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Beta 4-Strokes with JD jetting

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Ok, here's my question.

 

Since new my Beta has had a very slight blubber off-idle, but the second I start twisting it, it's nice and very very clean. I've played with needle position and my fuel screw back and forth a lot.

Please don't misunderstand it runs great, very clean, no popping on deceleration. And yes, no smog crap... Most people would think it runs great presently, but I know there is a better option for needles out there.

 

Honestly I'm just not liking the taper of the OEM needle and think there is a better option out there, plus a little tweak to the accelerator pump might be a bonus.

 

I've had good and some not so good luck with JD's jetting kits on other past bikes, so I guess I'm looking for some positive or real-time reports about JD's needles used within the Beta diesels...

 

Anyone?

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My 2010 520 has the exact same stumble just off idle. Everywhere else it's great. Been wondering about the JD kit myself. Hope someone can share some info.

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My 2010 520 has the exact same stumble just off idle. Everywhere else it's great. Been wondering about the JD kit myself. Hope someone can share some info.

I recently bought a used 2012 450RR. When I test drove it there was a slight stumble with crack of the throttle off idle. It idled a little rough. The previous owner suspected since it had been sitting several months with the same gas in tank and carb it was probably bad gas. Before I decided to really ride it I wanted to dump gas, clean tank and carb. Also I ordered the JD jetting kit, cuz I was going to be running it a higher elevation.

 

I had a mechanic buddy help me (more like I watched him) install. It took about an hour. The bike had not been started in over two weeks. After the install I put new gas in the tank, choked it, cracked the throttle twice and rather than crank the starter expecting it to take a while, I slowly kicked thru the stroke then kicked it once and she fired right up. On the first ride it was so smooth from idle, no hesitation what so ever. Power was spot on with the JD recommendations. Starts easy with the e button, The instructions are easy to follow and they also have great customer support. The kit comes with a neat little plastic container to keep all jets if you ever need to change the jetting. I highly recommend this product. IMHO at $70 +/- for the kit it is money well spent. 

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I recently bought a used 2012 450RR. When I test drove it there was a slight stumble with crack of the throttle off idle. It idled a little rough. The previous owner suspected since it had been sitting several months with the same gas in tank and carb it was probably bad gas. Before I decided to really ride it I wanted to dump gas, clean tank and carb. Also I ordered the JD jetting kit, cuz I was going to be running it a higher elevation.

 

I had a mechanic buddy help me (more like I watched him) install. It took about an hour. The bike had not been started in over two weeks. After the install I put new gas in the tank, choked it, cracked the throttle twice and rather than crank the starter expecting it to take a while, I slowly kicked thru the stroke then kicked it once and she fired right up. On the first ride it was so smooth from idle, no hesitation what so ever. Power was spot on with the JD recommendations. Starts easy with the e button, The instructions are easy to follow and they also have great customer support. The kit comes with a neat little plastic container to keep all jets if you ever need to change the jetting. I highly recommend this product. IMHO at $70 +/- for the kit it is money well spent. 

Yeah, that's what I thought. Most of the time he nails it on his tapers.  

Actually my bike runs pretty much spot on and since it has broken in, it fires up fast.  

I'll order one today.

Thanx kindly!

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Spending time dialing in the AC circuit will get rid of your stumble. Cracking the throttle off idle takes the needle out of the equation since it's no longer metering fuel since it's now on the main. My 520 needed the AC tweaked slightly, runs great across the rpm range now. It does backfire now and then but that's the nature of 4 strokes and not always a sign of lean jetting.

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JD takes the guess work out of it. Well worth the money. Every bike I have owned gets a JD kit and they always run spot on. Backfires/popping are from header leaks. Red high temp silicone the header pipe flange, make sure to let it dry for a few days before starting.

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I've used JD carbs and jet kits in the past and had great results. As Rick says it takes the guesswork out of jetting. If I didn't get Tokyo Mods to do my carb, I would have got the R&D Power Bowl and JD kit.

 

Yeah, that's what I thought. Most of the time he nails it on his tapers.  

Actually my bike runs pretty much spot on and since it has broken in, it fires up fast.  

I'll order one today.

Thanx kindly!

