RB carb

[101racing]

I'm wondering who out there has this mod done to there 300 and how they run ? I had the carb mod done and I can't get any response out of the air screw no matter where it is. It won't lean down enough to keep the motor clean when doing slow trail work. I'm down to a 38 pilot and 3.5 turns out on the air screw. I ride at 3800 ft and up. Do I need a different slide ? I have been around 2 strokes for many years and have tuned on them allot with great success. The motor runs very good other than extended slow work and then it loads up. Has anyone had the same experience ? Thanks

[RBD]

Hi 101racing,

Sorry you are having some problems with my carb mod. There is something defiantly wrong with your set-up.

Having the mixture screw out to 3-1/2 turns, means that it is not doing anything, and with the pilot jet so small, I think you are making the same mistake that most people with gasgas's do.

You are leaning out the pilot circuit so much you are running on the main circuit. I would bet you have the idle screw turned in just about as far as it goes too (wrong thing to do). You have not mentioned anything about gas leaking out of the vent tubes, so the float level should be ok and the needle valve must be sealing ok.

Now for the problem it self. If you are doing a lot of down hill with the clutch out and in gear (using the engine as a break), most all two strokes will load up a little. Most people will not use the engines as breaking and pull the clutch in and blip the throttle from time to time.

If that is not the problem, then maybe the power valves are stuck wide open? Or how about a shop rag left in the air box?

All kidding a side, if you think it is a problem with the carb, please send it back and I will have a look. If I new your name (real name you used when sending the carb) I could look up your work order and see if I have any notes about your carb. I always make notes and like to have records of the condition of the carbs as received and what other issues I find along the way when doing the carb mod.

It maybe just your style of riding that makes the basic carb mod not work right for you right out of the box.

Here are some suggestions;

Go back to the base line settings and jetting and needle position as the carb was sent to you. I did supply you with a spec sheet on what's in the carb as sent to you and I also sent optional jetting for fine tuning. I would first try different clip positions #2 #3 #4.

Follow the instructions that I sent with the carb on obtaining the best mixture screw position. REMEMBER you are not adjusting for the highest idle......, follow the instructions and it only takes less that 1/8 turn at a time to make big performance differences.

OK, all that being said, the needle is the personality of the carb. The needle I use is the WOW factor needle, comes on hard and goes to the moon.

The slide has been modified and is pretty lean, but it could go another step leaner you would like to try that. Also you might want to try a little leaner needle.

Again if you think it is a carb problem with something I did, send it back and I will look it over, oh, and what is your name so I can look this up.

I'm here to help if I can,

Thank you,
Ron
www.rb-designs.com

[101racing]

I will send you a PM for the name. No my slide screw is not even close to all the way in. I'm sending you the carb back because it does not respond like so many others have stated . Too small of pilot ? It is loading up at idle and just off idle. We ride on the flat 95% of the time.The float is adjusted to Kehein standards. Dribles when when bike is leaned over too far but so does the other 300 and the 200 also . They don't load up either. I'm looking to be able to lean the idle circuit to get the lean bog so then I know I've went too far and adjust from there. Haven't been able to get there .
I don't want to complain but wondering if everyone else has the same symptoms or if I'm missing something. Thanks for responding .

[RBD]

Thank you **** ******* for finally be willing and send the carb back so I can check it out, I have been asking you to do this for the past 10 months now, as I know how much you hate my carb mod. Each time you have made your complaint, I have ask you to send it back. You have been very argumentative when trying to help with this problem. I just hope I can live up to your expectations, but I don't know if I can.

When sending the carb back, make sure the carb is clean and gas free. Remove all hoses (do not send them) and make sure to send the slide and needle assembly.

Ron

[101racing]

Ron ,
I'm sorry that you took it as arguementive everytime. When I first talked with you about this you were sure that it was not what you have done to the carb but something simply irrational way out in left field that I have done on adjustment so I'm going to be apprehensive to send it back. We use the bike on an everyday basis for work. I'm looking at shipping both ways and down time. You can go ahead and say my name all over here if that is what you want. I'm being honest and never intended to drag you through the mud. I know you have many satisfied customers and will continue to and I hope that I'm one of them.I definatly want the problem to be something that I'm missing but I have enough confidence in long time tuning to believe I will have to send it back. As I told you before the carb and motor works very good except for the loading from slow trail riding.It cleans fairly easy and never loads until I have road slow for for a few minutes. When we get this problem solved I will definatly give you props on here ,you can be assured.

[webmaster]

My friend Jimmy had the carb mod done on his bike - he initially had trouble with the float level. It flooded on downhills - I didn't notice it because I instinctively blipped the throttle on downhills, but it gave jimmy fits since he had just switched to a 2 stroke from a 4 stroke. After he adjusted the float, on the next trip out, he had no issues.

His bike ran clean all the way through - very strong.

The only thing I can think of that might mess things up in terms of the carb itself is if the nozzle is worn - it will make the carb impossible to jet. Did he replace the nozzle when you had the bike? If it isn't this, then it could be that the squish is off so far that the bike won't run as it should. This is one variable that is very different from other bikes you may have jetted in the past - the gasgas squish is typically way off from the factory...

And if it isn't either of these things - then it is pilot error on your part on your jetting... Leaning the pilot continually will push you into a "pulling over" situation. You should recognize the air screw ineffectiveness as a symptom of this.



Jeff

[RBD]

Hello all,

First of all I would like to apologize for this thread getting out of hand and I should not have put here.

All I was trying to do is help (that back fired), as he thinks it's a problem with the carb mod, so I suggested that he send the carb back for inspection and fix anything found wrong if any?

Sorry, Ron

[GasGasDreamer]

For what it's worth, I friend of mine had his carb modified, not by any vendor here, and when he got it back the bike would not idle down.
Using my simple mind, I thought that a jet was bad.
We took it apart and a jet was plugged.
Put in a new jet, and all is well.
There might have been some junk on the screwdriver that was used to install it, or maybe some other weird thing.
My point is, things go wrong with mechanical devices.
If someone doesn't have the patience to deal with this fact, then they should not touch anything and take it to a mechanic to do.
And also realize that both parties are in the same boat trying to get to the same place. IMHO, any conflict is futile.

[webmaster]

I checked with Les Tinius at LTR (he is a childhood friend of mine..) - the float level on this carb should be set a little "low" relative to the spec ~2mm lower.

If it were me, I would go back to the baseline settings as supplied - e.g. 45-48 pilot, air screw not at 3.5 turns, etc. Then adjust the float level with the info above.

jeff

[iancp5]

Originally Posted by webmaster

I checked with Les Tinius at LTR (he is a childhood friend of mine..) - the float level on this carb should be set a little "low" relative to the spec ~2mm lower.

Makes sense. My Gassers piss fuel if I set them as per Keihin.