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Any DR370s still alive?

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Hello all,

great board you have here, I just joined today and am still exploring.

Ok, so here goes with my first question (I will also post in the general forum just in case...). I just got done re-building my first real dirtbike, which I have had since new, in '78. It sat neglected for over 15 years, as I moved on to "better" machinery (currently '91CR500). But I discovered the I missed the old bike, and with help from the on-line auction house, found enough parts to resurect her. I just fired the new (overhauled)motor last night! Woo-hoo!!

At this point I have :

overhauled motor; White Bro.s aluminum swing arm; works performance shocks(gassers); supertrapp muffler and pipe; terry kitt-ed forks.

I am looking for a seat, in good shape, and any old performance parts such as the powroll or White Bro.s stroker kit; cams, etc.

If you can help, let me know, my email is rad_ms@yahoo.com.

Regards to all;

M.R.

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You are the first in a long time that has mentioned a DR-370!

I had a 77 or 78, engine was stock, had a 40mm mikuni, some type of gas shocks, and a hooker header! You could pull stumps with that thing! What a mule!

I looked for another one a few years ago, bought a DR650 instead, but I remember the kill switch went out on the 370, you could lock the front brake, no gas just idle, and it would chug slide the front wheel.

I really liked it but it had no suspension. Tough on the butt.

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The bike is pretty much a stripped SP, carb specs were very slightly different on account of the less restrictive exhaust. Head angle may be 1 degree steeper.

I've trawled the net for specs of the White Bros 36mm carb for the 400, to no avail. Megacycle do a cam, R&D do the springs but don't have the spring keepers any more. Protec did do a valve spring kit and I got another one on Ebay a couple of years back, but the springs don't last and sack. Fine for offroad though, you've got to do several 1000 miles first.

I have a couple of aftermarket Protec copy road and track 400 cams [same lift] and you do need aftermarket springs. It does run with standard springs but there's slight valve bounce at high revs. It may be possible to slightly shim the spring stack to increase seat pressure but you have to check for binding at full lift. It's not a Honda, the head is tolerant of more spring pressure. In comparison with a standard cam it's meatier in the midrange.

There's nothing wrong with the standard carb but just one thing to remember. With these oval bore carbs when you derestrict the inlet/exhaust you generally have to go to leaner settings, smaller main jet, maybe idle jet and probably needle position. Set them in that order. The clymer manual is generally available on ebay and has airbox mods. The airbox is restrictive in standard form, as is the exhaust. Don't be tempted to put on the slightly bigger DR400 and DR500 carbs. The SP/DR370 carb has a special two taper needle. The DR400 carb at least does not, and doesn't take kindly to inlet box mods.

Hallman, Hagon and Dick Mann all did frame kits for these and I've never yet found one, though there apparently is an existing Hagon in Britain. The standard bike works better offroad than the standard TT500, but the TT/XT frame is fixable. Back in the day the DR frame needed extensive surgery. The SP400 frame is identical to the SP370 [actually has 370 stamps], the GN is pretty much the same too, but the DR400 frame is RM based.

By far the best tuning rewads would be to just derestrict the airbox, then try taking off the secondary silencer to check how restrictive the exhaust is, and finally, if it needs a rebore put the 400 piston in. I've heard this done but check the piston pin's the same first.

Your swingarm must be as rare as rocking horse manure!

Edited by cloggy

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Yeah, mine had the foam slip on filter, air box was gone, worked great though, just couldn't go swimming with it. But with drum brakes you sort of stayed away from deep water any way.

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