Yamaha DT1 250 MX

[firko]

I could see myself building a 360 version of one of these....mudcatchers and all.

That's exactly what I'm doing.....making an RT2MX that actually works (I hope). The main problems with the DT2MX/RT2MX is the frame geometry and weight so I think I've eradicated much of those problems in one fell swoop by using a Hindall Chro-Mo frame which comes in at less than half the weight of the Yamaha version and features tried and true Rickman geometry. Another problem is the under dampened forks that I've replaced with Can-Am Betors fitted with a pair of Walts PD valves and Profab magnesium triple clamps and titanium Gary Jones bars. I'm hoping to get the bike down to around 200lbs, about the same as my TM400 but one problem is the weight of the original steel tank. I could use an alloy tank from another bike but I want to keep the beautiful looks of the RT2MX intact. A mate suggested I try an RM250A/B tank painted silver with the Yamaha graphics as they're similar in shape. That decision's still at the committee stage . If anyone's got an RM tank in reasonable shape for sale I'm interested in buying it.

The peaky rev band is a tough one to solve but I think that by using DT400 CDI and a Rex Gaunt black box www.rexs-speedshop.com might smooth out the power delivery with its heavy flywheel rotor. It's got a bit of tricky stuff in the engine thanks to Frank Stanborough that I hope will make it a bit more versatile than the peaky RT2MX I last rode was. I've always believed that Yamaha came so bloody close with the DT2MX/RT2MX that if it'd been a bit lighter and had better suspension it might have changed the sport in the same way the Honda Elsinore did a year later. I like these engines so much I've fitted a similar (but stock) RT2MX 360 to my little red flat tracker and I'm building a DT2MX engine with a YZ-a transmission for my other Hindall frame......and as John aluded to, my Yamahas all have Takasago mudcatchers, you couldn't use anything else . I've just pulled the bike apart again for the final detail build.....at 3 years this is the longest bike build I've ever done so it ain't leaving the shed until I'm happy with it. 

[Slider29]

Howdy Firko,
Use the Yammy tank,.... just don't eat breakfast

[Iain Cameron]

How about a 75 mod TY250 alloy tank Mark . I know where one is in Tassie .  Iain

[firko]

How about a 75 mod TY250 alloy tank Mark . I know where one is in Tassie .  Iain

I've tried a steel TY tank and didn't like it Iain. I've also tried.....plastic Pacifico BSA style, Genuine Hindall, Wassell trials tank, YZ80A, DT1, AT1, BSA B44GP and the current MX250 tank (identical to the DT2MX except for the placement of the petrol cap). One alternative I would like to try is an MX125 which is still steel but a similar shape and smaller and therefore lighter. This is one of the reasons this bike has taken so bloody long, I just can't seem to get the look I have in my mind to translate to the bike. Below is the failed DT1 tank experiment.
                                                                               
                                                                             

[firko]

If you're looking for a DT2MX kit bike, this is a pretty good deal.
 http://www.vintagemx.us/cgi-bin/largephoto.cgi?C=Ta1hw3PC8cD1xszr&w=2

[Iain Cameron]

Mark Ive been thinking have you tried a YZ125x tank , a bit modern but it might have the right look .

[firko]

Oh Yeah Iain....that's the other one I tried. It's now on the Trackmaster 125 Yamaha project at Jonesy's. I want the bike to look like an RT2MX with an aftermarket frame, not a Hindall with an RT2MX motor and a mish mash of parts if you get my drift. I'm using the MX250 seat I got from you, and silver painted DC MX250 mudguards and left side panel (same as DT2MX) and genuine right # plate so the original tank is the best for the job, looks wise.

[Davey Crocket]

What does look funny is the clearance between the top of the front tyre to the mudguard.....the forks need to slide up. The RM250 tank would probably look alright.....has the flat bottom and the arched top.....they are probably the lightest tank around as well.I hope it's getting one of my clutch actuator assy's.

[firko]

What does look funny is the clearance between the top of the front tyre to the mudguard.....the forks need to slide up.

It's just the angle of the dangle making it look that way. Those forks are machined down MX250 Yamaha with Race Tech Gold Valves but they and the fugly plastic mudguard have been replaced with the Betors and MX250 front 'guard. The MX forks are eventually going into the other Hindall. And yes, it already has one of your super clutch actuators John . How's the aches and pains mate?

[Davey Crocket]

You'll have to give us a current photo. The aches and pains are definitely there....I was a couple of hours late on my med's this morning and was walking on the crutches a bit too long when Dodgee came around for a visit and boy did it start to hurt for a few hours.....How's the ma'dame Barista going?...have they kicked her out of the klink yet?. I'm still getting over the wobbilies last night....I don't know wether they lost or the poms won.....very strange game but the kiwi/pommy coach is definitely playing an All Black type game of years gone by....just toiling away....if the Wallabie's can stop knocking each other out and keep feeding Folau they will be unbeatable....hears hopping for the next one... they need to sort out a kicker as well....you cant kick that bad at that level.

[firko]

Quote from: Dave #6 on June 21, 2013, 09:15:59 PM
That right Johnny`o, I had one back in 2000, and on the head stem the frame number was DT1mx stamped on it, plus I bought one off Firko, and that bike would be very close in being restored by one of our club members. Mark would know if the serial frame number has DT1 on it or DT2.   

Dave im pretty sure that all pre 74 RT's and DT's will have "1" frame number prefix, but that doesn't make them a model designated DT1 or RT1, but this is really Firko or Ian's forte as far as folks here go! They will prob be able to elaborate much clearer than myself.

I just checked the frame # on Iain's DT2MX frame and it reads DT1F 181***. It's odd that Yamaha kept the DT1F prefix on the MX even though it's a totally different frame to that of the enduro trail bike.

You'll have to give us a current photo.

The bike's torn down to the bare frame for the final assembly John so no more photos until it's finished. I was trying to get it all done before the Show'n'Shine but I don't think it'll make it. Instead I'll aim to have it done before the OW arrives because once it's on the bikestand in Garaje del Firko, the big girl will be getting most of my attention.

.How's the ma'dame Barista going?...have they kicked her out of the klink yet?. 

They released her on Thursday last and she's now fit enough to see 100. She's at her Tai Chi exercise class this morning and is doing her Aquarobics on Wednesday arvo so she's not exactly sitting waiting to die. I've had to teach her to drive the coffee machine and Foxtel remote again but it's a small price to have the old chook home.
I was impressed with the Wallabies but for O'Connor to miss three goals and then Kurtley slipping over while putting the potentinal match winner over cost us. My heart bled for Kurtley, the look on his face was tragic....apparently he was inconsolable in the sheds after the game, it was just one of those "shit happens" moments and he'll get over it and I predict he'll play a blinder next week. Go the mighty Blueys on Wednesday, AND....advice from old Uncle Firko who knows these things .........Slow down and don't over do it. You need to relax and do some reading to help those old bones knit......jumping around the place on crutches entertaining all of your chums ain't going to help your rehab .

[albrid-3]

Just received  4 photos of this Yamaha DT1 250 MX, which has been offered to me to buy, The price is $500, plus shipping cost. what to do ?

[albrid-3]

[Davey Crocket]

Go for it Dave, we need another one in the country that you can on sell to a racer.

[paul]

why not