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  1. #1
    kurt1200's Avatar
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    Do i need to re-jet my carbs??

    I have a 1200pv that i have just rescently rebuilt, and i am unsure what to do carbwise as i am a newbie. I had the cylinders re nikilsiled, and im using wsm platinum top end... I have riva hig compression heads, d-plate, and free flow. Also using anew case, and crank. I already have the engine assembled, but before i go any further i want to address the stock carbs. I was told that with opening up the exhuast as much as i have that i need to re-jet or tune the carbs accordingly to compensate for the increased airflow or the engine will run too lean and my top end wont last long at all... Is this true??? If so what do i need to do to my carbs to make this engine run correctly, and to keep it from running lean? Thats the only big question i have. Oh and whats the trick to getting these engines in. I noticed that last time i tried to install it the exhaust was hell to wrestle with trying to get in. Do i put the exhaust(lower pipe) first, or do i wait until the engine is in?? And lastly if you have any other suggestions on building a new engine, or something i might run in to you advice would be greatly appreciated!!!

    p.s. Whats the best impeller to run with my mods? Looking for top speed, but still want some low end take off...

    thanks


    Kurt

    2000 Yamaha xl limited 1200pv
    Last edited by kurt1200; 12-10-2007 at 09:46 AM.


  2. #2
    mrbtd's Avatar
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    Quote Originally Posted by kurt1200 View Post
    I have riva hig compression heads, d-plate, and free flow. I was told that with opening up the exhuast as much as i have that i need to re-jet or tune the carbs accordingly to compensate for the increased airflow or the engine will run too lean and my top end wont last long at all... Is this true???
    Yes

    Quote Originally Posted by kurt1200 View Post
    If so what do i need to do to my carbs to make this engine run correctly, and to keep it from running lean?
    Are you going to use open flame arrestors ?

    Quote Originally Posted by kurt1200 View Post
    Do i put the exhaust(lower pipe) first, or do i wait until the engine is in??
    The stinger is last - you would never be able to bolt it down otherwise.

  3. #3
    kurt1200's Avatar
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    No im going to be using the stock intake... Im trying to resist spending any more money! I have already spend in excess of $3,500!!

  4. #4
    Moderator OsideBill's Avatar
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    Quote Originally Posted by kurt1200 View Post
    I have a 1200pv that i have just rescently rebuilt, and i am unsure what to do carbwise as i am a newbie. I had the cylinders re nikilsiled, and im using wsm platinum top end... I have riva hig compression heads, d-plate, and free flow. Also using anew case, and crank. I already have the engine assembled, but before i go any further i want to address the stock carbs. I was told that with opening up the exhuast as much as i have that i need to re-jet or tune the carbs accordingly to compensate for the increased airflow or the engine will run too lean and my top end wont last long at all... Is this true??? YESIf so what do i need to do to my carbs to make this engine run correctly, and to keep it from running lean?Re-jet the carbs Thats the only big question i have. Oh and whats the trick to getting these engines in. I noticed that last time i tried to install it the exhaust was hell to wrestle with trying to get in. Do i put the exhaust(lower pipe) first, or do i wait until the engine is in??install engine assembly then exhaust and carburetors And lastly if you have any other suggestions on building a new engine,Pressure test the motor air leaks will kill it or something i might run in to you advice would be greatly appreciated!!!

    p.s. Whats the best impeller to run with my mods? Looking for top speed, but still want some low end take off...

    thanks


    Kurt

    2000 Yamaha xl limited 1200pv
    • For your set-up carbs should be 110 pilot jets 120 main jets 1.5 needle and seat and 95 gram spring. disable the accelerator circuit. if you remove the choke plates take the main jet to 125
    • Do a search for pressure testing your motor there are several threads here on this. Pay attention to the case halves and the crank seals

  5. #5
    kurt1200's Avatar
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    Ok thanks! Do i need to buy different jets or what? Im sorry,but i know nothing about re-jetting... Is there a kit i can buy to do this? How hard is it??

  6. #6
    kurt1200's Avatar
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    Ok nevermind that... i found jets over on riva racings website for like 3 bucks a piece... Are all mikuni jets universal though??

  7. #7
    Moderator OsideBill's Avatar
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    Quote Originally Posted by kurt1200 View Post
    Ok nevermind that... i found jets over on riva racings website for like 3 bucks a piece... Are all mikuni jets universal though??
    Yes the jets are universal the ones from Riva will work fine go through the online store here with Riva orders and get a discount just PM Greenhulk with the part numbers if they are not listed in his store. if your carbs have not been rebuilt in a while it is a good time to do this. also consider t-handle adjusters Riva carries those also. do a search on carbs there are many threads on this.

  8. #8
    kurt1200's Avatar
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    Ok thanks man!

  9. #9

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    About your impeller, a 13/19 would work well with your set up. I cannot stress this enough, with the extra speed that you will have, get an aftermarket intake grate.... a double bar type for either a GPR1200 (for better hook up) or a GPR 800 grate (for better top end). The grate is a safety item and is an ABSOLUTE must for a modified GPR.

    The after market flame arrestors really work well with your set up.

    If money is a concern, then post on the Greenhulk want adds for the items. There is a lot of good to excellent parts for sale there. You will save some $$$$.

  10. #10
    Moderator OsideBill's Avatar
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    Quote Originally Posted by salty View Post
    About your impeller, a 13/19 would work well with your set up. I cannot stress this enough, with the extra speed that you will have, get an aftermarket intake grate.... a double bar type for either a GPR1200 (for better hook up) or a GPR 800 grate (for better top end). The grate is a safety item and is an ABSOLUTE must for a modified GPR.

    The after market flame arrestors really work well with your set up.

    If money is a concern, then post on the Greenhulk want adds for the items. There is a lot of good to excellent parts for sale there. You will save some $$$$.
    Salty he has an XLT

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