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Carb mods

Old 04-03-2015, 05:39 PM
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Carb mods

I did a revamp on my spare set of carbs over the winter. As some of you may recall, I had a set of Factory Pro High Dispersal Jet (HDJ) needle jets installed in my carbs last fall. I also got my hands on a carbon copy of the stock steel support plates and installed those (together with aluminum through bolts to further cut weight). I also removed all hardware used for the heated carb lines (never used that feature, so off it comes). I did some reading about folks "streamlining: and knife-edging butterflies and, after raising the issue with Roger D, decided to proceed (see pics). I knife-edged the leading edge of the butterflies (so as not to upset the idling) and ground down the excess thread from the small screws (installed them with red Loctite to make sure they don't move and fall into the engine). All the external screws have been replaced with Ti too. Finally, I put the dremmel to the rubber manifold that connects the carbs to the port and matched it up perfectly to the carb body.

You will also notice that there are fittings to hook up 2 Flo-Commanders. The pilot air circuit is standard stuff, but the main air jet circuit was modified by Factory Pro while installing the HDJ, they removed the stock brass fitting and tapped the hole to accept difference main air jet sizes. I had some custom fittings made (thanks to my buddy Jack Flash who hooked me up with a machinist) which allow me to change the MAJ jet but still use my F-C (MAJs on now are 100s, so 1.0mm). This will allow me to keep using both Flo-Commanders, giving me a great deal more flexibility when it comes to tuning.

The goal, as always was to drop weight and optimize everything (in case air flow and hence power).

Anyhow, I will be mounting these up in the next two weeks and will then fire up the bike......

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Last edited by mikstr; 04-03-2015 at 06:32 PM.
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Old 04-03-2015, 06:05 PM
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I'm stoked! Good luck. How soon to the dyno results?
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Old 04-03-2015, 06:30 PM
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My goal is to get it pretty close to sorted, then bring the bike in for a valve adjustment and dyno calibration. Should be within the next couple months (still not riding season here). I am pursuing my `H-wing` experiment too (seemed to work really well last year, hopefully will work even better now).

Last edited by mikstr; 04-03-2015 at 07:03 PM.
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Old 04-03-2015, 08:26 PM
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Awesome, just awesome Micky! I can't wait to see the results.

I knife edged my butterflies as well. Couldn't think of another way to mount the butterflies without those large phillips head fasteners. I was thinking of a rivit, but just didn't trust a rivit in that particular spot. I've had rivits come loose with past projects.

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Old 04-03-2015, 08:41 PM
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I used to own and tune some pretty well modified quads. One of the little things i did was round the leading edge of the butterfly, and knife edge the trailing edge, so it was like an airplane wing, for optimum aerodynamics.

I also used to remove one side of the shaft, and i countersunk the holes and mounted loctited countersunk hex head screws. This mod cut the mass by 1/3.

Just to give you a few more ideas

James
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Old 04-04-2015, 06:34 AM
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Originally Posted by thedeatons View Post
I also used to remove one side of the shaft, and i countersunk the holes and mounted loctited countersunk hex head screws. This mod cut the mass by 1/3.

Just to give you a few more ideas

James
I looked at doing this too but preferred to start modestly; I may get around to those later....
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Old 04-14-2015, 05:32 PM
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well, put the carbs in and fired up the bike. It idled well but ran like total crap at all throttle openings and speeds above (I suspect one the slides is sticking and not lifting; will have a look....). At least, it allowed me to get the bike fired up anyhow after its winter nap. As I don't particularly feel like dragging out another long carb experiment at this point, I think I will re-install the original set (which had the bike running superbly last year FWIW) and leave the experimenting to later in the year. Besides, I am getting tires installed on the Dymag rims and, God-willing, will have them mounted on the bike this weekend. Sticking to just the rims (not carbs for now) will allow me to better isolate and experience the benefits brought on them (and CMC rotors). So, the carb experiment is to be continued.......
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Old 04-14-2015, 07:50 PM
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Damn. I was hoping for some freakin' amazing results with those carbs. Just curious, but how do you tune those? Jets? Air jets? Are they possibly way out of tune?

You are not the least bit curious after waiting for so long? Un stick the possibly stuck slide and let 'er rip!
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Old 04-14-2015, 08:19 PM
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I essentially ran the same jetting as my "stock" carbs (ie. My fuel screws were almost fully in and my MJ Flo-Commander was close to full lean, so I dropped one size on pilots and mains). I played with the fuel screws and pilot jet Flo-Commander and the problem remained (again, have a funny feeling it's the slide; I may swap in the slides from my other carb just for a quick test.....)

As for curiosity, I am for sure... but I also want to ride some and not just wrench, chasing a perfect carb set-up, not at this point in the season.
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Old 04-15-2015, 06:52 AM
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Do you have a list of the hardware you used on the carbs? Always nice to know what to replace everything with
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Old 04-17-2015, 12:48 PM
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well, my trusted and proven originals are back on (though I took advantage of having the carbs out to lean the pilot and mains one size (was running with fuel screws almost closed last year, and F-C screw almost full lean)). Started the old girl up and ran superbly.

ON another note, I now have tires mounted on the Dymags.... may get them on the bike this weekend......
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Old 05-02-2015, 05:39 PM
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With my bike being out of service for a while, I decided to give my "modded" carbs a look to see what was up with the apparent hanging/stuck slides. Upon close inspection, I noticed the (HDJ) needle jet was lifting slightly (hard to judge with any accuracy but it seemed to be in the range of 0.5 to 1mm) when I would manually raise the slide. Definitely not supposed to do that.... I wrote Marc at Factory Pro and he offered to fix it for me; asked me to ship carbs back to him (he will pay shipping to and from). Seems like good after-sales support so far.......

I still have high hopes for this set-up as in theory, there is no reason it shouldn't prove superior for the obvious reason of better atomization. Will keep you posted.
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Old 05-02-2015, 06:33 PM
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that is awesome sales support, cant wait to see these carbs dialed in with the new rotating assembly.

You are the only person I know (well sometimes converse with), that has taken every oportunity on a new part or idea made for this bike to see if its worth the gains... you are an innovator, maybe not a manufacturer but you are always willing to drop the cash or put your bike under the knife to better your ride and I respect that immensely
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Old 05-02-2015, 06:51 PM
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thanks, very flattering words........ (Mind you, not sure if the process is the end result of curiosity or insanity, lol) My VTR is a rolling laboratory of ideas..... they don't always work as hoped, but I learn from every one..... Of course, I am not alone with this pre-disposition, and the beauty of this forum (and, if I may, the vtr1000.org forum too) is that it's a meeting place for "us"....

Last edited by mikstr; 05-02-2015 at 06:57 PM.
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Old 05-02-2015, 07:37 PM
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isn't a mix of curiosity and insanity the mark of a genius? lol

and of course they dont always work as hoped and thats what makes you an innovator, your willing to put up your cash and your bike to find out...

cheers brotha
we all appreciate you
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