#3 cylinder pipe cold and oil leaking from #3 cylinder

[suziman]

Hello All.
I have a 1979 gs1000 that I painted so didn't run for about 2 months.
prior to that was running great. Cleaned the carbs, replaced coils.
all cylinders have good spark but won't run on #3, plus I noticed oil seeping out of #3 stock exhaust pipe.
checked valve clearance and adjusted.
I don't know what else to do!
Made sure I cleaned #3 carb well.
Fuel petcock vac line connects to #3 carb. Any relation there?
Thanks in advance for any advise anyone can give me!

 

[suziman]

also swapped plugs then replaced all with new. SAME. #3 plug wet with what I think is oil???

 

[chuck hahn]

If you think its oil try lighting a wet plug with a match. if its gas it will easily ignite. Oil will not ignite so easily. Then youll know. If its gas then that carb has an issue.

 

[gtem]

A high likelihood of a stuck float valve dumping gas into the cylinder, do you get anything coming out of the airbox drain as well by any chance? Does the wet plug smell gassy?

 

[suziman]

thank you chuck and gtem for your quick response.
I will check these things suggested and will get back
What an awesome website!!
Thanks so very much!
I've had 2 of these bikes over the years and absolutely LOVE them...Stupid fast and great handling.
Do ya'll recommend specific clearances for valves?
Was gonna replace all to allow o.07-0.08mm
They are quite tight currently at 0.03 and 0.4

 

[chuck hahn]

click on link above in the forum information heading for bikecliffs and see if theres a manual there.

 

[suziman]

yes, I have a manual, was just thinking to have a bit more clearance to allow 5000 or so miles before rechecking.
Just picking your brain about it that's all.
Thanks

 

[chuck hahn]

Many here have said that .10mm is a max safe gap. I myself shoot for as close the the stated .08mm. I feel that at .08mm it will get that 5000 mark unless something else goes wrong with a valve seat or the valve pan itself.

 

[Steve]

yes, I have a manual, was just thinking to have a bit more clearance to allow 5000 or so miles before rechecking.
Just picking your brain about it that's all.
Thanks

Many here have said that .10mm is a max safe gap. I myself shoot for as close the the stated .08mm. I feel that at .08mm it will get that 5000 mark unless something else goes wrong with a valve seat or the valve pan itself.

The problem with trying to set them all to 0.08mm is that you will need a selection of "X" shims, as well a the standard ones. Shims come in increments of 0.05mm, so technically, you don't change shims until they get below 0.03mm, then change the shim to get it to 0.08mm. The "X" shims are half-way between the standard shims, making it easier to fine-tune the clearances. As stated, many of us will run as loose as 0.10mm clearance. Ever so slightly noisier (but who can really tell?), ever so slightly less power (due to less valve opening), but the increase in adjustment interval is worth it.

Also note: as the miles add up, the seats will stop changing shape as quickly, so the interval will naturally increase. I have gone over 20,000 without needing to change any shims. Yeah, they got checked, but no adjustments were needed. That was when the engine had about 60,000 miles on it.

.

 

[suziman]

The problem with trying to set them all to 0.08mm is that you will need a selection of "X" shims, as well a the standard ones. Shims come in increments of 0.05mm, so technically, you don't change shims until they get below 0.03mm, then change the shim to get it to 0.08mm. The "X" shims are half-way between the standard shims, making it easier to fine-tune the clearances. As stated, many of us will run as loose as 0.10mm clearance. Ever so slightly noisier (but who can really tell?), ever so slightly less power (due to less valve opening), but the increase in adjustment interval is worth it.

Also note: as the miles add up, the seats will stop changing shape as quickly, so the interval will naturally increase. I have gone over 20,000 without needing to change any shims. Yeah, they got checked, but no adjustments were needed. That was when the engine had about 60,000 miles on it.

.

I get ya and thanks for that info. Steve. Maybe I will shoot for .07

 

[Nessism]

Go max size possible, because the valves tighten with mileage and a big gap will last longer.

 

[Big T]

If your#3 plug is gassy, the petcock diaphragm has failed and extra fuel is entering the carb

Oil running down #3 is most likely failed tach drive seals

 

[Steve]

I get ya and thanks for that info. Steve. Maybe I will shoot for .07

Go max size possible, because the valves tighten with mileage and a big gap will last longer.

Shoot for "in the range of 0.03-0.08mm", but keep in mind that if you change a shim that has 0.03-0.05 clearance, it will jump to 0.08-0.10. Although slightly above "the range", it works out quite well.

.

 

[rphillips]

This being said, If I read this right, if you change a shim on a valve that is within spec. it will either be out of or right at the edge of out of spec. on the other end...

 

[chuck hahn]

Each shim size changes the gap by .002

 

[Steve]

This being said, If I read this right, if you change a shim on a valve that is within spec. it will either be out of or right at the edge of out of spec. on the other end...

That is correct. That is why the "X" shims exist, so you only move half-way through the range.

Each shim size changes the gap by .002

Chuck, be careful throwing numbers without specifying units. You are correct, one shim will change the gap by 0.002, but that is INCHES. All previous mentions of sizes have been one shim size equals 0.05 MILIMETERS. Also note the number of zeroes to the right of the decimal point.

It is too easy to confuse the numbers.
In Inches, the range is (approx) 0.001-0.003
In MM, the range is (exactly) 0.03-0.08.

Note that there is a "3" in both of those ranges, but one is MIN, the other is MAX.

.

 

[suziman]

Go max size possible, because the valves tighten with mileage and a big gap will last longer.

will do thanks!

 

[suziman]

That is correct. That is why the "X" shims exist, so you only move half-way through the range.



Chuck, be careful throwing numbers without specifying units. You are correct, one shim will change the gap by 0.002, but that is INCHES. All previous mentions of sizes have been one shim size equals 0.05 MILIMETERS. Also note the number of zeroes to the right of the decimal point.

It is too easy to confuse the numbers.
In Inches, the range is (approx) 0.001-0.003
In MM, the range is (exactly) 0.03-0.08.

Note that there is a "3" in both of those ranges, but one is MIN, the other is MAX.

.

yeah I see what you mean and I appreciate the advise.
while I got ya, when measuring the gap whether the lobe is vertical or horizontal, wouldn't that be the same clearance, looks symmetric to me. I will try and see if there's any difference though

 

[Nessism]

yeah I see what you mean and I appreciate the advise.
while I got ya, when measuring the gap whether the lobe is vertical or horizontal, wouldn't that be the same clearance, looks symmetric to me. I will try and see if there's any difference though

Follow the factory method to adjust the valves. They adjust in pairs so that two adjacent valves are on the base circle at the same time, that way the adjacent valve isn't depressed and pushing up on the cam, skewing it in the journal clearance.

 

[chuck hahn]

HMM.. Is that 17mm a typo? Typically the nut is 19mm. Im assuming that came from the service manual not you Ed.