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Base line jetting for a R&D Powerbowl 2

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I have a my sons 2014 CRF 150r that I just finished getting the valve specs right. I run 100 octane pump gas and just put on a FMF 4.1 full ti Pipe with mega bomb header. It runs great, however we have the dreaded bog. Didn't know what you guys had success with for jetting. I live in NC and I'm at 300-700 ft sea level. Thanks for you help!! 

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Is that really 100 octane pump gasoline or rather a racing fuel?

If the later, pump gas has a specific gravity of around 0.739  (call it it's 'density')

depending of the blend, race fuels can either be higher or lower and, jetting must be tuned to compensate for that.

 

Ambiant temps are a factor as well, cooler = denser air / leaner mixture = requires richer jetting.

As it is late fall, no doubt your regional temperature is much cooler than only a month ago.

 

Keep in mind a bog when quickly snapping the throttle open is likely more an accelerator pump issue rather than jetting.

Jetting (pilot/needle) issues will be more apparent when gradually twisting the throttle.

 

Edited by mlatour

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1 hour ago, mlatour said:

Is that really 100 octane pump gasoline or rather a racing fuel?

If the later, pump gas has a specific gravity of around 0.739  (call it it's 'density')

depending of the blend, race fuels can either be higher or lower and, jetting must be tuned to compensate for that.

 

Ambiant temps are a factor as well, cooler = denser air / leaner mixture = requires richer jetting.

As it is late fall, no doubt your regional temperature is much cooler than only a month ago.

 

Keep in mind a bog when quickly snapping the throttle open is likely more an accelerator pump issue rather than jetting.

Jetting (pilot/needle) issues will be more apparent when gradually twisting the throttle.

 

Its quick snap of the throttle for the bog. I have ordered the R&D Powerbowl 2 and would like to know a good base line jet setting. Im running a 100 octane pump gas offered at the local gas station. They call it race gas. Unleaded and im not sure of the specific gravity. thanks for the response

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My sons 2018 is all stock,and it had the dreaded bog.all we done was put the power bowl on went with a 42 pilot 3 1/2 turns out on fuel screw and bam the bog  was gone.

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16 minutes ago, Minidad1 said:

My sons 2018 is all stock,and it had the dreaded bog.all we done was put the power bowl on went with a 42 pilot 3 1/2 turns out on fuel screw and bam the bog  was gone.

whats you elevation? What fuel you using?

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23 hours ago, Minidad1 said:

We are at 1000 feet and using 93 pump fuel

In Charlotte using 100 octane pump gas. I ordered a R&D bowl, screw, a 140 main, 138 main, a 38 pilot, 42 pilot, and a 45 pilot.

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7 minutes ago, Wes Woodin said:

In Charlotte using 100 octane pump gas. I ordered a R&D bowl, screw, a 140 main, 138 main, a 38 pilot, 42 pilot, and a 45 pilot.

Do you know what jets are in it now

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6 minutes ago, Minidad1 said:

Do you know what jets are in it now

138 main, 45 pilot, 58 leak, (this is where my problem is) all else stock. the bowl when i get it, will be set to 1 3/4 out. should work

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2 minutes ago, Wes Woodin said:

138 main, 45 pilot, 58 leak, (this is where my problem is) all else stock. the bowl when i get it, will be set to 1 3/4 out. should work

Yeah I think it comes factory adjusted to a 40 leak jet

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1 minute ago, Minidad1 said:

Yeah I think it comes factory adjusted to a 40 leak jet

no 65. the guy who thought he knew what he was doing, put in a 58. it not enough. at 2000-3000 roll on, it would bog bad. AP circuit needs more gas.

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1 minute ago, Wes Woodin said:

no 65. the guy who thought he knew what he was doing, put in a 58. it not enough. at 2000-3000 roll on, it would bog bad. AP circuit needs more gas.

No I was talking about the power bowl cones factory adjusted to a 40 leak

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By 'rolling-on' the throttle, the accelerator pump shot is less of an issue than having the proper pilot jet and especially needle settings.

2000-3000rpm is just above idle, not in the rpm range the engine is designed to pull it's best,

like it's bigger brother the 250R, the small thumper likely only starts coming alive by 7000 rpm or so.

