TT250 Keima Carb Numbers

mtiberio · 06-17-2020, 09:59 AM

I wanted to know what the dimensions on the stock TT250 Keima carb were in case I want to replace it. After measuring it, I believe these bikes come with such small carbs as a pollution measure. Smaller carbs run higher vacuum and carburate more cleanly. The numbers I was able to glean:

carb to manifold stud holes: 48mm center to center (no surprise here)
carb exit to manifold ID: 29.5mm
manifold intake ID: 30mm
carb intake OD (snorkle i'face): 42mm
Venturi: 21mm by 28mm

It is the last number I find most distressing. An Aermacchi 250. An Italiam 250 pushrod single from the 60's had a 28mm round bore carb stock. I find it hard to believe that a stock 229cc CG motor could not have decent drivability and a better top end with nothing less than a 28mm smooth round bore carb. Right now the only carbs I see out there that look promising are the PWKs that all have the power jet attachment. Does anyone know if they are round bore or oval bore?

06-17-2020, 09:59 AM	#1
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	TT250 Keima Carb Numbers I wanted to know what the dimensions on the stock TT250 Keima carb were in case I want to replace it. After measuring it, I believe these bikes come with such small carbs as a pollution measure. Smaller carbs run higher vacuum and carburate more cleanly. The numbers I was able to glean: carb to manifold stud holes: 48mm center to center (no surprise here) carb exit to manifold ID: 29.5mm manifold intake ID: 30mm carb intake OD (snorkle i'face): 42mm Venturi: 21mm by 28mm It is the last number I find most distressing. An Aermacchi 250. An Italiam 250 pushrod single from the 60's had a 28mm round bore carb stock. I find it hard to believe that a stock 229cc CG motor could not have decent drivability and a better top end with nothing less than a 28mm smooth round bore carb. Right now the only carbs I see out there that look promising are the PWKs that all have the power jet attachment. Does anyone know if they are round bore or oval bore? __________________ 4 time WERA SuperVintage Roadracing National Champion, SCTA Land Speed Record Holder, 3rd AMA Motorcycle GP of Miami Last edited by mtiberio; 06-17-2020 at 10:30 AM.
	0