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Discussion Starter · #1 ·
hi guys, new member here from arkansas. i just bought an 81 gl500 yesterday for $300. guy didnt know much about it, said he was told it needed clutch work and some tlc. throttle tube was also broke so all he could do was start it but not rev it for me.



well, i have been messing around with it yesterday and today and so far have noticed a couple of things

1- there appears to be a little water in the oil, i have found the writeup on changing the mechanical seal

2- crankcase hose is puffing out a good bit of air

3- right side exhaust seems to only puff out about half of the left side

4- left side plug looks nice, right side is oily and oil looks to be leaking from the exhaust manifold

5- i rigged it to where i could rev it some and it also smokes a little from the right side, not while idling tho



speedo reads to have 34,000 miles







sound like rings?
 

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Well first off if the bike sat for a long time it's possible water leaked in..



Depending on how long the bike sat I would:



1. drain the oil.

2. pull the carbs and clean them out completely, used compressed air and lots of carb cleaner.

3. look at the spark plugs.



that's where I would start.. then go from there.
 

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Discussion Starter · #5 ·
The engine seems to be solid, sounds good. No knocks, ticks, etc
 

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Does not sound like rings to me. Sounds like a bike that's sat for a long time that needs a complete clean-up and tune-up. As was already mentioned, change the oil and oil filter. Since there is a possibility of having a weak clutch, new oil should be 10W30 API SG. Motorcycle dealers nearly always carry this oil. It is not as slippery and automotive oil and can be the difference between your clutch grabbing or slipping. This is exactly the situation with my own '81 GL500 and I've run it this way for over two years. My '82 GL500 has a strong clutch and isn't fussy about what oil I use.



Yep, clean those carbs. If you don't know where to start on the carbs tell us and we'll walk you through it.



Is your coolant right up to the radiator cap and is the level remaining? Or are you mysteriously losing coolant? If you're losing coolant, you may need a mechanical seal.



Besides being dirty, your carbs are likely not synchronized. A properly tuned GL500 should easily idle on only one cylinder. If you pull one spark plug and note the rpm, it should be exactly the same rpm when you run the bike on the other cylinder. To adjust this, turn the little screw on the linkage that connects the two carburetors.
 

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Discussion Starter · #7 ·
yep, plan on the carb clean as it wont idle without the choke. have rebuilt carbs, but never this style, always a round slide or lawnmower type. have not ran it long enought o know if im losing coolant, i did remove the cap today and could see water. didnt have a flashlight handy so i couldnt note the condition. what is a normal amount of blowby? heres the story on the blowby issue- i got the bike home yesterday and i was having problems starting it so i took off the side cover to the airbox, there was some water in there i figured prob from rain. when i tried to start it it was bubbling water up through the bottom. took off the airbox and the box that the crankcase tube goes into and that box was full of water. finally got it started and sitting on the bike it felt like an exhaust leak was pattering on my leg, go tto looking around and it was coming from the crankcase tube. that amount didnt seem normal and the only thing that i know that causes that is worn rings, no?
 

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Worn rings or blown head gasket, - monitor your coolant but it sounds like a probable ring problem though they may be jammed in their grooves from years of inactivity and may free up with a bit of use and lube.
 

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Discussion Starter · #9 ·
does the engine need to be warm when doing a compression test? ive also heard that throttle and choke being open or cosed will affect readings, this true? what range am i looking for? thanks guys
 

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Compression tests should be done with engine at normal operating temp.Choke should be off and Throttle opened several times as the engine cranks.Best done with the kill switch activated.



Standard cheap engine oil is all that is need for these bikes(See manual e.g 10w40 mineral oil) or as many of us use 15w40 cheap made for diesel car engines from the Supermarket.Just never use any oil that has friction modifiers e.g,"Energy Saving" type oils.

The most common cause od clutch slippage is actually incorrect clutch cable adjustment at either end(See manual).



The bike really needs a few road miles if possible to let the engine settle and show it's true needs.



HTH
 

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Discussion Starter · #11 ·
So, should I just try to run it as is or put some oil or sumthin in that cylinder to try to loosen the rings?
 

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I would pull the head on that side. I'm guessing the water in the induction system got into the cylinder. Maybe some rust damage on the wall. If there is a ring problem it will be easy to see looking at the cylinder. If its good, its easy to check the valves and possibly reseat them. Blowby in quantity is never good. But if it were mine, I would take it for a 10 mile ride before I took anything complicated apart. Then check the compression. Valves tend to seat themselves given a chance. Rings, not so much...You might get lucky!

Capt Frank
 

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Discussion Starter · #14 ·
WOOHOO! Well, I got off work last night and went out to try a different tank on the bike. I noticed that the vacuum line was off of the carb, put it in and voila! Both exhausts are putting away.....couldnt run it long as it was 2:30 this morning, but im feeling good guys. Supposed to get a throttle tube and oil filter tomorrow, so wont be able to ride it til then
 

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I would suggest buying a small inline fuel filter and put it between your petcock on the tank and the carbs. That way it will catch any crap coming out of the tank. Also you'll save yourself from your carbs getting possibly jammed up.
 

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PS

I also do a running compression test to give more of an average e.g one side of the engine running and see what the highest figure I can get on the other side.



I've found compression tests are not an,"Exact Science" and are just a good indicator of possible problems.It has been posted that some people are running engines with as low as 110 Psi per cylinder and still doing ok-ish.



My preset ride/engine build runs a 170 Psi/Right hand side and a 162 Psi left but had good rings when re-fitted and I,"Glaze Busted" the cylinder walls and,"Hard Run-in" procedure.
 
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