Good evening folks. I am new on here and new to owning a twin as always been a 4 cylinder kinda guy.  Anyway need guidance and advice. I bought a GS500 as a project after being told it had zero compression on one cylinder. So after getting engine out (nightmare) and taking the head off I have found no damage to either piston crowns or valve heads. I didn't check the compression personally myself as the chap that I bough it from thought he could repair it had already removed the cams and dropped the chain into the engine. My intention is to rebuild the engine with new gaskets and compression test it on the bench. My questions are, does anyone have any other idea what would cause zero compression on one cylinder and does anyone have the torque setting for the head bolts and the timing settings for refitting the cams?

Thank you kindly.

Maybe he didn't test it when the valves were closed?  Maybe he thought he did but was mistaken?  I mean even with worn rings you'd still have 'some' compression, not zero.

Welcome aboard!  I have manual at home I can get specs on later if someone doesn't beat me to it.

Any pics? 

zero compression is what happens with a broken rod, hole in piston, bent valve. You can see the pistons and valves. Maybe turn the crank and verify the pistons move as expected?

Thanks. Both pistons are moving up and down independently when I turn the engine over with a socket. There is no movement of the piston in the barrel so don't suspect the rings are faulty. It has only done 19000 mile. I turned the head over and filled the valve space with petrol and it never leaked through the valves so pretty sure the valves are sealing. I don't know if it's possible for a valve to stick open on these twins without the piston striking it. My intentions are to get a new gasket and rebuild it and check the valve clearances to see if they are ok and then bench compression test it. Not sure how to time these twins but no doubt I will try. Cheers.

I hate to link outside GSTwin but here is a great write-up with clear pictures on timing.

http://beergarage.com/GSTiming.aspx

I don't have torque specs handy but someone will be along shortly.


Welcome to the forum's, and welcome to the world of twins!

I'm curious why you say removing the engine was a nightmare, I found it relatively easy to do even without a guide to follow.

Sounds like the compression test results may have been incorrect. Howecer my own gs did need a top end rebuild at about the same mileage so it is possible.

Thanks guys. The engine had to be kinda twisted to get it away from the frame. Not looking forward to getting it back in. Would love to put it in without the head but from what I have read the head can't be removed or fitted with engine in the frame??
I am trying to find a head gasket but so many different onefor the different years. Mine is a K2. I need the 4 oil seals as well. Joys.

Thanks

Head, jug, whole top end can be swapped while the engine is in the frame.

Quote from: twinstacks on December 13, 2018, 03:07:59 AM
Thanks guys. The engine had to be kinda twisted to get it away from the frame. Not looking forward to getting it back in. Would love to put it in without the head but from what I have read the head can't be removed or fitted with engine in the frame??

My notes when I reinstalled mine "Put engine back, Must back it in with the exhaust side  first and then turn to fit into frame - easy."

Can go back as a unit.

Quote from: mr72 on December 13, 2018, 06:41:31 AM
Head, jug, whole top end can be swapped while the engine is in the frame.

thanks. Will give it a go. Might fit bottom half back into frame before fitting head and rockers. A bit lighter and more easy to fit into frame. Thanks

Guys I rebuild the engine but the timing chain tensioner plunger does not move in or out and the chain feels very tight before I have fully tightened the tensioner bolts up. Is this correct or does the tensioner need tweaked in anyway? Thanks