1981 gs550m katana

[johny]

Hi hope everyone is keeping well .

having a few minor problems with gs550 m i have fitted new ramair air filter pods now it starts ok ticks over just fine around 1500 revs when warm

but when i take it out on the road it all goes wrong in excess of 3000 revs it just dies.   i dont know what causes this 

tank is clean , new fuel , carbs have been stripped and cleaned .

any advise or thoughts would be much appreciated  

thanks john

 

[TonyGee]

you've just opened a can of worms. did you jet the carbs to suit the filters ? 

[johny]

Hi Tonygee thanks for your reply i have fitted 2 jet sizes up from standard pilot and main jet 

can i assume from your valued thoughts and experience that this is more likely a fuel issue and not a timing issue as really have nio idea .

thanks john

[wraith]

If it was running ok before, then yes.

When you remove the air box and put filters on you need to increase the main jet (don't usually need to replace pilot jet just alter the screws)

As to main jets, this can/will all depend on the exhaust system you have on.

3000rpm is where abouts the pilot jets over lap the needle and then the main jet.

I'd put the standard pilot jets back in, and put 2 more size up on the main jets. Once you get it reving over 3000rpm (on the road) then start altering the pilot and needles to get it just right.

You may still be able to get the jet kits for the gs550?

[johny]

Thanks for that Wraith ill give a go next week ..

[cnap504]

Yep prolly not getting enough fuel when it needs more.  Since you have just done the tank cleaning, carbs and filters it might be worth checking fuel delivery ie. do the carbs get an adequate amount of fuel to run thru the rpm range.  A plugged gas tank vent or clogged petcock can starve the engine for fuel.  Don’t be hesitant to try a big main jet, you’re getting a lot more air than with the original air box.  I recently did some 36mm carbs, removed the original box to run pod filters, the stock mains were 110’s, I had to use 140’s.  Runs very good and the plugs look right

[wraith]

This was years ago and the grey matter is not as good as it was  if I recall on a 550 with CV carbs I had k&n filters and open exhaust ended up with 125 mains

[johny]

hi wraith i would have used the k&n pods but cylinders 1 and 4 the pods are to long and catch on the frame and the ramair are foam so they squashed in

ive only put in a 100 main jets (stock is 92.5) perhaps i should go bigger 

cnap  thanks i will double check my fuel lines again i have an after market pet cock maybe i should repair the original one, i will strip it all down again 

thanks for all your help plenty to keep me going .john