Carb mods

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mik_str
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Joined: Thu Apr 01, 2004 10:45 pm
Location: Montreal, Canada

Carb mods

Post by mik_str »

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 :thumbup: 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). 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. All the external screws have been replaced with Ti too.

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, he of fuel screw fame, 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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99 VTR1000F Firestorm, a.k.a. The Carbon Express
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lloydie
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Re: Carb mods

Post by lloydie »

Very interesting project this :thumbup:


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AMCQ46
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Re: Carb mods

Post by AMCQ46 »

Looking forward to seeing the dyno run and if it gets the AFR nice and smooth, especially through 5000 rev region
AMcQ
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VTRDark
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Re: Carb mods

Post by VTRDark »

+1 on both above comments.
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)
Have you got any more info on this Mik. Isn't this where that single hole in the throat below the butterfly comes into play here :think: Allows just another fuel through the pilot circuit to keep things ticking over smoothly with the butterfly fully closed and then the two on the opposite side, I think, allow some air through.

Your carbs look like new and I like the little details like the dome head caps on you brackets. Keep up the good work :thumbup:

(:-})
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mik_str
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Location: Montreal, Canada

Re: Carb mods

Post by mik_str »

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.......
99 VTR1000F Firestorm, a.k.a. The Carbon Express
mik_str
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Joined: Thu Apr 01, 2004 10:45 pm
Location: Montreal, Canada

Re: Carb mods

Post by mik_str »

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...... :beer:
99 VTR1000F Firestorm, a.k.a. The Carbon Express
tony.mon
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Re: Carb mods

Post by tony.mon »

Always good to get an update from you, Mik, you make me feel lazy :lol:
It's not falling off, it's an upgrade opportunity.
mik_str
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Re: Carb mods

Post by mik_str »

lol, know that the feeling is mutual Tony :)

It feels good to know that the bike runs ok. I will have to tear into the modded carbs again to see what the problem is; I suspect the slide for the rear cylinder is sticking, but it may also be way too lean. I just re-read up info on the effects of the HDJ and not having compensated sufficiently (ie. richened) may also part of my problem...... I continue to be optimistic that there is something to be found with the modded carbs, the physics say it should work.... Oh well, will enjoy it the way it is for now (with original mixers) and hopefully get those rims on soon....... :crazy: (P.S. they are incredibly light!!!!! should give the bike a lot more snap and responsiveness)
99 VTR1000F Firestorm, a.k.a. The Carbon Express
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sirch345
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Re: Carb mods

Post by sirch345 »

lloydie wrote:Very interesting project this :thumbup:
+ 1
Keep up the good work Micky :thumbup:
Your carbs are looking great :clap:

Interesting to hear about the knife edge work on the butterfly's, and the dremel work on the manifold connecting rubbers,

Chris.
mik_str
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Re: Carb mods

Post by mik_str »

thanks Chris. I haven't given up on the modded carbs yet, but for now I will get some saddle time with what works, my "old" carbs...... Besides, my OCMD will not allow me to simply walk away, lol
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sirch345
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Re: Carb mods

Post by sirch345 »

mik_str wrote:thanks Chris. I haven't given up on the modded carbs yet, but for now I will get some saddle time with what works, my "old" carbs...... Besides, my OCMD will not allow me to simply walk away, lol
I had forgotten about that handicap you have :lol:

I have been looking at your photo's again, they are really good shot's, nice and sharp so you can see all the details :thumbup:

Chris.
mik_str
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Re: Carb mods

Post by mik_str »

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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VTRDark
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Re: Carb mods

Post by VTRDark »

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.......
They are highly recommended for their after sales support. Good on them. :clap: :clap:

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sirch345
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Re: Carb mods

Post by sirch345 »

mik_str wrote: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....
Not something you want I know, but much better to find this out now rather than later when all fitted to the bike, well spotted,

Chris.
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