Orion RXB 150 tuning, please help so close

[nritchie30]

Hi, I am new here. first post. not sure if this is the right category.

Last week i got my RXB 150 xl street legal bike, i need help tuning. I am almost there, real close but kinda stuck. Heres the run down.

Bike shipped with no clutch disengagment, barely had enough adjustment available to get it to work.
Knock off mikuni was crap, bike barely ran, sputtered, backfired, made a quick sucking noise and died.
Yesterday, i installed the following
nibbi 26mm carb
new racing cdi
K&N filter
and bought jets.
I am at 300' in washington state. sometimes humid, more often comfortable.

I started with 115/38 jets needle 2nd from bottom........... bike actually idled but still died on throttle release.


tried 120/42 needle in 2nd from top... too rich wet plug, but started easier and idled better



tried 115/42 needle in middle.... a little dark on plug but not wet and bike started the best, idled the best, and almost threw me off in first gear, i wasnt expecting the extremely sensitive response.

however, a tad sluggish in second, a little bog under way that you dont notice on sitting still.

whats my next move?????? im so close not sure which way to go

thanks!!!!!

[Beast250]

Hello! Where in the throttle does it bog? Is it from quarter throttle all the way through wide open? Or is it just between quarter and three quarters?

My understanding of carbs, breaks the jets down into contributors to the overall flow. You may need to just drop down on the jet needle or needle jet if its between. Or the main if its wide open throttle.

Check out the image toward the top of this page:
https://www.howtomotorcyclerepair.co...ircuit-mikuni/

Hope it helps.

[Goob]

Originally Posted by nritchie30

Hi, I am new here. first post. not sure if this is the right category.

Last week i got my RXB 150 xl street legal bike, i need help tuning. I am almost there, real close but kinda stuck. Heres the run down.

Bike shipped with no clutch disengagment, barely had enough adjustment available to get it to work.
Knock off mikuni was crap, bike barely ran, sputtered, backfired, made a quick sucking noise and died.
Yesterday, i installed the following
nibbi 26mm carb
new racing cdi
K&N filter
and bought jets.
I am at 300' in washington state. sometimes humid, more often comfortable.

I started with 115/38 jets needle 2nd from bottom........... bike actually idled but still died on throttle release.


tried 120/42 needle in 2nd from top... too rich wet plug, but started easier and idled better



tried 115/42 needle in middle.... a little dark on plug but not wet and bike started the best, idled the best, and almost threw me off in first gear, i wasnt expecting the extremely sensitive response.

however, a tad sluggish in second, a little bog under way that you dont notice on sitting still.

whats my next move?????? im so close not sure which way to go

thanks!!!!!

I have an Orion 150 also and was able to get the Mikuni VM26 Flange mount working pretty well. I am changing out to a VM26-606 spigot mount, as it is a better quality carb with more flow. I have heard good things on this site about the Nibbi and considered one, but wanted to avoid a clone.

You should not change more than one thing at a time. I learned from several tuning manuals the following order for tuning: Idle, pilot screw (between 1 to 2 1/2 turns), pilot jet (if screw is less than 1 or greater than 2 1/2), needle clip (down richer, up leaner), LAST main. Here are a few of them...put them all together and the whole process begins to make sense:

http://www.vintagebikebuilder.com/mi...ing-guide.html

http://www.ccwthariders.com/uploads/...ing_manual.pdf

http://www.iwt.com.au/mikunicarb.htm

http://www.takegawa.co.jp/files/03-05-0031.pdf

[Dusman]

I am currently helping a gentleman tune his TBR7 carb and he did the standard 110 main that is frequently recommended for most initial CG250 engine set-ups. He got that classic "rich bogging" at 3/4 to full throttle. He pulled the plug and it indicated a rich condition. I forgot to ask him what elevation he was at (we did the carb tuning via FB messenger video chat). I then asked, "What elevation are you at?" His response: "Huh, dunno." He checked and it was @ 300'. His elevation definitely wouldn't work with the typical go-to initial carb set-up for most CG250 dual sport riders here in N. America.

His bike runs well with a 103 main jet due to his elevation being lower (on average) than most who own & operate the same bike.

