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Offline evo550

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ID help
« on: May 19, 2010, 09:01:46 pm »
Anyone Id this engine number 450-203785.
It looks like a mid '70's 400/425 yamaha engine.
Thanks in advance.
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TT

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Re: ID help
« Reply #1 on: May 19, 2010, 09:43:39 pm »
My Yamaha 'Bible' claims 450 is a '75 or '76 DT250.  ???
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Offline Stan S

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Re: ID help
« Reply #2 on: May 19, 2010, 10:11:23 pm »
Quote from: evo550 on May 19, 2010, 09:01:46 pm
Anyone Id this engine number 450-203785.
It looks like a mid '70's 400/425 yamaha engine.
Thanks in advance.


Hope this helps

Regards Stan.

DT2 SERIES
DT2   Year: 1972   Start Engine#: DT1F-105101
DT250A   Year: 1974   Start Engine#: 450-000101
DT250B   Year: 1975   Start Engine#: 450-200101
DT250C   Year: 1976   Start Engine#: 450-500101
DT250D   Year: 1977   Start Engine#: 1M1-000101
DT250E   Year: 1978   Start Engine#: 1M1-100101
DT250F   Year: 1979   Start Engine#: 2N6-000101
DT2M   Year: 1972   Start Engine#: DT1F-185101
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Offline evo550

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Re: ID help
« Reply #3 on: May 19, 2010, 10:13:05 pm »
Bugger, not quite what I'm looking for :(
Thanks Tony and Stan
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Offline evo550

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Re: ID help
« Reply #4 on: May 20, 2010, 07:32:13 pm »
The seller claims it has a 446 cc cylinder ??? ???
A visual might help identification.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=250635662039&ssPageName=ADME:X:RTQ:AU:1123
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Offline Nathan S

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Re: ID help
« Reply #5 on: May 22, 2010, 11:04:06 am »
Its clearly a B/C motor. The radial head and ignition/sprocket cover show this.

Ignore this bit - Jim's next post points out something I missed: 446 is probably the prefix cast into the cylinder. My brain's pretty fuzzy right now, but I think 446 is one of those numbers that doesn't directly link to any particular bike.
I'm 99% sure that I've got a couple of 446 barrels in the shed, and they're both from DT250B/C motors.
« Last Edit: May 22, 2010, 11:50:29 am by Nathan S »
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Offline jimg1au

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Re: ID help
« Reply #6 on: May 22, 2010, 11:10:21 am »
i dont think its a 250 as it has a compresion relese in the cyl 360cc and bigger
jim
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Offline Nathan S

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Re: ID help
« Reply #7 on: May 22, 2010, 11:59:33 am »
Indeed - I'd missed that. Serves me right for not looking carefully enough!

OK, on a closer look, the frame appears to be from a monoshock bike - foot pegs, foot peg mounts, brake pedal, cable guides are all different to the twin-shock bikes I've seen. And it has a chain tensioner, and the clutch arm is on top of the cases.
The clutch cover is also the monoshock style.

So... revised guess is that its probably a boring old DT400 monoshock motor with a dodgy engine number. Maybe rebuilt using a RHS DT250 engine case at some stage in the past (I'm a long way from being certain, but I think this is possible but requires the case to be bored out to take the larger cylinder).

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Offline evo550

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Re: ID help
« Reply #8 on: May 22, 2010, 04:03:42 pm »
O.K. so we think it's a dt 400 donk.
Did this model have seizure probs ?
I have a KLX rolling chassis that I'm trying to convert to a 2 stroke evo bike, good choice of motor or bad ?
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Offline Nathan S

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Re: ID help
« Reply #9 on: May 22, 2010, 05:25:24 pm »
So-so choice.

They're a trail bike motor, with all the things that brings with it. You'll be way down on power compared to the 'real' big bore MXers, but it will be reliable, low-maintainence and easy to ride. Simple hot-ups like a decent sized carb and a better pipe will help a lot, but it still won't blow the Maico 490s away...

FWIW, I've got a KLX frame here that's been hacked to take a RM250X motor, and YZ125D/E seat and tank. I've been pondering what motor to fit to it, and I keep coming back to the conclusion that you'd want a decent motocross motor - and then I immediately figure that I may as well just use the whole bike that the motor came from.
Maybe an 78ish motocross motor in the KLX frame would make a bike that's a better MXer than both the stock KLX and the 1978 Whatever - but its probably still not going to be a match for a RM125T/YZ250H/YZ465, so what's the point?

My modified KLX frame is yours if you want it ($0). 


« Last Edit: May 22, 2010, 06:25:57 pm by Nathan S »
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Offline evo550

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Re: ID help
« Reply #10 on: May 22, 2010, 06:02:48 pm »
Nathan,
I'm going to take you up on your offer (second time 'round) Thanks. Will p.m. you.
What's the point?
A. something different.
B. Can't afford the price being asked for big bore evo mxers right now. This way I should have some semi decent for approx $1000. Shocks will be the biggest hurdle.

Rumour has it there's a guy (or should I say a Ji ) in Brisbane who loves to weld.   8) ;)
« Last Edit: May 22, 2010, 07:05:33 pm by evo550 »
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Offline Nathan S

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Re: ID help
« Reply #11 on: May 22, 2010, 06:30:15 pm »
Fair enough - if its about the low budget, and you're cool with the limitations, then go for it.

Forgot that I'd offered the frame before... :D Probably organise something around CD7, for transport?
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Offline jimson

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Re: ID help
« Reply #12 on: May 22, 2010, 11:20:20 pm »
EVO55 I have a DT400 and on the barrel it reads 397cc .jimson
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Offline JC

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Re: ID help
« Reply #13 on: May 23, 2010, 09:14:20 am »
#446 is DT360 Japan according to VJMW ID list & from memory I thing aussie DT360s were 446 too

There's something rather dodgy about this listing. Its clearly not a DT360 engine or top end. Looks to me like DT-D/E/F engine. Frame its cut out of also looks like monoshock DT frame (D/E/F) not IT. No such thing as a 446cc Yam barrell as we all know

DT360 barrel had weird stud spacing (6 studs) cos of weird transfer port arrangement at bottom of barrell. Would be major job to fit it to DT250 bottom end.

DT400 had much wider stud spacing than DT250 also (but not a weird pattern like DT360) so would also be fairly major job to fit it to 250 cases.

Cut-outs on fins also don't look like standard DT400D job, but E/F barrell could be diff

I'd be leaving it alone unless I could see the top end pulled off
« Last Edit: May 25, 2010, 08:46:49 am by JC »
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