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Author Topic: has anyone gotten the dt250 engine to work  (Read 285 times)

Offline bracketmaker

  • Posts: 20
has anyone gotten the dt250 engine to work
« on: Feb 16, 2019, 11:03:59 »
this bike rides like a moped. has anybody gotten this turd to run properly. I'm ready to do an engine swap but before I do it I figured I'd ask the talent here. unhappy with the 5 speed wr tranny and not enough horses. the 1/4 mile of blue smoke behind this turd is also a big negative. I like dykes but dykes rings are lame.

Offline Pete12

  • Posts: 290
Re: has anyone gotten the dt250 engine to work
« Reply #1 on: Feb 16, 2019, 16:58:42 »
Find a yz250 motor the same model and swap all the bits out - lighter crank, c/r gearbox, straight cut primary gears, ported cylinder, centre plug cylinder head etc. Build an expansion chamber, squish the head and you have an instant rocket ship.

Offline bracketmaker

  • Posts: 20
Re: has anyone gotten the dt250 engine to work
« Reply #2 on: Feb 17, 2019, 00:55:57 »
Find a yz250 motor the same model and swap all the bits out - lighter crank, c/r gearbox, straight cut primary gears, ported cylinder, centre plug cylinder head etc. Build an expansion chamber, squish the head and you have an instant rocket ship.

guess I should have told you what year it is. its a '74 with points. its not a rare bike but it was the first. they sold well and had no design improvements. what it has in style it lacks in balls. I'm not so sure that a '74 yz250 cylinder would be any better. I already have center plug and squish .04" from stock. I can ride 50 all day with street sprockets but thats it. 55 tops.
« Last Edit: Feb 17, 2019, 01:13:22 by bracketmaker »

Offline Pete12

  • Posts: 290
Re: has anyone gotten the dt250 engine to work
« Reply #3 on: Feb 17, 2019, 03:55:00 »
I've got a '74 YZ250 in a Maico frame that I race on flattrack. It's running on methanol, has a trick cylinder I ported myself, a homebuilt pipe, 38mm Mikuni carb, electronic ignition with a YZ85 black box, just to name but a few things, and is almost as quick as a current model YZ250. It certainly goes a lot better than 55mph, but hey, it's all up to you now.

Offline bracketmaker

  • Posts: 20
Re: has anyone gotten the dt250 engine to work
« Reply #4 on: Feb 17, 2019, 07:54:49 »
I've got a '74 YZ250 in a Maico frame that I race on flattrack. It's running on methanol, has a trick cylinder I ported myself, a homebuilt pipe, 38mm Mikuni carb, electronic ignition with a YZ85 black box, just to name but a few things, and is almost as quick as a current model YZ250. It certainly goes a lot better than 55mph, but hey, it's all up to you now.

I'm totally wrong about this site. did not know there were fellow serious dirt bikers here. you can even answer my burning question, how much difference does the yz rev box make. I bought a chinese 2T dc racing rev box but have not played with it yet. looks like the only mistake you are making is racing on flattrack and not on the street.

Offline teazer

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Re: has anyone gotten the dt250 engine to work
« Reply #5 on: Feb 17, 2019, 12:02:25 »
There are a couple of guys racing modified DT1s in AHRMA and they are pretty quick.  I have never worked on a DT, but we had a couple of CR and XL and XR Honda singles and they were all a lot of fun. 

Dt is 70mm by 64mm or so I read and has a tiny 28mm carb.  That's the same as a GT750 or GT500 Suzuki and it's not hard to get 25-35 hp out of one of their cylinders and possible to get closer to 40 per cylinder with work. I'd take a guess that a stock YZ250 makes somewhere in that sort of range depending on the year and that's enough for way the wrong side of a ton on the street with the right set up.

Sounds to me like a YZ250 motor in that rolling chassis with some suitable mods and a decent pipe should be wicked fast for a small street bike. Or port and modify the stock DT if there's enough metal to port it to the right spec.  Fit an RD or similar front end and different seat and maybe a replica TZ tank and decent pipe and you would have a nice little pocket rocket. In fact there's something like that on 2strokeworld.net owned by Uwe Stressa, but his is a race bike not street.  He used a modified MV5 chassis IIRC, but I don't recall which 250cc single two stroke motor he used.

Time to start thinking outside the box.

Offline bracketmaker

  • Posts: 20
Re: has anyone gotten the dt250 engine to work
« Reply #6 on: Feb 17, 2019, 20:43:29 »
There are a couple of guys racing modified DT1s in AHRMA and they are pretty quick.  I have never worked on a DT, but we had a couple of CR and XL and XR Honda singles and they were all a lot of fun. 

Dt is 70mm by 64mm or so I read and has a tiny 28mm carb.  That's the same as a GT750 or GT500 Suzuki and it's not hard to get 25-35 hp out of one of their cylinders and possible to get closer to 40 per cylinder with work. I'd take a guess that a stock YZ250 makes somewhere in that sort of range depending on the year and that's enough for way the wrong side of a ton on the street with the right set up.

Sounds to me like a YZ250 motor in that rolling chassis with some suitable mods and a decent pipe should be wicked fast for a small street bike. Or port and modify the stock DT if there's enough metal to port it to the right spec.  Fit an RD or similar front end and different seat and maybe a replica TZ tank and decent pipe and you would have a nice little pocket rocket. In fact there's something like that on 2strokeworld.net owned by Uwe Stressa, but his is a race bike not street.  He used a modified MV5 chassis IIRC, but I don't recall which 250cc single two stroke motor he used.

Time to start thinking outside the box.


that's what I wanted to hear. that engine is a turd. all the dt's that run good have engine swaps. I think someone here has a rd350 in a dt frame. looks like an engine swap is the easy way to get that vm34, cr ratcheting 6 speed transmission, loose 100 pounds and gain 20 years of port and ignition tech. the antique graphics of the stock tank rules. the pipe is a scrambler type with a chrome heat shield. want to keep it a restomod sleeper and I have an engine in my closet.