Diagnose this.....

[ctandc]

Haven't had time to look at the Kat yet. Thought it would be fun to see how this went.

Bike: 91 Kat 600 frame with 01 Kat 750 Engine / 01 750 Carbs

Ivan's Jet Kit
FP Advancer
Stock Air box and new OEM filter


Been running fine for more than a few thousand miles. Zero issues.

The other day coming home from work, dropped it down a gear on the Interstate and tach'd it up a bit...about 9K RPM or so..it just seemed to die. Let of the throttle when I noticed, when I went back into the throttle it was fine. Did it a couple of other times...same thing. Little afterfire from the exhaust, so leads me to believe the ignition / power actually cut off for a split-second.

Acted like the kill switch was hit and turned back on immediately. (It wasn't...by me).

NOTE: Several months ago I replaced the stock pre 98 Kat control / switch pods with later model Suzuki stuff. Wired into stock pre 98 harness connectors. ZERO ISSUES till now.

Plugs are more than a season old.

I did not solder the connections on the new switch pods. They are crimped very securely and wrapped.

So what is everybody leaning to? The switch pods? Plugs? CDI? Hmmmm?

[Black_peter]

Side stand switch, diode package?

[ctandc]

Hmmm...interesting. Never thought of that.

[akarob]

Yea, if nothing else, check the cheap switches first. Sidestand, clutch, kill switch.

I'd start with the side stand

[ctandc]

I may try bypassing the side stand switch tonight. It did it again today on my morning commute. Bumps / rough road do not trigger it. Only when I get higher in the RPM range..say around 8-9K. It will act just like the kill switch is triggered. Then when I let off the throttle, then ease back in, it runs fine.

[steves]

problems on rough roads make me think of loose connections.

[ctandc]

problems on rough roads make me think of loose connections.

That's the thing. I purposely ran over bumps / potholes I would normally avoid. It did not trigger the problem. Only happens when wrapping it up a bit.

[Black_peter]

I may try bypassing the side stand switch tonight. It did it again today on my morning commute. Bumps / rough road do not trigger it. Only when I get higher in the RPM range..say around 8-9K. It will act just like the kill switch is triggered. Then when I let off the throttle, then ease back in, it runs fine.

So that means no matter what gear?

Sweet Lou is having a similar issue, though at 4000/4500 RPM.
He mentioned that someone had a similar issue and it was the tach..

[ctandc]

On the commute home...

Reproduced the problem.

Bumps / potholes etc DO NOT cause the cut out.

Tried in more than one gear, when revving to @ 8K RPM bike cuts out. Almost like the kill switch hits. Let off gas, roll back in, hear afterfire in exhaust, bike continues on just fine.

Had 'em sitting around so tonight just got finished replacing all 4 spark plugs, reseating all wiring harness connections.

Will test tomorrow on the ride to work.

Side stand switch bypass will be next....but I doubt it would produce the symptom just at one certain RPM range regardless of vibration / gear selection etc.

[ctandc]

UPDATE

Four new plugs in. The plugs in the bike were actually a bit loose...if that makes sense. Installed new NGK plugs. Checked all wiring connections. Everything looked fine.

In neutral. Kickstand down. Bike will rev freely to red line, no hesitation, no miss, runs great

Took it for a ride today. Took it to about 10K RPM in low gear, ran GREAT.

Got on the Interstate. Hit @ 7.5K RPM (steady acceleration not wrapping it up quick) and the tach immediately drops to zero, bike literally acts like it cuts off. Let off gas...small backfire out of the pipe, bike picks right back up.

Took a full throttle run...quickly up to @ 10K RPM and it does it again, but this time it cut out, cut on, cut out etc...until I eased off...then it started running fine again at lower RPM.

What in the world?

I don't see how it could be the side stand switch. Bumps etc don't effect it. Purely RPM based, gear choice doesn't matter.

So what's next?

Air filter is new OEM replaced a couple of months ago. Same time I added the jet kit. Also of course plugs are now brand new. Carbs were sync'd.

I've got a spare set of coils. I may try installing those.

Any thoughts? I'm wondering if the new switch controls I wired in could be somehow causing it?

So that means no matter what gear?

Sweet Lou is having a similar issue, though at 4000/4500 RPM.
He mentioned that someone had a similar issue and it was the tach..

Yeah no matter what gear. Any info on the tach problem??

[HemiKat]

Sounds like the rev limiter is kicking in. Maybe the tach is messing with the CDI or the CDI has issues itself?

[suzukiray]

Also, keep in mind, free reving the engine with NO load on it is a GREAT way to bend valves! Take it for what it's worth from an engine builder. Ray.

[ctandc]

Also, keep in mind, free reving the engine with NO load on it is a GREAT way to bend valves! Take it for what it's worth from an engine builder. Ray.

Appreciate it. It wasn't done repeatedly. Just trying to see if I could duplicate the issue without a load.

[ctandc]

Well I'm off tomorrow. I'm going to redo the wiring for the switch pod (kill switch side) I Wired in a couple of months ago. Probably go ahead and solder everything to be sure. Then I'm going to check all harness connections and at this point I think I'm going back to stock on the carbs.

[kevin2502000]

I definitely think it sounds electrical and not fuel.