Bike won't go past 7000 RPM!

[Mat]

Hey,
This is my first post but I have been reading on the forum for a while now and have gotten a lot of useful tips. I have an issue with my Katana, it will not go past 7000 RPM in any gear including and past 3rd. In first and second I have tried and it will go past 7000 but if I try in those gears and open the throttle the acceleration is actually less good than half throttle. 3rd gear and beyond it will not accelerate past 7000, not at 1/2 throttle, WOT or in between.

The bike:
I bought it off a guy who had it parked and untouched for 2 years, he had no real idea of the PO or about the bike. According to him and the registration, it's a 1994 750, the frame also has that sticker. The engine on it is a 600 and the carbs are 88/89 BST31ss, stock air filter, a fuel line filter, Honda CBR exhaust and an 88/89 model petcock to match the carb.

I have taken the carbs apart and cleaned them according to carbs 101. All the jets and the needles are set according to the manual. The carbs have been synched and spark plugs are only 2 weeks old. the fuel screws are turned at 2 1/4 and the bike is running a bit lean but overall smooth except for the problem above. I have also tried it on prime while riding to see if there is any change but none at all. I drained the tank last night and noticed the petcock was leaking slowly, not sure how fast half a tank should empty but it did take over 30 mins. Any help would be greatly appreciated.

[05RedKat600]

Do they do restricter kits in canada?

[Mat]

I don't believe they are used. Not sure what they look like on carbs but I will do a little research and take a look.

[05RedKat600]

They would be in the rubber boot between the engine and the carb, IIRC.

[Kreylyn]

Will it rev over 7k when not in gear?

What size main jets are you using?

Ditch the inline filter and put a new fuel line on. (it can restrict fuel flow preventing the bowls from refilling quickly enough).

Nothing is in front of the air filter inlet, and nothing is stuffed inside correct?

Krey

[Mat]

We don't use restrictors for licensing purposes in Canada so if there is one it would have been done by the previous owner. I will have a look later. I am also going to remove the inline fuel filter. I thought the airbox boots were properly seated but I will also have a 4th look!! I also have no idea how much fuel flow comes out of the petcock when on prime but as I said it seemed to have been a bit slow. I really am lost for ideas on what to do/where to look for the lack of RPMs.

Sorry Kreylyn I just saw your post. It will go up to redline when not in gear. Nothing in front of the air filter inlet nor anything stuffed inside.

Main jets are 137.5 on 1 and 4 and 135 on 2 and 3.

[Kreylyn]

We don't use restrictors for licensing purposes in Canada so if there is one it would have been done by the previous owner. I will have a look later. I am also going to remove the inline fuel filter. I thought the airbox boots were properly seated but I will also have a 4th look!! I also have no idea how much fuel flow comes out of the petcock when on prime but as I said it seemed to have been a bit slow. I really am lost for ideas on what to do/where to look for the lack of RPMs.

Sorry Kreylyn I just saw your post. It will go up to redline when not in gear. Nothing in front of the air filter inlet nor anything stuffed inside.

Main jets are 137.5 on 1 and 4 and 135 on 2 and 3.

So you have stock jets. What setting is are the floats at?

krey

[Mat]

Needles are forth down from the top as per the manual and the floats are at 14.5 mm.

[arsenic]

The stock needles aren't adjustable. And no jet kit recommends 4 grooves down. Wow, nevermind, I read 1994 750. Then it says the engine is a 600 and you have 88-89 carbs. Well, the 88 needles are adjustable, and the main jets are stock so yeah. You got yourself something there.

[Kreylyn]

I'm starting to think it might be something electrical...

If it's fuel related, it is probably going to be fuel flow issue. Petcock, fuel line, or something keeping the bowls from refilling fast enough.

If it's not fuel related, then you might have something causing a problem electrical wise. I would check the coils.

Krey

[Mat]

I have a new battery and I will check the coils later. Maybe after the Stanley Cup comes out at the end of tonight's game, hahaha.

[05RedKat600]

The stock needles aren't adjustable. And no jet kit recommends 4 grooves down. Wow, nevermind, I read 1994 750. Then it says the engine is a 600 and you have 88-89 carbs. Well, the 88 needles are adjustable, and the main jets are stock so yeah. You got yourself something there.

I'm starting to think it might be something electrical...

If it's fuel related, it is probably going to be fuel flow issue. Petcock, fuel line, or something keeping the bowls from refilling fast enough.

If it's not fuel related, then you might have something causing a problem electrical wise. I would check the coils.

Krey

1994 750 chassis, 600cc motor....case of the wrong carbs on the wrong motor mayhaps? I thought I read somewhere that those carbs were only good for those two years of motors. If the PO didn't know that, maybe they put the wrong carbs on the motor?

[Mat]

Could be the case of the wrong carbs on the wrong motor, really hoping it's not though. If the PO did put the wrong carbs in he also changed the petcock as it is correct for the carbs. Not sure where to find the markings though.

[Mat]

Hey guys,

Update.
thanks a lot for all the help, it is very much appreciated. I think I have my problem pinpointed. The inline fuel filter was removed and I put in a new fuel line but no change. I pulled the spark plugs and found #1 and 4 to be good. #2 was a bit dark and #3 was showing very rich. Took a look at the coils and found that the right side coil used for 2 and 3 was somewhat melted/screwed up where the lead for #3 comes out. I found a coil in town and will be replacing it by the end of the week end. Hope this solves the issue, I have missed a few good riding days and the season is short up here.

Mat

[MikeHawk]

hmmm