Shim size going up?!?

[bwringer]

Unite your units, please...

Let's back up a bit. Are you working in inches or millimeters? I see people in this thread mixing units, and that's a great way to get confused.

The correct clearances on an 8 valve GS are .03 to .08mm. It's fine to go up to .10mm, and if your clearances are .03 - .04mm, you should probably change the shim anyway, since they tend to tighten over time.

And yes, these clearances are TINY compared to most engines.

.03mm = 0.0012 inch
.08mm = 0.0031 inch

.003" = .076mm
.008" = .203mm

I have seen clearances set WAY too wide by people who get confused and mix "thousandths of an inch" with "hundredths of a mm". So perhaps that's something a PO did, and may explain what you're seeing.

Most inch sets don't even have an .001" blade, so if all you have is an inch set, you'll probably only have one or two blades in the correct range. A metric set will have more blades in the correct range and costs less than $10.


Shims are dead easy compared to diddling screw and locknut tappets, and wondering if and when one of the locknuts is going to come loose. Shims also hold adjustment longer. I will freely admit that building up a collection of shims is a bit of a pain, though.

[tom203]

"Typical GS camshaft journal clearance new 2 - 3 , service limit 6. For me there is the probability that new or thirty years old a GS has enough journal clearance to significantly affect the measured valve clearances depending on whether it's being lifted by a spring or not and that's good enough for me for now."

You are overthinking this! lots of these cam journals probably see 100k without any problems.

[tkent02]

You are overthinking this! lots of these cam journals probably see 100k without any problems.

A lot more than that if they have oil the whole time.

[chuck hahn]

I wondering the same thing about the feeler gauges....use metric ones.

[chuck hahn]

Hows the exhaust on the left side? Collapsed baffles of mice nests in there causing serious restrictions???? Cant suck in gas if it can expel the air in the cylinders..............Maybe take that side off and run a garden hose in there and flush it real good?

[Brendan W]

"Typical GS camshaft journal clearance new 2 - 3 , service limit 6. For me there is the probability that new or thirty years old a GS has enough journal clearance to significantly affect the measured valve clearances depending on whether it's being lifted by a spring or not and that's good enough for me for now."

You are overthinking this! lots of these cam journals probably see 100k without any problems.

Precisely the point I am trying to make. The valve clearance is easily swamped by ordinary levels of journal clearance. I'll bet that service limit is conservative and there are hundreds of machines whizzing around with no problems above it.

[chuck hahn]

It can be at .10 MM and still open with the lobes rotation and allow fuel to be taken in. If he has new wires and caps, and gas is obviously flowing, then hes got some kind of restriction somewhere maybe in the exhaust. Least it seems logical to me.

Air....check
Fuel to carbs....check
Spark....check
Some breathability from the exhaust...questionable??


If it cant breath it cant drink in fuel and maybe that's why his colortune is only sporadically flashing???

[esmithers]

Checked

Okay, here what i have discovered.

the compression has went up since i have gotten it running.

1-160, 2-170, 3-150, 4-150 psi.

checked all the valves once more and ENSURED i used metric..
all but one are within the .03-.08. number 2 cylinder intake is .09-.10. seems they are all within spec.

only thing i think is the problem is may have burnt valves in both 1st and 2nd cylinder.

my wife has made it clear that i have invested too much time and money into this bike and suggesting i get rid of it. we all know when the wife is suggesting its more of command than a request.

So this being said anyway one to purchase this bike. if you would like to know what all has been replaced and fix just PM me.. thanks.

[Ghostgs1]

Eric, You can rule out valve clearance problems. .09 or .10mm is ok, lot's of folks set all valves to these specs. May be a bit more tapping noise, but no harm will co,e of it and it will run exactly the same as .03-.08. Sounds like you may have either a coil/ wiring problem or carb issues still. Good luck with it. Ray

[tom203]

Your compression is too good for burnt valves; honestly get valve clearances close (no obsessing) and move on to carb and electrical checking (these are the more likely culprits).

[esmithers]

well the carbs are spotless and clean.... i have replaced the coils and with plugs out and arching on the side of the block it has a consistent and deep blue spark. this goes for all four of the plugs.

at first i thought maybe a thermal breakdown, but i have changed the coils to include making sure there is no arching from the plug wires. changed those as well to ensure that's not happening.

everything is checking out and only thing that seems plausiable would be valves are not seating properly.

anyone in the southeastern portion of Ga willing to come check it out, i shoot you some money and you can try your luck on it. I am in the middle of buying a house and well the wife doesnt want me purchasing or working on this thing till i have moved to the new house and we have established ourselves.

[Ghostgs1]

Eric, If your valves were the problem, you couldn't get that kind of compression. If you are sure about the coils and wiring, then you must have something going on with the carbs. Do the carbs hold the correct bowl levels? If so, then you may still have some sort of passage plugged? If not that are you sure the petcock vacuum is holding? Carb boots and orings good? I'm running out of ideas. Ray

[esmithers]

Do you think the signal generator could be causing the problems? the carbs were rebuilt initially by Chef. they were spotless and clean and was set by him. He did a great job cleaning and bench sync them. i torn them apart and separated the floats according to carb body to keep the same setting as they were just set. i soaked them for two day and pushed over 110 PSI through the passages. with the bike running i can have fuel dropping from the bowls no problem.

Vacuum port is working and the petcock is flowing the fuel.

[chef1366]

Bad igniter?

[chuck hahn]

It cant BREATH!!!!!! What about an exhaust obstruction....like I mentioned before? 100% proof positive its open to the fullest extent? Doesnt take but overnight for mice to fill it with nesting material.