Big 'ed RB250

[jonashford]

A scoop is always good if u can put one in, but the fin mod is also good to utilise the air from the flywheel. Its not a design fault of the head because its designed for the avanti barrel which it fits perfectly. im gonna look at a scoop for the avanti head cowling as its fibre glass it shouldnt be too hard to do

[Lamaddict]

^ that's another way, I suppose. The cowl that comes with it seems a fibre-glass come plastic material, so the manufacture might put a 45 degree scope on internally but that might effect the whole flow around the area.

I'm only going to cut the area on the flywheel side.

Those Avanti barrels must have some long fins around the barrel if the head is anything to go by.

[rosscla]

Same diameter as the head

[bsso78]

So isnt the whole point of having a larger fin area to dissipate the heat more efficiently than standard size fins? And surely as such the head does not need as much of the slight breeze generated by the flywheel as a standard head/cylinder? As the head is subject to higher running temperature than the cylinder, is a cowling needed at all with fins of that size?

[Lamaddict]

Maybe but you know me, I'm out with the hacksaw, file or grinder quicker than you can say Lambretta

[Lamaddict]

Head has been cut. I didn't go too deep but the fan air should be able to travel through the slots. Only cut the side you can see.

[psychedelicropcircle]

Pal that's no where that 1st gear go's

[OAP]

I was planning to but I was going to make the cuts all the way round, unless I don't need to?

Ron will do them pre-cut if you ask....

Thanks Dan!

Lets just clarify this, I have asked the machine shop who machines our cylinders & heads if he can slot the fins for a reasonable fee!
He is not keen.
I am going to try to alter a head pattern with slots in the flywheel side so they will be pre-cast but as they are sand cast this my not work.
Will keep you posted on this.

Has anyone actually checked scientifically if the slots make any difference to head temperature or is it just an assumption? RM

[Adam_Winstone]

^... are you suggesting that science should stand in the way of tinkering? (lol)

I can see why it might well help when used on a standard fin diameter barrel, as it helps some of the flow get over what is otherwise a big step in the profile, but I don't think it would help the TT3 as the air flow is already on the correct path. That said, it would be interesting to see whether theory is mirrored by reality as focussing the fresh air flow along the step at barrel head gasket face/first fin of head might actually result in better cooling... who knows?!

This is certainly an interesting topic.

Adam

[OAP]

As Adam says the TT3 kit is irreverent to this post, does anyone ever check your out box at work Adam?