Carb Idle

[Leftysdad]

New to the fourm and to the motorized bikes....
Got this bike for free....it has the runtong carb with the single idle/mix screw on the side....is their a base to start at on setting this screw.....it wont idle but cranks easy....takes throttle but sorta bogs....
Also, what's the best mixture 50-1....thanks
Looking forward to getting this bike right

 

[wolframore]

screw It all the way in and back out about 1/2 to 1 as a base. I like those carbs but the jet size is very sensitive. You need to rejet for them to idle correctly which depends on your engine and altitude. The stock jet is usually too big for our engines.

usually bog on throttle Is rich but best to check spark plug, use a clean one to see if you get a clean burn.

 

[Leftysdad]

Can you tell what engine it is by the pic
Is 50-1 a good mix by the gallon(1 gallon)

 

[Deleted member 27811]

There's a lot on the forum about this in carbs. Jag has some great info on the Real Dellorto, and the runtong clone version with ways to improve the idle function of these carbs. Just dial the idle screw in .... fire it up ...then , after it's warmed up dial it back till it stays running. You'll find the sweet spot. (carryon)

 

[GreasyChris]

Looks like a regular 66cc. 32:1 mix for break in then you can run 40:1 after that. You can probably get away with 50:1 if you're using synthetic quality oil. Getting it jetted right is your first priority. If you add another hole in your emulsion tube on that carb it will run and idle better as well. Use the search function and you should be able to find a post on how to do this. Welcome to the circus

 

[wolframore]

It’s one of the newer 66/80cc one piece cast jug. I’ve seen them but have stayed away since I like porting so much.

check jaguars website about adjusting the Dellorto SHA clone.

this is the engine you have. I have not tried this and have no idea what it looks like inside. The newer generation have improved casting and design so I would assume they’re fine. It’s a good way for them to control the squish band and leaky heads.