Speed Carb petcock Mod

TexMex · Jan 29, 2015

So, my friend bought a kit last summer and it came with a speed carb, he had no problems with it until now the winter when the petcock cracked off on him in the off position, when i took it apart and i realized its just a little channel in the petcock valve letting fuel through i got to thinking, this just needs to be removed and sealed off, so this is what i came up with

essentially, its a piece of tube over the hole where the petcock valve would go and i have it clamped down with the same piece of metal that held the petcock in

heres a picture of the inside of the petcock if anyone was interested in what it looks like

bairdco · Jan 30, 2015

i've had problems with those before, too, mostly leaking fuel.

i've made tiny triangle covers from thin aluminum and got rid of all the inside plastic and rubber parts.

i figure my bikes didnt need two petcocks.

Dave31 · Jan 30, 2015

Mine the guts have been removed and it does nothing as well. Like Bairdco their is no need for two valves.

Its the first thing I do with the speed carb is eliminate the valve on the carb. Many times just opening the fuel flow up a little will allow your motor to run so much better.

Davezilla · Feb 1, 2015

I gutted mine as well, it wasn't leaking but it kept shedding rubber from that rubber disc in there and after about a mile or so the bike would start to cut out on me and I would find the main jet blocked by tiny chunks of rubber, gutted it out and problem solved.

YesImLDS · Feb 1, 2015

This is something I never really considered on my speed carb. I never had any problems with it, but I could see how it could possibly restrict flow and improve reliability if it were to start leaking. Seems like something I'll have to put on my to-do list!

bairdco · Feb 2, 2015

one of the first "performance" mods i ever did was to gut it out and drill the hole bigger.

if i remember correctly, the top part where the fuel line goes is larger than the hole after the petcock. .

seemed to help. i also used brass washers to index the banjo bolt. the banjo bolt has 2(?4?) holes for the fuel pickup and i wanted it lined up. if that makes any sense...

Davezilla · Feb 2, 2015

Yup... I understand about the banjo bolt too... I didn't mess with mine but I did drill out everything else then ran the screws on the selector valve down tight then encapsulated the whole thing in jb weld to prevent the valve from being able to move after cutting off the selector tab. The jb also acts as an extra line of defense from leaking in this area. Its sealed on the inside but the jb is just a secondary way of sealing the whole thing.

Shortly after I did all this I ordered a standard nt carb and keep the speed carb as a spare.

Dave31 · Feb 3, 2015

One thing to remember I'd like to mention is not to over do it with drilling out the banjo bolt.

Even though it lasted me two years I went a little further then I should have on one. The non-broken one is one that was not drilled out.

MotorBicycleRacing · Feb 3, 2015

The Speed carbs I get do not have a shut off valve so the problem is solved.

Search

Speed Carb petcock Mod

TexMex

New Member

bairdco

a guy who makes cool bikes

Dave31

Active Member

Davezilla

New Member

YesImLDS

Member

bairdco

a guy who makes cool bikes

Davezilla

New Member

Dave31

Active Member

Attachments

MotorBicycleRacing

Well-Known Member