

Hurry it up and you can still make the last rally of the season end of Sept. We could use a few more younger folks like you.

[Meista007]

I checked clearance today and here is what I found.
Do I need to swap out shims? There are 2 intake valves just out of tolerence.
The bike was running well when I put it up but had a tick. I believe the tick was the cam chain and that problem is being addressed.

Intake:
#1: .007
#2: .005
#3: .006
#4: .005

Exhaust:
#1: .008
#2: .008
#3: .008
#4: .009

[DiverRay]

I would pull the shims from 2,3,&4 to see what they are. 2&4 MUST be changed, 3 is at the bottom so I would also change it if you can put one from 2 or 4 into it. The local shop should "swap" shims with a small fee, $2.00 at most. Remember that the shims are marked in METRIC, so use the chart in the book to get the proper shim. I expect one size up on #3, and two sizes up on 2&4.
For the cam chain, look into the "replacement" adjusters. Ebay has them off the VMax or Venture V4 engines that will bolt in place. Once installed, no more adjustments until you need to replace the chain.

[Winterhawk]

You never said how many miles are on the bike?

Exhaust leak maybe at the header piper.

[Meista007]

This was the answer I expected but not the one I hoped for.
I need to look into the process but I'm not really interested in messing with cams.

The bike only has just under 18,000 miles.

[IanDMacDonald]

Replacing valve shims is just about the easiest task ever after removing all 372 allen head cap screws on the valve cover! Get the MP valve tool (same one for the 750/850), and ur golden!

[Meista007]

I have one more question before I move forward (can't do anything till the tool comes in the mail anyway).

When checking the gaps I ran into a bit of confusion as to where the cam should be when testings. Normally on a car I would expect the cam to be 180 from the open (wide side) of the cam when checking the gaps but I noticed that when at top dead center the cam was about 45 degrees away from what I would expect. Since this is the bikes top dead center position I check the clearance on all of the valves at this position. Did I do it correctly or should I have measured them in a different position?