She Redlined Herself -

Hey gang. Hadn't had a chance to ride for the past few days so my old girl decided to start acting up. Musta been just to get back at me for not squeezing in a last few rides:)

I had changed the clip settings a couple of night back as it seemed to be running rich and backfiring a bit.

i did the clipping up to the second notch from the top, put 4 brand new 5DL13 needles into the Mikuni 28's as I am trying to dial out a flat spot around 7 grand at wide open throttle.

The bike started very poorly and sounded like it was only running on 3. This thing usually fires up on the first couple of turnovers of the starter. The plug caps were all snug and I had just cleaned the plugs.

The air temp was right around freeeeeezing so I let it warm up for a little over 5 minutes thinking it might clear itself. When I hit the throttle the motor revved to around 12 grand on the tach before I could hit the kill switch. I fired it up again with a little twist of the throttle and the same thing. Full revs.

I checked the throttle cable and it was pulling and returning normally so I suspect the sliders may have been hanging up. I only have the pull cable on the carbs as the return spring is very strong and snaps back if my hand lets go of the throttle grip.

I wheeled the bike into the shop and felt the pipes. I could hold my hand against #3 while the others were in the proper heat range. #3 was warm to the touch but not as hot as the other pipes.

Pissed off I let the bike cool down and noticed later that there was a little fuel leaking from the bottom of the #4 bowl.

I am going to check the #3 plug to see why it is firing intermittently and pull the bowl off #4 to check to see if it is hanging up.

So, my question is this. Has this overrevving happened to anyone before? I am somewhat puzzled given the throttle cable was working freely.

Any comments or suggestions would be apprectiated.

Cheers-Colin Firth-Ontario Canada
1977Kz650 Custom, 810 big bore, Mikuni 28's, Dyna Coils and electronic ignition.

cold air should have leaned your carbs. Running rich after all summer? Did you crack the throttle all the way ? Maybe a jet needle hung up on the outside of the hole? Maybe you outa quit ridin that pig so much. Joke.
You got one flooded carb thats for sure. Read labels before eating..

carbs that ran rich in summer would be leaner(maybe still just a bit rich, but maybe if it was cold enough too lean) with cold air.
could your choke be sticking open? hmmm 12000 seems high for that though.... maybe its a couple things acting up at once?
at the local strip guys usually jet up at the last few races due to the colder air. its like dropping elevation, the motors work better, make more power, and they get better ETs, but due to being run all yr, and then a slight power increase, lots of people break something.... lots of winter projects are started that way

Hey gang. Just a follow up on my overrevving deal from a few days ago.

I finally had a chance to pull the carbs and found the slider on #3 wasn't re-assembled properly from when I had installed the new set of needles. Rookie mistake. I should know better.

Next time I will not talk to my buddy while re-assembling anything on my bike. Complete, 100% concentration or I will have to do the job again.

The bike is purring like it should, hopefully I will get a chance for one or two more squirts before it gets too nipply outside.

Cheers-Colin Firth-Ontario Canada

:ohmy: 12,000 rpm? Isn't that way past redline? Hope you didn't damage anything.

Nope, the bike is singing sweet again, but I couldn't believe how the motor pinned the tach so quickly. Luckily I caught it in time.

It is incredbile how this motor hits the high revs compared to the stock 650 or the Wiseco 700 kit I had in last season. This 810 I built with the milled, ported and polished Kz650 head, Kz750 cams/valves and Gpz springs just loves the higher rpm. Kawasaki built one helluva bullet-proof bottom end with these middleweight superbikes.

Some might find this hard to believe but I had it out on a deserted stretch of highway and wound it out in third gear. I wasn't going to shift until I felt the power drop off. I chickened out when the tach spun up around 11 grand. It was still pulling. A buddy of mine who drag races an older Z1 says he can't believe the powerband which almost feels linear to him.

I know it isn't the best for engine longevity but the occasional blast to the stratosphere is something that I just never grew out of enjoying. Luckily I had a really meticulous and careful engine builder put the motor together:)

Cheers-Colin Firth-Ontario Canada

1977Kz650 Custom, bought new by brother. Latest re-incarnation includes 810 big-bore, Ported, polished and milled 650 head, 750 cams, valves, springs, Wired George Mikuni 28's, Velocity stacks, Dyna Ignition and Dyna Coils, MAC pipe, 14 tooth sprocket, 130 rear tire, Barnett Clutch, Stainless Braided brake lines