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06 134 BB jetting issues

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I recently rebuilt my motor to a 134 by Eric G. I did a full motor rebuild and threw on V Force 3 reeds with a fatty and shorty. To cut to the chase Im having trouble jetting. I want to show a little lay out of what my jets have been and how the bike is acting. This is with Amsoil Dominator mixed 40:1 with VP C12 fuel.

 

1st Attempt 

  • Main Jet- 430
  • Pilot Jet- 50
  • Needle Clip- 3rd down from the top
  • Air Screw- 1.5 Turned Out

 

Response- Bogged at higher RPM's. Kinda chocked up at higher speeds.

 

2nd Attempt 

  • Main Jet- 410
  • Pilot Jet- 42.5
  • Needle Clip - 2nd down from the top
  • Air Screw- 1.5 Turned Out      

Response- Re-acted similar to my 1st attempt. got better what still was sharp at low ends and was bogging a little on the bottom.

 

I spoke with eric and he had reccomended that the bike likes to be a little more lean that usual. This is what he told me to try.

 

3nd Attempt

  • Main Jet - 390
  • Pilot Jet - 40
  • Needle Clip - 2nd From the top
  • Air Screw- 1.5 Turned out

Response- The bike definitely  produces a lot more power and has fast delivery now at high RPM's. Very little Boging once Revving hard and fast. The bogging accrues when the bike is trying to rev up. Its almost like when the bike is under load it struggles. But in my yard on grass terrain the bikes rips. Im aware 125 lack low end power. I own a 01 CR 250 to compare bikes to. My brother owns a 99 CR 125. This bike is completely stock and is much more sensitive  to the throttle and snaps like a rubber band. My bike is a fresh motor and feels slower and seems like its lagging from 1/4 Throttle - 1/2 throttle or even more throttle. 

 

Any resin this bike should be lagging once under Load? Also what if i tried a 

 

Main 410

Pilot 50

2nd Clip Down 

1.5 Turns out ? 

 

Im making a list of what i need to build a Leak Down Tester and get a gauge for my float height. Any advice is a plus. Thanks Everyone 

 

 

 

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Get an airstriker 38mm from jd jetting. 259$ and they jet it according to where you live and the temp. I have it on my cr eg 134 big bore. I had the same problem and as soon as I bolted it up it ran 100x better

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The lagging under load  at low/mid is evidence of lean condition in my opinion.  125's are finicky to jet, and BB's are even finickier.  

 

When I did my 144, I re-jetted, and found a same or similar condition.  I also noticed an off idle hesitation with a sudden aggressive whack of the throttle from idle.  I'm running mine with a PWK, so I can't really advise you what to do with the mikuni.  I can tell you what works for me with a PWK.  I've tried several needles and slides in different combination, and have many useable settings that work well, with minor compromises.  My best setting is using an alternate 2000 CR250 needle:

 

A685/294R 3rd clip, 45 pilot, 178 main, 2 turns, and #6 slide.  This runs clean from bottom to top without compromises.  I have cleaner settings with compromises.  If you are interested, PM me with your email, and I'll send you my jetting notes.

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I recently rebuilt my motor to a 134 by Eric G. I did a full motor rebuild and threw on V Force 3 reeds with a fatty and shorty. To cut to the chase Im having trouble jetting. I want to show a little lay out of what my jets have been and how the bike is acting. This is with Amsoil Dominator mixed 40:1 with VP C12 fuel.

 

1st Attempt 

  • Main Jet- 430
  • Pilot Jet- 50
  • Needle Clip- 3rd down from the top
  • Air Screw- 1.5 Turned Out

 

Response- Bogged at higher RPM's. Kinda chocked up at higher speeds.

 

2nd Attempt 

  • Main Jet- 410
  • Pilot Jet- 42.5
  • Needle Clip - 2nd down from the top
  • Air Screw- 1.5 Turned Out      

Response- Re-acted similar to my 1st attempt. got better what still was sharp at low ends and was bogging a little on the bottom.

 

I spoke with eric and he had reccomended that the bike likes to be a little more lean that usual. This is what he told me to try.

 

3nd Attempt

  • Main Jet - 390
  • Pilot Jet - 40
  • Needle Clip - 2nd From the top
  • Air Screw- 1.5 Turned out

Response- The bike definitely  produces a lot more power and has fast delivery now at high RPM's. Very little Boging once Revving hard and fast. The bogging accrues when the bike is trying to rev up. Its almost like when the bike is under load it struggles. But in my yard on grass terrain the bikes rips. Im aware 125 lack low end power. I own a 01 CR 250 to compare bikes to. My brother owns a 99 CR 125. This bike is completely stock and is much more sensitive  to the throttle and snaps like a rubber band. My bike is a fresh motor and feels slower and seems like its lagging from 1/4 Throttle - 1/2 throttle or even more throttle. 

