Valve Advice....

[71Iceman]

Hello all,

I am hoping I can get some help from gurus on the site. I have 2 of these old girls in the stable: an 80 GS850G (58K), and an 82 GS850GLZ (104K) both of which are completely stock.
This may end up being a bit of a novel because of the situation.....but here goes.

Last fall I changed and set the points and timing on the 80 gs850 as she was due. The process was easy and made a huge difference in the way it ran. life was good, then the head gasket let go in the front corner of #1 cylinder.
Over the winter, I pulled down the top end and replaced the barrel gasket, replaced rings, lightly honed the cylinders, new head gasket, lapped the valves, new valves seals, overhauled the auto tensioner...the works. (have years of experience with auto engines, have a chiltons manual as well as a the suzuki repair manual and tons of great advice courtesy of Basscliff and lots of others here at GS resources..thanks!)
Here is where the problem starts, after putting all back together I had a bugger of a time getting the points and timing to set right...started at .012 and then .016 and was only able to get the base timing marks to line up properly when the points were set to .014..??? Needless to say this was way more problems than I had originally! (makes one appreciate electronic ignition!!)
After getting that hurdle out of the way, we went for a test drive and the engine just feels like its "struggling" (thats the best way I can explain it), so I figure I will check everything from the ground up, starting with valve clearance (I don't want burnt valves) and followed the procedure in the suzuki manual to the letter....this is where I'm having issues, the manual states that the valve clearance is to be checked with the valve profile in 1 of 2 positions (valve lobe up or horizontal) so I check each valve clearance in first 1 position then the other..they should be the same and that's being thorough right...no such luck, i got 2 different readings, one in spec and one out of spec!
Soooo, I contact a local Suzuki mechanic and ask his opinion on this..his answer was to find the spot where it has the most clearance and adjust from there. Ok this makes sence, so I recheck all clearances using this process and record. I then take the shims out one at a time, record their number and replace back in the bucket. I can't find my copy of the excel chart for shims that I previously downloaded from a generous forum member (thank you!) but managed to find a similar chart in my chilton's manual.
Here are the clearances and shims and the shims I think I need on my valves:
#1 - Exh - .004" / .102 mm shim - 265 > 285
#1 - Int - .003" / .076 mm shim - 270 no change

#2 - Exh - .002" / .051 mm shim 270 > 240
#2 - Int - .004" / .102 mm shim 265 > 285

#3 - Exh - .004" / .102 mm shim 270 > 290
#3 - Int - .005" / .127 mm shim 265 > 315

#4 - Exh - .003" / .076 mm shim 270x no change
#4 - Int - .004" / .102 mm shim 260 > 280
I know this process shouldn't be this frustrating, but it has me worried as I just want to make sure the valves are adjusted properly so i don't burn valves...then I can continue with the cleaning of the carbs (cleaned last year but should be done again), checking for air leaks etc.. (plugs are evenly colored but running a little leaner than i like... more whiteish than the tan I'm used to seeing.)
My question is this, does it sound like I checked things right? Do my calculations on the new shims required look correct?
Thanks in advance for any help you can provide!

 

[Guest]

First off, if you have a 1980 850 shouldn't it have electronic ignition, not points? I thought the last GS to have points was in 1979. With what you state about the bike running rough it sounds like you have the cam timing off by a tooth or two. A very easy thing to do when putting the engine back together. I would check that out for sure. As for the valve shims, I've never checked my clearances in both positions before, I just check it in the first one that comes, but the mechanics advise makes sense I guess. As for your shim calculations they're way off as I read it. Take #2 exh. you say the gap is .051, well that's between you clearances of .03 to .08mm so why would you want to change the shim? and you're making mistakes with shim size changes. Most shims are only a .05 difference, so if you are at a gap of .10 with a shim of 2.70 in there, if you replace it with a 2.75 shim your gap should now be .05, virtually in the middle of the allowed specs. A lot of people including me will leave a .9 or .10 clearance alone as it's better to be a tad loose than too tight, but to each their own. I too get a bit muddled with shimming at times, always good to double check things.

