DT1 / DT250 gearboxes.

[mx250]

DT1 / DT250 gearboxes, do the gears swap over.

[vandy010]

i've not done it myself but i'm led to believe they do.

[Freakshow]

are Some part numbers are differant, somewhere before the DT1F its seems to be a bit weird like Dt - E 69-71, after 72 some numbers seem to line up,

but if i remember i had pinion 3rd 's from both i was putting away and  seem to think they where differant sizes or shape in the inside dogs or somthing if that means anything.

The DT and the MX are the same as you know.  but i dont have DT1F case apart to confrim it either way. i would err on the no.  But check the part numbers on the Shafts, if the shafts are the same surely how the stack the gears wont matter much except where the forks pull, which is where i recon you need to recheck.

[firko]

Graeme............I'm almost certain that some of the gears and shafts do interchange but it's been 20 years since I investigated fitting an MX250 gearbox or parts thereof to DT1 cases so it's been lost in cloud of mid life senility. If you lay both gearboxes out next to each other you'll see what can and can't be interchanged fairly quickly.

[mx250]

.....when I was thinking of making a replica of .....

A visual replica that is , none of the tit bits 

Hence the questions re the gearbox. I've got a DT2, barrel etc., a YZ125 alloy tank  and the late YZ rear hubs look pretty close. A bit of paint and who's to know  , until they motor pass :'(

I'll probably have to do the frame mod - a pity I didn't think of it before the end of that ebay auction hey .

[vandy010]

what frame are you thinking of using?

[mx250]

what frame are you thinking of using?

Cut and shut/ lowered DT.

[firko]

You bastard Graeme! I was also thinking of replicating the Hallman bike when I get around to rebuilding my DT1 from Hell. I reckon it'll make a great project. Yours will be done long before I even think of starting as I've got the Cheney Yamaha, Cotton Villiers and Trackmaster flat tracker next on the list so it'll be a while before I even consider it. Instead of doing a YZ replica I may now turn the DT1 into a period Baja style desert racer with 19" front wheel and that kind of stuff.
The one good thing about DT1s is that you can cut 'em up, chop, channel and modify the living shit out of them and you won't upset the purists as there are plenty of them to go around. They're the perfect bike for the bloke who loves to fork around with different ideas. Although my first love is old Maicos, I have a real soft spot for DT/RT1s. In 1969/70 there were shitloads of DT1s at just about every MX meeting, most of them lowered and lengthened which has given me an idea.

In England they have a BSA Bantam only class in road racing, grass track and possibly vintage MX. Wouldn't it be a great idea to create a DT1 only vintage class ? Imagine the ingenuity that'd come out of that concept! You'd have to have some rules and probably insist that the bikes be legal for the pre 70 class to keep it all in perspective but I reckon it'd be a lot of fun building and racing them. I know it'll probably never happen but it would be a good cheap entry level class that would allow us to express our artistic and engineering "genius" without resorting to big dollar unobtainium and bling.

[Freakshow]

Great idea firko, proven success in simplyfied classes and entry level maintence and level playing field machine consitancy.

Thats what made the buckets so popular and now so in the RD LC racing. its a level sports and plenty of machines still about for new commers to buy a bike or build and ride, feild s full grids even today that theory.

Id love a class for my DT, it would run well against other DT1F motors , but is a bit outclassed by other pre 75 units.

Keep the idea going has merit !  National DT titles :O)  only need 10 bike to make it a national class dont you ?

[mx250]

Sorry Firko , only thought of it recently .

I change my desk top photo from time to time and currently its the Hallman bike (Terry Good provides such great shots on his site ). Gradually the idea occurred.

I was only recently rooting through my brothers shed, one of my stashes, checking a few things including the DT2 (I thought it was a RT2 - silver tank). I was specifically looking at the barrel, noticed the reed and the capacity. The image must have been on my subliminal because when I next looked at the desk top the thought process started slowly cranking over.

By mentioning it I've 'staked the claim' but also over committed myself. I've already got a shit load in front of me including house reno's, but I estimate it should be pretty easy  .

My biggest challenge is to either find a lowering kit or sweet talk George into crank up his lathe. Damn, I should have been thinking, that kit on EBay at about $40US was good value. Do they bob up every now and again or was that pretty unique?

[Freakshow]

Depends what it sold for.  if it got good money more will surface, if it sold for 99cents it might be awhile before they list the other 5 bags of them they already have,  where there is one you usually find more. ID be emailing the seller.

[firko]

They pop up from time to time. Webco, Profab, Kosman, Skunk and even more companies made them but if you know how to drive a lathe you can run a set off in an hour or so. It ain't engineering degree stuff. When I was an aprentice I made a bunch of sets and sold 'em at the races. All of the Vic Lyons Yamaha team bikes had my frame kits in them. Jim and Peter Scaysbrook rode for the shop and I remember being pretty chuffed at seeing my foreign order kits in semi factory supported Yamahas.
If making a kit is too hard, try putting a wanted ad on Mark Holloways Swap Meet site.
http://www.vintagemx.us/cgi-bin/swapmeet.cgi  I've seen want ads requesting all sorts of odd stuff over the years so you never know your luck.

[mx250]

Interesting Firko. I remember seeing lowering kits regularly advertised in the American Dirt Bike mag of the time and thinking that it was pretty dodgey engineering . And now you tell me semi works teams used them  .

Did they try different lengths or was there a standard agreed to 'improvement'?

[firko]

1 1/2"- 2" seems to be the average. My own DT1 is lowered 2" as werem  the kits I made up in '69/70. An extra two inches in the swingarm also works a treat.

[mx250]

An extra two inches in the swingarm also works a treat.

2''. Gee thats a big variation. Little wonder the original was a bit ordinary in the handling. I was gonna measure up an MX/DT250 swinger. I think they are about 25mm longer.

If I'm gonna go 2'' why not 4'', or is that 6''.