GS650GT Carb Sync

[Anonymous]

Before I start to balance my carbs, is there a cmHG range I should be aiming for as the manual just says get cyls 1 & 4 the same and cyls 2&3 half a ball lower?

I can see the throttle stop screws easy enough on the outer carbs but the middle one is obstructed by both the choke cable and throttle cable, is there a way of getting to this stop screw? Or do I just use the outer ones and get it the best I can?

Thanx in advance

Rich

[KEITH KRAUSE]

I've always found that if your motor is in good condition, then the levels you initially observe are within the "range". It's getting the levels as close as possible that's important.
Remember that the ignition timing, valve clearances, and mixture screw adjustments should be correct before synching.
If your model has a "master" carb, you should adjust all the carbs to that carbs vacuum level. I don't know what your initial reads will be, but I've always found that adjusting the higher levels DOWN to match the lower levels is much easier/quicker. If you find it difficult to adjust the middle carbs, you may be lucky and find them both close to each other and simply adjust the outer two to match. If not, you'll have to gain access to the adjusting screws. I've always adjusted the levels uniformly. Try to get the levels so the difference between the highest and lowest level is about 1/2", closer if you can. Use two large fans to avoid over-heating!

[gs650gt]

I've never seen exact values but first You adjust the inner carb readings to the same level and then the outside carbs 2-3 cmHg higher than the inside (assuming that the airbox & air filter are still mounted. according to Clymer all 4 readings are at the same level when airbox is removed).

a great link: http://www.carbtune.com/

[Anonymous]

Thanks guys, I've just tried gs560gt's method of removing the air box and balancing them up so that they are all level, I got there in the end and they are all perfect! Couldn't have done it without my carbtune from the link above it makes it so easy as their is no more bouncing balls, cool. I then stuck the air box back on and it made a tiny bit of difference to the setting but not that much, any way she no runs alot smoother so i'm quite happy. Colortuned as well while the tank was off and an oil change for good measure, she seems to be burning quite a bit of oil nowadays (400ml in about a 1000 miles) saying that she has done over 62k so maybe that normal and I'll just have to keep an eye on the levels.

Thanks again for all your help and Keith I did take your comment about the fans but being in the UK didn't need them as it was bl&*%y freezing, just took lots of tea breaks

Cheers

Rich

[KEITH KRAUSE]

Yes indeed! The more tea breaks, the better the job!

[gs650gt]

she seems to be burning quite a bit of oil nowadays (400ml in about a 1000 miles)

If You say that's "quite a bit", what do You think of my record 1,5 liters / 1000 km ? Well, I had then 220 000 km on the clock.

[Anonymous]

OK, that sort of puts my oil consumption in perspective then I'm off for another cup of tea then!

As you have a high mileage bike I don't suppose you have ever heard a rattle that sounds like a cam chain rattle but isn't have you? I have posted stuff about this but to no avail. If I ride at 60mph at 4500 rpm it's as sweet as can be, this seems to be when the engine is neither pulling or decelerating, but as soon as I put on the gas an awful rattle starts and is quite load, I have changed the cam chain and refurbed the tensioner.

It's just a real pain to find as it's gotta be under load, so running the engine while on the center stand doesn't recreate the fault, only when riding. I seen a few posts about the clutch basket rattle, do you have any thoughts about what could be my problem. Have you ever had to change the cam shaft sprockets as yours is a high mileage bike also?

Ignition timing setup perfect, carbs synced, mixture set, I haven't checked the tappets for a while but think this would tap all the time and this is more of a rattle. As you can probably tell I'm at a complete loss as to what to try next and how much more work to put into this bike before I move on.

Sorry if I've gone on a bit, but hope I've hit you at a time of insperation!

Cheers

Rich

[gs650gt]

my best guess for the noise is the cam chain tensioner: sounds like it does not follow the movement of the chain smoothly enough. (You know the test: turn the tensioner knob fully counterclockwise. turn also the crankshaft counterclockwise to tighten the chain and lock the tensioner knob. then turn the crankshaft slowly clockwise to release the chain. the tensioner knob should also be rotating smoothly clockwise. if not... check it, according to the manual).

I haven't had this kind of problems with my gs650g but my gsx1100s that I ride now while my gs650 is under construction seems to have all kinds of strange noises in store...

the gs650 mainly suffers from (typical) electrical troubles, oil consumption / leaks, lousy fuel petcock and finally 2nd gear jumping off at high revs. the only engine or transmission troubles have so far been worn out exhaust valve at 150 000 km and worn out rear wheel joint assy at 180 000 km.

During these years I've learned not to panic because of engine noises as long as there's enough good oil in the machine.

[Anonymous]

Thanks for that, I am pretty sure it's not cam chain related even though that is what it sounds like, I know what you mean about not panicing as she still drives real good but it is just the annoyance factor.

Thanks for taking the time in replying though I appreciate that.

Take care

Rich

[gs650gt]

hmmm...

I know that feeling when You have gone through all the possible causes and there are only unlikely causes left...

I doubt that anything could be wrong with cam sprockets. but maybe next time You drain the oil You could take a look at the clutch, if there's something loose. You also told that the cam chain is new so I suppose that You've checked the chain guides are OK. By the way, does this rattle come in all gears?

Other "unlikely" objects to check for loose items/worn parts: starter gear, final drive gear, exhaust system, oil pump...

GS650 microfiches (If You do not have them yet...) http://shippsmc.com/fiche_section_de...98R0&fveh=1444