Time for another Port Job - YT125 - Pics on page 2

[Chazz of Blades]

I've been waiting for you to do up that 125 forever man! Keep in touch on it.

[RubberSalt]

:-p It only took me.. what? 2 years? lol

I'm not going to make a screamer, simply because who it's for.

[RubberSalt]

I decided to go with a 180 exhaust and a 124 transfer duration. I figured it would match the original 175 pipe a little better.... thats my excuse and im sticking to it.


Truthfully i just want a little more umpth from it lol

[RubberSalt]

I got most of the porting done now. I decided to go with a muliple transfer timing. 124 closest to the exhaust port, 124.5 on the next set of transfers, 125 on the intake.

I widened the transfers some. I reshaped the transfers at the base. Made them appear useful. Reshaped the intake track a little, made it contour into the main intake port better. Thats about all i did. Should help this little guy out a ton. I need to get pics. Give me a few minutes.

[RubberSalt]

Well I didnt take many pictures. The cylinder is way beyond this stage. These are prior to cutting and reshapping the base.

Stock Transfers in cylinder
Stock base
Stock Transfers on the base

Raised and slightly widened exhaust
Sleeve cut down to open the transfers
left transfer widened in jug. Maker is where the rings meet. (roughly)

I'll get more pics this evening.

[El Camexican]

Have you placed the cylinder onto the case halves individually to check for obstructions and mismatched surfaces? Great post!

[RubberSalt]

Nope, but thats not a bad idea... I do have a spare case already seperated sitting around!

Normaly i just stick grease on the case and put the jug on there. See where it leave it's mark.

[El Camexican]

I’d never done it before, always just focused my attention on matching the cylinder base to the cases and, smoothing the transfers ports where they meet the cylinder and a little smoothing and raising of the exhaust port as I don’t have the tools to raise the transfer ports. However, on my last project I wanted to experiment with case stuffing and took the time to drop the barrel onto the case halves to see how they lined up. I was surprised to see what kinds of angles and sharp turns the factory machining and casting restrictions leave. Because my induction tract is in the cases and not in the barrel you may not have as much to deal with, but any sharp edges you can smooth out should help throughout the power-band. The only danger I can think of is that you remove so much material that you lose bottom end, hence the need case stuffing. I look forward to hearing your engine run on a video.

[RubberSalt]

Case stuff.. Yeah, its a compromise of top end and bottom end. I know the newer bikes(YZ125s and what not) run close to a 1:1 ratio on space of the top and bottom. The older bikes built more pressure below for that bottom end.

Im going to have to look into matching the jug to the case. I wasnt going to.. but now that you mention it i need to. I'm not going all our by any means, its for the kid >.<

I may pull my 175 apart and do some more work on it

[old-yellow]

Thanks for the pics. Alex

[El Camexican]

its for the kid

LOL! Yea, right! Just as soon as you finish testing it, breaking it in, making sure it’s stable at speed, etc., etc., I’m guessing it’ll need a rebuild by the time you hand it over!

[RubberSalt]

LOL! Yea, right! Just as soon as you finish testing it, breaking it in, making sure it’s stable at speed, etc., etc., I’m guessing it’ll need a rebuild by the time you hand it over!

SHHH
or every one will know!!






So true lol