Carbs rebuild kit mismatch .. GS650

[lapls]

Hi,

As the final step before I try to start this bike I am rebuilding the carbs ( BS32ss ). The kit looked OK to me until I removed all the parts of the carbs. Main jets, pilot jets are same ( 110 and 42.5 ). Needle valve is OK, bowl gasket the same.. But 2 things annoy me:

1- The air jet, the one on the left side of the the carb throat, is a 160 ( On my carbs it is currently 140, but damaged a bit by a previous owner's screwdriver )

2- The idle screw are quite different. On the kit the length is 20.5mm , the "original" one is 26mm but the difference is only above the thread part, the needle size and length are the same. In fact, I assume the longest top is only to make it even with the carb body, so I think I will put the old ones . Problem is, the old one did NOT have the small washer and o-ring that usually are under the spring.. Since I've never started this bike I don't know how it was running, should I install the washer/o-ring anyway? ( I guess I should..).

If someone could help with these 2 questions I would really appreciate, I plan to have the bike inspected ( and running! ) for next weekend.

Regards,
Sylvain
GS650GL ( an 82, not 83 if I believe the naming plate )
XS650SG

[ddaum]

1 - Both the 1982 and 1983 GS650GLs came with stock 160 air jets. If your bike is fully stock, then I would use the 160s provided in your kit.

2 - The pilot air screws in most aftermarket carb kits are a little different from the stock ones. When I rebuilt mine I noticed the same thing, but I used the new screws from the kit because the original screw's heads were stripped. If your original pilot air screws are in good condition, I would re-use them, but replacing them with the new screws from the kit shouldn't matter at all.

3 - The one carb that you said had no washer and o-ring under the pilot air screw should be re-inspected using a metal scribe or something small to get in there and make sure that the washer and o-ring aren't still down in the air screw hole as they sometimes get stuck down there. If you are sure they are missing, then go ahead and replace them using parts from your kit.

[lapls]

These are GREAT replies :-)

I will go ahead and installe the old idle screws with new washer-orings, I am pretty sure there was none ( checked with light, magnifier and a couple os "special tools" I made . small hooks actually ;-) )
As for the air jet, I will follow your advice and use the new, 160 jets since all other jets are stock size.. Forgot 1 thing though, I noticed that the previous owner had put a Uni-filter one the airbox, maybe that was the reason?

Thank you again...

Now I will have a choice, just bought a K&N on eBay and this Uni-filter seem to be in good shape..

Sylvain
GS650GL
XS650SG

[ddaum]

Glad I could help, just keep in mind, going to a K&N replacement filter in the airbox shouldn't hurt, but if the bike already has an aftermarket high-flow exhaust like a MAC 4-1, then you could have some performance issues with the K&N filter.
Just install the K&N filter, install the carbs, adjust the pilot air screws, do a good vacuum sync on the carbs, then road test and check your plug readings. Plug readings will tell you if you need to do further tuning to your carbs. Don't get discouraged though, just do research and reading here on the site and you'll learn everything you need to know to get that 650 tuned right. Good luck.