Stops reving at 10,500? ('93 750)

[buffalobill]

Hey Guys,
Funky stuff, at 10,000 it's pulling like monster, then at exactly 10,500 rpm the engine just stops revving, won't go past that?
Like the rev limiter kicked in.
Well, I did some adjustments over the winter: all main jets changed to 112.5 and adjusted the valve clearances.
Could it be I got the clearances just a mite, too tight?
Let me know.
Bill

[arsenic]

No, that IS the rev limiter
Why did you change the main jets to 112.5, that's the 600 that's 112.5. The 750 should be cylinders 1, 2, and 4 105 and 110 on #3

[Black_peter]

Why would the rev limiter kick in 2000 RPM before redline?

[arsenic]

I have zero clue to be honest with you, but if it doesn't rev past 10.5 like the rev limiter is kicking in, it must be kicking in. So as I stated, in my opinion, that is the rev limiter, why it's kicking in at 10.5, I can't answer that. I would lean more toward something electrical before valve clearances. I really doubt maladjusted valve clearance would cause that to happen.

[Slofuze]

Just curious..... but how do you diagnose a tach??????

[buffalobill]

Yea, I suspect the rev limiter, but…

So, how do you diagnose the rev limiter? Or actually the ignition module? Maybe it's getting a bad signal, so it's reading the rpm's higher than actual?
Got any ideas?

[arsenic]

If I'm not mistaken, I believe the rev limiter is part of the CDI. That is not possible to test on your own. A dealership service department needs to do it. There is a CDI tester, but it's very expensive. The pre 750 rev limiter kicks in a about 13000 RPM. Could it be that your tach says 10.5 when you're actually turning 13K RPM? That's really the only idea I have.

[scottynoface]

Sounds like a cdi issue, or maybe a loose plug wire?

Weird.

[phil823]

my post 750 hits the rev limiter at 11500

[Black_peter]

The pre 750 rev limiter kicks in a about 13000 RPM. Could it be that your tach says 10.5 when you're actually turning 13K RPM? That's really the only idea I have.

I'm going to second that...

Although there are some goofy loose wire/bad ground issues that can kick in a specific revs. You could work backwards and calculate RPM by speed.

[Crotch Rocketeer]

I'm new to Katanas so forgive me if this is a foolish question but, assuming his tach is correct, could have a module from another model Kat that has a lower rev limiter?

[arsenic]

Yes, that is possible. the pre 600 and 750 CDI is the same, but the rev limiter is lower on the 600. I don't think it's 10.5 though, but I'm not sure.

[Black_peter]

The Rev limit should be 500 RPM over redline.

[arsenic]

Well, I have a pre 600 speedo somewhere, but I don't feel like finding it

[hardlydangerous]

I would assume either the CDI if from the 600 or bandit or the tack is incorrect.
the rev limiter is set in the CDI and can not be changed unless you go with a different ignition system such as the dynatech