'79 IT250F motor into '79YZ250F ?

Shawbridge Husky
Edited Date/Time 10/18/2015 5:34pm
Anyone know if an IT250F 2X7 motor can be dropped into a YZ250F 2X4 frame ?
There's a nice one ( complete motor and carb with CDI ) available locally and I think
it would be a good backup to have on the shelf as it's complete and functional without
issues.

I did run the case numbers on Boats.net and they do not match up,
so I'm wondering if it could just be magneto / crank issued that makes the
cases different, thus hoping the bolts patterns are same on both bikes
for a direct drop in fitment.

The top ends are interchangeable that I know, both center port just different
milder porting I would guess.

Project is going well have most parts on hand now, frame sandblasted.
|
MaxPower
Profile picture for user MaxPower
Posts
2653
Joined
8/15/2006
Location
NJ US
MaxPower 10/18/2015 1:25pm
10/18/2015 1:25pm Edited Date/Time 10/18/2015 1:27pm
get that bike built .Unadilla is going to come up again.. You need to build it,sort it out, and get your body ready because you have been off for a while .
Im telling you its the best weekend ever.
project racer 10/18/2015 2:18pm
10/18/2015 2:18pm
Just a quick glance at the motor mount plates / brackets on the parts fiche shows the 79 YZ and IT using the same part numbers. That is the small case engine. I used 78-79 YZ250's in my old Champion short track bike.

Always wanted an IT for the heavier, flywheel ignition.

There is a local guy here that has a Viper framed short tracker. When I first saw it, I thought it was a 78-79 YZ250 engine. Looked at the prefix on the cases, and it was an IT engine.

Point is, I do not think, in the small world of flat track frame builders, that Viper would make two different frames. One for an IT and another for the YZ.

I say it will fit right in your YZ. Also used an '87 YZ80 ignition on those YZ's. Taper on the crank ends are the same, since Yamaha not only shrunk the cases, but the crankshaft as well on 78-79 YZ .





Shawbridge Husky 10/18/2015 5:22pm
10/18/2015 5:22pm
Thanks Max, I've been a busy boy but I'll see you next summer at the 'dilla for sure !
Here is pic of my progress, as a matter of fact am going for a run in a few minutes now,
only way I can control my anxiety ( genetic ) Always have to pace myself when I start off or
I overdo it hehe :

Shawbridge Husky 10/18/2015 5:24pm
10/18/2015 5:24pm Edited Date/Time 10/18/2015 5:39pm
Thanks PJ cool I'll check out the mounting brackets, it had crossed my mind but got sidetracked thanks man !

On edit here is pic of the animal, some kid stuck it in an '80 IT175 frame, uh..

OK just looked at Boats.net the front brackets are same for 78 79 IT-YZ 250, the rear same as 78 IT YZ 250, which means the 79 rear brackets bolt on as same cases E F YZ250 YAY ! Thanks PJ !

The Shop

See All »

Post a reply to: '79 IT250F motor into '79YZ250F ?