VTXOA - View Single Post - Coldbloodedness & Carb Fiddling
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post #1 of (permalink) Old 10-09-2019, 07:54 AM Thread Starter
rwantin's Avatar
Join Date: Jul 2019
Location: Royal Oak, MI
Posts: 45
Coldbloodedness & Carb Fiddling

Hi again. I think I have reached my VTX Noob Quota, so hopefully this is the last bother for a while. I love this damn bike so much (and am a bit of a perfectionist), so just trying to get it all dialed in.

I'm at the office, and just rode it this morning, so top of mind. I love riding this time of year in Michigan, and stubbornly keep at it until temps are consistently below 40. Because the VTX has a windshield, it will be a go-to and often.

I get that a big, liquid-cooled V twin is going to be coldblooded, but am wondering if it can be improved. And if my carb situation is making it better or worse.

I installed a Dynojet Stage 1 kit (stock airbox and pipes), something I have done with numerous other bikes and was always happy with the results. And that is the case here. When it's warm out, the bike runs and pulls great.

I pull the choke fully, give it a few seconds, go about halfway (maybe 1500 rpm) for another half minute, and then give it a few revs as I close it (and make sure it is off completely), and it settles into a nice idle. I gave it another five minutes or so after that. It was in the upper 40's this morning. Even after a generous warmup, I was still getting random sputters and coughs, even a few miles in. And what responded so perfectly in warm weather feels, well, laggy from the low-end in cold. This is counter to my normal experience. Most of my bikes run great on the cool, dense air.

Do you think the jetting is helping or hurting in this situation?

I'm playing with some ideas for the weekend.

-Adjust A/F another 1/4 - 1/2 turn out (from memory, it's two turns out), use the stock diaphragm spring (an inch or two longer than the kit), adjust the Dynojet needle (also from memory, 3rd position)

-Swap the entire kit out back to stock (easy enough to do, but reluctant as it runs so well otherwise).

-Shut up and just deal with it, it's cold outside.

One thing to add, this appears to be under load only - the throttle responded nicely to small inputs from one finger once I got here, but that is static in the parking garage (and well warmed up).

Again, many thanks in advance.

The correct amount of motorcycles to own is always N+1, N being the current number you own.
2005 Honda VTX1300S, 2009 Triumph Speed Triple,
2007 Triumph Bonneville T100, 1992 Ducati 900SS

Last edited by rwantin; 10-09-2019 at 07:56 AM.
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