RB Designs Carb Mod
 

I see that Ron has announced his carb mod in the Products Review section, so I'll post my thoughts on it.

Some background info:
I have an 04 EC300.
I was running it with the LTR jet kit.
Live and ride near Portland, OR. Riding temps range during my use of the carb ranged from 50 to 70 degrees F. Portland is near sea level, and I probably climb a few thousand feet.

I was generally happy with the LTR kit. The bike had a good midrange. The only faults I had with the LTR kit was a hesitation off idle that I couldn't seem to shake and a lack of over-rev on top. I probably could have fixed the over rev with a different main, but I rarely ride the bike wide open and just short shifted when I did.

I tried to get rid of the hesitation, but got frustrated and gave up. That said, neither of those problems were big deals to me. Like I said, I don't ride wide open and adjusted my riding to account for the off idle hesitation. It only was an issue when coming up to a log crossing and I just gave the bike a quick rev with the clutch in before tackling the log.

I put on the RB Carb last fall. I instantly noticed a difference when I fired up the bike in the driveway. The mixture screw had a bigger impact on how the bike idled, and I was able to dial it on and get rid of the hesitation I had. Right then, I was happy and a quick ride up and down my street didn't show any weaknesses in the carburation.

I took it riding a few times with the set up as I got it from RB Designs.
Riding on the trails, I again noticed the lack of hesitation off idle. The bike really snaps to life. Mid range seems cleaner as well, though I never had any issues with the mid range prior to installing the carb.

Now although I appreciate the low speed improvements most of all (I tend to ride technical stuff and enjoy trials as well), I must say that the top was very impressive. Where I found myself short shifting before, now the engine just keeps going. For a mid range rider like myself, it is "scary fast." It's quite the rush.

I run a trials throttle on my bike (plan to get a G2 some day) so I could really tell how the carb was behaving. I enjoy good throttle control and did a number of runs on the fire roads at various throttle settings.

During these runs, I noticed a flat spot in the mid range. The bike ran clean, but it was stop pulling for a bit, then pick up again. I rode the bike like that for a while because I didn't have a chance to mess with it. I finally got some time and played with the needle position and was able to work that out. Now the bike seems to run perfect everywhere.

There are two issues I have with the carb, but I had these with the stock carb as well, so I don't think they have anything to do with the mod, though maybe can be worked out with more jetting work.

The first is that the engine will stall on long descents if I have the clutch in. I just blip the throttle every now and then and it's fine.

The second is that after running it a bit, when I let it return to idle, it idles high for a few moments, then settles into my normal idle. Note that in an effort to keep my bike as quite as possible, I run my idle pretty low, and that is possible the cause for both problems. In any case, except for blipping the throttle on descents, there is no impact to how I ride.

I plan to try a fatter needle next week to see if I can get a bigger hit in the midrange. Personally, I love the bike like it is, but want to try different things to see how the carb reacts. I'll report back.

Overall, I am extremely happy with the work:D

James

Anything new to report? I'm getting ready to send my carb in for the "Mod"

Idaho do it because it is well worth it!:D

Sent off yesterday!! I generally ride techy singletrack at 6-10k ft elev. so I think this will be a big improvment in terms of tunability and riding quality in the lower part of the throttle.

Got my carb back. Basically I'm having the same experiences as the other posts so I won't go into great detail. The mod makes a dramatic improvement from low to high throttle and the tunability is now very precise and responsive...especially on the low-speed circuit. On the top end my bike friggin' screams like it never has. Money well spent!!! If you are having carb issues I would simply drop the extra bucks and send your carb to Ron.

I told you so! :D

If mine wasn't so damn good the way it is it would be out there already. This winter for sure the carb and head go at the same time.

I must say that the RB Designs carb mod is a must do.

I've had the modified carb on my bike for a couple months now. I finally found the time to jet it properly today..
Talk about a big difference, went to a 42 pilot, 180 main, and needle in the middle position.

I found that I was shifting way less, the bike would lug down low. A quick blip of the cluch would pick the revs up and the bike would keep pulling. The bike also did not stall at all today.
There was no smoke out the muffler at all.


I am running race gas at 32/1. The race gas cured the pinging concern I was having.

Yes you must be scared that my bike will beat yours!:p

Glad you got it figured out. Guess you are now better than me because of the race gas.;) :cool:

Yup.:D

I know fist hand about the horrors of ethanol blended fuels.
If the fuel sits for a couple months or so, it turns into molasses. Every time I use my pressure washer I have to clean the carb out.