Jump to content
Sign in to follow this  

2 stroke expansion chamber swapping?

Recommended Posts

Can anyone help me with the general rules of expansion chamber design and the impact they have on power delivery?

I have the kxf/ktm300 swap bike, and im about to swap the top end to a ktm360.

The bike is totally disassembled so I cant check fitment but the 360 pipe looks distinctively larger. Fmf and oem part#s are different from 300 to 360.

I dont know how hard it will be to make the 360 pipe fit. How would it run with the 300 pipe?

I know they sell spacer to tune exhaust, does the increased header length improve low end or top end?

Share this post


Link to post
Share on other sites

Can anyone help me with the general rules of expansion chamber design and the impact they have on power delivery?

I have the kxf/ktm300 swap bike, and im about to swap the top end to a ktm360.

The bike is totally disassembled so I cant check fitment but the 360 pipe looks distinctively larger. Fmf and oem part#s are different from 300 to 360.

I dont know how hard it will be to make the 360 pipe fit. How would it run with the 300 pipe?

I know they sell spacer to tune exhaust, does the increased header length improve low end or top end?

get two 360 pipes and cut and shape then weld them around the frame. if you keep the expansion chamber the same length you wont really feel a power difference

good luck

 newworkspipe.jpg

Share this post


Link to post
Share on other sites

Sorry i'm not sure i follow what you mean...

 

You can see my thread on the engine swap kxf300exc, the bike is all complete but the clearance was so tight getting the 300 pipe to fit, i'm curious what the implications of running the same 300 pipe on the 360 displacement might be.

 

My thought is that making the expansion chamber longer (such as with exhaust spacers) helped with low rmp power, so wouldn't using the "shorter" 300 pipe on the 360 just be more beneficial on top end/overrev?

 

Also, we're only talking about a 60cc difference, i think of examples such as the 300cc kits done on yz250s, aren't they just using standard yz250 expansion chambers?

Edited by Jeezo

Share this post


Link to post
Share on other sites

Sorry i'm not sure i follow what you mean...

 

You can see my thread on the engine swap kxf300exc, the bike is all complete but the clearance was so tight getting the 300 pipe to fit, i'm curious what the implications of running the same 300 pipe on the 360 displacement might be.

 

My thought is that making the expansion chamber longer (such as with exhaust spacers) helped with low rmp power, so wouldn't using the "shorter" 300 pipe on the 360 just be more beneficial on top end/overrev?

 

Also, we're only talking about a 60cc difference, i think of examples such as the 300cc kits done on yz250s, aren't they just using standard yz250 expansion chambers?

it would just constrict the engine like running a baffle and spark arrestor   

Share this post


Link to post
Share on other sites

Can anyone help me with the general rules of expansion chamber design and the impact they have on power delivery?

I have the kxf/ktm300 swap bike, and im about to swap the top end to a ktm360.

The bike is totally disassembled so I cant check fitment but the 360 pipe looks distinctively larger. Fmf and oem part#s are different from 300 to 360.

I dont know how hard it will be to make the 360 pipe fit. How would it run with the 300 pipe?

I know they sell spacer to tune exhaust, does the increased header length improve low end or top end?

Increased header length improved the low and mid range

  • Like 1

Share this post


Link to post
Share on other sites

Increased header length improved the low and mid range

so does it stand to reason that the smaller 300 pipe used on a 360 would be most effective at high rpm, improved overrev?

 

 

I wonder how signigicant

Share this post


Link to post
Share on other sites

If the 300 pipe fits I'd run it, tune it.  The cones are long enough on the 300 pipe that it'll tune a pretty wide range of rpms. You might verify the relationship between the exhaust port diameter and the stinger diameter is in a "safe" range for how long a wfo pull your intending to make.

  • Like 1

Share this post


Link to post
Share on other sites

so does it stand to reason that the smaller 300 pipe used on a 360 would be most effective at high rpm, improved overrev?

I wonder how signigicant

I would think it would depend on where it's smaller. I assume the header would be the bigger deciding factor than the cone or stinger.

I would bet it would be a minor change, although I agree that it would be noticeable on top.

Edited by poldies4

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...