Carb sync / valve adjustment / service manual **** 1982 gs850gl

[Guest]

my left cylinder is running colder than the other 3. i checked the vacuum AND it is higher on that cylinder. which could also,in addition to the throttle slide adjustment, have to do with the valve adjustment correct?

-which carb is the "master" carb when syncing?

-why is there 3 adjustment screws? im used to there being 2 or 4 for 4 cylinder bikes. i would think in the event of 3 screws, one would be a stationary "master" carb and the other3 adjustment screws were made to set to that one unadjustable one. but when i adjust the 3 screws all 4 vacuum lines seems to change.

-what are the valve clearance specs?

-where do i find a FACTORY service manual for this bike?

i have a 1980 gs850gl clymers manual, but i dont know if the specs are the same.

i have a terrible knocking in the top end of this bike. only seems to do it when warming up. ive heard a couple suggestions but what do you think. the timing chain would be a whirring sound like the ocean, piston slap or worn conrod bushing would knock. and i would think valve chatter would be more of a high pitched tinging but apparently can be a low toned knock like im getting. somebody also suggested it could be worn cams and warped head. and in that event it will run fine, just be annoying.

thanks for your help!

also i have an extra tank for this bike in nice shape if somebody is in in need, im looking for a nice set of side covers. the brown/maroon color with gold striping

[chanceafrica]

here she is

IMG_20120710_172725.jpg bought from the original owner, he showed me pictures of him at the dealership.

[mikerophone]

Nice, I own a similar L and a G too. You are correct about the master carb. #3 is the master, you sync the others to it and yes all will change slightly when you change one. The manual is here on Basscliff's website, the carb sync and valve adjustment are there too along with a whole lot more.

I wouldn't use the Clymer for anything more than a reference, some might consider it better used as a doorstop

[chanceafrica]

Nice, I own a similar L and a G too. You are correct about the master carb. #3 is the master, you sync the others to it and yes all will change slightly when you change one. The manual is here on Basscliff's website, the carb sync and valve adjustment are there too along with a whole lot more.

I wouldn't use the Clymer for anything more than a reference, some might consider it better used as a doorstop

this doesnt specify year, nor does it specify is the GL model. is it still relevant information?

my 1980 tells me to calibrate my manometer to the left carb, solidifying the notion that it is not suitable reference material......so thanks!

[chanceafrica]

oh that manual also suggest syncing to the left or right carb. its difficult to shuffle through 500 pages on the internet by scrolling!
anyways. ill try to check my valve clearance then retry to sync the carbs, calibrating the tool to the third carb(from left to right?)

[chanceafrica]

valve adjustment: all that needs to happen is the cam lobes need to be perpendicular to the case half? as long as its completely not deppressing the the shim/valve? in that position is where i take my valve shim clearence measurement? i dont need to find tdc on the compression stroke? just be sure the cam lobe is oriented away from the valve shim?!

[mikerophone]

Yes the L and G only have minor differences, mostly cosmetic but electrics and engine components are the same.

Valve adjustment pdf is here. Carb sync is here. And yes master carb is 3rd from the left while sitting on the bike.

[Steve]

valve adjustment: all that needs to happen is the cam lobes need to be perpendicular to the case half? as long as its completely not deppressing the the shim/valve? in that position is where i take my valve shim clearence measurement? i dont need to find tdc on the compression stroke? just be sure the cam lobe is oriented away from the valve shim?!

This is probably the most confusing part of general maintenance, at least until you understand the principle behind it.

You don't just position the cam lobe perpendicular to the case half. What you do is point BOTH cam lobes on that side of that cam so they are BOTH pointing away from their respective valves at an angle. In that position, neither one is pushing on a valve. With that cam positioning, measure the clearance of BOTH valves on that side of the cam.

I usually start with EX1 and EX2. Position the cam properly, measure both valves. Use the 19mm nut on the right end of the crank, rotate the crank 180 degrees (1/2 turn), you will find that IN1 and IN2 are now properly aligned. Measure them. Give the crank another 1/2 turn, measure EX3 and EX4. A final 1/2 turn on the crank will let you check IN3 and IN4.

Now that you know what your clearances are, it is necessary to know what the shim sizes are, especially if you need to change any of them. This is when I will invite you to take advantage of the offer in my sig.

I have never paid any attention to relative crank position (TDC or not) when adjusting the valves, as it does not really matter. What matters is positioning the cam lobes so that two of them are both away from their valves.

If you are doing a valve adjustment and a carb sync, always do the valves first. Changing shims will change valve lift and timing ever so slightly, which will affect how much air the cylinder is trying to draw through the carb. That will affect the vacuum level that is generated, so do valves first, then carb sync.

.

[60ratrod]

your knocking sound could be from piston slap since it goes away as it warms up. as the bore and pistons wear, there is more room for the pistons to expand as the engine comes to operating temperature. once fully warmed up, the piston will fill the extra space, bringing the clearances back to where they should be. cast and hypereutectic pistons don't really suffer from piston slap as much as forged pistons do, due to the higher amount of silicone in cast and hypereutectic pistons, but can develop it as the engine continues to wear normally and tolerances expand.

[hannibal]

Doesn't a lean cylinder run hotter than a rich cylinder, not colder?

[chanceafrica]

i never said anything was lean.
why is it important to have 2 lobes perpendicular? it would seem that the lobe depresses the valve shim and as long a its not, and in the opposite position, it should be in a proper position for the clearence measurement.

[chanceafrica]

ok also these things:

-the manual i have (1980 gs850) says that the came lobe needs to be str8 up, perpendicular to the case half. doesnt mention two lobes being up.(my bikes is an 82)
this info is also true in the pdf linked on this post as well....

-you did your exhaust port measurements with the lobe facing forward,why? the manual doesnt say to do it this way.

[Steve]

Read the manual very carefully, compare it to what I said in my post. The two cam lobes on that side of the cam need to be NOT pushing on their respective valves. If you put the cam lobe directly away from one of the valves, the other lobe on that half of the cam might be pushing on its valve. That will push the cam slightly in the bearing, giving you an incorrect reading on the one you are trying to measure. Making sure that NEITHER valve is being pushed on that side of the cam will ensure that the cam is centered in the bearing, giving accurate readings for BOTH valves.

The pictures in the manual are confusing because they only show the lobes from the end of the cam. It is hard to tell which lobe gets pointed which way, until you realize that there is only one possibility. What most newbies don't realize is that you set the cam lobes to that position, then measure BOTH valves. They try to align the lobes that way for each valve, instead, but that does not work.

To help visualize the situation, note that the valves go through the head at an angle. It's not quite a 45-degree angle, but somewhat close. With one cam lobe UP and the other one FORWARD or BACKWARD (for exhaust and intake, respectively), the angle of the valve goes away from both cam lobes. Although neither lobe is perfectly aligned with the valve's axis, neither one is off the base circle, allowing proper measurement of the clearance.

If you don't follow these directions (yes, they are the same as in the book, but in different words), your clearance measurements will be wrong. Wrong clearances can result in burnt valves and blown engines. Your choice.

.

[Nessism]

Follow the factory method on valve adjustment. Basscliff's tutorial is true to this method. If you adjust by pointing the cam lobe away from the valve that will work as well, but the clearance will be wider than using the Suzuki method (which also happens to be the Kawasaki method too), so you should shift your clearance to the upper end of the range, extending the clearance to .10 mm.

[chanceafrica]

i stand corrected. i checked the pdf again. it does suggest this. but it is not the same year model as my bike, but probably the same anyway? i will double check my clymers when i get to the shop shortly. thanks for your help i definitely want to do this the right way.