93 600

[fazersteve210]

new here. thanks in advance to everyone. got a curious problem with mine. runs great most of the time. but above like 8k it starts to act like its runnin outta gas, unless you get it revved halfway wait and then nail it the rest of the way. i think im just gonna get the factorypro jet kit and new rubbers. kit comes with ti needles, new emulsion tubes, jets for every altitude and intake/exhaust setup, and stainless allen head screws for the bowls. new float needles.(i think mine are sticking and thats why its actling like its running outta gas.) 5degree timing advance key. shift kit. all from factory pro.... im velocity stacks with individual k&n filters.it has a new fuel filter, fuel lines, spark plugs, battery and relays as far as engine parts go...i cut out the dimples that are recessed into the tank for the handlebars to clear so it gets colder air. it has a full yoshimura exhaust. headers and all. i drilled out the rivets on the can and chopped about 6 inches off of the length and re riveted it back together. sounds great, looks great, runs great..... until you get to 6th and try to go over 8k.... carbs right? will what im gonna change fix it? i just bought it about 5 months ago and had been sitting for about 2 years

[ragedigital]

First off, welcome to the site. I moved the thread to a new area, because you have more of an issue than an intro - no biggie.

It certainly sounds like a carb issue and since it appears that you're running stock jets, then I would certainly look into the Jet Kit with the Emulsion tubes. That will be a great place to start.

Typically, whenever you modify the intake or the exhaust, you should have a Jet Kit installed so you can have the ability to adjust the carbs over the whole throttle range.

darrin

[fazersteve210]

i am not sure if the carbs were jetted when the mods were done originally.... i bought the bike for 800 a few months back from a fat dentist... he bought it a while back, rode it twice and dropped it on the stator side hard on his leg... never rode it again. decided to sell it a few years later. didnt run. needed parts. etc... i went by his house with 800 a new battery, new side covers, oil+filter, silicone gasket maker and got the bike running in an hour or so. gave him the cash and took off. i have a 1991 600 parts bike that was my brothers but was wrecked on the front end. (bent forks) everything else is fine except its been chopped into a single seat streetfighter. naked with single headlight. been takin parts off that. its a california/euro model tho with exup. carbs on it have been jetted but the throttle linkage is different.... should i just swap out the controls out too so the linkage matches?

[ragedigital]

exup. carbs on it have been jetted but the throttle linkage is different.... should i just swap out the controls out too so the linkage matches?

EXUP carbs have some different jets, so I wouldn't do it. Plus, without looking at them, the emulsion tubes may be worn on them too and you'll end up having the same issues.

[yamaha_george]

First off, welcome to the site.

It certainly sounds like a carb issue and since it appears that you're running stock jets, then I would certainly look into the Jet Kit with the Emulsion tubes. That will be a great place to start.

Typically, whenever you modify the intake or the exhaust, you should have a Jet Kit installed so you can have the ability to adjust the carbs over the whole throttle range.

darrin

+5 on the moddifing inlet or exhaust screwing with the engine running clean thro the revs..If you have individual pods the distance of the tuned inlet tract has been cut short by removing the carb to air box tubes .

If you put those back on and mount the pods on the end then that tuned length is more or less restored.
The trick is to line the rubbers with PVC pipe and use that as the mount for the pod .

Welcome to the site

[fazersteve210]

i have stainless steel polished tubes that extend the pods the same as the mounts for the airbox did before so thats not it. thanks tho

[yamaha_george]

i have stainless steel polished tubes that extend the pods the same as the mounts for the airbox did before so thats not it. thanks tho

FS2,
well I am glad you had that bit right, you need to mark the throttle grip with a piece of tape and put a line on it as a marker. this line points to another piece of tape on the switch housing at fully closed, 1/4 throttle movement , 1/2 & 3/4 and fully open.

Yes i know you say 8k but that does not tell you what part of the carb is being used when the bike engine stumbles/ hesitates. The tapes will tell you and you need to know if it is gear dependent rather than rev dependent for your own peace of mind.
If you know where the carb is when it stumbles you will know which jets are the main ones in use at that time , then you need to start dealing with the overlap in use to remove that stumble.