VHM Heads

Camus14 · Post by **Camus14** » Tue Mar 22, 2011 8:34 pm

Hello everybody

I'm new in this great forum!
I'm from france where it's probably harder than in UK to find parts for that wonderful bike...so, I asked the pro to make ones!

I would like you to know Heikki from VHM is interested by making heads (separates not one piece as the OEM one) if there's enough people interested!

Could you be interested?

Post by **alimorg** » Tue Mar 22, 2011 10:35 pm

Hello and welcome, sounds interesting what would these heads cost?
Cheers
Al

the-elf · Post by **the-elf** » Tue Mar 22, 2011 11:45 pm

Yep I would be interested in some with removable combustion chambers.

Oh and welcome

Charles · Post by **Charles** » Tue Mar 22, 2011 11:49 pm

Welcome! We've discussed this before ( viewtopic.php?t=1907&start=30 ) :

mj43 wrote:Take care with it. I was told that the cylinder head holds the engine together.
This mod was apparently tried in the early '90s and the crankcases on modified bikes cracked!

When I designed my billet heads, though the heads were individual the design allowed a bridge to be fitted to replicate the bracing a one piece head provides.

Charles

Luders · Post by **Luders** » Wed Mar 23, 2011 12:10 am

What is the performance benefit from having seperate heads?

I do not see this as much of an enhancement and more of a stress on the engineering to be honest.

Can you please explain?

Thanks, Ben

JanBros · Post by **JanBros** » Wed Mar 23, 2011 12:19 am

Luders wrote:What is the performance benefit from having seperate heads?

I do not see this as much of an enhancement and more of a stress on the engineering to be honest.

Can you please explain?

Thanks, Ben

it has some advantages :

* you can switch combustion chambers so the needed power matches the track

* in case off engine failure, you only need a new insert, which is fairly easy/cheap to make.

* same for experimenting engineconfigurations : if you are good with a lath, you can make the inserts yourself, in stead off having to re-weld your cylindre head and re-machining.

* if designed properly, the head even has better colling.

Luders · Post by **Luders** » Wed Mar 23, 2011 12:36 am

Something just doesn't quite stack up for me, but i would be interested in what you lot decide to do with these.

KR-1R · Post by **KR-1R** » Wed Mar 23, 2011 12:43 am

...from my discussion with VHM (a while back)

the main grief is new hoses and thermostat housing solution (extra expense)
smaller solvable problems...
the extra sealing o-rings would be required around the KIPS (gasket side runs very close to where the chamber o-ring, and insert sits)
and the fact that even a universal individual head design would require slight deviations for the KIPS cable end mounts (see top photo)

the price was inline with the other products at around £400 mark (KR set)
I think will have to get some 56mm (KTM) inserts and modify the KR head for inserts first

organising people to front up and rely on them is another story

CHARLES' machinist was keen on having a go to make heads as well
a group buy on stainless pipes (bring them below £400 pair again) and Im in

Charles · Post by **Charles** » Wed Mar 23, 2011 7:37 am

KR-1R wrote: CHARLES' machinist was keen on having a go to make heads as well

I first need to sell off the valves and pullies I still got before I start another project.

Charles

KR-1S.co.uk Forum

VHM Heads

VHM Heads

VHM individual separate heads

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