VFR600 - where would you start?

[R6_kid]

VFR400 crank + cases, new heads + pistons.

or

VFR750 crank + cases, new heads + pistons.


Frame + suspension of your choice.

What would be a more ideal start point?

[Coyote]

VFR400 crank + cases, new heads + pistons.

or

VFR750 crank + cases, new heads + pistons.


Frame + suspension of your choice.

What would be a more ideal start point?
What inspired this?

I remember hearing that 400 cranks are pretty weak (so turbo's will just wreck the motor) so I imagine the 750's crank would be the one to go for. Though why would you want to detune a 750 down to 600? Wouldn't 800 be cooler?


So long as it's updated with all the tech that's gone into bikes in the past 15 years since the 400 came out, I'd be keen. Keep the 400 frame, maybe strengthen it, then get some good suspension.

[R6_kid]

I'm thinking for supersports racing/track riding etc. Better torque, but still keeping the revs.

Just seen that the VFR400 has pretty much the same stroke as a CBR600, but with the difference in size you probably woudn't be able to fit 600cc of pistons in there as there is a substantial difference in the bore.

Perhaps a VFR750 engine a start point. With a new head for 600cc pistons with a stroke of around 42mm (what most 600's are currently using) which would help keep the rev-limit up.

I was thinking 07 CBR600RR frame - why not go with the latest tech.

[FROSTY]

The viffer 400 struggles to get a reliable 435cc due to space issues-talk to Gary Pendleton --if it coulda been done he woulda done it

[Coyote]

Copy the heads off a 600 but spilt them into 2 heads with 2 cylinders in each and put that on the 750 crank.

An 07 CBR frame would be good. I was just thinking 400 dimensions would be fun with more power.

I must get into engineering. I'd love to be able to make this.

[R6_kid]

Yeh, the only thing is the CBR600RR frame wont take advantage of the much more narrow engine.

[MVnut]

probably end up costing more than an 07 CBR600 and may not be eligible for many events anyway, sounds like a waste of time, but if you're capable, engineering wise, good on ya, I hope it works

[Coyote]

Could have side radiators like an SP1

[HenryDorsetCase]

there has been a lot of work done on this over the years.

its a relatively common mod to take them to 434 cc, and they can go to ~500 I think but the issue would be crank strength, and the case strength as well. remember these were purpose designed to own a 400cc class (with supporting race class) in Japan, so it was built to a specification to allow that. increasing the cubic capacity by half again will lead to all sorts of issues: piston skirts banging into one another at bottom of stroke perhaps. bore centres, water jackets. clutch basket strength. (these are already suspect even at 60hp) gearbox shaft and bearing issues.

And one you're done, you've got a 15 YEAR old chassis and suspension package.

even if you staple current tech suspension on it, its still not a CBR600.

You've looked at the two motors side by side? You would be well better off starting with a 750. IMO ofcourse.

and do post pics.

I will hunt up the linkage for the high HP ones. I recall some very good tech discussion.

[Little Miss Trouble]

probably end up costing more than an 07 CBR600 and may not be eligible for many events anyway, sounds like a waste of time, but if you're capable, engineering wise, good on ya, I hope it works

All hypothetical... I dont have the money or the skills to go through with it, but we're allowed to dream right!


oops it's R6_kid.

[Qkchk]

VFR400 crank + cases, new heads + pistons.

or

VFR750 crank + cases, new heads + pistons.


Frame + suspension of your choice.

What would be a more ideal start point?


Not like you to take an interest in a Honda, or have they become the new black? ;)

[MVnut]

All hypothetical... I dont have the money or the skills to go through with it, but we're allowed to dream right!


oops it's R6_kid.

It would be a sad day if we couldn't dream.:niceone:

[HenryDorsetCase]

http://www.akhara.com/nc30/pistonrod1/index.html

450cc kit

[R6_kid]

Not like you to take an interest in a Honda, or have they become the new black? ;)

Heh, easiest point to start... I would look at a twin-pulse 600 IL4 if I wanted to stick with Yamaha but it's not that 'special', and since hearing the Desmo and the RSV4 i've now got an obsession with big bore V4's :sweatdrop


http://www.akhara.com/nc30/pistonrod1/index.html

450cc kit

Not big enough!!!

[Coyote]

It would be a sad day if we couldn't dream.:niceone:
Dreams make reality harder.

[Qkchk]

Heh, easiest point to start... I would look at a twin-pulse 600 IL4 if I wanted to stick with Yamaha but it's not that 'special', and since hearing the Desmo and the RSV4 i've now got an obsession with big bore V4's :sweatdrop



Not big enough!!!
If only they had made more RC30's..............

[R6_kid]

If only they had made more RC30's..............

Amen sister! I'd like to think that we'll see something similar in the next 5 years or so, but that may just be wishful thinking.

[MVnut]

If only they had made more RC30's..............
Beautiful, one of the only Hondas for me (2 down, one still required):beer:

Dreams make reality harder.

Only if you let it.....:yawn:

[Coyote]

Only if you let it.....:yawn:
My minimoto is a dream come true :D

[quallman1234]

Sounds like not such a good idea. Mmmm.

I reckon the money is with an RS250 Chassis and a decent motor.

[vagrant]

If only they had made more RC30's..............

But then we wouldn't be so special!!!:laugh:

I have a friend in the UK who is currently building up an RC big bore kit, to take them out to 888.

The Moriwake factory racers from the early 90's were good for around 145 horseys, but over that they started busting the cranks. The rest of the engine is pretty bulletproof.
The RC45 has a way stronger crank design, perhaps that would be the go,
888cc and fuel injection!!!!

[mark247]

The viffer 400 struggles to get a reliable 435cc due to space issues-talk to Gary Pendleton --if it coulda been done he woulda done it

I get all the parts i need from him. His VFR is pretty bloody tricked out. He knows his shit.

Really helpful guy, i just rock up to his house and he sorts me out every time.

[mark247]

oh and if you want good rods for a vfr400, look into this

http://www.akhara.com/nc30/pistonrod1/index.html

im not too sure if they make them anymore tho...