RB Designs-must do/
 

Ever since I got my 2011 250 Six Days bike, I've been fighting with the jetting.
Tried the JD kit, it was close but not suited to my riding style.

I have the Keihin 38mm Air Striker II carb.

I had some down time from riding so I decide to have my head modified to reduce the squish and have the full carb mods done.
I've had RB designs machine work done on my previous bikes, so it was a no brainer.

Finally got to ride the bike with the head/carb mod this past weekend.
AMAZING!!!!!
I did not have to change any jets, just some minor fine tuning with the air screw. (sea level, 98F)

The roll on throttle response pulls like a freight train. It was totally lacking before.
I like to roll the throttle on at the apex of the turns, the bike just pulls away cleanly. Before, the power would not start building until the throttle was 1/2 way open.
I even found myself riding a gear higher. If I got sloppy and let the revs drop, a quick blip of the throttle and I'm back up to speed.
The JD jet kit NEVER ran this good.

My compression jumped up 15psi after the head mod. I'm pleased with that.
The bike would ping before-now it doesn't.

For the price, I would say the RB Designs head and carb mods are the best thing you can do to your Gas Gas.

http://www.rb-designs.com/

Sea level, 98F, and 110% humi-ditty. :p

What did he take the squish down to for your sea level riding and general mugginess?

Humm.... my 2010 300 runs very good with the CCK and current jetting but I've been thinking about the head and full carb mods so I may just do it. Thanks for the report.

I have had Ron do head and carb mods on 3 bikes all with excellent results.

toffer88 good to know, thanks.

Actually, only 35% humidity. We are in a severe drought right now.

It would not be fair to RB Designs for me to post the final squish measurements.:(

Ron is the man!

He's done 2 KDX's for me and helped with my fork conversion on 1 of them. He is very professional and can transform your bike. Saving up now for carb and head mod on my 300.


It's also nice that he is only 45 min from my house:)

The carb mods really cleaned up my 250 07. The throttle response is perfect.

Good to hear. I've about had it futzing with the jetting on my bike and this is all I need to hear to motivate me to do the same. I've been considering it for a while and was thinking just the head, but I may as well get the carb done as well.

The jetting you aren't messing with is the jetting Rob did or yours?

The jetting and needle is all Ron's selection. Ron sent some extra pilot and main jets with the carb for further fine tuning.
All the previous JD jets and needle that were in the carb were returned to me.

As per the instructions with the carb, all I had to do was adjust the mixture screw a 1/16 of a turn at a time until the engine reved cleanly. A 1/4 turn did it for me.