Benelli 250 2c Carb jetting
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Thread: Benelli 250 2c Carb jetting

  1. #1
    Junior Member
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    Dave Lloyd
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    Benelli 250 2c Carb jetting

    Hi All

    I am just completing a build of a benelli 250 2c and have new expansion pipes fitted. The carbs are VHBZ 25 B with 98 main jet. I have been sort of told that I would need to jet up 3 or 4 sizes. i spoke with a guy who has done similar things to his bike (250 2c) and has jetted it up to 130, which seem a massive jump.

    I would appriciate any help and guldance if possib;le please?
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  2. #2
    RUSSBUS
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    RUSS
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    Quote Originally Posted by lloydy1 View Post
    Hi All

    I am just completing a build of a benelli 250 2c and have new expansion pipes fitted. The carbs are VHBZ 25 B with 98 main jet. I have been sort of told that I would need to jet up 3 or 4 sizes. i spoke with a guy who has done similar things to his bike (250 2c) and has jetted it up to 130, which seem a massive jump.

    I would appriciate any help and guldance if possib;le please?
    I drilled mine out to 128 and it was still lean, I have put the project away for awhile as it was not running strong but I would concour with the other guy that with the expansion pipes you'll need big jet holes, you have your work cut out to get it right.
    Good luck and please post your results to help us lazy buggers.

    Russ

  3. #3
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    Jetting

    Quote Originally Posted by RUSSBUS View Post
    I drilled mine out to 128 and it was still lean, I have put the project away for awhile as it was not running strong but I would concour with the other guy that with the expansion pipes you'll need big jet holes, you have your work cut out to get it right.
    Good luck and please post your results to help us lazy buggers.

    Russ
    I'm running 126-128 on my race bike. That has 30mm Dellortos though.

    Hi Russ hows it going? You at the Classic TT?

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  5. #4
    RUSSBUS
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    RUSS
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    Quote Originally Posted by Wezzo View Post
    I'm running 126-128 on my race bike. That has 30mm Dellortos though. Hi Russ hows it going? You at the Classic TT?
    Hi Colin, no Ive got into the dirt biking just got back from France, we are going to the GP Manx next year but for the tail end to catch the Classic trials.Not turned a wheel on the Guzzi project, Pete and I want to pop to see you race so please post up your meetings.Russ

  6. #5
    Junior Member
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    Dave Lloyd
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    Project Complete. Jetting still not quite right!

    Benelli 250 2c Carb jetting-img_0065.jpg

    The bike is now completed. MOT was done and on the road. I read many threads on here/elsewhere and there seem to be differences of opinion about the fuel mix. Also going off the manual which calls for 3% or 32:1. I read something somewhere about a guy who claims his bike seized using this mix. what do you guys think? My jetting still needs work as it isn't clean.

  7. #6
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    Jetting

    I'm thrashing mine on 40:1 but using Pro2 fully synthetic, ie the best 2 stroke oil available. Hasn't seized yet

    Quote Originally Posted by lloydy1 View Post
    Click image for larger version. 

Name:	IMG_0065.JPG 
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    The bike is now completed. MOT was done and on the road. I read many threads on here/elsewhere and there seem to be differences of opinion about the fuel mix. Also going off the manual which calls for 3% or 32:1. I read something somewhere about a guy who claims his bike seized using this mix. what do you guys think? My jetting still needs work as it isn't clean.

  8. #7
    Junior Member
    Name
    Dave Lloyd
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    Quote Originally Posted by Wezzo View Post
    I'm thrashing mine on 40:1 but using Pro2 fully synthetic, ie the best 2 stroke oil available. Hasn't seized yet
    Thanks. I will check that out then.

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