T350 Pilot B Jet

[Vintageman]

The T350 carbs have the extra Piltot Jet B, that sets below the regular pilot jet.

I was wondering if any ran this bike without them.

Supposedly they are there to prevent bike from stalling if you let off throttle real quick.

These are obsolete and I only have one... need one more or just omit them all together?

Thanks

[yeadon_m]

Interesting, I've never seen such a device, but that says more about me than the T350 carb

According to online parts lists:

12 09492-30003
.JET, PILOT A
2 1; #30
13 09492-60003
.JET, PILOT B
2 0.7@

I don't know what the '0.7' indicates but on later GT carbs there is a pilot air intake jet of similar size (for example the GT750 BS40 carbs have, I think, a 1mm or 0.9mm jet which could be replaced with 0.9 or 0.8 air jets to reduce surging/bucking on a closed throttle. If yours is a fuel jet my hunch is it wouldn't like to run without them! if its an air jet it may or may not matter so much.

Will watch for guru advice, as mine isn't!

Mike

[Vintageman]

The pilot Jet B is unique in my experience at least. You put in the regular pilot jet as you would (sets down a ways into carb body pilot tube casting as most do). Then you add the other jet below that (by below I mean closer to the bowl. I think the carb body pilot casting tube is normal length with respect to other VM carbs that have no additional B jet.

I think the B jet keeps/holds fuel stored between it and the regular pilot jet set statically by fuel level in bowl. And, when you close round slide quickly all the gas liquid is not pulled down (must be a quick suction caused by closing slide?) and away from the regular pilot jet as quick as it would be since the hole in the B jet is much smaller than pilot casting tube if B was not there.

The size of B must be a flow rating. I can say the hole look very small so I was thinking it limits the fuel some when it is supplying the pilot circuit needs, but that would not make sense and think it was sized such that it did not restrict engine idle circuit flow needs significantly.

It has the same thread pitch as the pilot air screw (I though about fabricating one out of this)

I think it would fine without it , not sure if stalling was a real problem for this bike or any VM carb bike in general

But I await others who have experience. I had to sacrifice mine for it was stuck. Since it sets way down towards bottom of bowl I think it was more subjected to water

[Vintageman]

Maybe the Pilot B does restricts the otherway from what I said: When you close the throttle it prevents too much fuel spike sucked through pilot passage. Maybe dampens any disturbance for either side? I don't know what they were thinking when they designed it in. Also Don't know why this bike/carb is unique from others like it. Maybe just a fad

So if I omit maybe I'll be too rich on Pilot.

Well, awaiting any T305/T350 owner to see if any one has omitted it or all lucky and their was OK

No luck finding one so far

[Ivan]

I tested the affect that these have on my 305....
They are there to prevent loading up on downshifts and heavy braking (which they do a pretty good job.) I tried leaving them out when I was playing around with it and it was much happier with them installed.

The sizing is the same as Mikuni air jets.... an actual measured diameter.... Ex: 0.7 = 0.7mm

These were available from Sudco at one time .... Not available any longer...

Probably what is wrong, is that the needle jet is too large, and rather than design a new needle and needle jet, the easiest way to fix the problem was to restrict the pilot.

Ivan

[Vintageman]

Thanks Ivan

I thought they were similar to air jet with regard to flow criteria

I was going to skip them (no choice) and back off Pilot jet one size

The little Mikuni BS30/90 series air jet is too small to screw into Carb bodies pilot tube.

But here is what I may do ... based on fact I am not a machinist

The tread diameter needed is the same used on the external pilot air screw.
I am not sure what size/pitch that is ( need to clean up threads in my carb if any one knows)

If there is enough spare diameter I may be able to use the air screw and drill and tap a hole to fit the BS30/90 into it

Then cut the Pilot Air screw down to length to be about what the Factory Pilot jet B be is II have one... wish I had one more)

I mean this may be easy enough for me to do in a little vice with had drill and hand tap... the only concern is will the Pilot Air screw have enough diameter left to accept the BS30/90 air jet.

Again anyone know what the Pilot Air screw is for MM dia/pitch in the carb body

The BS30/90 info can be found in Suz Bulletin "GT750 Surging"

Thanks

[Ivan]

I probably have a used one that I can send you.... give me a call at work when you have time.

Ivan

[Vintageman]

Ivan,

Thanks!

I got a #70 drill to enlarge the 0.6mm Pliot B from the T305 to be at 0.7mm called out for in the T350

Do you recall what the thread dia/pitch is on that Pilot Jet B?. I need to clean up the thread in my carb.

If I could not have found one I think the other choice was to find a way to use a BS series air jet.

Thanks again and enjoyed the tips you gave me on my GT550 carb tuning.

I just got my cyclinders in from shop with fresh 0.5mm bored pistons and this old girl is heading back together

Thanks again everyone

[Ivan]

Mike,

The thread pitch is .75 (I triple checked this)

The jet measures 5.85mm OD, so I think it's accurate to say it's 6mm diameter.

This is a very hard tap size to find. (M6 x .75)
Try here:
http://drillsandcutters.com/DWTSMT6X.75 ... OgodO1AAKg" onclick="window.open(this.href);return false;

Sudco sells a kit that includes the tap that you need... you can try to call them and see if they will sell the tap separately. (310-637-8330)

The kit part # is 021-920, it's a throttle idle screw kit for the Banshee/Blaster.

The jet is on it's way, I mailed it this morning.

Good luck,

Ivan