impact of valve clearance being too low

[dansmith65]

I bought an 80 special last summer and have only ridden it home and started to work on it so far. It's got 34,800 km's (21,600 miles) on it and I don't really know it's history. I just checked the valve clearance, and they are all too small. I'm wondering if, because of this, I should take the head off and inspect the valves for damage/wear? It seemed to run pretty well before I took it apart: here's a video of it: https://youtu.be/AVO1pdY1dUk

Exhaust: (target: 0.21 - 0.24mm)
1. 0.178
2. 0.152
3. 0.178
4. 0.152

Intake: (target: 0.11 - 0.15mm)
1. 0.102
2. 0.076
3. 0.102
4. 0.076

[DiverRay]

I would not worry about it yet. Adjust the valves, warm it up, and do a compression check. If they are all within the 10%, even if low, just ride it hard for about 700Km. If they ARE over 15%, then yes, probably need to pull the head and look. JMHO

[MPittma100]

Valve lash

I agree. Adjust the valves first. Run compression test (WOT). If any are too low, run a cylinder leakage test prior to any tear down.

[dansmith65]

Thanks for the advice, I'll try that.

[MPittma100]

Mechanical cam valve clearence

In the OHC engines, the valve lash gets smaller with valve train wear. A pushrod engine does just the opposite - lash increases with wear.

I bought an 80 special last summer and have only ridden it home and started to work on it so far. It's got 34,800 km's (21,600 miles) on it and I don't really know it's history. I just checked the valve clearance, and they are all too small. I'm wondering if, because of this, I should take the head off and inspect the valves for damage/wear? It seemed to run pretty well before I took it apart: here's a video of it: https://youtu.be/AVO1pdY1dUk

Exhaust: (target: 0.21 - 0.24mm)
1. 0.178
2. 0.152
3. 0.178
4. 0.152

Intake: (target: 0.11 - 0.15mm)
1. 0.102
2. 0.076
3. 0.102
4. 0.076

[dansmith65]

Got my cams out and current shim size logged. After shuffling the shims I have around, I should only need three new sizes. Does anyone out there have these they could send me? If so, let me know what you want for them:

• 265
• 275
• 280 x 2

P.S. I have both a US and Canadian mailing address, so you won't have to bother with mailing to Canada.

[jetmechmarty]

If you have no luck here, try your local Yamaha dealer. Mine charged me $5 each. Jets-R-Us has 29 mm shims for your bike.

[DiverRay]

let me look in my stash. I think I have the sizes you need, as they are the larger ones. I'll send you a pm if I have them. OK, just checked and I have the two 280's. if you need them, send a pm and pay shipping cost.

[motoman]

dansmith, keep in mind also, that vintage and a bit later Kawasaki shims are same millimeter shims. That adds to your options.

[dansmith65]

jetmechmarty,
Thanks for mentioning Jets-R-Us, they are on my list of parts suppliers, but I didn't think to check them for shims. I'm taking my carbs apart now, so I might need parts from them anyways (TBD).

My "local" Yamaha dealer is a few hours drive away (I live in the "sticks"). I did check the motorcycle shop in town, but they didn't have any 29mm shims. I know I can order them online from various places and will do so if needed. My main reason for posting here before ordering is from reading old posts; multiple times I've seen someone say they just ordered shims and someone else say "you should have asked first!"... So I'm asking here first since this is such an awesome, helpful community!

DiverRay,
Thanks, I'll give it another day to see if anyone else replies, then I'll get back to you.

[TopCatGr58]

Your in LUCK

Hey Dan,

Okay, Diver has your 280's, and I've got your 265 and 275, just had 1 of each, all of the rest of mine were 280+.

So...send me a PM with your snail mail for USA, and I'll get them off to you ASAP. BTW, the size stamp was a little difficult to read, so I checked them with my Micrometer for true accuracy.

T.C.

[dansmith65]

Thanks! PM's sent to you both.

[dansmith65]

Thanks again; picked up the shims this weekend... sadly I didn't get a chance to put them in Will post an update when I do, though.

[dansmith65]

Finally got the valve shims in, new measurements are:

Exhaust:

1. .203
2. .254
3. .229
4. .229

Intake:

1. .127
2. .127
3. .127
4. .127

Compression before valve shim adjustment:

1. 154
2. 142
3. 140
4. 147

Compression after adjustment:

1. 105
2. 72
3. 75
4. 98

Not sure if it matters, but the "after" compression test didn't have carbs, exhaust, or any spark plugs installed.

It seems to me like this means the head has to come off; does that sound right? Is there anything else I should check before I do that?

Also, I noticed I need a new cam chain. My tensioner has very little travel left; I didn't measure it, but it's probably only a few mm.

[bikerphil]

I would not take the head off until the motor has been run a few hundred miles. The rings are still stuck from long period of non-use. Those numbers will come up after some use, they always do. JMHO