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woes of carb syncronization

  • Thread starter Thread starter scottsgs
  • Start date Start date
S

scottsgs

Guest
Hi all,

I need some help. I am on my second attempt at gettting my carbs sync'd. I am using the Motion Pro Sync Pro to tune the carbs. I tried once and I get a real raspy exhaust note. My Clymer manual says to run the motor at 15- 2000 rpms and sync off cylinder #3. I also tried to get the carbs so that #'s 1 &4 run slightly higher than 2 & 3. Is there a way to allow for the drop in rpms while adjusting the screws? Should the liquid read the same at idle as it does at 2000 rpms? I am really startimg to tear my hair out on this one.

Thanks,

Scott

P.S. This an 81 GS850G (x).
 
I"m not much good with BS carbs (I have VM's which are synched a little differently), but a few things.

1. Use fans to keep the motor cool
2. Make sure your vacuum line that hooks up to the petcock is plugged.
3. Your gas tank is hooked up or you have an auxilary tank, you can't synch with just the fuel in the carbs.
4. Make sure your airbox is on.
5. Valve adjustment should be correct.

If your rpm's are dropping you can adjust with your idle screw where your throttle cable hooks to the carbs. Also, your vacuum readings should be about the same throughout the rpm range as long as you hold the throttle steady.
 
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Vacuum will drop whwen you snap the throttle. Vacuum is caused by the difference in pressure between the opposite sides of the throttle plates to put it simply. the reason I think for synching off 3 is that's where the vacuum port for the petcock is. Hows the carb condition? mixtures good? carbs clean?
 
I certainly don't know as much as the more 'senior' members on this forum, but it seems that your idea about making 1&4 run "higher" than 2&3 is not right. Why exactly are you doing that?
 
Where's my manometer?

Where's my manometer?

I'm a babe at this carb stuff too, but Mr. bwringer has an excellent "how to" here:
http://www.bwringer.com/gs/carbsync.html

Here is a page from the Suzuki shop manual for GS850 1980 and later (BS) carbs:

carb_bal.jpg


Here is a page from the same manual for the '79 GS850 (VM) carbs:

carb_bal_vm.jpg


Don't forget that the instrument itself needs to be calibrated before these measurements are taken. Plus you should check valve clearances before syncing carburetors.

Thank you for your indulgence,

BassCliff
 
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carb sync update

carb sync update

Well I finally got it! Thanks again Mark for the input. I re-checked the vacuum line for the petcock, and sure enough the stopper I used wasn't sealing enough. A little electrical tape and......problem solved.

Thanks again,

Scott
 
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