 

7000 to 12000rpm is still a pretty wide power band though, wider than most 2-stroke MX'ers.

Edited by mlatour

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16 minutes ago, Minidad1 said:

No I was talking about the power bowl cones factory adjusted to a 40 leak

oh, ok, not sure what it is at 1 3/4 turns out. great question!!!!!!!

 

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16 minutes ago, mlatour said:

By 'rolling-on' the throttle, the accelerator pump shot is less of an issue than having the proper pilot jet and especially needle settings.

2000-3000rpm is just above idle, not in the rpm range the engine is designed to pull it's best,

like it's bigger brother the 250R, the small thumper likely only starts coming alive by 7000 rpm or so.

 

7000 to 12000rpm is still a pretty wide power band though, wider than most 2-stroke MX'ers.

it may have been 4000-5000 rpm. either way, when it up and running and you dump it, it bogs bad!! its not like you dumping the throttle on the stand.  O believe the my motor guy, who i will add is very good, mistakenly read the specs for the 2007-2008 model year instead of the 2014 like mine. he kept saying the the stock needle was a NMQS where the real stock needle is a NMQT. he kept telling me the the needle had been changed, AND he wired the ap cam like they did on previous versions. In 2012 they changed the cam, where it now pushes instead of trailing.

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I'm not familiar with the 150R's needle ID codes but it's no doubt similar in deciphering them as the larger Keihin FCR's used on bigger bikes.

 

Last letter indicates the root diameter, meaning what starts metering first as you open the throttle 

(A=rich Z-lean) so, a NMQS would be one step richer right off idle than a NMQT. 

(maybe something you should have experimented before ordering a Powerbowl, nevertheless it give you more tuning options)

Other letters refer to taper angles and clip notch height relative to length.

 

Tuning the needle circuit is what made the biggest difference in getting the best 'roll-on' power from

my trail ridden CRF250X which is often lugged well below it's intended power range.

Edited by mlatour
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12 hours ago, mlatour said:

I'm not familiar with the 150R's needle ID codes but it's no doubt similar in deciphering them as the larger Keihin FCR's used on bigger bikes.

 

Last letter indicates the root diameter, meaning what starts metering first as you open the throttle 

(A=rich Z-lean) so, a NMQS would be one step richer right off idle than a NMQT. 

(maybe something you should have experimented before ordering a Powerbowl, nevertheless it give you more tuning options)

Other letters refer to taper angles and clip notch height relative to length.

 

Tuning the needle circuit is what made the biggest difference in getting the best 'roll-on' power from

my trail ridden CRF250X which is often lugged well below it's intended power range.

Thank You for the input!! The stock leak jet in the manual states a 65. The jet I took out of the leak jet circuit was a 58. This seems like this might be on of the reasons it 's bogging when you roll it on. If the squirt is not enough, it would starve and bog. What do you think?

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Every thing I read when I was looking for a solution was a 40to 42 leak with some fuel screw adjustment was what is needed, or a power bowl 

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5 hours ago, Minidad1 said:

Every thing I read when I was looking for a solution was a 40to 42 leak with some fuel screw adjustment was what is needed, or a power bowl 

Powerbowl will be here Wednesday. Looking forward to getting it together. We have a race this coming up weekend!

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1 problem is a relatively large carburetor on a small engine. She doesn't have a lot of vacuum at low rpm. Your bog on roll on may be due to a dirty pilot circuit. At 700' in Ohio my daughter's 13 ran beautiful with a 45 pilot and properly set fuel screw. If the bike sat for any length of time the pilot would partially clog causing a bogging issue.
You also have to keep in mind that it is important to ride in the proper gear. It's a bit 2 stroke like in that regard compared to 250 or 450fs

Your comment about the valves is a point of concern. 20 years in and people still don't quite understand the significance of valve adjustment. It's not routine maintenance. It means the valves faces have started to wear and the wear rate will only increase at an exponential rate. If the bike is new to you keep an eye on the valves for a while. If you see they are continuely moving than the faces are cupped and you need a valve job.

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