 

Any resin this bike should be lagging once under Load? Also what if i tried a 

 

Main 410

Pilot 50

2nd Clip Down 

1.5 Turns out ? 

 

Im making a list of what i need to build a Leak Down Tester and get a gauge for my float height. Any advice is a plus. Thanks Everyone 

 

The question here is; is it bogging or blubbering?  A "bog" is when the bike feels like it is going to die while under throttle load, a "blubber" is the bike feels like it is spitting and sputtering at that throttle position like it is going to drown on the fuel.  My impression from what you posted is that the bike ran much better after Eric Gorr told you to lean out your jetting so if it got better but not quite good enough under his recommendations, you might try going 1 step leaner on the pilot jet and re-test.  +1 on the PWK carb, IMO you would have spent your money better by not getting the reeds and pipe and going with the PWK in the first place.  Since you have an 06, I would recommend getting a PWK from a 00+ Yamaha YZ250.  The JD carbs are awesome and JD's jetting kit is awesome, and JD will go out of his way to help you get your bike dialed but guys like RTV and Magpie have done extensive research on the bb cr125's with a PWK carb so you could use some needle combinations recommended by them and get it dialed without having to spend $80 on a JD jet kit and the Yamaha carb will fit your bike better than the 00 CR250 carb that JD is using for his JD jetted PWK carb.

Edited by frdbtr

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There have also been posts here recommending the Yamaha YZ 125 needles for your TMX carb, you might do some searches for CR125 jetting and see if you can find some of those posts.  From what I remember, the Yamaha needles really help clean up the TMX jetting on the 125.

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I recently rebuilt my motor to a 134 by Eric G. I did a full motor rebuild and threw on V Force 3 reeds with a fatty and shorty. To cut to the chase Im having trouble jetting. I want to show a little lay out of what my jets have been and how the bike is acting. This is with Amsoil Dominator mixed 40:1 with VP C12 fuel.

 

1st Attempt 

  • Main Jet- 430
  • Pilot Jet- 50
  • Needle Clip- 3rd down from the top
  • Air Screw- 1.5 Turned Out

 

Response- Bogged at higher RPM's. Kinda chocked up at higher speeds.

 

2nd Attempt 

  • Main Jet- 410
  • Pilot Jet- 42.5
  • Needle Clip - 2nd down from the top
  • Air Screw- 1.5 Turned Out      

Response- Re-acted similar to my 1st attempt. got better what still was sharp at low ends and was bogging a little on the bottom.

 

I spoke with eric and he had reccomended that the bike likes to be a little more lean that usual. This is what he told me to try.

 

3nd Attempt

  • Main Jet - 390
  • Pilot Jet - 40
  • Needle Clip - 2nd From the top
  • Air Screw- 1.5 Turned out

Response- The bike definitely  produces a lot more power and has fast delivery now at high RPM's. Very little Boging once Revving hard and fast. The bogging accrues when the bike is trying to rev up. Its almost like when the bike is under load it struggles. But in my yard on grass terrain the bikes rips. Im aware 125 lack low end power. I own a 01 CR 250 to compare bikes to. My brother owns a 99 CR 125. This bike is completely stock and is much more sensitive  to the throttle and snaps like a rubber band. My bike is a fresh motor and feels slower and seems like its lagging from 1/4 Throttle - 1/2 throttle or even more throttle. 

 

Any resin this bike should be lagging once under Load? Also what if i tried a 

 

Main 410

Pilot 50

2nd Clip Down 

1.5 Turns out ? 

 

Im making a list of what i need to build a Leak Down Tester and get a gauge for my float height. Any advice is a plus. Thanks Everyone 

We're running our - 02 CR 134 with 38mm TMX

- Phat head H12 combustion chamber

- 420 mj

- 37,5 pj

- needle on the 3rd

- air screw we have to adjust almost every tie at the track

Bike runs really well and is very fast. Cylinder is ported by yours truly. We're in Finland close to sea level.

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Hi guys I have kind of the same problem, mine bogs out of corners and goes nowhere then all of a sudden the power valve kicks in and it just goes insane, my mate who races them went on it and he thinks power valve needs adjusting? But I'm sure it's jets, I spoke to the guy who rebuilt it and I brought it off and he says the jets was set for warmer conditions? And just keep her pinned she'll be fine lol I'm going to strip it tomoz and service it, new plug air filer, change oil and clean carb and jets, It was running on 40-1 so I'm going to drain fuel and put new mix at 32-1. I live in Leicester, going Coventry moto 45 on sat temp about 5 degrees what jets would you recommend? Thanks guys

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