Carby thatsdax RT carb vs other SHA 15:15 clones What's the difference?

Local time
5:51 PM
Joined
Apr 19, 2013
Messages
50
Location
ma
Like the title says, what's the difference between the thatsdax.com rt carb (which is an SHA 15:15 clone) and all the other SHA clones out there?
 
If they are stamped with the name "Runtong" on the side there is no difference. Some places sell these with the jets AND cable included for the same price as other places do for them carb alone. Check the spinsor's prices on these & decide for yourself.

Matt
 
It's funny you're the one who responded Matt. I was JUST about to post saying I got mine from bicyclemotorworks.com and it's indeed stamped with Runtong and looks exactly the same in every way PLUS came with 5 extra jets and the cable (vs thatsdax which only includes 3 and no cable)

Can't wait to get it installed and try it out. Tired of trying to coax any life out of my crappy NT carb.
 
I should mention I also contacted thatsdax to ask them directly what the difference was, especially since I've seen a lot of people compliment their SHA clone whereas most people debate whether the SHA or CNS is better when it comes to generics. Their response was simply "I do not know the SHA..." literally. Not the people I wanna be buying a carb from if they don't even know what they're selling. Much rather go with someone who knows what's what.
 
The NT carburettor is not a crappy carburettor. It works perfectly fine, so long as the thing is assemble correctly, and jetted correctly.

To eliminate air leaks between the intake tube and the carburettor clamp, just place an appropriately sized o-ring inside the carburettor clamp area.
The carburettor clamp is one of the biggest potential sources for air leaks, which manifests itself in poor idle and poor throttle transition issues.
 
It's also not a great carburetor in general. But my statement wasn't about NT carbs in general. It was about my specific NT carb. Which was running so rich that it would basically only run with the filter off. I was going to buy some micro drill bits to re jet it but the cost of bits and a micrometer, etc wasn't far off of a new carburetor with a full set of jets. So I decided to just do that.

Idk if the sha jets are the same size as the nt jets. If so I may try them with it. I had a hard time deciding between the cns and sha carbs. There's pros and cons to both. But I got a good deal on the sha so I went with that.
 
At the end of the day, a float style carburettor such as the NT or the Dellorto or the CNS etc is not the most optimal solution.

The best option is a Walbro style diaphragm carburettor with externally adjustable high and low jetting screws, allowing infinitely variable jetting with the simple twist of a screwdriver.
The other benefit of a diaphragm carburettor is that they are far more resistant to fuel and air leaks that a traditional float style carburettor.

My advise is not to use drill bit to open up the main jet on the NT carburettor because a standard home specification drill press does not have the accuracy to properly drill a perfect sized hole.
You would be much better advised to purchase a range of Dellorto 5mm jets from No #70 through to N0 #84 in 2 jet size increments, like 70, 72, 74, 76 etc.

Because i wanted nothing less than perfect jetting (when previously using the NT carburettor), i have every jet size from No #68 through to No #94 in single jet size increments i.e. 70, 71, 72, 73, 74 etc.
 
That's absolutely true and that's exactly what I wanted to do. And perhaps after the winter I will. But the problem with that is the price. How much did you spend for that carb and all those jets?

I paid about $25 for this carb, the air filter, throttle cable and 5 extra jets. Nothing else comes remotely close to that. I'd be paying 4-5 times that for a diaphragm carb alone.

Not to mention at that price you're not getting 4-5 times the performance increase. You're only getting a small performance increase and a lot more tunability. Which you may not need if the cheaper carbs are close enough to begin with to optimal.
 
I have bought a few carburettors over the 6 years i've been playing with these engines, and have a few carburettors set up with 3 jet size increments that are around the average of what my engines normally use, eg, one carburettor with a No #73, No #76, No #79, No # 81

For the most part my engines (using Australian lower eastern states 98 octane fuel, which is equivalent to American 93 octane fuel) run optimally using a Dellorto No #76 main jet. I have had one engine run optimally using a No #70 main jet and another engine run optimally using a No #86 main jet, but for the most part, they seem to run best around a No #76.
It's a lot quicker (and less messy) to change the jetting (of a float style carburettor) by simply unbolting one carburettor and bolting on another with different jetting, then perfectly optimising the jetting once you know which way you need to go; using 1 unit jet size increments.

From past experience, i have paid around $3.50 (per jet, in Australian money, and i must have around 30 jets, so it works out to around $100AU for all of my jets.

My current engine uses a No #77.
The only reason why i am using the NT carburettor is because i've been too lazy to put the Walbro style diaphragm carburettor back on the engine, but i'll endeavour to put it back on in the next week or two.
 
I'm amazed you can get jets that cheap in Australia. Seems like everything is taxed to hell over there. What's $10 here ends up costing $100 over there for the same thing. Lol

Either way $100 just on jets is ridiculous. I guess if you have the money to dump into it it's personal choice but if price isn't a major concern why not just buy a real motorcycle or something.
 
Back
Top