 

For fast wide open throttle blue needle, for trail riding red needle. The JD tapers are well worth the money!!

 

BTW for some reason I get you and Jeff McKay mixed up. Sorry!

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I've used JD carbs and jet kits in the past and had great results. As Rick says it takes the guesswork out of jetting. If I didn't get Tokyo Mods to do my carb, I would have got the R&D Power Bowl and JD kit.

 

 

For fast wide open throttle blue needle, for trail riding red needle. The JD tapers are well worth the money!!

 

BTW for some reason I get you and Jeff McKay mixed up. Sorry!

Lol! Yeah you don't want to insult McKay like that...Too funny!

I ordered his kit yesterday. The OEM jetting has always acted a little weird. Look forward in a little better low end...

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Spending time dialing in the AC circuit will get rid of your stumble. Cracking the throttle off idle takes the needle out of the equation since it's no longer metering fuel since it's now on the main. My 520 needed the AC tweaked slightly, runs great across the rpm range now. It does backfire now and then but that's the nature of 4 strokes and not always a sign of lean jetting.

You are correct however the JD needles are leaner then OEM and this starts the fueling off leaner to overcome the poor AC settings. There's a noticeable response even without AP change. I struggled with my 350's jetting, it was hard starting, boggy and fat thru the midrange. Fat enough to smell gas while riding. First make sure the float is set at 9mm, not the eyeing BS spec Beta has posted. Either buy a external leak jet or contact JD for recommended size (can't remember). If you use the QS3 external leak jet don't go by the instruction sheet for setting. That sheet is 2-3 jets off (rich), this is based on JD's testing. Yes JD tested this set-up for me since I had issues after installing this combo, JD kit and QS3. I have used JD's jetting kit on several bikes all with good results. Some bike ran better and others were nigh and day difference. It's worth the price just for the needles. For the people that believe their needles are colored OEM's, there not. JD jetting uses leaner needles and fatter jets to provide a more precise jetting.

Edited by weantright

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For fast wide open throttle blue needle, for trail riding red needle. The JD tapers are well worth the money!!

 

 

This is incorrect, these needles are for elevation and temps mostly. Needle work is gone at WOT.

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You are correct however the JD needles are leaner then OEM and this starts the fueling off leaner to overcome the poor AC settings. There's a noticeable response even without AP change. I struggled with my 350's jetting, it was hard starting, boggy and fat thru the midrange. Fat enough to smell gas while riding. First make sure the float is set at 9mm, not the eyeing BS spec Beta has posted. Either buy a external leak jet or contact JD for recommended size (can't remember). If you use the QS3 external leak jet don't go by the instruction sheet for setting. That sheet is 2-3 jets off (rich), this is based on JD's testing. Yes JD tested this set-up for me since I had issues after installing this combo, JD kit and QS3. I have used JD's jetting kit on several bikes all with good results. Some bike ran better and others were nigh and day difference. It's worth the price just for the needles. For the people that believe their needles are colored OEM's, there not. JD jetting uses leaner needles and fatter jets to provide a more precise jetting.

I ended up shimming the diagram to shorten the AC timing. All other circuits are spot on. If anything, I'd say mine might be on the leaner side with the looks of the discoloring on the exhaust but it runs great. Lately I've had to raise the needle 2 clips and the fuel screw to 3.5 turns out just to be able to run without the choke. On a good day the motor struggles to hit 150º but always fires up instantly whether cold or warm. 

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This is incorrect, these needles are for elevation and temps mostly. Needle work is gone at WOT.

 

I did not state it correctly. Blue is richer, red is leaner. 

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First make sure the float is set at 9mm, not the eyeing BS spec Beta has posted.

 

BS spec? Beta spec is the same. Flush is perfect. BTW, flush is also 9mm. How about we have some positive comments instead of negative ones?

 

http://www.thumpertalk.com/topic/1113551-beta-carb-rebuild-started/?p=12070800

 

I just finished rebuilding and fine tuning my carb. No weird stuff like "0" ring mods or shimming diaphragm. Just straight up old school fine tuning. IMO one of the most important adjustments for a clean running carb is the TPS setting. It's easy to adjust with meter but also very easy to have it out of whack. 

