Jump to content

Tc250 to 300 conversion ?

Recommended Posts

Living in Western Pennsylvania, the jetting was way off on my 2017 TC250. But working with Tri-State Powersports, we got the bike jetted really well.

I've added the # Plate Uni Filter round push ins, for more air flow.

But I may be looking for more....

I'm questioning if I need to start playing with the Power Valve or purchase the 300 head and Piston conversion kit.

If you have any experience with this, please chime in... 1669d30dfdbf3a2fd26fd94f6734db46.jpg

Share this post


Link to post
Share on other sites

try the standard powervalve spring and wind the powervalve screw out 1 turn i found that works best on my tx 300 which has been dyno set up

  • Like 1

Share this post


Link to post
Share on other sites

Hi, I got the same bike, 50 y/o slow Vet C - Mx practice only

What are your jetting specs if you don't mind sharing?

I'm using JD blue#3, PJ 32.5 main 440. There's a small rich spot down low but short shifting the bike makes it unnoticeable.

I had good results too with OEM jets (40 pilot - 43-73 clip 1 and 450 main). Moving the clip from 2 to 1 cleaned up a mid-throttle overly rich condition but I did not like how it resulted in a loss of torque. Tried 1/2 clip position but still not to my liking

I am running the red PV spring at 1-1/4 in from full out.

You need to play by 1/4 or 1/2 turn increments to figure out what suits you best.

I have an FMF factory fatty (not on the pic here) and Powercore 2.1 silencer 

The FMF was an improvement (for me) over stock as spreading out the power where stock would have more of a hit.

Back in 2013 I had a KTM 250SX that i converted in 300 using the Hardparts kit (used the XC version). Definitely more low end but was not revving as fast as the 250

I'm considering doing the conversion on my TC

 

TC_Bostwick.jpg

Share this post


Link to post
Share on other sites
3 hours ago, mxstate said:

Hi, I got the same bike, 50 y/o slow Vet C - Mx practice only

What are your jetting specs if you don't mind sharing?

I'm using JD blue#3, PJ 32.5 main 440. There's a small rich spot down low but short shifting the bike makes it unnoticeable.

I had good results too with OEM jets (40 pilot - 43-73 clip 1 and 450 main). Moving the clip from 2 to 1 cleaned up a mid-throttle overly rich condition but I did not like how it resulted in a loss of torque. Tried 1/2 clip position but still not to my liking

I am running the red PV spring at 1-1/4 in from full out.

You need to play by 1/4 or 1/2 turn increments to figure out what suits you best.

I have an FMF factory fatty (not on the pic here) and Powercore 2.1 silencer 

The FMF was an improvement (for me) over stock as spreading out the power where stock would have more of a hit.

Back in 2013 I had a KTM 250SX that i converted in 300 using the Hardparts kit (used the XC version). Definitely more low end but was not revving as fast as the 250

I'm considering doing the conversion on my TC

 

TC_Bostwick.jpg

That rich spot down low is the #4 slide, you can find some KX/CR/YZ slides that are leaner 5/5.75 or have RB designs cut yours to whatever you want($24). 5 would be a good starting spot or just go to 6 off the bat like I did. 

And yes, when ever going to a "over bore" you will loose some off the top but in most cases gain some on the bottom. 

  • Like 1

Share this post


Link to post
Share on other sites
Hi, I got the same bike, 50 y/o slow Vet C - Mx practice only
What are your jetting specs if you don't mind sharing?
I'm using JD blue#3, PJ 32.5 main 440. There's a small rich spot down low but short shifting the bike makes it unnoticeable.
I had good results too with OEM jets (40 pilot - 43-73 clip 1 and 450 main). Moving the clip from 2 to 1 cleaned up a mid-throttle overly rich condition but I did not like how it resulted in a loss of torque. Tried 1/2 clip position but still not to my liking
I am running the red PV spring at 1-1/4 in from full out.
You need to play by 1/4 or 1/2 turn increments to figure out what suits you best.
I have an FMF factory fatty (not on the pic here) and Powercore 2.1 silencer 
The FMF was an improvement (for me) over stock as spreading out the power where stock would have more of a hit.
Back in 2013 I had a KTM 250SX that i converted in 300 using the Hardparts kit (used the XC version). Definitely more low end but was not revving as fast as the 250
I'm considering doing the conversion on my TC
 
TC_Bostwick.thumb.jpg.0d33b9e1df7c123b5537fbf1b15393db.jpg
When I get home from the beach, I will get you my settings. I don't have them memorized (just didn't want ya thinking I was ignoring ya)

Share this post


Link to post
Share on other sites

hi hostile silence (great name by the way the wife said that describes me to a tee)with the powervalve screw 1 turn out from stock works best when my bike was on the dyno we found anymore more than that and the bike started making less peak power and the torque line became uneven hope this helps.

  • Like 1

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:


×