750 5 speed to 6 speed swap

[Ian in Holland]

I know that with the original Z650, the 6 speed gear clusters from a Z550 could be made to fit with a bit of machining work.

Does anyone know if there's a similar modification (using bits from another 6 speed engine) available for the 750 Zephyr engine? The intention would be to reduce engine rpm's at cruising speed. Yes, i know that "fours are supposed to spin" etc, but it's nice to have the option of a sixth speed as an overdrive.

Thanks,

Ian

[David Richard]

HI IAN I HAVE A 750 D1 YOU DONT SAY WHAT MODEL YOU HAVE BUT THERE IS A EASY WAYTO ACHEIVE WHAT YOU WANT THE FRONT SPROCKET IS 15 THEETH CHANGE IT TO 17 TEETH IT MAKES A HUGE DIFFERENCE 6 K IS 80 MPH AND ITS STILL VERY TORQUEE BUT WAY MORE RELAXED YOU MAY HAVE TO MAKE A SPACER TO GO ON THE SHAFT BECAUSE OFF THE SIZE THE SPROCKET BUT ITS EASY DONE OR JUST GET THE SPROCKET LOCK TABS WASHERS TO PACK IT OUT DAVID

[Freddy]

HI IAN I HAVE A 750 D1 YOU DONT SAY WHAT MODEL YOU HAVE BUT THERE IS A EASY WAYTO ACHEIVE WHAT YOU WANT THE FRONT SPROCKET IS 15 THEETH CHANGE IT TO 17 TEETH IT MAKES A HUGE DIFFERENCE 6 K IS 80 MPH AND ITS STILL VERY TORQUEE BUT WAY MORE RELAXED YOU MAY HAVE TO MAKE A SPACER TO GO ON THE SHAFT BECAUSE OFF THE SIZE THE SPROCKET BUT ITS EASY DONE OR JUST GET THE SPROCKET LOCK TABS WASHERS TO PACK IT OUT DAVID

Correct width 'hub' larger front sprockets for the D1 (I think the change was made at the C5 model) are available. No need to add spacers. I've got one somewhere laying in the bottom of my used parts bin.

My suggestion to achieve a low revving highway bike, buy a Harley.

P.M. I've tried both higher and lower gearing on the 750. IMO, Kawasaki have got it spot on. At 100 kph the motor should be spinning as smooth as silk just below its power band. If it isn't there is something wrong. Knock it down to 4th to overtake and GO!

[Ian in Holland]

All,

Thanks for the replies.

Yes, I do know that I can swap to a taller final drive ratio with the chain, I've done that in the past, and it does sort of work - at the expense of a higher first gear obviously.

I guess I just want a six speed gearbox! Manual cars used to come with 4 speeds, now they're pretty much all 6 speed, and I wouldn't want to go back. Having a 6th speed (with 5th roughly where the bike presently has 5th) could only be an advantage - you want to hum around in 5th, well, do that. Bit less noise, lower revving engine, change up to 6th.

So back to my original question: "Does anyone know if there's a similar modification (using bits from another 6 speed engine) available for the 750 Zephyr engine?"

Oh, and no, I don't fancy a Hardley Dangerous thanks - I could never find a brown paper bag big enough to go over my helmet

Ian

[Freddy]

All,


I guess I just want a six speed gearbox! Manual cars used to come with 4 speeds, now they're pretty much all 6 speed, and I wouldn't want to go back. Having a 6th speed (with 5th roughly where the bike presently has 5th) could only be an advantage - you want to hum around in 5th, well, do that. Bit less noise, lower revving engine, change up to 6th.

So back to my original question: "Does anyone know if there's a similar modification (using bits from another 6 speed engine) available for the 750 Zephyr engine?"

If you search the forum you should be able to find a thread where someone attempted to fit a Zephry 550 6 speed gear box into a 750. Don't know if they ever finished the project, but they had certainly run into some serious problems, can't remember exactly what it was but as I recall the dimensions were out somewhere.

I was only half joking with the Harley comment. My recommendation is do NOT do what you contemplating, there is a high likelihood the bike may never run again (based on the track record of observing so many 'projects' over the years). Problems arise, frustration sets in, other things take over, interest wains. If you really don't like the high revving nature of an I4, my recommendation is to sell the bike and buy a twin cylinder (which will likely have a 6 speed box standard). Something in the Triumph Bonneville range may be a good choice if you like the retro look.