Z650 into 810 project

[Crofty]

Thanks for that BL, I might give it a miss and see if it dulls a bit.

[Crofty]

Picked up my top yoke which I had a bit more machined off from underneath to allow front end to sit a qtr inch higher. Also got swing arm bolt, rear wheel axle and spacers, brake arm and disc bolts back from plater



Also have been using GPRD Gary's ultrasonic cleaner to bath my carbs, then a bit of elbow grease to get them shiny.



Two done, two to go
Got a set of bigger carb rubbers off padders, they just required a slight 1.5mm elongation of the mount holes to allow them to fit the GPZ head.

[Crofty]

Finished rebuilding the smoothbores today, new float gaskets, drain plug and carb joint o rings, plus 1 air pilot screw.
Then matched inlet rubbers to head by dremelling away surplus rubber to eliminate any step where they meet. Then secured them to head with a small bead of hylomar.

[Padders]

Looking good

[sanderz]

All coming together now

Picked up my top yoke which I had a bit more machined off from underneath to allow front end to sit a qtr inch higher

Is this to keep it close to the original Z650 geometry with using ZX9 forks and a 18"wheel?
Keep it going.

[Crofty]

Sanderz, I figured that I have gone 17" rear, 18" front (18r/19f is std). So that drops it half inch overall.
The ZX9R forks are actually same length as my 650 forks at rest, but the top ZX9 yoke is flat, the 650 top yoke steps down 3/4 inch, so by machining 1/4 inch off top yoke underside and the fact I have a lower tapered bearing with a good step which spaces lower yoke down a bit, i will only be about 1/2 inch lower at front, I can creep forks down a few mm in the yokes too.
The frame I am using started life as a 650D, custom style and these had a bit more rake, so we will have to wait and see if the 0.5 of a degree more trail will help.
I have heard of 650 owners dropping the yokes up to 1 inch down the forks to sharpen the steering, so have a feeling it won't be too bad.
Have you any experiences of these type of mods? crofty

[sanderz]

Have you any experiences of these type of mods? crofty

In a word - No ...... way, way too complex for a numty like me

I am 'aware' of what changes to a bikes geometry can have - although i think in reality a bike set up for one person wont neccessarily suit another.

Using 'more modern' yolks from later bikes usually occurrs a Decrease in fork offset which Increases trail.
Lowering the yolks on the forks would Decrease trail and quicken the steering.
The offset of yolk, fork length, wheel size changes on bikes such as Zeds is the Increased trail will generally cause the bike to 'flop' into corners.

All depends how one rides i suppose - me, im like my uncle these days - wanting to take in the scenery without the pipe going out

Doubt this has made sense and i hope i've got the offset / trail bit right - my excuse if not ..... its early in the day.

Keep it going Crofty

[Crofty]

Those are the carb rubbers I got from you Padders, they fit the smoothbores perfect as you said. I did need to file the holes inwards about 1.5mm and smooth out the inner to match the size of the ports after Ray had enlarged them.
I used a blue hylomar bead of sealant around the mating surface where it joind the head for final assembly. I hope this is OK for that?

[Rich]

blue hylomar - yes - stays flexible and immune to petrol. wipe excess off with acetone

[j.b]

coming along realy well crofty

i've also used blue hylomar when i fitted z1000j inlet rubbers onto my plenum to fit the gpz1100 throttle bodys...has worked a treat

[Crofty]

Can remember using a lot on my Mini cooper s, to put on gaskets between g/box and block and clutch housing to block/g/box. This is a copy of the original hylomar, have not seen it in shops. Have to look online.

[750steve]

Very interesting thread Crofty, jus read it in full. I'll hopefully be doing something similar with my Z650B1 build. So far i've got 750 Zephyr wire wheels for 160/120 rubber, FREE ER6 forks (41mm) & Yokes & ER6 Calipers (i can use the ER6 m/c but i'll probably go radial with this one). I was going to use a ZRX 1100 swingarm but for handiness i know where there is a 750 Zephyr Swingarm, caliper, torque arm , axle & spacers.......takes alot of spacer making & bearing changing out of the equation!

Anyway, the engine. I HAD hoped to use a 750 Turbo lump but i have v little mechanical skills so i thought the maintainence of that is beyond me. Then my thoughts turned into doing a 810cc conversion cos the motor will be fully rebuilt then & i know it'll be sound, can i pick your brains on a couple of things though please?


1/ If i use a 650 block which GPz 750 head can i use? I read about the cam chains being different or something? I'm actually considering using a full GPz750 engine but i think the 650 looks nicer!

2/ I know my front wheel's rolling radius will be different to yours but are you changing clocks or have you found out if you can re-calibrate the std clock?

3/ Will the Z650 gearbox & clutch stick the power increase?

4/ Where did you find the piston kit? (i see they are available in USA)

5/ What will the new rev ceiling be?

Cheers, brilliant thread, it'll be interesting to see how she turns out, a guy on the 650.info forum has just finished a 810cc build as well.

[Crofty]

have pm'd you with the answers to questions

[steve.w]

810 steve hold on ta ya hat .. i had an 810 unitrack a few years back wot a difference it makes well worth the money

[750steve]

have pm'd you with the answers to questions

Recieved & replied, thanks Jim

810 steve hold on ta ya hat .. i had an 810 unitrack a few years back wot a difference it makes well worth the money

Ahhhhh........the man to ask! Steve, which felt best to ride before i spend silly money somewhere! An 810cc conversion or a turbo motor? Fookin choices!!!

Oh......and.......you're a bollox!!:lol: ..........when you said the chrome was good on those wheels i didnt realise it was THAT good...........have to fookin rethink my whole colour scheme now!! But y'know what, those wheels may have seemed expensive to some but im gonna save £100 on powdercoating them & i might not have to replace the bearings, the axle diamater used for them is the same as the ER6 front end im using & the 650 speedo drive is the same too so just 1 custom spacer needed for the opposite side, an ER6 or Zephyr one might even do the job!! A 750 Zephyr swingarm setup would make things VERY handy!!