Building a DRM 400

[Jens]

LWC, yes they are useful. I´d rather have the CLymer manual than the factory one, but hey, who can afford to be picky!

Bahnsy, i think I can find a -84 drumbreak, otherwise a Husky front wheel might do the trick. The shield holder on those are much easier to attach to almost any fork, of course with some small adjustments.

[LWC82PE]

both will have good useful info. you can never rely solely one source of information when doing a resto/project. the factory manuals can be very good and have info the clymers dont. its always good to have several differnt manuals.

[DR Fan]

Can anyone tell me if DR 370 and 400 centre cases are interchangeable, what are the differences, I know the bore size is different  370 has points etc, thanks for any help.

[oldfart]

LHS is only differs at the mag cover , much larger at case screws .  And no you can't mix match the cases

[cloggy]

Oldfart I have 38mm forks, have you found any springs that don't need air assist?

[oldfart]

Will keep you posted, as I will be working on bikes over Xmas period Too FN hot and no spare time leading up to xmas break
I have Honda XR 250 springs in at the moment plus a top out spring ...... too harsh on the flip side the Rm springs are too soft 

[cloggy]

Progressive Suspension in USA do springs for 38mm forks. They have a useful chart that allows you to select at least roughly the right spring. From posts I've seen S&W springs marked 430 for a 1980 Maico work.

1980 38 mm RM forks  allow you to use the original front wheel. The later 38mm forks   fit 1981 onwards RM 125 through to 500  drum brake wheels, which all use the same  size wheel spindle and dust cap. The 125 465 and 500 use the same hub , the bigger bikes using two types of TLS brake. The  first 250 uses a bigger SLS, I'm not sure about the later. With hindsight, if they'd used the 250 hub for  a TLS brake they might have had  a decent brake, maybe the works bike did?
The assortment of different brake plates  fit both 38mm and 43?mm forks,  apart from the 465 type TLS brake plate which has the cable stop on the stanchions so you need a matching set for that. Other than that it has the same brake parts as a 500
If you use the yokes off the  38mm RMs you have to press in the longer steerer tube from the DR400 which is juuuust long enough as the yokes are thicker. If you use the DR 400 yokes you have to get them reamed out by 2mm, which from what I've seen is all Suzuki did when they switched to the first 38mm stanchions.
The first 38mm stanchion forks lack the 4  [10mm]  nut clamp on the non brake side which looks to be copied from Maico
All the above is culled from personal DR experience and checking USA mags. Of course OZ and UK models may not have been the same. UK and USA  late PEs used different forks and front wheels.

[cloggy]

Just bought by phone an ally swingarm identical to Mike Jolly's. Turns out it's off a 78 400 RMC or 78 late model 250 [C2]. The shock mounts are further outboard than the 175 PE ally arm but the same width at the pivot [190mm including end caps].
 Might also fit an XT500

[oldfart]

Check swing arm on LHS at pivot bearings, as they normaly flog out a bit. A bit thin for my liking 

[Graham]

Well had one a SP 370, RM400c  alloy swinging arm , Koni shocks, XL500 front end, Rm125 tank. KTM 250 seat, port and polished head, DR400 piston,through magneto away, use a gel cell battery to power the points, went like stink.

But alas a freind of mine introduced me to a machine I never thought much of a 1980 TT250 yamaha, after riding his I went and got one and sold the SP370.

The TT250 has  IT175 shock, IT 250 front forks, 18inch rear wheel, ported head ,race cam, tuned exhast, 34mm carb,went from a standard 17.49 HP to 29.8HP on Serco's dyno, and she half the weight of any DR/SP thing

For this coming season she is going to have a high top Venolum piston giving 12.8 comp and some lightening to the crank, cant wait to pass a few more big bores

[cloggy]

Thanks Oldfart, I've checked and it's been returned.

[JC]

Graham,

Any pics of the TT250?

Be interested to know who did the port work on the head (Serco?) & whose cam are you running.

[Graham]

Hi  JC, The port work was done by George McKenzie, in Brisbane and the cam was designed by him and ground at Ivan Tighs, Brisbane.

Photo taken at Tamborine chasing my mate Brian

[bazza]

My DRM was in VMX mag.The DR400 frame is all so close to a rm400 frame,email me on   [email protected]   for any help or photos,i now have rm125b tank and seat on to "slim up" bike

[oldfart]

I had a fair Idea it was you Mr haha, are you comming over for CD6 - if so you can have a ride on the sister bike