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Speed
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Discussion Starter #1
Hi Guys,

I am trying to get up-to-speed with regard to tuning my carb for optimum performance. I bought a used 2002 FXDWG TC88 with stage one. As purchased, it was advertised to have the SE Air Filter Kit, Dyno-Jet Carb Kit, and V&H Long Shots.

I'm making a couple of change right off the bat. I am changing the pipes to Vance and Hines Big Shot Staggerds and I'm changing the air filter from the paper SE to the K&N HD-0800.

I want the bike to run 'right' - Not too rich and not too lean and be tuned properly for maximum power.

So, I was thinking of taking it to my local dealer to have it dyno-tuned after these small changes.

I read this marathon read and came away with the notion that the Dyno-Jet kit can be properly tuned and it is flexible with regard to tuning. However, it appears that some tuners tune these way too rich resulting in mpg in the low to mid thirties.

http://65.38.172.84/forums/showthread.php?t=43934&highlight=stage+tuning+jets

The questions:

  1. What is the proper A/F ratio I should look for on the dyno graph
  2. Does anyone have electronic documentation on this kit that I could read to get more famalier with how to tune the kit?
  3. What changes are made to the carb during the install of the kit?
  4. Is there a 'sweet-spot' set-up on the Dyno-Jet kit documented for a Stage 1 bike with SE Air and V&H BSS pipes? If so, then maybe I can by-pass the dyno tune and make the changes to the carb myself.
  5. Do you think this dyno tune will be value added?

Looking for guidance...:thanks: :thanks:

Kevin
 

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1. Can`t remember :huh: (but something like 13.7)
2. Yes - it is PDF
3. You change the jets, needle, drill the slide , change spring in carb and adjust mixture screw
4. The ONLY way to tune carburator (or EFI) is dyno tuning. You can find start point but I`m affraid it will not be 100% correct.
5. I don`t understand this question ;)
 

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Premium Member
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3,289 Posts
KLars1 said:
Hi Guys,

I am trying to get up-to-speed with regard to tuning my carb for optimum performance. I bought a used 2002 FXDWG TC88 with stage one. As purchased, it was advertised to have the SE Air Filter Kit, Dyno-Jet Carb Kit, and V&H Long Shots.

I'm making a couple of change right off the bat. I am changing the pipes to Vance and Hines Big Shot Staggerds and I'm changing the air filter from the paper SE to the K&N HD-0800.

I want the bike to run 'right' - Not too rich and not too lean and be tuned properly for maximum power.

So, I was thinking of taking it to my local dealer to have it dyno-tuned after these small changes.

I read this marathon read and came away with the notion that the Dyno-Jet kit can be properly tuned and it is flexible with regard to tuning. However, it appears that some tuners tune these way too rich resulting in mpg in the low to mid thirties.

http://65.38.172.84/forums/showthread.php?t=43934&highlight=stage+tuning+jets

The questions:

  1. What is the proper A/F ratio I should look for on the dyno graph
    13.2-13.5 at high load, 13.7 -14 at light loads
  2. Does anyone have electronic documentation on this kit that I could read to get more famalier with how to tune the kit?
    Check Mikuni America website, all there even though it's for a butterfly carb
  3. What changes are made to the carb during the install of the kit?
    jets, needle and spring replacement, boring of the skide vacuum port
  4. Is there a 'sweet-spot' set-up on the Dyno-Jet kit documented for a Stage 1 bike with SE Air and V&H BSS pipes? If so, then maybe I can by-pass the dyno tune and make the changes to the carb myself.
    Nothing that I know of. Spend time on the Dyno with an expert dialing the carb in
  5. Do you think this dyno tune will be value added?
    What's value to you? If you want a bike that runs 'right', only way to do it, is to get it in the hand of an experienced Dyno tuner.

Looking for guidance...:thanks: :thanks:

Kevin
Hope that helps a little bit. In case you are looking for performance, there are better pipes out there. A good 2-1 like V&H PropPipe give you power and tunability. Any good 2-1 will do better than the one's you preselected
 

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If better performance is what you're after, throw the Dyna jet kit in the trash. Drilling the vacum port decreases performance, A good tuner can get better performance out of the stock carb using jetting and needle height adjustments.
 

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Premium Member
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3,289 Posts
HD Tech said:
If better performance is what you're after, throw the Dyna jet kit in the trash. Drilling the vacum port decreases performance, A good tuner can get better performance out of the stock carb using jetting and needle height adjustments.

Any supporting evidence for your claim that you are willing to share with us? I have a carb with a drilled port, a modified vacuum slide with a custom needle. Should run like crap, but doesn't do it.......
 

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Pestilence
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2,092 Posts
HD Tech said:
If better performance is what you're after, throw the Dyna jet kit in the trash. Drilling the vacum port decreases performance, A good tuner can get better performance out of the stock carb using jetting and needle height adjustments.
Which is exactly how the DJ needle is designed. And the jets that come with the kit. As far as the slide being drilled...different rate of vacuum mated to the spring tension DJ supplies.
You can get close with Sporty needle and shims, but you just can't get the same level of performance, and gas mileage. A competent dyno tuner can make that kit shine. So can tuning it yourself, just takes a little longer.

Best thing you can do to your carb for performance & gas mileage.
 

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Twin Fan
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80 Posts
I was in a similar situation when I bought my 2001 Night Train this past summer. It had a Dynojet kit installed. It also had Samson short drag pipes which I dumped in favor of a Pro Pipe HS.

There are no dyno tuners near me so I had to get advice from folks on this board and as well as from Vance & Hines on how to tune it.

Vance & Hines tech support was very helpful. Dynojet manufactures the jet kits they sell so they were able to provide me guidance on jet sizes and mixture settings based on my rig.

Worked out well for me.

Oddly enough I asked V&H if I had to get a dyno tune and they said no, the jets/settings will work and dyno tuning is for "numbers guys." Thought that was an interesting comment.
 

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While attempting to tune a bike probably close to 5 years ago I found it performed better at the bottom and mid range before the installation of the kit. After much frustration I replaced the slide with a stock one and the performance improved. After discussing this situation with other techs who also had access to dynos I found that they had discovered the same thing. The only thing that we ended up using out of the kits was the needle and jets. Because of the cost of the kit compared to a sporty needle and Harley jets, which yielded better results, we no longer use them. Watch the slide with a timing light while it's on the dyno, it flutters in the midrange if you drill the slide no matter what spring you use.
 
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