Author Topic: Fueling/jetting help  (Read 1653 times)

marty

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Fueling/jetting help
« on: August 21, 2012, 06:43:28 PM »
I have a Pulsar 125 (engine is a clone of a Honda XLR125)
I have fitted a free flowing exhaust, cone filter, so called "RACE" CASOLI CDI along with a BBK (63.5mm piston=157cc)
The original carb was 26mm with a 0.92 main and 0.40 idle jet. I bought a 30mm carb thinging the bike would need something bigger.

With the 30mm carb it starts and idles OK but if you open it up too fast it nearly stalls. I was thinking too lean? The needle was on the 3rd notch so I moved it to the last one and it helps a bit but it really feels like its holding back. I took the 30mm carb off and had a look at the jets and checked the float level. The floats  wern't too bad but I was supprised to see it only had a 0.90 main jet and I can't read whats on the idle jet. I'm guessing it's far too weak?

As an experiment I refitted the original 26mm carb (never used with the BBK before) The needle again was in the middle notch so I moved it to the lowest.
The engine seemed much more responsive and doesn't bog down when opening it up fast yet it feels like it just hasn't got enougth flow for higher speed/RPM's.

My question is should I stick with the 26mm carb with a bigger main jet (it so what size to start with?) or try re-jetting the 30mm carb?

I have orderd two main jets (97.5 and 107.5) to play with.

Any help/suggestions welcomed :)


Here's a short vid of it running ;)


zombie

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Re: Fueling/jetting help
« Reply #1 on: August 21, 2012, 09:46:51 PM »
What jets are in the 26mm?
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Peters

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Re: Fueling/jetting help
« Reply #2 on: August 22, 2012, 01:47:18 AM »
I'm willing to bet a larger main jet will fix the problem
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marty

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Re: Fueling/jetting help
« Reply #3 on: August 22, 2012, 05:07:45 AM »
What jets are in the 26mm?

The original carb was 26mm with a 0.92 main and 0.40 idle jet.

marty

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Re: Fueling/jetting help
« Reply #4 on: August 22, 2012, 05:08:14 AM »
I'm willing to bet a larger main jet will fix the problem

In which carb?

zombie

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Re: Fueling/jetting help
« Reply #5 on: August 22, 2012, 11:03:22 PM »
95/40-42 should do it. Larger carbs have a slower flow rate on the venturi so they need larger jets to allow enough fuel to flow. I wouldn't think any bigger would be needed.
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