1980 GS550L w/ K&N filter. Need jet recommendations

[Guest]

Picked up a 1980 GS550L about a month ago. Got it to running and the thing runs sweet. I pulled the plastic air boot off the carbs and replaced it with a K&N dual pod filter. I am also looking into adding a MAC 4-1 exhaust in the near future but for now i would like to get the bike back to running nicely with just the K&N filter on it and stock exhaust. The bike is running pretty lean. I pulled the carbs off and it's running 92.5 main jets. Can i get away with just going up on the main jets? if so, what size? K&N recommends a 15% increase so that would put me at a 107.5 main jet. Any help and recommendations would be great.

 

[rwnielsen]

Start with what's recommended by K&N. Exhaust changes won't have nearly as much effect as pods

 

[tom203]

"Picked up a 1980 GS550L about a month ago. Got it to running and the thing runs sweet"

Hopefully, you have got other maintenance issues up to date, before you fiddle with carbs. Don't count on others before you- have you seen this link?
http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html

 

[Guest]

I went through everything except for popping the valve cover and the carb boots on the bike before firing it up. The only issue that I could find was a stripped stud on the oil filter cover. Gave it a fresh oil change, fresh gas, marvel mystery oil, and a can of seafoam, and she ran excellent. For a $200 bike w/ title I can't complain one bit.

I have ordered some 107.5 main jets per k&n recommendation. If I see no improvement or crappy performance I think I will just take it back to stock. No need in ruining a good thing.

Also just picked up a 77 gs550. Another $200 w/ title find. Hopefully she's as good to me as my 80 has been. Regardless, I look forward to the future conversations through this forum. Thanks guys

 

[8ball]

You are not going to be able to just throw in a jet kit and have it work, optimally, first thing. Carb jetting is not "plug and play". You will need to do quite a few adjustments to get it right.

Since your bike has CV carbs, which have vacuum operated slides, your task will be more difficult than with the earlier type VM carbs with the mechanical slides. I can guarantee that your stock jetting will not be right with the K&N filters (but those are miles better than the cheapo Emgo pods). It will take patience and a methodical process to get it right, but you can get it there, or there abouts. I will venture to say that getting CV carbs to work better than stock, without the airbox, is darn near impossible. But you can get them to work OK, You just will have to choose whether you want good cruising performance, or good full throttle performance.

Good luck with it!

 

[tom203]

"I went through everything except for popping the valve cover ..."

don't wait- checking valve clearances is NOT to be avoided. The small clearance drifts to no clearance over time.

 

[8ball]

"I went through everything except for popping the valve cover ..."

don't wait- checking valve clearances is NOT to be avoided. The small clearance drifts to no clearance over time.

+1. The clearance on these things is stupid small. (.008" intake and exhaust, for mine) You need to check it before trying to sort carb issues.