Engine chokes/stutter

[giuse96]

Hello everyone,

I’ve bought an ‘81 suzuki GS 500, and she has this problem: 

at around 5500 rpm has an hole, the engine stutters for a moment and then gets over and continue to rev up till red zone high rpm no problems.

 

She has this problem at every gas opening, 

I’ve tried almost everything on the carbs, I’ve mounted on a 4 to 1 exhaust and separate air filters.

 

jets mikuni bs carbs

47,5 pilot jet 

130 main 

needle 2 position (tried almost on every position this seems the best)

120 air jet

1 rotation fuel screw

fuel level ok, 

synchro ok.

the bike idles fine, and below this point and above it’s pretty good

chain distribution it’s as manual,

spark plug correct

8 bar on every cylinder 

thanks, 

bye

 

[Gixer1460]

16 hours ago, giuse96 said:

Hello everyone,

I’ve bought an ‘81 suzuki GS 500, and she has this problem: 

at around 5500 rpm has an hole, the engine stutters for a moment and then gets over and continue to rev up till red zone high rpm no problems.

 

She has this problem at every gas opening, 

I’ve tried almost everything on the carbs, I’ve mounted on a 4 to 1 exhaust and separate air filters.

 

jets mikuni bs carbs

47,5 pilot jet 

130 main 

needle 2 position (tried almost on every position this seems the best)

120 air jet

1 rotation fuel screw

fuel level ok, 

synchro ok.

the bike idles fine, and below this point and above it’s pretty good

chain distribution it’s as manual,

spark plug correct

8 bar on every cylinder 

thanks, 

bye

 

There's yer problem ! ^^^ in Red. CV carbs just do not get on with separate air filters without LOADS of work! If an aftermarket jetting kit is available - DJ or Factory - it may cure it or go back to std. airbox!

[giuse96]

3 hours ago, Gixer1460 said:

There's yer problem ! ^^^ in Red. CV carbs just do not get on with separate air filters without LOADS of work! If an aftermarket jetting kit is available - DJ or Factory - it may cure it or go back to std. airbox!

Thanks for the answer but also with the stock airbox I had the same issue at the same rpm range

[wraith]

The exhaust can make a big difference if it's a open end can.

So carb work still needed

[Dezza]

This is one of those times a LeDAR induction kit is required, one of the greatest inventions known to humanity. Fit an air-corrector and a larger main jet to each carb; seperate filters and 4 into 1 to your aircooled four, now runs perfectly

[Reinhoud]

My GS1000 had the same problem, but at a lower rpm, it had K&N filters, AFR was all right through the whole RPM range, except that one dip.

I just learnt to live with it, till I started to modify stuff