 

http://www.thumpertalk.com/topic/1113551-beta-carb-rebuild-started/?p=12074827

 

Times sure have changed. I remember my dads Triumph. Push the button until gas comes out, start bike and let her rip! Very simple Bing carb. Never even had to jet it. 

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Spending time dialing in the AC circuit will get rid of your stumble. Cracking the throttle off idle takes the needle out of the equation since it's no longer metering fuel since it's now on the main. My 520 needed the AC tweaked slightly, runs great across the rpm range now. It does backfire now and then but that's the nature of 4 strokes and not always a sign of lean jetting.

I've been putting off messing with my carb because of the complexity of the pumper carb over traditional carbs. I'm not up to date on all the parts and names. What is the AC circuit? And how do you adjust it?

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I've been putting off messing with my carb because of the complexity of the pumper carb over traditional carbs. I'm not up to date on all the parts and names. What is the AC circuit? And how do you adjust it?

AC is just the accelerator pump circuit. There is a screw for adjusting the timing of when it starts( under the plastic cover on the carb). The diaphragm for it can be shimmed/spacer added with parts offered through aftermarket or dealers. Yamaha,Honda and KTM to list a few offer diaphragms with various lengths to adjust the duration of the stroke if you don't want to shim it yourself. I wouldn't worry about the complexity, it's quite simple to work on. Just work on one circuit at a time till you get familiar with the circuit overlaps.

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BS spec? Beta spec is the same. Flush is perfect. BTW, flush is also 9mm. How about we have some positive comments instead of negative ones?

 

http://www.thumpertalk.com/topic/1113551-beta-carb-rebuild-started/?p=12070800

 

I just finished rebuilding and fine tuning my carb. No weird stuff like "0" ring mods or shimming diaphragm. Just straight up old school fine tuning. IMO one of the most important adjustments for a clean running carb is the TPS setting. It's easy to adjust with meter but also very easy to have it out of whack. 

 

http://www.thumpertalk.com/topic/1113551-beta-carb-rebuild-started/?p=12074827

 

Times sure have changed. I remember my dads Triumph. Push the button until gas comes out, start bike and let her rip! Very simple Bing carb. Never even had to jet it.

Chris, how did your Beta run at those different TPS positions?

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Spending time dialing in the AC circuit will get rid of your stumble. Cracking the throttle off idle takes the needle out of the equation since it's no longer metering fuel since it's now on the main. My 520 needed the AC tweaked slightly, runs great across the rpm range now. It does backfire now and then but that's the nature of 4 strokes and not always a sign of lean jetting.

 

Bike should not be backfiring at all. I can whack my throttle open and chop it with no popping. As stated it could be a indication of leaking pipe connections which in turn creates a lean pop. A well tuned 4 stroke should never pop on decel. Exception would be race machines that are tuned to the ragged edge of being lean.

 

Chris, how did your Beta run at those different TPS positions?

 

I have not tried it other than by proper setting. I already know it will run like crap with it set wrong.

 

 

I've been putting off messing with my carb because of the complexity of the pumper carb over traditional carbs. I'm not up to date on all the parts and names. What is the AC circuit? And how do you adjust it?

 

It's not that hard at all. Check out my thread. I have detailed pics and settings.

 

http://www.thumpertalk.com/topic/1113551-beta-carb-rebuild-started/

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I have not tried it other than by proper setting. I already know it will run like crap with it set wrong.

 

 

How do you know if you haven't tried it? Where did you get the spec? I'm at the edge of my seat waiting to hear your wisdom.

Edited by weantright

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Bike should not be backfiring at all. I can whack my throttle open and chop it with no popping. As stated it could be a indication of leaking pipe connections which in turn creates a lean pop. A well tuned 4 stroke should never pop on decel. Exception would be race machines that are tuned to the ragged edge of being lean.

 

 

 

I'll have to disagree with you. I'm not talking about just whacking the throttle. I talking about going from wide open in gear and using engine braking to come almost to a stop. When your flowing that much fuel and air through the carb and shut it off with the slide you create a massive amount of vacuum in the intake track. The carb will not flow the proper mixture for the cylinder to fire properly and the result is fuel self igniting in the exhaust. You actually stated it in your reply, aren't well tuned motors and race engines one in the same,"well tuned"?

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