KR-1S.co.uk Forum

Where to begin.....
After seeing the rgv/rs cylinder heads stan stephens is selling on ebay I got to thinking if a similar design could be used to make a replacement head with: removable combustion chamber domes for easy tuning, o-ringed mating surfaces, improved water volume and flow (this I have no idea about as the original seems to have a pretty good volume already) and that could be fully machined so as not requiring a casting stage like the original.

Here are the renders I’ve done for the assembled head, the main head block to show the water channels and a few colour variants on the anodised parts.











I’ll be happy to answer any questions posted but as for actually attempting to make this as the costs would be massive to have it commissioned, it all depends on what my next job turns out to be, hopefully with access to an automated workshop but that’s up to her majesty (that doesn’t mean prison in case you were wondering).

My next bit of designing will be to see if (in theory) barrels could be made using two machined halves clamped around a steel cylinder liner. This should allow for easier tuning/flowing and allow the liner to be replaced.

Tofty

Got to admire your computer skills

Ummm lovely. if you ever get some made I'll have some of you

WOW... =D>

Cheers Guys,
I'll keep you posted if i'm ever able to manufacture it and i'll try to make a batch if all seems well with it.
Unfortunately at the moment the head needs custom barrels to work properyl as the water channels wont align very well with the standard barrels and i also moved the pins that align the head and barrels to around some of the screws.

for those of you who would have worked with them in the past; vehicles with steel lines, removable or otherwise, did any of them have an extra surface coating layer or is it just bare steel?

Cheers,
Tofty

Most were just stell liners, although I've seen ceramic ones as well.

You mean a ceramic coating right?
and at what angle are the barrels lent over at?
Cheers,
Tofty

Now that's some serious dedication to the cause, and some damn fine design work. =D> =D> =D>

Wouldn't mind something like that for my old Tandem Twin but doubt I could ever afford it.

500cc V4 [-o<

Is it possible??? I mean... If we are able to design the heads and cylinders so that the cooling channels line up etc....

How far off is it from altering crank etc to fit another couple of conrods

Or maybe we start with a V3 (that would be er.... 375cc) and see how it goes... Kinda like a mini V5 like h***a and ducati use in the Moto GP...



Nate

nate wrote: Kinda like a mini V5 like h***a and ducati use in the Moto GP...

not on this planet

@ScottaKR: looking at the old KR's heads they are much simpler design due to the lack of powervalves. If i only had a kr250 head or its important dimensions i could at least draw you up one with removable combustion chambers and other modern features, but i feel that might be ruining a classic.

@nate: haven't you heard, everythings possible......however there are two major problems: finding space for four (or even just 3) sealed cranks would be difficult without sacrificing their volumes and much loved KR dynamics, secondly the other cylinders would go right where the reed blocks and carbs are for the first two cylinders, and visa-versa.

The barrels and heads are the easy part as they could be pretty much the same, using the KR bottom end is the real difficulty as almost all of it would need to be heavily modified. A V shaped square four could be done but that means it would have the loses of using two cranks, however it would be much more achievable than a GP style V4. The only cylinder increase for a KR engine is the inline triple but perhaps there have been others.

Tofty

Tofty wrote:@ScottaKR: looking at the old KR's heads they are much simpler design due to the lack of powervalves. If i only had a kr250 head or its important dimensions i could at least draw you up one with removable combustion chambers and other modern features, but i feel that might be ruining a classic.

Perhaps, but I know I have 3 bottom ends, and only enough for 2 top ends, so one could argue that it would be reviveing a classic (and I'd love to have powervalves on mine)...
Although the hardest parts to get for us Tandem Twin owners are pistons and Barrels. So if Barrells and heads were designed to fit pistons from something else like an RGV (that you can still buy pistons for), youd probably sell a few, and see more Tandems on the road.

Tofty wrote:@nate: haven't you heard, everythings possible......however there are two major problems: finding space for four (or even just 3) sealed cranks would be difficult without sacrificing their volumes and much loved KR dynamics, secondly the other cylinders would go right where the reed blocks and carbs are for the first two cylinders, and visa-versa.

The barrels and heads are the easy part as they could be pretty much the same, using the KR bottom end is the real difficulty as almost all of it would need to be heavily modified. A V shaped square four could be done but that means it would have the loses of using two cranks, however it would be much more achievable than a GP style V4. The only cylinder increase for a KR engine is the inline triple but perhaps there have been others.

Tofty

Maybe (if you really wanted to build a 500cc varient) you could borrow from the old KR500 racers and do a Tandem Sqaure 4 (instead of a V config). You could borrow the twin crank design from the Tandem Twin, and use the cranks, barrels etc from the KR1. It's still a LOT of work, but would be the easiest to do if you wanted to do something that mad. Personally, I'd love to see it!!!!!! [-o<

Tofty wrote: The only cylinder increase for a KR engine is the inline triple but perhaps there have been others.
Tofty

dont know what happened to this one. who ever was building it was on the
old forum and has never updated us on any progress

Beautiful bit of design work =D>

How about designing separate heads, as this would allow for differences in barrel lengths

I hadn't really thought of using separate heads but would solve the differing height issues with the cast barrels.
However it would mean that different plumbing would be needed as well as an external thermostat which are both things i wanted to avoid.
The tolerances achievable on machined barrels should solve the barrel height problems and o-ringing the bottom of the barrels should also help.

Tofty