Quick question about throttle response

[sonosam]

So today was my first full test of the bike after struggling for 4 months to get it back together and running. It passed inspection yesterday, but that doesn't really check any of the mechanics.

Today on the super slab on the way to work I was in 6th cruising at about 70-80. Just to test the response in the throttle, I opened it up all the way. I got nothing. It slowly sped up to 85, but was no where near what it should be. My question is would this be a problem with the jets or a vacuum leak? Am I running lean?

I probably won't have time to tear into the bike until this weekend, but if it is a problem that would require immediate attention, I will make time for it.

[Kreylyn]

So today was my first full test of the bike after struggling for 4 months to get it back together and running. It passed inspection yesterday, but that doesn't really check any of the mechanics.

Today on the super slab on the way to work I was in 6th cruising at about 70-80. Just to test the response in the throttle, I opened it up all the way. I got nothing. It slowly sped up to 85, but was no where near what it should be. My question is would this be a problem with the jets or a vacuum leak? Am I running lean?

I probably won't have time to tear into the bike until this weekend, but if it is a problem that would require immediate attention, I will make time for it.

My first though is too much air and not enough fuel. Aftermarket airfilters, vacuum/air leaks, and clogged main jets/emulsion tubes/needle jets.

Could also be an issue with the diaphrams not lifting right... incorrectly mounted, springs not seated right, needles in the wrong position (with jet kit) or OEM needles improperly installed.

Krey

[mykat]

Really unlikely to be the problem, but my bike acts like that when it's running on 2 or 3 cylinders (and yes, Katanas will run on 2/3 cylinders).

Simple test, after a long ride get a wet rag and push it against each of the headers individually. You should get an immediate sizzle. If one of the cylinders isn't running, the header will probably be cool enough to tough with your hands.

[boomer_95]

hows the throttle response with lower gears higher RPM's? say 3rd gear, 7000 rpm. my 750 doesnt really like to take off to quickly in higher gears lower rpm's, say 5th gear, 4000 rpm. a bit more info might be needed to really diagnose the problem. what rpm's? im guessing lower. also what is your bike? 6 gears im guesing a 600. also what do you mean "back together"? have you ridden it before "tearing it apart"? if you did anything with the head you may have changed the cam timing (i retarded my intake cam by a tooth and the throtle response was worse), maybe the carbs wernt put back together right, like the jet needles are in the wronge position

[MikeyZ]

Yea the Kat is not going to take off on you on the highway.

If the acceleration and throttle response is fine in the lower gears...Its the Kat being slow.

Time for a BUSA!

[sonosam]

when it's running on 2 or 3 cylinders

All cylinders are firing. Checked that first.

6 gears im guesing a 600

Bike info is in my garage. Not just 600s have 6 gears.

Yea the Kat is not going to take off on you on the highway

I understand (and have ridden this bike since 07) that the Kat isn't going to wheelie in 6th gear, but it will get up and go pretty quickly from 80 to 100 normally in 6th gear. This is not happening and it used to.

Some more symptoms and possibly a change in direction as far as what the problem is. Rode it home last night and back to work today. Throttle response in 1st through 4th is fine all the way through the rev range. 5th and sixth have problems higher up. My gut feeling is clutch slippage because it feels similar to when I didn't have the clutch cable adjusted properly before I tore the bike down. I will mess with the clutch adjustment first then dig into finding a problem with the carbs.

[boomer_95]

does the rpm's raise? and again what was done to the bike? carbs? top end? full rebuild? if carbs then again the needles may be maladjusted, if top end, again the cams may be out a tooth. if full rebuild, then cams, or just because it hasn't broken in yet. if the clutch is slipping the engine will rev but the bike just wont go. honestly this doesn't sound like the case in my opinion but then im not working on the bike and only reading whats wrong so i cant really say yay or nay

also i didnt know the post 750's had 6 gears. my 89 750 has 5

[Badfaerie]

also i didnt know the post 750's had 6 gears. my 89 750 has 5

Our 93 750's have 6 gears, I didn't know there was a difference in the 89 and the 90-97 750 transmissions.

[Slofuze]

my 89 750 has 5

You might want to check that again. My '89 had six.

[boomer_95]

haha i apologize mine does have 6 i guess i never stopped to count, and just assumed it had 5

but none the less....

[sonosam]

So I re-adjusted the clutch on Wednesday night. Rode to work on Thursday and Friday to see if the problem was resolved. It wasn't.

Today I read up on CV carb tuning and decided to swap some jets around. Found that in carb #3 the main jet and the slow air jet were completely unscrewed and sitting in the bowl. Rechecked all of the carbs to make sure the #15 pilot jet, 117.5 main, and the stock slow air were in and tight. Hopefully riding in to work on Monday will be better.

[05RedKat600]

So I re-adjusted the clutch on Wednesday night. Rode to work on Thursday and Friday to see if the problem was resolved. It wasn't.

Today I read up on CV carb tuning and decided to swap some jets around. Found that in carb #3 the main jet and the slow air jet were completely unscrewed and sitting in the bowl. Rechecked all of the carbs to make sure the #15 pilot jet, 117.5 main, and the stock slow air were in and tight. Hopefully riding in to work on Monday will be better.

Ya, that might cause a problem!