Carby Re-jetting NT carb to prevent four stroking- what size jet to try first?
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Fabian
Well-Known Member
I've been through this process and if i were to do it again (starting from scratch) i'd be ordering a twin needle Walbro carburettor from one of the Vendors.
In Australia, Rock Solid Engines carries these carburettors on their website.
No more jets to fuss about and you have independent low speed and high speed mixture screws that can be adjusted on the fly - reliable, dependable and just brilliant for a motorized bicycle application.
In Australia, Rock Solid Engines carries these carburettors on their website.
No more jets to fuss about and you have independent low speed and high speed mixture screws that can be adjusted on the fly - reliable, dependable and just brilliant for a motorized bicycle application.
Fabian
Well-Known Member
The best way to go is Electronic Fuel Injection.
One of the Vendors on here is working on it but the time line for public release is unknown.
One thing is for sure: i want to be the first person to have a laptop programmable Ignition system and EFI system and i don't care how much it costs...
One of the Vendors on here is working on it but the time line for public release is unknown.
One thing is for sure: i want to be the first person to have a laptop programmable Ignition system and EFI system and i don't care how much it costs...
tooljunkie
Member
lol,Fabian i know what you mean.
as a diagnostic tech for computer controlled cars,i had to deal with efi faults almost daily.
i'm out of it now,and know i never have to go back.
i like efi,as long as its durable.
MegaSquirt has a laptop programmable efi computer.1 cylinder to 12 cylinder.
runs up to 10 or 12,000 rpm's.
been a while since i looked at the site,if it even still exists.
the biggest issue would be powering it.
as a diagnostic tech for computer controlled cars,i had to deal with efi faults almost daily.
i'm out of it now,and know i never have to go back.
i like efi,as long as its durable.
MegaSquirt has a laptop programmable efi computer.1 cylinder to 12 cylinder.
runs up to 10 or 12,000 rpm's.
been a while since i looked at the site,if it even still exists.
the biggest issue would be powering it.
Fabian
Well-Known Member
@ tooljunkie
My bike is already equipped with a 12 volt system, so powering the EFI is no problem (depending on the current draw) but i'm very interested to hear about you method of getting such an system to work, i.e. the listed weight, the physical size, the method of mounting and the complexity of installation?
Cheers
Fabian
My bike is already equipped with a 12 volt system, so powering the EFI is no problem (depending on the current draw) but i'm very interested to hear about you method of getting such an system to work, i.e. the listed weight, the physical size, the method of mounting and the complexity of installation?
Cheers
Fabian
tooljunkie
Member
i would think megasquirt would have something that would work for you,do a search for megasquirt and if you make some enquiries i think you would get an answer.
the show efi for motorcycles.
they used to have a build your own system,you buy the injector,and various other parts.
happy hunting!
the show efi for motorcycles.
they used to have a build your own system,you buy the injector,and various other parts.
happy hunting!
Anthony 4k
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Adam88
Guest
Just to chime in, whoever said the stock nt carb jet is a 64, is way off. I'm a professional tech and build engines for a living, the 64 jet in my kit is twice the size of the stock nt or speed carb jets, FYI.
With a reed valve, v stack and filter, expansion pipe, decked jug and high comp head I run the by carb with a 60 jet, still runs rich. I just ordered a kit for 30 through 60. Btw the nt carbs accept Holley style jets. Good luck with your build. Btw these engines come out of the box with vacuum leaks, tighten things up before you rejet. They tend to leak at the crankcase seal, manifold gaskets, the carb flange, the carb throttle bore where it accepts the cable, an oring under the cap helps allot, also an o ring between flange and carb helps. If you is3 the rce reed valve, it leaks air out of the box as well, just disassemble and coat gaskets with a fuel resistant sealer, and do not use the flange gasket it comes with it's trash. Good luck. Btw my top speed is just under 42 mph. Scary on a bicycle
With a reed valve, v stack and filter, expansion pipe, decked jug and high comp head I run the by carb with a 60 jet, still runs rich. I just ordered a kit for 30 through 60. Btw the nt carbs accept Holley style jets. Good luck with your build. Btw these engines come out of the box with vacuum leaks, tighten things up before you rejet. They tend to leak at the crankcase seal, manifold gaskets, the carb flange, the carb throttle bore where it accepts the cable, an oring under the cap helps allot, also an o ring between flange and carb helps. If you is3 the rce reed valve, it leaks air out of the box as well, just disassemble and coat gaskets with a fuel resistant sealer, and do not use the flange gasket it comes with it's trash. Good luck. Btw my top speed is just under 42 mph. Scary on a bicycle
M
Mike f
Guest
Where do i get the jet kit i need low 50s thx
Re-jetting the carb only applies to your WOT while the c clip position determines your throttle mixture up to WOT. So whether you’re lean or rich (4 stroking) at anything besides WOT that needs to be adjusted by the c clip. You can only really determine if your jetting is correct by doing a plug chop, or if you know enough you can hear/feel if you’re close to it. I’ve always had the best luck tuning my carb by getting my mixture correct at the c clip first and then moving on to re-jet and hone in on my high rpms.
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