Triumphrat

SLOBonnie · 06-01-2007

Hey y'all. I could use some help trying to figure out why I'm having the following trouble cold starting my ('06 790) Bonnie. When I start her, I do all the standard stuff: sit on the bike, put up the kickstand, turn the petcock to the "ON" position, pull the choke out, turn on the key and let her rip (note: the same problems occur even if the bike is resting on the kickstand and I ain't on it). In most cases, the bike starts straightaway; in some cases, I have to give it a slight turn of the throttle. The engine immediately runs up to 2k rpm. However, within 5-10 seconds, the rpms drop down to 500, struggles to keep running and then dies. When I go to start it up again, I have to give it a turn of the throttle.

Similar troubles persist for about 10-15 minutes once I leave where I was parked. Yeah, I know these are "cold beasts" and take about 20 minutes to be fully warmed up. However, when I stop at a light, the engine sometimes remains at 2k if the choke is fully out and other times the engine speed immediately drops down to 500rpm, struggles to keep running and dies. No matter what, if I push the choke in (even a mere 2-3mm), the engine does the drop/die thing again. The only way to keep it running is to keep the throttle open for approxiamately 10 minutes (as noted, that's even true in some cases with the choke fully out).

So that's the trouble I'm having. Here's some more information to help diagnose this issue. First, when finally warm, my bike idles at 1100. Second, the ambient tempature outside is on average 55-62 degrees when I go to start her in the morning. However, these problems even occur later in the daywhen the ambient temp is 80 or above. Finally, the ABox is stock, jets are 110 mains/42 pilots, pilot screw is at 3 1/2 turns, and I've got D&Ds. (Yeah, I'm ready to ditch the Abox, but I've got to wait a bit before I can do even the PMARK [the "Poor Man's" ARK]. Even so, I'm not sure that the ABox is the problem per se so long as my jets are properly set.)

Any help would be greatly appreciated. Cheers.

sweatmachine · 06-01-2007

you sure you have 42 pilots 3 1/2 turns, and not 40 pilots (stock) at 3 1/2 turns?

If you really have a stock airbox, 42 pilots, 3 1/2 turns, then you are probably really rich on your idle circuit.

Try turning in to about 1 turn out and see if that helps, or sticking the stock pilots back in there, or just ditching the airbox.

Just a thought...

Geoff · 06-01-2007

That was my take as well..
G

SLOBonnie · 06-01-2007

Sweat...yeah, CynCrzr and I changed out the pilots. We did so because I was getting so much lean pop with the D&Ds. I've been trying different adjustments to the pilot screw (everything from 2 to 3 1/2 turns), but I haven't tried less than 2. I'll give it a try. Thanks.

sweatmachine · 06-01-2007

FWIW, with my 904'd, big valved, no air box'd, Bub'd bonnie, I'm running 42 pilots @ 1 turn, runs great!

(also, if you're interested, thruxton needles w/ 1 shim, and 155 mains, but I may be removing the shim this weekend...)

badrufus · 06-02-2007

SLOBonnie--I'm absolutely convinced that the cold starting problem is due to the Pirellis you just put on. You should take them off immediately and send them to me for safekeeping.

meatwagon · 06-02-2007

Bite the bullet ,pony up the 50/60 $ and put that thing on a dyno to see where the A/F ratio(s) is at each setting .I would pull the snorkle to go with those D+Ds and up the mains to around 120 or so.That of course has nada to do with the idle circuit but hey ,they are all part of the same carb and interact somewhat.
Try some carb cleaner in a tank of gas ,sounds like the choke is getting stuck.
It's that high priced S L O gas ! :-D

SLOBonnie · 06-02-2007

Quote:

SLOBonnie--I'm absolutely convinced that the cold starting problem is due to the Pirellis you just put on. You should take them off immediately and send them to me for safekeeping.

That is extremely altruistic of you, Badrufus. Thank you. I'll make sure to get on that right away! :razz:

SLOBonnie · 06-02-2007

Quote:

Bite the bullet ,pony up the 50/60 $ and put that thing on a dyno to see where the A/F ratio(s) is at each setting .I would pull the snorkle to go with those D+Ds and up the mains to around 120 or so.That of course has nada to do with the idle circuit but hey ,they are all part of the same carb and interact somewhat.
Try some carb cleaner in a tank of gas ,sounds like the choke is getting stuck.
It's that high priced S L O gas ! :-D

I may end up doing that & I think I'm gonna chop the ABox. Carb cleaner in a tank o' gas, eh? Hmm...never heard of doing that.