 

[71Iceman]

Thanks Azr,

I was concerned that i wasn't doing the shim calculations correctly, and the clearance measurement was a little frustrating..lol
Ideally i don't want to change any shims that I don't have to, I was shooting for a .003" clearance on all but maybe I am getting too fussy?
I will check the cam timing again, I checked the position of the cams and number of link pins, but i will take the chain idler off so i can get a prescise count on the pins.
I will take another look at the chart in the manual I have as well and see if I cant come up with some better numbers on the shims sizes.
And you are correct, the bike is actually a 79...build date of 10/79.
This is where the car mechanic in me screws me up, as with car anything past the 9th month bumps up to the next year...and believe me i will definately be looking at an electronic ignition upgrade next year! I have not had a lick of ignition problems with my 82 in the last 6 years.
Again thank you for the advice, its very much appreciated!

 

[2BRacing]

I suggest you use the Suzuki factory OEM procedure for checking the valve clearances, as any other method could result in false readings. The most important thing is to make sure that you use the valve clearance specifications corresponding to the units of measurement (thou or mm) on your feelergauge.

The #1 exhaust cam lobe should point forward and parallel with the top of the head. This is the position to check the exhaust clearances for cylinders 1 and 2.

Once you've checked exhaust #1 and #2, turn the motor so that the #1 intake cam lobe is pointing straight up, perpendicular to the head. Check clearances for intake #1 and #2.

Now on to #3 and #4. Turn the motor so that the #4 exhaust cam lobe is parallel to the head, pointing forward. Check clearances for #3 and #4 exhaust.

Next, turn the motor so that the #4 intake cam lobe is pointing straight up, perpendicular to the head. Check intake clearances for #3 and #4.

Find a post on the forum by member "Steve". Look at his signature line to make use of his kind offer to send you the spreadsheet that will do the task of calculating which shims you need. Rather aim for the top (larger) end (or just over) of the specification instead of the lower (smaller) end, because the clearances get smaller over time and you will have to repeat the adjustment procedure at a shorter time interval to prevent the clearances falling below the lower end of the specification.

 

[alke46]

I agree with the info provided by the 2 previous posts. I would just add my own personal opinion as to the clearances. Suzuki recommends .001-.003" and I think Kawasaki uses .002-.004" and since these are similar in design, I always preferred the Kawi settings because I felt it gave me a little more wiggle room over the next 3000 miles.

A loose valve is way better than a tight one. Good luck with your decision.

 

[Guest]

the Suzuki spec for your bike is 0.03-0.08mm. You are far better off staying to the 0.08 side of things, even 0.09 or 0.010 than the tighter side of 0.03. Remember, your gaps will get tighter as you ad the miles to the engine, not looser. Checking the cam timing again is a good idea, post up if you have any issues. There's a shim club on the site as well if you want to look into trading shims.

 

[Lorenzo]

Here are the clearances and shims and the shims I think I need on my valves:
#1 - Exh - .004" / .102 mm shim - 265 > 285
#1 - Int - .003" / .076 mm shim - 270 no change

#2 - Exh - .002" / .051 mm shim 270 > 240
#2 - Int - .004" / .102 mm shim 265 > 285

#3 - Exh - .004" / .102 mm shim 270 > 290
#3 - Int - .005" / .127 mm shim 265 > 315

#4 - Exh - .003" / .076 mm shim 270x no change
#4 - Int - .004" / .102 mm shim 260 > 280

Hi there,
I am in the same doldrums, so offer my little advice.
Ponder what as been said above about erring on the loose side rather than too tight;
As of your survey:

#1 exh > 270 that would bring the gap to .052 mm (0,052 metric) NOTE --with a 285 shim you would end up with a .98 (0,098metric gap--)
#2 int > //

#2 exh > //
#2 int > //

#3 exh > 275 that would bring the gap to .052 mm (0,052 metric)
#3 int > //

#4 exh > //
#4 int > //

 

[71Iceman]

Hi Guys,

Sorry to have taken so long to post reply, but had some family issues to attend to...
I would like to thank ALL that contributed to helping me out....I cant tell you how much I appreciate it!
Cam timing was bang on, and once I got used to how the metric chart works I recalculated my clearances, and decided that this time around I will not do any adjusts (as it makes alot more sense when the calculations are done right) the only valve I am still a little concerned with is the #2 exhaust, but I will keep an eye on it.
Now that I can rest easy with regards to the valve issues, I can continue with the rest of the check over...lol

Thanks again folks!