So is the Rt Carb really all it's cracked up to be?

Discussion in 'Intake & Exhaust' started by stevolandis, Sep 14, 2011.

  1. stevolandis

    stevolandis New Member

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    I've been looking at various carbs and comparing pros and cons. I hear great reviews about the RT carb- better pulling power and high end performance than the NTs. My question is is it worth the $30 to replace my old NT carb with an RT?

    The CNS seems to cause to many problems for most people and I hear the RT "blows the CNS out of the water". Does the RT really perform this much better?

    I will have an SBP expansion pipe by the end of the week- does the RT perform good with the pipe?

    And one more question- will I need to modify my intake manifold(if the RT is a larger diameter carb then I would benefit from a larger intake manifold)
     
  2. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The RT is a good carb but it needs to be jetted way smaller for HT engines.
    I've found that the RTs have a really crisp mid throttle cruising feel.

    The stock NT carbs also work very well if you jet them smaller... Some of the fastest bikes i've ever seen run the NT carbs!
     
  3. 2door

    2door Moderator
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    Your stock intake manifold will work fine with the RT. No need to increase the size.
    It's been my experience that the plastic sleeve that comes in the RT needs to be sealed to the intake manifold. I ran them for a while without sealing but then they developed some air leaks. I used Seal-All, gasoline resistant sealer and no more problems.
    Tom
     
  4. stevolandis

    stevolandis New Member

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    Thank you Venice!
    So the thing I'm looking for most is some low end torque for getting around the mountains here- it sounds as if both carbs are good for speed- are either any better for low end?

    Also why is the slide on the RT flat? I'm curious to know the benefits of that.
     
  5. stevolandis

    stevolandis New Member

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    2door- Yesterday i opened up the end of my manifold a little with a dremel for better intake- and these manifolds aren't able to be wide enough to match the port because of their small diameter. So my thoughts were to expand the end of the intake(maybe a larger pipe) to match the port, but that wouldn't be worth it because the manifold will still wind up at the same diameter because of the small carb- so no benefit. So it seems to match the size of the port , you would need a larger carb, and then you would be able to increase the intake manifold's diameter to match the size of the intake port, offering more power because of increased intake.
    That's why I was asking whether it would be a good idea to get a bigger intake manifold with the larger carb.
    So is all my thinking there wrong? What do you guys think?
     
  6. Tohri

    Tohri New Member

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    A better carb than the RT is available off Treatland, but is out of stock at the moment. Personally, I'd reccomend that you pay more and get a real dellorto. I have an RT and while it runs well, it has an aggrivating air leak, and isn't all that tunable. I've been looking at Walbro carbs as a possible solution, but haven't found the right one.

    Check out www.treatland.tv moped parts superstore and look at their carb selection.
     
  7. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    I'll repeat this... "some of the fastest bikes I've ever seen have NT carbs".
    You should try installing a size (or two) smaller jet first! (It's cheap enough, & you might really like what you get!) ;)
     
  8. F_Rod81

    F_Rod81 Dealer

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    I used the NT carb for about 6 months, I had it jetted and dialed in perfect. Then Duane released the RT carb, I bought it to see if it would be worth it. Since then I have not taken the RT carb off. It is definitely smoother through-out the RPM range and has better top-end fuel delivery then the NT (no sputtering). It has a staged jet and flat slide instead of a needle, clip, and barrel slide. If you compare the 3 carbs side by side (price, performance, reliability) the RT in my opinion will win. You can't beat the Performance and reliability for only $30.
     
  9. F_Rod81

    F_Rod81 Dealer

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    Works really good with the manic ported intake.
     
  10. Tohri

    Tohri New Member

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  11. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Just so everyone knows where it's at... I'm gonna install a re-jetted RT carb on my new Felt. ;)
     
  12. PerryP180

    PerryP180 New Member

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    I've used the NT, CNS v2, and RT all on the same motor and bike. I'm 240 pounds and my bike is a 23" steel frame. The NT with the SBP HD air filter had the best hill climbing power(I'm in Atlanta, GA. Big hills). Top end of about 25 mph. The RT had excellent throttle response. It would not idle consistently and was very weak on hills. It reached about 27 mph wot. The #70 jet is still too rich as there was a lot of 4 stroking past 3/4 throttle. I did not like the CNS with the stock jet. It is so lean that it wouldn't even run when I put on the SBP air filter. I accidentally drilled the jet to a #85 jet(#66 drill bit) when my bits got mixed-up. It was way too rich with stock air filter. I was about to toss it and then thought I might as well see if the SBP air filter would help. It was like magic. It is decent on hills(still not as good as the NT) and will rocket me all the way to 30 mph. I can easily cruise at 25 mph without the motor sounding like it's tearing itself apart. I'm sticking with the CNS setup. Remove the tube from the bowl to the air filter. It creates negative pressure in the carb restricting fuel flow. The RT is my third choice. It needs either a #68 jet or a less restrictive air filter. I don't know where to get either.
     

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