250R onto a 350x chassis anyone?

[350XBigbore]

I just bought a 93CR250 dirtbike and plan on using the engine for a drag racing/duner, on either a 85 350x chassis or a 91 250x quad chassis. I already sent the cylinder to get renickled, have a new Wiesco for it, milled the head .030, porting the cylinder once it gets back on Monday. Those 93+250's make 40+HP stock so I am pretty sure it will make at least 50+HP with more compression, little portwork, new pipe and it fits perfectly on the 250x chassis. But has someone tried one on a 350x chassis? Are there any things different when using a DIRTBIKE ENGINE on a 3 or 4 wheeler?

[SWIGIN]

we have bin useing dirtbike motors for years in quads

400-450 yzf hybrids..... nothing different then any other swap

[Duner]

I just bought a 93CR250 dirtbike and plan on using the engine for a drag racing/duner, on either a 85 350x chassis or a 91 250x quad chassis. I already sent the cylinder to get renickled, have a new Wiesco for it, milled the head .030, porting the cylinder once it gets back on Monday. Those 93+250's make 40+HP stock so I am pretty sure it will make at least 50+HP with more compression, little portwork, new pipe and it fits perfectly on the 250x chassis. But has someone tried one on a 350x chassis? Are there any things different when using a DIRTBIKE ENGINE on a 3 or 4 wheeler?


To get a stock bore/cylinder 250 to produce 50 rwhp, you will have to port the pizz out of it, and run quality parts in other performance areas. However, putting it into a heavier frame, I would have to ask why you would want to do it. Weight is not what you want for racing. The CR motors have the igniation that is what most want...

[350XBigbore]

I uderstand that it's no different but didn't know about maybe different gearing in the trannies or I was thinking about not having a counterbalancer too but I wanted to hear you guys say go for it since I was doing it anyways. I kind of don't like modding 350x chassis b/c they arev getting rare and I don't have any use for another 250x frame besides making an allout dragbike. I don't plan on running any fenders or misc. brackets, just seat, tank, frame engine, paddles or dirt drag tires. I am also going to get the cylinder professionally ported and may even run alcohol on the 250. Later

[Duner]

I uderstand that it's no different but didn't know about maybe different gearing in the trannies or I was thinking about not having a counterbalancer too but I wanted to hear you guys say go for it since I was doing it anyways. I kind of don't like modding 350x chassis b/c they arev getting rare and I don't have any use for another 250x frame besides making an allout dragbike. I don't plan on running any fenders or misc. brackets, just seat, tank, frame engine, paddles or dirt drag tires. I am also going to get the cylinder professionally ported and may even run alcohol on the 250. Later

Good luck with it. If you run alky, then 50rwhp is well within reach.:headbang:

[SWIGIN]

it can be done no problem on race gas

http://www.exriders.com/vbb/showthread.php?s=&threadid=347126

[350XBigbore]

Cool, what else could I do to the engine to run alky? I have a 55gallon drum half full so I would like to burn it and go back to race fuel /mixed with pumpgas. Is there anything that I am missing to make this 93 250r engine make 50hp?   

[Duner]

Cool, what else could I do to the engine to run alky? I have a 55gallon drum half full so I would like to burn it and go back to race fuel /mixed with pumpgas. Is there anything that I am missing to make this 93 250r engine make 50hp?***


It's all in the port work. You will need a bigger carb to run alky. Have you ever ran meth before?

[350XBigbore]

It's all in the port work. You will need a bigger carb to run alky. Have you ever ran meth before?

OK, what needs to be done to ports, besides opening them up? I have run alky on a few racecars so I know it's very finicky on tuneups with changing weather. Thats why i don't plan on leaving it on alky. But there are a couple ported, cammed, big bore 450r's, Im am looking to beat, they only beat my 350x powered quad by a couple bikes and it only makes about 35-38HP.

[Duner]

OK, what needs to be done to ports, besides opening them up? I have run alky on a few racecars so I know it's very finicky on tuneups with changing weather. Thats why i don't plan on leaving it on alky. But there are a couple ported, cammed, big bore 450r's, Im am looking to beat, they only beat my 350x powered quad by a couple bikes and it only makes about 35-38HP.


I dont port, so I cant answer it "exactly", and the ones that can, usually wont say "exactly"..best thing to do is take it to a local builder, and have them port it. 50 rwhp on gas will be tough to achieve, but on alky, should be no problem with a good port, carb, intake.

Your 350x power quad must be built to the hilt to stay only 2 bikes back from a big bore 450 bike. Stock they are low 40's hp, so anything going up for them is large numbers. I race with a guy who has a gas powered 488cc YFZ that runs neck and neck with my old 370 all the way down the track, and it make 70 rwhp. I am fixing that though.:D

[350XBigbore]

I dont port, so I cant answer it "exactly", and the ones that can, usually wont say "exactly"..best thing to do is take it to a local builder, and have them port it. 50 rwhp on gas will be tough to achieve, but on alky, should be no problem with a good port, carb, intake.

Your 350x power quad must be built to the hilt to stay only 2 bikes back from a big bore 450 bike. Stock they are low 40's hp, so anything going up for them is large numbers. I race with a guy who has a gas powered 488cc YFZ that runs neck and neck with my old 370 all the way down the track, and it make 70 rwhp. I am fixing that though.:D
My 350x is big bored, 11.5.1 compression, cam, ported, 400ex carb, custom pipe etc.. and itn does run well but not enough to beat the hopped up 450's. I can whip a stock 450 for 300'. Do you guys think the FMF pipe off the bike would work well on a QUAD?