what your 380 jetting? with chambers?

[zk0ot]

the bike runs great now. in its stock form.
i have some pipes on the way. and want to combo with some foam uni filters.

just want to know a good starting point... i know every bike is different.

[Craig380]

If you've got the standard airbox & filters, the 380 will run chambers without jetting up.

I have some period 70s UK-made Allspeeds fitted (stock motor, airbox & filters, I just removed the airbox intake snorkel which is restrictive) and have ridden hard in the past three years / 5,000 miles on stock jetting with just a 1/4 turn needed on the pilot screws to get a nice pick-up from idling. This includes a lot of fast open-road riding, holding a genuine 85+mph in 6th gear for miles at a time. Plug & piston crown readings show the bike is happy with this.

Admittedly, I don't hold it WFO for long, but with the stock brakes, that's not a good idea anyway

If you're planning to use foam pod filters, then I'm sure you WILL need to jet up, at least 10%.

[zk0ot]

Very good thanks.

[Vintageman]

I agree with Craig380.

I have an 1974 GT380 with 3 into 3 chambers

I also use stock ignition timing.

The bike may be a whisker lean everywhere , but it is one of the smoothest running engine at any throttle position and while independent of egine RPM (To me that is in tune!)

Have a couple thousand miles since pipes and done some long rides on both cool and hot days. I will aslo get after it now and again but never for a long time

I took the air box snorkel off too, then put back on. The intake noise hurt my ears when wearing a full face helmet..

Here is a notable change that worked for me on this bike in particular: Iridium plugs.

For example, I got another 1000 RPM top end. Not just over rev either. I do not like to go there, but it will quickly .

As far as pods/UNIs. I have tried this on other bikes over the years and as a street rider only, everything I have is stock intake mostly. Yes, you can up on mains and get a nice WOT, but everywhere throttle postion can beaffected. It can take a long time to tune and times I never got it quite right everywhere and not fully happy. I find it all depended how restrictive the air box was to start when staying with factory carbs. Also things like other size Needle Jets or Throttle Valve Slide Cuts if needed aren’t always readily available anymore .

If you do try pods and get it nice post your findings.

Somewhere on web it is stated to put the bigger GT550 carbs as a performance add on for the GT380 if that's what you want.

[Craig380]

+1 on the Iridium plugs (B8EIX), you can get these pretty cheap online these days. Sure, a single Iridium costs the same as 3 standard B8ES plugs, but they just never foul, never need gapping and do give clean, sharp running. Just fit and forget.

They do have resistors fitted so they need non-resistor plug caps (a couple of $ each online).

[zk0ot]

Talked to someone today. With uni pods and chambers.
And ended up with a set of 115 and 120 mains and a size up in pilots.
Stock was 80 mains and 25 pilots.

[ctluba]

I am running jemco chambers with pod filters on my 550. I ran the bike with stock jetting (95 mains) when I first put the chambers on and blew a hole through the center piston. Had the bike bored one over and went to 110 main jets, raised the needles all the way up and tweaked the air screws. Ran good, but a little rich. This summer went to 105 main jets and lowered the needles 2 clips, bike is running great.

PS I dont really know anything about tuning carbs, just what I experienced with this bike.

[zk0ot]

Love the info. Might make me think I'll be rich for sure.... no one seems to have any numbers for me to start at for a 380
..... I'll take what I can get thanks

[zk0ot]

ill be tearing the airbox off this evening. anyone with a 380 have any jetting advise?
chambers and unis

[Ivan]

I am about to release a carb tuning kit for the 380...

Very nice increase in performance across the whole range with better driveability than stock and even smoother.... more power everywhere.

The kit will include an assortment of mains, pilots, new custom multi angle needles, new needle jets and a setup and tuning sheet with recommended settings.

http://www.ivansperformanceproducts.com/GT380.htm" onclick="window.open(this.href);return false;


Ivan