Based on what you've said, I suspect your main jet is still too rich. (1) If you are bogging primarily from 3/4 to to full throttle, that is the throttle range controlled by the main jet. (2) Idle to 1/4 throttle is your pilot system (pilot jet, fuel-air mixture screw). (3) Mid throttle is controlled by needle & needle jet (1/4 to 3/4 throttle).

Re: # 3 above, the needle jet is the long, tall brass thing that the main jet screws into and it is what the needle (the tapered, long flat round thing) sits into. We normally don't change the needle jet on our Chinabikes, but it's helpful to know what it is when studying carb mechanics and how to tune your carb. The needle sits down into the jet needle and the needle raises up and down within the needle jet when you twist your throttle. As you probably already know, you *can* adjust your needle. Moving the e-clip further up on the needle makes your needle sit further down into the needle jet and limits the amount of gas that is let into the air-fuel mixture, thus leaning the air-fuel mixture out. Lowering the e-clip on the needle makes your needle sit higher up, thus allowing more gas to enter the air-fuel mixture, thus enriching your mixture. Again, most of us don't mess with changing our needle jet, but we change the height of our needle via the e-clip to tune the mid-throttle range (1/4 to 3/4 throttle).

Nevertheless definitely follow the advice you've already been given or you'll be chasing your tail forever trying to figure it all out.

[nritchie30]

Ive settled on 115\40 needle in center.. seems to run the best, i appreciate all the help.. tokk me a while to understand how they all work together, i appreciate the links for understanding......






ORION RXB 150XL
TAO DBX1

[nritchie30]

[nritchie30]

in case your wondering... yes, i put 19" on front and 16" in rear... it really brings this bike up to a mid size enduro kinda.. it came with 17\14

[nritchie30]

Originally Posted by Dusman

I am currently helping a gentleman tune his TBR7 carb and he did the standard 110 main that is frequently recommended for most initial CG250 engine set-ups. He got that classic "rich bogging" at 3/4 to full throttle. He pulled the plug and it indicated a rich condition. I forgot to ask him what elevation he was at (we did the carb tuning via FB messenger video chat). I then asked, "What elevation are you at?" His response: "Huh, dunno." He checked and it was @ 300'. His elevation definitely wouldn't work with the typical go-to initial carb set-up for most CG250 dual sport riders here in N. America.

His bike runs well with a 103 main jet due to his elevation being lower (on average) than most who own & operate the same bike.

Based on what you've said, I suspect your main jet is still too rich. (1) If you are bogging primarily from 3/4 to to full throttle, that is the throttle range controlled by the main jet. (2) Idle to 1/4 throttle is your pilot system (pilot jet, fuel-air mixture screw). (3) Mid throttle is controlled by needle & needle jet (1/4 to 3/4 throttle).

Re: # 3 above, the needle jet is the long, tall brass thing that the main jet screws into and it is what the needle (the tapered, long flat round thing) sits into. We normally don't change the needle jet on our Chinabikes, but it's helpful to know what it is when studying carb mechanics and how to tune your carb. The needle sits down into the jet needle and the needle raises up and down within the needle jet when you twist your throttle. As you probably already know, you *can* adjust your needle. Moving the e-clip further up on the needle makes your needle sit further down into the needle jet and limits the amount of gas that is let into the air-fuel mixture, thus leaning the air-fuel mixture out. Lowering the e-clip on the needle makes your needle sit higher up, thus allowing more gas to enter the air-fuel mixture, thus enriching your mixture. Again, most of us don't mess with changing our needle jet, but we change the height of our needle via the e-clip to tune the mid-throttle range (1/4 to 3/4 throttle).

Nevertheless definitely follow the advice you've already been given or you'll be chasing your tail forever trying to figure it all out.

I am following advice.. bike most certainly idles the best with a 40.. purrs like kitten... i wouldnt say its boggy at 3\4 with the 115. but your right still a little rich... shes very snappy now. Its hard to tell because the gearing difference. 1st is so short and second seems too long, so its hard to tell if i'm pulling everything i can get out of it.

[Goob]

Originally Posted by nritchie30

Ive settled on 115\40 needle in center.. seems to run the best, i appreciate all the help.. tokk me a while to understand how they all work together, i appreciate the links for understanding......






ORION RXB 150XL
TAO DBX1

Hope you have some fun now! I can't wait to get mine up on some mountain trails at the end of the month. It is quicker than my TT250...which makes sense only 4.26 hp less but 145 lbs lighter.