RB Designs Carb Mod

M

Magellan

New member
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
 
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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.
 
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.
 
Unfortunately the only non-ethanol fuel here is race gas as well. Mine runs great on pump premium, but come spring when its still cold and the first rides are in damp sand, I'll mix race gas.

I run the carb out and drain my tank into a steel VP can after every ride/wash when the bike will sit for more than a few days. I'll keep this fuel for for two weeks tops, then its weedwacker gas.

I'm a little reluctant to do the carb mod, as the bike is running clean and pulls hard. Never stalls and even idles for as long as I need it to. Milage is outstanding. If I had a second carb I'd do it but I want to keep this one as is.
 
gasgasman said:
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.
Click to expand...

Really please tell us about it!;) :p :D

No better yet please don't.

I plan on sending Ron my carb here in a few weeks and then sending my suspension to Les to boot.
 
I had both mods done at the same time. the carb, and head on my 04 300. What a big difference well worth the money. No stumbles, clean revving, and I haven't really jetted it yet. I always had a minor stumble, and it would load up even with the plug showing light brown. The air screw actually does something. The plug is a dark brown after a mixed terrain ride. I explained my riding style to Ron. Trail riding, so I don't need a big "hit". He provided the correct needle. Low end is very strong, with a little "hit" midrange, and the speedo saw 83 yesterday, tucked. Factor in 10% error, it's still fast enough.
Fuel economy seem very good, just a tick over 2 gals to do 88 mile loop. Speed range was 15mph in the rocks to sustained 50mph, hard pack, rocks, and shallow sand. At any speed you can hold a steady throttle, no hunting, or blubbering.
Mike.
 
I had the same mods done as well.....huge difference! I was wondering what elevation are you running at and the needle you are using? I'm currently running the CEK needle. The CEL had a bit too much mid-hit and a little boggy off idle.
 
Idaho,
Vegas elevation, 2200' to maybe 3K to 3200'. It was cool and over cast Monday. We rode from a dry lake up to where my GF wished she would have brought a light jacket. I'm very happy with the mods. I also have to say I not a young aggresive heavy handed rider. I'm happy with a little excitement. A few wheelies, a little air and a good running bike with no crashes or injurys during a ride. I ride by myself 90% of the time, so I'm careful about taking chances and riding over my head. I'm sure I could jet this to a nats ass. It runs and starts better than when I sent the head and carb to Ron.
The pilot jet is 42, main is 180, but I not sure about the needle, I do remember it's in the middle groove, whatever it is it's deliver's smooth power.
 
Sounds good man. If you have the needle out sometime and think about it please post. It should have something etched in at the top near the grooves. Better yet, post your settings in the jetting post on this forum. I'm running at 6000ft and up. Running 175MJ/40PJ/CEK#2 /AS 2.5 out...in case you get yourself up to higher elevation.

05' EC300/Rekluse
 
The RB carb mod uses a CEK needle, and the carb is sent back with the clip in position #3 as a startng point.
 
Thanks Idaho, I'll post the settings
Looked like position #3 was middle :D:D:D I guess I'll have to put the readers on next time I look at the clip.
 
2007,2008 Ec 200 Gas Hog?

we have 2 200's that ride with us and they are always running out of gas when the rest of us have 1/3rd. tank left?? One is a 07, and my son has an 08. We have a 07 EC300, and a 07 EC250. The rest of the bikes are pumpkins, and they get the same mileage as our 300 and 250. Does anyone else have this problem with there newer EC 200? I know the 03, 04, and 05, get normal mileage Thanks Tom
 
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