1983 Yz250 Pipe Options?

[andrew busby]

So a little while ago I picked up a 2004 Yz250f that had a non running 1983 Yz250 motor swapped in. I rebuilt it and got it running and all but the pipe thats on it currently looks the be a haggard chopped up version of the old 83 pipe made to fit the newer frame, however it does interfere with the shock spring a touch as well as coming close to or even touching the fuel tank. What im wondering is if I'd be able to use a pipe from a newer model yz thats made to fit this frame? Anyone know if the flanges are close or would I need to cut and weld the old one? Also will the pipe work with the porting and all the two stroke magic stuff that goes on or will it run like pile of trash? Im planning on re jetting the bike either way so thats not an issue.

[YZDOC]

1 hour ago, andrew busby said:

So a little while ago I picked up a 2004 Yz250f that had a non running 1983 Yz250 motor swapped in. I rebuilt it and got it running and all but the pipe thats on it currently looks the be a haggard chopped up version of the old 83 pipe made to fit the newer frame, however it does interfere with the shock spring a touch as well as coming close to or even touching the fuel tank. What im wondering is if I'd be able to use a pipe from a newer model yz thats made to fit this frame? Anyone know if the flanges are close or would I need to cut and weld the old one? Also will the pipe work with the porting and all the two stroke magic stuff that goes on or will it run like pile of trash? Im planning on re jetting the bike either way so thats not an issue.

Some photos of the bike, and pipe routing would help to figure what "might" work.

[ss-racing66]

I believe the bore and stroke are different compared to a modern bike, so unfortunately, no.

[edit] im sorry, I was thinking you said you had a 125 engine ? But the 250 bore and stroke also changed ...current configuration is 66x72

Edited July 11, 2019 by ss-racing

[andrew busby]

On 7/10/2019 at 3:46 PM, 2 STROKE YZ DOC said:

Some photos of the bike, and pipe routing would help to figure what "might" work.

Ill grab a few of her in all her glory tonight 

[andrew busby]

On 7/10/2019 at 6:32 PM, ss-racing said:

I believe the bore and stroke are different compared to a modern bike, so unfortunately, no.

[edit] im sorry, I was thinking you said you had a 125 engine ? But the 250 bore and stroke also changed ...current configuration is 66x72

Ahh yes, and I think my 83 runs a square set up at 68×68... that 2mm would make a big difference then eh? Would it be worse than running a red necked chopped up 83 pipe thats on it?

[ss-racing66]

4 hours ago, andrew busby said:

Ahh yes, and I think my 83 runs a square set up at 68×68... that 2mm would make a big difference then eh? Would it be worse than running a red necked chopped up 83 pipe thats on it?

Lol. Hard to say ... we ain’t seen how rednecked it’s been chopped. ?

[DEMI]

can't wait to see this bike!

[andrew busby]

On 7/10/2019 at 3:46 PM, 2 STROKE YZ DOC said:

Some photos of the bike, and pipe routing would help to figure what "might" work.

[andrew busby]

Still got alot to do on it but here's what we're working with right now... also while this thread is going does anyone know if the 04 yz250 used a 38mm carb? I've been getting conflicting results and need to find one that works or stretch a smaller one with some heat.

[DEMI]

oh my..applaud the bravery to tinker and post. You'll have to piece this pipe together. 83 head pipe and probably a late model YZ 250 pipe.

[Kinger317]

Still got alot to do on it but here's what we're working with right now... also while this thread is going does anyone know if the 04 yz250 used a 38mm carb? I've been getting conflicting results and need to find one that works or stretch a smaller one with some heat.

Yes 04 is 38mm carb

[SmokinJoe]

[Familyman6000]

Time is money and that project looks like a lot of time spent for a bike at the end that won’t really blow your socks off. Must be a labor of love.

[andrew busby]

10 hours ago, SmokinJoe said:

Very interesting, ill make sure to save this!

[andrew busby]

9 hours ago, Familyman6000 said:

Time is money and that project looks like a lot of time spent for a bike at the end that won’t really blow your socks off. Must be a labor of love.

Got lots of time and not much money so projects are what I do wether its a dirt bike or a truck hahaha. But if I'm looking for somthing to take the socks off I'll just hop on my crf450r with a high comp in it, ended up trading another project I had with lots of time and not much money into for that then rebuilt it from the bottom end up. For now im just kinda hoping for a fun reliable two stroke I can just mess around with or use as a back up if my 450 needs work.

[YZDOC]

I wouldn't be surprised if you could get the 99 up pipe on that. Not 100% on outlet spigot, but the routing may get you real close to a cut, and a bend maybe. 

[DEMI]

what about air box and such?

[andrew busby]

46 minutes ago, 2 STROKE YZ DOC said:

I wouldn't be surprised if you could get the 99 up pipe on that. Not 100% on outlet spigot, but the routing may get you real close to a cut, and a bend maybe. 

I think I may pull the trigger on a used pipe from that era and see how it goes. Found a few fmf set ups with the silencer for around the $100 mark so worst case im not butchering a $300 pipe alone.

[andrew busby]

The original one follows the theme of this bike closely being the smaller yz250f stock airbox made to fit with some copper pipe and a bit of rad hose lol... but since the 2004 yz250 uses the same size carb as my 83 (38mm) im hoping to find one cheap and toss that on and be done.