Cool DT1 Head

[firko]

I just bought this rare Kennedy Mfg head offline from the seller after I missed the auction.
I've been tooling around with DT1's for a long time yet I've never seen a head like this before. Check out the weird squish area!
I'll replace the two broken fins, blast it and fit it to the new flat tracker or maybe the Hindall DT1. That makes three different aftermarket heads in my little stash now...Webco, CRC and soon..Kennedy.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=200664383363&ssPageName=ADME:B:WNA:AU:1123#ht_3870wt_934

[fatboyracing]

Mark , Cool looking head we have a funny head also on my DT1 it has almost no squish area we started jetting at 200 , melted one piston now we have got 380 jetting to make it rich enough not to melt another piston, I have got a standard head from Iain on my way home from SA which I think we will put on it so as we can jet it down a bit and alter the timing to make it a bit more reliable and easier to start.

Cheers
Fatboy

[John Orchard]

Wow what a weird combustion chamber; I'd be very interested to know the power differences & jetting requirements needed for that head; I'll store them in my memory banks for sometime in the future when I am modifying engines  :-)

[firko]

I've got a highly modified GYT head that we welded up the combustion chamber and machined it to a similar shape to a late Maico with a straight 'walled' outer area. It too was a pig to jet to until I put the bike on methanol which transformed it into a ripper. I'm probably better trying this weird head on my upcoming Champion flat tracker with the ported cylinder from the DT1 from Hell and Amal 36mm carb on methanol. It's worth a bit of experimtation.

[GD66]

Jeez that's a weird combustion chamber shape for a two-stroke, mate. Bathtub shape like that is normally seen on two-valve fourstroke heads, and lazy fourstrokes at that. You would think it wouldn't have the necessary swirl to get the mix in and out. Keep us posted with how it goes, stuff like that is always worth trying. Maybe you could share Frank's thoughts on it as well.

[micks]

maybe there was a piston to suit the head? a bit like a 2t outboard where they ramp the crown of the piston.

[firko]

I've Googled and Binged all over the 'net and can't find one reference to Henderson Mfg or their wacky DT1 head. There must be someone out there in motoland who has some information or even an ad showing this unique bit of motocross history. I'll post something on Marks Swapmeet and see if anyone can pass on some information.

Finding parts like this is why I love building bikes from the era when the factories didn't always get it right, prompting all sorts of weird and wacky inventions, modifications and aftermarket frames. I'd love to use this on my Harry Hindall framed DT1 with the Skunk Works inlet and flat slide Posa carby...all early 70's gizmos designed to make the DT1 a better racer. Somehow I don't think it'll be a life changing bit of gear and after failing to make the cut on both the Hindall and Champion flat tracker it'll probably end up in 'Museum de Firko's' motocross oddity collection along with the Skunk inlet and Donkey Dick grips!

[tony27]

Shape looks similar to a CZ except this 1 looks to run from the front to the back rather than across the cylinder

[Lozza]

Maybe a great place for it is on the proposed 'shitter' with plastic levers, nylon sprockets etc etc.
Trust me the old Maico head is WAY ahead of it's time, it is very close to modern GP 125/250/500 head shapes.

[firko]

Trust me the old Maico head is WAY ahead of it's time

That's why I replicated it on my GYT DT1 head. Works a treat.

[JC]

That combustion chamber shape was very common on early bultacos till they changed to better design

[lukeb1961]

I wonder if they were trying for a stratified charge type of combustion?

Luke