PSI carb : V-Twin Forum: Harley Davidson Forums

hrdtail78 · 03-19-2008, 01:29 PM

Looking for new info or comparison dyno's. Heard all about them about 4 month ago and now nothing. Notice some shops that were selling them aren't now. Anything new?

sulconst2 · 03-19-2008, 08:51 PM

i have the new gen 4 model. manufactured by r&r cycles. I installed it in december but couldnt get the slight hiccup out from WOT because of the cold weather. finally got out in 50+ weather and it ran like a champ. i've had a few different carbs on this bike and with the gen 4 psi i'm impressed.

TXCHOP · 03-19-2008, 09:00 PM

Keep us posted sulconst..I have a CV51 for my new build, but may change it out next winter to do some experimenting....

immrwhite · 03-20-2008, 11:16 PM

After a long wait to get the first one (Gen 1) . A lot of problems with the single pull. Made the upgrade to Gen 2. I am now working with the Gen 4. Hard to keep tuned. The Gen 4 while a better carb leaves a lot to be desired. Wish I had of went with a modified CV51

Tedowski · 03-22-2008, 11:17 AM

I just put a 4th gen Big Air carb on a customers bike yesterday.
It's a beautiful looking design.
I'll see what it does once I get to fire it up.

Tedowski · 03-28-2008, 06:24 PM

So, I got to finally fire this pig up today and play with the carb.
I am very impressed with the throttle response from the Big Air carb.
It has no accelerator pump, but you would never know the difference.
It's smooth and has very nice response.
I haven't ridden the bike yet since it's not road ready, and only has 10 minutes on the engine so far.
The only things I didn't like were that it has the same Mikuni slide rattle and the throttle cables were a pain in the ass to set up.

sulconst2 · 03-30-2008, 07:35 PM

i finally got some riding time with the psi. from the factory it was set up rich. i was getting a stumble at WOT. leaned out the main needle a couple clicks at a time and i got a nice tan color on the plugs. very impressed with this carb. the bike is running strong and long.

didnt think the cable mod was hard. the new barrel is a decent piece and it looks engineered well how the barrel sits in the slide. looks like R&R got it right for PSI.

oh1deuce · 03-31-2008, 08:45 PM

Can you elaborate on the cable set up?

Thanks!

sulconst2 · 04-01-2008, 07:08 AM

i just run the single cable.

from memory,

loosen the cable adjuster all the way. pull slack towards carb end of cable, cut cable at 2 3/4" from sleeve. with top cover of carb removed install cable thru guide, install the barrel to cable end and lock down with set screw. install spring to cable and then place barrel in slot of carb slide (set screw facing inboard and spring tab end covering barrel.) adjust cable, set idle, adjust cable again.

here you can see the barrel slot in the slide. also the tab of the spring that would cover the barrel when installed.

Tedowski · 04-01-2008, 02:04 PM

I had to use the dual cable setup only because the stock harley controls do not have a built in throttle stop inside, therefore the grip will continue to roll forward and cause a lot of slack in the pull cable.
It wasn't a nightmare to install them, but it's definately easier if you have a second set of hands.
You need to have the cables hooked up and adjusted to the carb you are replacing first. Mark the grip position with some tape so you know where it needs to sit at idle position.
Next, remove the cables from the old carb and hold the throttle exactly where it was marked. Cut the end off the idle cable first and slide it through the second (back) hole of the big air carb.(with the top cover removed)
The instructions don't mention that you do not use the tiny cushion spring on the carb end of the idle cable.
I left the cable adjuster about midway. Take the throttle stop plunger and hold it against the top cover with the cable running through it.
Cut the idle cable flush at the bottom of the plunger. Install the supplied cable end and spring and plunger.
Next, roll the throttle grip to the mark made before and hold it there.
Measure from the bottom of the throttle cable sleeve down the cable itself.
Cut the cable at about 2 3/4 inches. Run the cable through the center hole of the top cover. Install supplied cable end and the longer, heavier slide spring that comes with the kit. Install the cable end into the slide with the set screw facing the back of the slide and position the tab on the spring to the front of the cable end to cover it. Install the slide and plunger into the carb at the same time and snug down the 2 top cover screws. Turn the throttle grip about 1/3 to relieve spring tension and continue to tighten top cover. Always use a good cable lube, I use Dri-Slide.

The problems that I had were the cables started to unwind as soon as I cut them and it was a pain to get the new ends on. Also, the aftermarket grip I used does not lock the cable ends into it like the stock ones do, so the cables kept popping out of the grip.

Hope that clears it up a bit.

.

Tedowski · 04-01-2008, 03:14 PM

Here's a short crappy video. You can kinda see the carb.
I had to throw an old used thunderheader on until the new one arrives.
And, Damn the clutch is noisy as hell.

http://www.youtube.com/watch?v=I2mv4UIO6D4

2002 Softail
S&S 95" cylinders and pistons
510G cams, lifters with HL2T
pushrods, roller rockers, rocker boxes
stock heads ported
SE cylinder studs
PSI Big Air carb, Forcewinder style air cleaner
Thunderheader
Dyna 2000 ignition
Performance Machine Phatail
PM wheels, rotors and calipers
PM Contour primary, BDL ball bearing lockup clutch
DNA foot controls
DNA front end, 3 degree trees, 4 over tubes
and more...

bpeer1 · 04-03-2008, 10:45 PM

I haven't heard of this carb before. What about it would make me buy one?
BP

oh1deuce · 04-04-2008, 05:06 PM

Quote:

Originally Posted by Tedowski

Here's a short crappy video. You can kinda see the carb.
I had to throw an old used thunderheader on until the new one arrives.
And, Damn the clutch is noisy as hell.

http://www.youtube.com/watch?v=I2mv4UIO6D4

2002 Softail
S&S 95" cylinders and pistons
510G cams, lifters with HL2T
pushrods, roller rockers, rocker boxes
stock heads ported
SE cylinder studs
PSI Big Air carb, Forcewinder style air cleaner
Thunderheader
Dyna 2000 ignition
Performance Machine Phatail
PM wheels, rotors and calipers
PM Contour primary, BDL ball bearing lockup clutch
DNA foot controls
DNA front end, 3 degree trees, 4 over tubes
and more...

Sounds brutal!

Any plans for a dyno tune?

sulconst2 · 04-04-2008, 10:54 PM

got a clip also. was running rich but leaned it out a bit since then.

117 ssw+
ported heads
640 cam
travel limiters
10.8-1 comp
psi carb

Tedowski · 04-04-2008, 11:40 PM

Quote:

Originally Posted by oh1deuce

Sounds brutal!

Any plans for a dyno tune?

It needs a Dyno tune. No doubt.
I had just put the carb on and tweaked the idle speed and mixture fast enough to run it. I'm hoping the owner of the bike will dyno the bike to see the true results. (and tune it)
I don't have a dyno in the shop, but I friggin' want one!
That video was pretty much the way the carb came set up.