22nd May 2021 at 9:16 pm #27626
I’m in the market for a winter project for a z750 to modify (update) & compliment my Ducati. Not fussed what model or spec with wheels, discs etc would take a basket case if it’s all there.
Would also be interested to know what tuning mods there are out there, big bore kit, non CV carbs, not looking for big hp gains, more torque ideally.
Thanks in advance
Andy23rd May 2021 at 7:50 am #27627coleighfParticipant
They are around, look on FaceBook, Ebay etc. Although specialist engineers have enlarged them etc, there really aren’t special tuning parts for these engines. Quite honestly the outstanding feature of them is their mid-range torque, more at 3,000 rpm than a Honda CB750K does at 7,000. The best thing really is to restore one to good original condition and enjoy riding it. Quite honestly this characteristic is far more important than straight-line top speed (speedo 110/115 mph) and makes them really suitable for today’s roads, particularly because they are slimmer, lighter and handle better than the contemporary four cylinder bikes.23rd May 2021 at 8:15 am #27628KaptainkwakKeymaster
Hello Andy and welcome.
I’ve never been that keen on Ducati styling but that really does look nice and a bit of a beast. I compliment my twins with a ZRX1200R.
It is an interesting request you make there as to what you want but more so about what you want to do with it and i’m sure I can help with both.
I have a dismantled K model here, the belt drive version which originally looked like this
I bought it stripped down and it has waited for me to get round to it.
With regards to the tuning side of things there are several ways you can go forward but you need to be aware that these bikes did not sell in large quantities so the aftermarket guys tended to ignore them. Most mods tend to be the owners imagination.
Carbs: I have 2 manifolds here for single carb conversions. One is for an SU carb which I also have and the other is for a twin choke webber. I have not fitted either so cannot tell you how they affect performance. GPZ500 carbs go straight on the 750 twins as I believe XS650 carbs do so if your aware of any upgrades done to these then they should be a comparatively easy job.
Big Bore: Some members have done bored their engines out. The maximum ‘standard’ you can achieve appears to be 865cc. You cannot buy a kit that I am aware of and you will have to have the required parts made. Bigger has been done but that requires machining of the crankcases and new liners being made on top of the other parts. Bigger bores have been achieved in Germany where one of our members who races one of his twins has achieved around 930cc. I also believe that one of the Germans has done over 1000cc. My understanding is that it ran but other compensating engineering hadn’t been considered.
Torque: One of the main characteristics of the twins their torque. If you haven’t ridden one before I think you will be pleasantly surprised on what they can do. At around 54hp it does sound a little sluggish but don’t forget that is 27hp each cylinder which is more than the z900. Surprisingly up to 70 mph the stats show little difference. Big changes in this area can be achieved by simply altering the drive chain sprocket ratios.
KK24th May 2021 at 8:58 pm #27629
Thanks for the reply, I’ve never had a bike I’ve not modified or improved, I do like old bikes with a modern twist & want to do something similar to a z750, I’ve got an idea of how I want it to look.
It will be just a Sunday bike for me & the wife to go to the coast on etc, not really practical for her on the Ducati.
Andy24th May 2021 at 9:16 pm #27630
A Ducati has always been my dream bike since seeing a Hailwood Replica as a kid, wouldn’t swap it for anything else.
It’s heavily modified, has 170hp at the back wheel & is a cracking trackbike.
I’d be interested in that 750 but would need to know if it’s easy to convert the belt drive to chain & whether the seat & tail piece from the B model (or z650/900) would fit? I want a flat seat rather than a stepped seat
My plan is to convert a z750 into a supermoto/flat tracker style with LED lights, indicators & a set of spoked 17″ wheels.
Andy25th May 2021 at 11:27 pm #27631KaptainkwakKeymaster
The conversion to chain drive is simple. All you need to do is remove the pulleys and fit the chain and sprockets. The rear hub is the same fitting for both as is the drive output shaft splined section.
With regards to seat and tailpiece etc then no they do not interchange. However I do have a pattern here that a mould can be made from to then mould a flat tracker seat unit.
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