Case Reed Porting question for Eric

[MikeT]

Eric, I have some questions about porting. I have a '96 YZ125 that has (as you know) case reeds. If I were you have you port my bike would you port just the cylinder, or have me send you the whole engine? If I just sent you the cylinder, would I be short changing myself as far as power gains? Also, how does my bike/year respond to porting? I don't know where I would need the power bottom or top so, in your opinion, where would my engine/year benefit the most? :think

 

[Yamamoto]

MikeT

I am sure Eric can help you with the porting however, I think you can help him by riding your bike and knowing what YOU want. In other words if you feel that you need more low end power then thats what you should ask for, or if you felt that you need more top and do not care about low then ask for that.

He also does a Mo-Power every where and I understand that its a pretty good port job that does not sacrafice top or low, However if you want to gain the MAX amount of top end out of your motor then you will have to lose some low end power.

 

[MikeT]

I think the mo-everywhere is what I want, but I don't ride a wide variety of bikes so I am used to the way my bike is now. What I'm saying is tha I have adapted my riding style to my bikes current power output. If my bike has a lot of potential gains with low end porting, and it has top end up there with the best of them, then that's where my engine will benefit the most. That's all I'm saying.

 

[RM_guy]

Mike,
Since porting deals with the ports size and timing, Eric probably only needs the cylinder and head.

 

[MikeT]

Oh, that's fine but I am wondering if he'll need the bottom end also because it has the reed block in it. I just don't know. Have you had this done before with a case reed engine?

 

[RM_guy]

I had a case reed engine ported in the past (not by Eric) and all they modified was the cylinder and head.

 

[MikeT]

:think So I'm still wondering....... I'm sure Eric will touch base here later today.

 

[marcusgunby]

All 125s have case reed engines and the only one i know of which had crackcase porting was the 1990ish cr125s.Crancase porting is a major undertaking which requires complete strip down and so costs more than its worth to most.

 

[MikeT]

So is it something that my bike wouldn't need?

 

[EricGorr]

Marcus is right, the gain from porting the cases is minor compared to the cost. However if you're having the cases split and the engine rebuilt, then deburring the edges in the case is cost effective ($25-$40). Some bikes like KX125s 1993 and newer have very smooth cases and don't require any work.
Most of the porting packages for case-reed engines on the market are limited to cylinder mods.

 

[MikeT]

So Eric, From my initial post, where does my bike/year benefit the most with your porting and does my bike respond well to porting?