TRX250r.org

Author Topic: Jetting advice  (Read 654 times)

Offline Red89

Jetting advice
« on: February 24, 2018, 01:07:05 AM »
Alright guys I need some insight again. I have a CT310 bored at 73mm with a basic clean up port job, a 36mm carb, and a K&N filter with no airbox lid. I will be running 100 octane with 32:1 klotz super techniplate. Where should I start at on the jetting? It currently has a 40 pilot/slow jet with a 150 main and needle in center position (was at very top of needle). I believe that with those jets it would be too lean. Thanks in advance

Offline Sand_Blaster

Re: Jetting advice
« Reply #1 on: February 24, 2018, 02:11:07 PM »
That's lean. On my drag ported esr 310, I ended up with a 175 main if I remember right, 52 poilet, and clip in the middle slot. This was in a 39mm carb and it was still a tad rich.
87 Trx250r & 99 Banshee

Offline Red89

Re: Jetting advice
« Reply #2 on: February 24, 2018, 02:24:56 PM »
So mine being a 36mm I should start around 175 and a 48 being I'm not ported just cleaned up

Offline Sand_Blaster

Re: Jetting advice
« Reply #3 on: February 24, 2018, 03:24:31 PM »
If I were you I'd start with Atleast a 52 and if need be work you way down. Someone can correct me, but I think most bigbores prefer a 52-55 poilet.
87 Trx250r & 99 Banshee

Offline Sand_Blaster

87 Trx250r & 99 Banshee

Online The norm

Re: Jetting advice
« Reply #5 on: February 24, 2018, 04:09:20 PM »
Elevation? Temperature? My  310 stroker is jetted at sea level with a 52 pilot and 185 main. Needle center groove. I would recommend a 50 pilot and 180 main to start.  You will probably work your way down. A lean pilot isn't that big of a deal.  Loren
I had a BDT motor once.....It SUCKED!
Currently: Hybrid Engineering 310 stroker built by Pete

Offline Red89

Re: Jetting advice
« Reply #6 on: February 24, 2018, 04:35:11 PM »
Thanks guys! I will use a 50 pilot and the biggest main I have is a 172 for now, so I will see how well that does. I'm in Kansas so I'm about 2000-4000 above sea level. And weather, well it's Kansas so all over the place!

Offline broken1

Re: Jetting advice
« Reply #7 on: February 24, 2018, 10:04:23 PM »
Just be sure to go easy on it until you know for sure the 172 isn't too lean.
overkill is an often underrated achievement