Katana won't rev past 7500rpm

[jbloudg20]

Yesterday I got to take my new (to me) Kat out for a spin, and noticed there was a severe power loss at about 7500 rpm. After reading, I thought it might be the clutch cable.

I adjusted it today, and upon taking it for another drive, discovered that the bike physically wont rev past ~7500 rpm.

What might be causing this? Thanks for any help you can provide.

[SSearchVT]

Check the easy stuff first like a loose throttle cable...

Is it popping and spitting at all? - Bad gas.

Drain as much as you can from the tank, fill it up with fresh, and add a good slug of carb clean to each tank for a while.

Could be bad plugs - or one not firing as well...

Good luck...

[The Snowman]

It's a Suzuki, that's why. Should've bought a Honda.

Seriously though, does it have a clutch switch? If so, check to see if it is disconnected. If it is, this might lower the rev limiter to protect the engine from redlining.

[jbloudg20]

Check the easy stuff first like a loose throttle cable...

Is it popping and spitting at all? - Bad gas.

Drain as much as you can from the tank, fill it up with fresh, and add a good slug of carb clean to each tank for a while.

Could be bad plugs - or one not firing as well...

Good luck...

I'll check the throttle cable, in a few minutes.

It was sitting for a while before I bought it, and there was old gas. I just filled it up completely today, and put in about a 1/4 tank earlier this week.

I also probably should have mentioned that the bike has 5500 miles on it, and is a 2001.

I was also thinking fuel filter, so I think I'll grab one of those as well.

Thanks for the suggestions.

EDIT: The bike revs just fine with the clutch pulled in, up to 11k or so.

[RandyO]

is there any kind of sound deadenng foam.material on the underside of the fuel tank that is coming loose and getting sucked into the airbox opening ?

[spydah]

It was sitting for a while before I bought it, and there was old gas.

How long was it sitting / how old is the gas? If its more than 8 months I would bet on bad gas having gummed up your carbs. I just went through this on my sisters bike. The new stuff they are cutting the gas with is making it go bad faster.

[loridin64]

this happened to my RC last summer, problem was a bad ground. Absolutely would not rev over 4k on the road, but not moving it was fine.
if you've checked the obvious like prevously mentioned, i'd move to this route

[jbloudg20]

this happened to my RC last summer, problem was a bad ground. Absolutely would not rev over 4k on the road, but not moving it was fine.
if you've checked the obvious like prevously mentioned, i'd move to this route

My father ( Infiniti Master tech, and previous rider for many years) just took it out, and said it seems like its an electrical thing. We're gonna open it up, and check the plugs, wires, etc.

From what I'm told, the bike sat for about a year. While we have it apart, we'll probably clean the carbs. He used to deal with carbs all the time, so hopefully this won't take a trip to Suzuki to get sorted out.

While we are at it, we'll take care of the 4000 mile service, since I kinda doubt the previous owner did it.

Thanks for the ideas guys, I'll let you know what happens.

[Ericthejet]

Clean carbs IMO.

[Pigman]

Check your battery loose connection make for some weird symptoms>>>

Its kookie but I have seen it..

[spydah]

While we have it apart, we'll probably clean the carbs.

I bet you will find sludge in the bowls inhbiting the flow through the jets. Hope this is it and its a quick fix! Good luck!

[jbloudg20]

I bet you will find sludge in the bowls inhbiting the flow through the jets. Hope this is it and its a quick fix! Good luck!

Thanks, and thank you all! I'll let you know what we find.

[vintage ex race]

ck for mice in airbox, those mouse house's sure can slow a bike down

[KB]

Kill yourself now before that Katana does first.

KB

[jbloudg20]

Just wanted to add that we have narrowed it down to a select few things. The most likely of which is the ignition coils. I haven't really had a chance to tear it down, yet to check them, however.

[OreoGaborio]

If you can get it up to Beverly MA then shoot a PM to TLRMan and your problems would be solved.

not a shred of doubt in my mind.

[jbloudg20]

If you can get it up to Beverly MA then shoot a PM to TLRMan and your problems would be solved.

not a shred of doubt in my mind.

Thanks for the recommendation. That seems like a better alternative to the Stealership if we can't figure it out.

[minutiesabotage]

With carbs, the general (emphasis on general) rule is:

RPM related = ignition or electrical problems
Throttle Position related = carb problems

Try connecting the positive lead of the coils directly to the battery, that will bypass the stock wiring and any internal resistance problems. I've done this on two of my bikes and my spark distance almost doubled. May not be the issue...but a thing of wire and slide ends will cost at most $5.

Edit: By spark distance, I mean the farthest I could hold the plug from the block and still get spark.

[SVRACER01]

if it was carb related it would be the opposite. fine up top and shitty down low. the jets are way smaller in the slow speed/idle circuit which is why they clog first.
sounds like the problem im having with my pit bike. im gonna flush out the fuel and if that doesnt work then its gotta be electrical.

[minutiesabotage]

Yea....so since its RPM related, its probably electrical.

[jbloudg20]

Yea....so since its RPM related, its probably electrical.

And that is the first thing my father said when he got on it. The entire Katana forum, however, is convinced its my carbs.

I trust my dad's judgement, so that is where we have been concentrating our efforts.

[ChR1s]

Have you drained the fuel tank completely (symptoms described seem like what can happen with water in the tank) and checked the airbox for debris and/or oil contamination, as others have suggested?

[jbloudg20]

Have you drained the fuel tank completely (symptoms described seem like what can happen with water in the tank) and checked the airbox for debris and/or oil contamination, as others have suggested?

I have not emptied the tank, but I did check the airbox and it was fine.

[minutiesabotage]

A test I used to do to see if there were carb problems was to spray ether into the intake, NOT directly into the engine, and see if it helped out. Saves the hassle of taking everything apart if its not necessary.

[jbloudg20]

I'm pretty damn sure that its not carbs at this point.