Author Topic: Best jetting for Stock 2008 CRF250  (Read 7520 times)

Offline DRX350

  • Pro
  • *****
  • Posts: 2476
  • DRX IN EFFECT
    • View Profile
    • Mobile industrial Equipment repair
Best jetting for Stock 2008 CRF250
« on: April 24, 2017, 09:53:37 PM »
I have a customer with a Bone stock 2008 CRF250R.  They've complained it has always been a hard start. I was thinking of going up a size on the primary, but figured I'd check here first.

Bike has 6 hours on it right now...

I want it.
#advbob
@rjg967

"Ah yeah, I meant to do that"

Offline socal18

  • Pro
  • *****
  • Posts: 7127
  • If you're gonna die, die with your boots on.
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #1 on: April 28, 2017, 11:02:01 AM »
If it's hard to start, you need to go up a size on the pilot.
[img]https://scontent.fsan1-1.fna.fbcdn.net/v/t1.0-9/18119329_10212905879145837_8423340295712611452_n.jpg?oh=3e8ef4dc8c61d6437066af6d73062d92&oe=597E119E[img]

Offline Shamus

  • Pro
  • *****
  • Posts: 19249
  • Google Shawn's Peformance
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #2 on: April 28, 2017, 08:17:39 PM »
Ive got an idea, introduce them to the choke/enricher circuit.

1 twist, pull the choke, kick it. It'll run.

Bumping the pilot so it starts easy when it's cold will just make it super rich when it's warmed up.

First, get it fully warmed up, and adjust the fuel screw to the highest idle speed, then readjust the idle speed to the correct setting. When the fuel screw is wrong, its also tough to start. When its right, they start easy.
The meek shall inherit the earth - a scorched, un-inhabitable earth. Shawn's Performance- Engine and Suspension mods. Two stroke and four strokes.

Offline crc245

  • Pro
  • *****
  • Posts: 1739
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #3 on: April 28, 2017, 11:49:50 PM »
Hope this helps!

http://motocrossactionmag.com/news/ask-the-mxperts-please-help-me-jet-my-2008-honda-crf250


At the very least, a good carb clean (watching out for the slide 'o-ring' and ensuring proper accelerator pump passages...) coupled with a one factor richer pilot and a #55 leak jet should be an improvement...
« Last Edit: April 28, 2017, 11:52:38 PM by crc245 »

Offline Shamus

  • Pro
  • *****
  • Posts: 19249
  • Google Shawn's Peformance
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #4 on: May 01, 2017, 12:48:24 PM »
Hope this helps!

http://motocrossactionmag.com/news/ask-the-mxperts-please-help-me-jet-my-2008-honda-crf250


At the very least, a good carb clean (watching out for the slide 'o-ring' and ensuring proper accelerator pump passages...) coupled with a one factor richer pilot and a #55 leak jet should be an improvement...

Quote
The 2008 CRF250 does bog. MXA’s recommended jetting changes consist of changing the stock NMGU needle for an NMUU needle, going from the stock 70 leak jet to a richer 65 leak jet and running the fuel screw 1-1/2 turns out. If you are really fast, go to a 190 main, 55 leak jet and set the accelerator pump adjustment screw at 1 to 1-1/2 turns farther in to speed up the squirt.

Please note that not even MXA suggested bumping the pilot jet. And they're notorious for that. The needle they suggest is leaner, the leak jet being smaller is richer for a bigger pump shot, but that pump shot is only momentary. The leaner needle will clean that up.
The meek shall inherit the earth - a scorched, un-inhabitable earth. Shawn's Performance- Engine and Suspension mods. Two stroke and four strokes.

Offline flipside

  • Pro
  • *****
  • Posts: 8983
  • N2dirtsuspension
    • View Profile
    • N2dirtsuspension
Re: Best jetting for Stock 2008 CRF250
« Reply #5 on: May 01, 2017, 09:51:34 PM »
Sat forever. Might need the mid body.

Offline DRX350

  • Pro
  • *****
  • Posts: 2476
  • DRX IN EFFECT
    • View Profile
    • Mobile industrial Equipment repair
Re: Best jetting for Stock 2008 CRF250
« Reply #6 on: May 02, 2017, 08:59:21 PM »
Thank you all for the advice, so after spending some time with it I found 3 problems with it;

1). it sat for approximately 2 years, with super minimal use prior to that.

2). the gas was 2 years old

3). replaced the gas, cleaning the carb and doing a full service on it, and replacing the fuel inlet fitting o-rings.

After all of that, the bish ran pretty good.  They didn't want to have me spend any more time than absolutely necessary on it as they had a loader down in the middle of a grade.

I think I need to convince them I need the bike more than them... lol

Or would a 2005 YZ250F be a better bike (also with about 20 hours on it since new)?
#advbob
@rjg967

"Ah yeah, I meant to do that"

Offline crc245

  • Pro
  • *****
  • Posts: 1739
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #7 on: May 02, 2017, 09:49:43 PM »
2005 YZ250F or 2008 CRF250R?! Haha that's an easy win for the Honda 8)

05' was the last year of the steel frame Yamaha 4T's...

Offline Shamus

  • Pro
  • *****
  • Posts: 19249
  • Google Shawn's Peformance
    • View Profile
Re: Best jetting for Stock 2008 CRF250
« Reply #8 on: May 04, 2017, 08:06:35 PM »
2005 YZ250F or 2008 CRF250R?! Haha that's an easy win for the Honda 8)

05' was the last year of the steel frame Yamaha 4T's...

Ya, thats kind of a no brainer. CRF, all the way.
The meek shall inherit the earth - a scorched, un-inhabitable earth. Shawn's Performance- Engine and Suspension mods. Two stroke and four strokes.