Should I redo the valves?

[alstensby]

I'm just curious what everyone's take is and how difficult it might be. I have an '82 GS650GL that I got running with the choke open, but I need to do the carbs all the way since they're pretty gunked up. After getting her to run, I noticed that the valve cover gasket is leaking so I bought the seals for that. It idles fine with the choke on and I'm guessing the valves should be OK, but as long as I have the cover off, should I go ahead and do some valve work? My only thing is, this is a bike I bought for $50 and will be selling/giving to a buddy of mine to get a new bike this Fall/next Spring. Plus, never done a valve job so I have NO idea what goes in to it. Any of your wisdom is greatly appreciated.

[Billy Ricks]

While you have the cover off check the valve clearances. Aside from that you won't be able to do anymore without pulling the head. A good carb job and getting clearances in spec should do wonders if the motor is in decent shape. If you can handle a carb cleanup you can handle checking valve clearances with a feeler gauge. You have shim adjustment and you can find threads dealing with shim adjustments if nobody covers it here for you.

[Nessism]

The idea behind doing maintaince is to keep from having to make repairs.

Valve clearances reduce with time as the valve recedes into the head. Eventually the valve clearance will be gone and the valve will not seat fully - always open. Exhaust valves will burn if they are being held open.

Check the valves before they get bad. The engine will last much longer - and your reputation as a master mechanic will grow in the eyes of the person that you give the bike to.

[80GS750]

on that note....

i have the head off of my motor.... the cam has to be on to check the clearances right?

so i reinstall my head, new gaskets and all, then put my cams in, timing and such, and then check valve clearances? what if they are off, do i have to pull the head back off and redo my valves?

[Billy Ricks]

on that note....

i have the head off of my motor.... the cam has to be on to check the clearances right?

so i reinstall my head, new gaskets and all, then put my cams in, timing and such, and then check valve clearances? what if they are off, do i have to pull the head back off and redo my valves?

The engine does have to be assembled. All measuring and adjusting is done topside using either shims or threaded adjusters.

[80GS750]

thanks, i need to get a gasket set and reassemble...

[Nessism]

on that note....

i have the head off of my motor.... the cam has to be on to check the clearances right?

so i reinstall my head, new gaskets and all, then put my cams in, timing and such, and then check valve clearances? what if they are off, do i have to pull the head back off and redo my valves?

Yes, everything needs to be assembled before you can check the valve clearances. And no, you do not have to pull the head to change shims. There is a special tool to depress the valve shim bucket while the cams are installed so you can pop the shim out - costs about $20. Some people use alternate tools to depress the bucket or you can always pull the cams out to get at the shims. In my view a $20 tool is well worth it. Had to grind on it though since there was a couple of valves that the tool could not get at on my 550 - not sure why but it worked fine after some "tuning".

[dardoonk]

The engine does have to be assembled. All measuring and adjusting is done topside using either shims or threaded adjusters.

I'll add another question to this. I have the head torn down and will do valve seat/face reconditioning, cleaning, valve guide seals, guides, valves lapped etc... After and everything is back together, when do I check the valve clearances? Should I just use the original shims to get the motor started, then go back in and do a valve adjustment after I've run it long enough to seat the valves, or do I have to do a full adjustment before I start her up?

In other words, how close do my tolerances have to be on my initial build?
How long does the engine need to run before the valves are fully seated?

[Nessism]

I'll add another question to this. I have the head torn down and will do valve seat/face reconditioning, cleaning, valve guide seals, guides, valves lapped etc... After and everything is back together, when do I check the valve clearances? Should I just use the original shims to get the motor started, then go back in and do a valve adjustment after I've run it long enough to seat the valves, or do I have to do a full adjustment before I start her up?

In other words, how close do my tolerances have to be on my initial build?
How long does the engine need to run before the valves are fully seated?

You should adjust the valves after you get the engine back together. If possible, set the lash at the high end of the spec. range. After 800 miles or so (Suzuki break in period) recheck the valves and adjust as necessary.

[chef1366]

Click here Valve job

[DimitriT]

In other words, how close do my tolerances have to be on my initial build?
How long does the engine need to run before the valves are fully seated?

I just put the top end back together on the 550. After reassembly I turned the motor over a bit with the starter (plugs removed) and then adjusted clearance using the tool and shims. After 500 miles its a good idea to go back and check them again. Especially since you've done valve work.

In my case I replaced two valves due to blown piston so I will have to check them again.

BTW, I didn't see any recommendation for lapping valves in the shop manual so I didn't do that part. I'm getting 140 psi on that cylinder even before the second valve adjustment so I guess it didn't matter.