More questions

[DEmily]

Guys,

I am not the experts that you all are but I ponder this: If he has any clearance at all the valves are closing right? Maybe not when the engine is running. maybe like a floating valve?

[MartyA]

Yes, and maybe, that's what I am thinking. He had the exhaust valves replaced. Intakes were not replaced, and he can't get a 0.06mm feeler under the intakes. The compression is too low on 3 cylinders and adding oil doesn't change that. But there is some compression. So when the engine is cold the intakes *might* be closing just enough for a compression test.

But if any valves are staying open from the clearance numbers teck says he has the intakes would be suspect. Wouldn't that light up the carbs? Backfire?

Ken mentioned the wrong feeler gauge, might be something there. Spec is Exh = 0.21- 0.24 mm or .008" - .0095".
Intake is 0.16 - 0.20 mm or .006" - .0079".
The guy could have used a .06 mm feeler thinking it was .006", but that would still give .002" clearance.

What else might cause low compression readings? Head gasket leak? If the guy who did the valves had the wrong feeler gauge, what else might be wrong? Valve seat ground wrong?

Could the cam be out of time with the pistons? The cam chain was off, teck says the dots line up on the cam sprockets, but is the piston at TDC?

Need more info I guess.

[DEmily]

Well, I would be looking at the head gasket. I had lost compression on two and three down to 90 lbs. Brand new everything in the motor. Realized that I had put the gasket in that goes between the jugs and the head for the cam chain cavity but the head gasket I had was made to not use one. I retorqued the head three differnet times after warming the engine up and finally all the compression was back. Runs great now.

[teck_mountain]

Valve issues

Hi

Okay, I'm off to remeasure with the cam lobes at the lowest point. I'm going to pull the cams then remove the shims to identifie the size.

Stay tuned

[teck_mountain]

Measurements and Shim sizes

Hello

Okay measured, tested and pulled the shims from my 79 xs1100 special.

Compression

1-110 2=85 3=72 4= 80

Cam to shim pad measurements

Intake
0.06 mm the smallest I have and I couldn't get the feeler to budge

Current shim sizes (intake)

1=265 2=270 3=270 4= 280

Exhaust

Cam to shim pad measurements

1-0.08 mm okay 2,3,4 = 0.06 the smallest I have and I couldn't get the feeler to budge

Current shim pad size (Exhaust)

1=290 2=290 3=295 4=295

What should I be doing?

[MartyA]

Let's assume you have some compression, and the valves-shim clearance is 0 for those where you can't get .06 under. You will probably have to do this more than once, since you really don't have a starting number. You need thinner pads.

Since you don't have excess clearance, simply subtract the nominal spec from the pad you have, round to nearest 05.

Intakes - clearance is 0.00, spec is .19:
#1 - 265 -19 = 244 = Pad #245
#2 - 270 -19 = 251 = 250
#3 - 270 -19 = 251 = 250
#4 - 280 -19 = 261 = 260

Exhausts
#1 - 290 -15 = 275
#2 - 290 -23 = 267 = 265
#3 - 295 -23 = 272 = 270
#4 - 295 -23 = 272 = 270

This should get you in the ball park, assuming nothing else is wrong. Be sure after you replace the pads to turn the engine a couple of times by hand to settle the pads in. Then check the clearance. If it is close to specs then check compression.

[TopCatGr58]

Re: Measurements and Shim sizes

Originally posted by teck_mountain
Hello

Okay measured, tested and pulled the shims from my 79 xs1100 special.
Cam to shim pad measurements
Intake
0.06 mm the smallest I have and I couldn't get the feeler to budge

Current shim sizes (intake)
1=265 2=270 3=270 4= 280

Exhaust
Cam to shim pad measurements
1-0.08 mm okay 2,3,4 = 0.06 the smallest I have and I couldn't get the feeler to budge

Current shim pad size (Exhaust)
1=290 2=290 3=295 4=295

What should I be doing?

Okay, book says you want ~.16-0.20mm INTAKE clearance, couldn't get the .06mm gauge inbetween, but there is a small gap, possibly .03-.04, so add that to the lowest clearance of .16 would get you the max, so a drop in shim size of 15 from each intake so you would want to put in:
250; 255; 255; 265 for intakes!
So far you can swap #1 shim to # 4 place.

Exhaust range 0.21-0.25mm, #1 has .08, subtract that from .21 equals .13...round to .15 from #1 size gets you 275.
Again, estimating the others clearances around .03-.05mm, from 0.21 again gets you about .15, so reduce the other shims also by 15:
#1=275; #2=275; #3=280; #4=280

You can use the old #4Int. shim for #4 Exh,
You could try one of the 270Int shims in #2 Exh....might be closer to the .25 clearance than the .21, but it looks like you'll need to trade 5 or 6 shims!
HTH. T.C.

[ratbyk]

Feeler Guages.

Instead of all this playing around and guessing go out and spend a couple of dollars and buy a new set of feeler guages. A set that starts at .001 or .0015. Then you will know where you are and can make sensible decisions on what sizes to put in the first time around.
Ken/Sooke

[MartyA]

What, quit our charades?
Good idea Ken.

[teck_mountain]

Ken's suggestion

Good one

However, I have the bike apart so will ball park it. Thanks to all for the help. I will let you know the outcome. Hopefully tomorrow evening

[teck_mountain]

update

good day all

new shims are in and I have 145 compression in all four.

[MartyA]

Wow that was fast! Good for you!! Now how's it run?

[teck_mountain]

Update

Hi

Had to kick start the thing. Started on the third kick. ran rough for the first 10 to 15 minutes but after adjusting the idle and a couple of sight adjustments to the idle mixture screw?? it seemed to settle in.

I had to put a new left control on and I cann't get the head light to work. any suggestions were to start?

[TopCatGr58]

Hey there Teck,

Congrats on the valve shim work and great compressions! Okay, kick starting it sounds like you either ran the battery down, or the charging system isn't kicking in, and the headlight is designed to be switched on when a relay and diode senses the engine is running and charging current is going to the battery, so after you start the bike, does the headlight come on?

Secondly, you can take a jumper wire and direct test the bulb to make sure it's not burned out. Are your fuses really good, glass fuses can be misleading, pull them, check the holders, etc.!!

With it running at 4-5k, are you getting ~14 volts at the battery on a voltmeter, if only 12....then your charging system isn't right, could be just corrosion in connectors, could be voltage reg, etc., there are several threads and tech tips for checking these things, I'm definitely not a guru in this, or for that matter, any area!!
Good Luck. T.C.

[teck_mountain]

Wow

Thanks for the help regarding my head light. The wire colors faded enought that a couple of the green look brown. Any way I was able to get things fixed.

Had it out for a run around the block. Wow, more power and pep than I remember. Still a little wonkie but I it may be related to low fuel. Will try again tomorrow.

I initially set the carbs at 1.25 turns from a slightly seated positon. However, I'm finding that the bike seems to run better at a half turn out. can this be right?