Engine Power not good

BSKZ650 wrote:

just had a thought, does the bike pull hard thru the gears?

it has great pick up but just doesnt on the open road

wiredgeorge wrote:

Foam air filter? Hmmm, you may have added so much air, it is actually running out of gas. I would check the throttle cable first (good idea) and then look at the filter second. Does this foam filter require cleaning/reoiling?

I never thought about the filter since it was the one used by the last guy I will go buy a new one after I get it all back together

Sounds to me like you are either running out of gas or you got a pluged exhaust. I'm going to put my money on gas since you can go through the gears fairly easy.
These engines are gravity fed and the slightest restriction will leave the bowls dry.

I dought .002 on one cylinder is going to stop it from going over 55.

dadams7161 wrote:

BSKZ650 wrote:

what rpm are you turning at 55?

since you had a broken cable are you sure you were able to open the throttle all the way?

what does it feel like, is it like it is maxed out or does it shutter like its not getting enough fuel, poss a venting problem at the tank

well before the new cluth I was at 4500 now it is around 3000 I believe it is very possible the throttle was not opening all the way I did not check just went ahead and bought a new cable and I just feels like it just looses power when you go up the smallest of a rise in the road it slows down,

You changed the clutch and you are now turning 3000 rpm at 55 mph, while before changing the clutch you were turning 4500 rpm at 55 mph?

Are you sure that's right? Can you provide some details like what exactly you changed? That makes no sense at all to me, so I must be missing some info.

There is no way to re-gear a 750 twin to turn 3000 rpm at 55 mph without major modifications, sprocket change won't do it (unless you custom make a 20 some tooth rear).

I currently have three 750 twins, plus another six spare motors, and a bunch of other 750 twin parts. I know the 750 twins inside out.
Just so you'll know that I do know what I'm talking about on 750 twins. I had a 82 KZ750M1 but sold it because I didn't like it.

steel is the twin godB) any advice he has I would listen to, I think you have a simple issue, just work thru it

this might be an idiotic remark and doubtful but maybe the previous owner changed the sprockets and the old clutch was slipping the engine to 4500rpms and now with the new clutch its hard for the engine to turn the bike up to 55mph but its only spins at 3000rpms. that still seems kinda doubtful though.

im a fan of the clogged exhaust though. stock exhaust on an old bike spells trouble to me

Post edited by: Makarth, at: 2007/06/08 21:14

On the 750 twins, an 18 tooth front sprocket is a really tight fit, so that's the limit up front. stock on the 750 twins is 16 tooth, and every one tooth increase drops about 400 rpm at 60 mph. so two additional teeth on the front sprocket will drop the rpm to around 4000 rpm at 60 mph. Stock rear sprocket size is 38 tooth, and conventional wisdom says three teeth off the rear = one additional tooth on the front, so to get from 4000 rpm to 3000 rpm, we have to take 7-8 teeth off the rear, which means we need a 30-31 tooth rear sprocket. The smallest rear sprocket that is commonly available (AFAIK) is the stock 38 tooth, so to get a 30-31 tooth rear, we have to call Sprocket Specialist and see if they will make us a 30-31 tooth aluminum rear sprocket. Assuming they will do that (and I think they will), we end up with a 18 front and 30-31 rear. 18/30 gives a 1.67 final drive ratio, while 18/31 gives us a 1.72 final drive ratio. Now given the massive 54 crank hp of a 750 twin, and it's near 500 lb wet weight, I figure this bike is going to have the acceleration of a tortoise, and fifth gear is going to be totally useless, plus the clutch is going to have a lifespan measured in days.

I prefer a 17 tooth front and 38 rear on the 750 twins, which is no problem for me as I spend 98% of my time riding solo, it's a bit of a pain riding double with that ratio when taking off from a stop though.

And just replacing the clutch is not going to affect the drive ratios, so the original poster left something out of his description, or is missing something.

steell wrote:

dadams7161 wrote:

BSKZ650 wrote:

what rpm are you turning at 55?

since you had a broken cable are you sure you were able to open the throttle all the way?

what does it feel like, is it like it is maxed out or does it shutter like its not getting enough fuel, poss a venting problem at the tank

well before the new cluth I was at 4500 now it is around 3000 I believe it is very possible the throttle was not opening all the way I did not check just went ahead and bought a new cable and I just feels like it just looses power when you go up the smallest of a rise in the road it slows down,

You changed the clutch and you are now turning 3000 rpm at 55 mph, while before changing the clutch you were turning 4500 rpm at 55 mph?

Are you sure that's right? Can you provide some details like what exactly you changed? That makes no sense at all to me, so I must be missing some info.

There is no way to re-gear a 750 twin to turn 3000 rpm at 55 mph without major modifications, sprocket change won't do it (unless you custom make a 20 some tooth rear).

I currently have three 750 twins, plus another six spare motors, and a bunch of other 750 twin parts. I know the 750 twins inside out.
Just so you'll know that I do know what I'm talking about on 750 twins. I had a 82 KZ750M1 but sold it because I didn't like it.

The clutch was bad it had 5 broken friction plates and slipped real bad so I put in a new clutch

BSKZ650 wrote:

what rpm are you turning at 55?

since you had a broken cable are you sure you were able to open the throttle all the way?

what does it feel like, is it like it is maxed out or does it shutter like its not getting enough fuel, poss a venting problem at the tank

it is like it is maxed out and I am not sure if the throttle was opening all the way or not I should have it all back together tonight and will test it in the morning.

well Guys I got it fixed. Thanks for all the help, of all things for it to turn out to be was just the Plug Wires. It had suppression wires on it and Kawasaki told me that it was the wrong wires so I ordered copper core Plug Wire and end caps put them on and it runs like a rocket now. Thanks everybody for the help I am so glad I found this site.