321 specs

[Tom Cronk]

Looking for a set of specs for the Yamato new 321 motor.
Is this motor been aproved for APBA PRO OSY400 in 2016???
Tom
tcronk@tampabay.rr.com

[DiGia54D]

Yamato 321 Yamato 302 Horse power 33h.p. @ 6,800 rpm 33h.p. @ 6,600 rpm Maximum Torque 26.8 ft lbs at 6,000 rpm 26.8 ft lbs @ 5,500 rpm Bore X Stroke 66 mm×58 mm 66 mm×58 mm Piston Displacement 396. 9cc / 24.2 cubic inch 396. 9cc / 24.2 cubic inch Piston Clearance 0.004 " ~ 0.005" 0.003" Port Timing Intake 55 degree B.D.C Intake 55 degree B.D.C Port Timing Exhaust 85 degree Exhaust 85 degree Piston Clearance Volume 26 cc 26 cc Induction System Reed Valve 1 set Port size 29×13 mm 1 set Port size 29×13 mm Carburetor One Ventury 28mm 28mm Flywheel weight 2.86 lbs.(Min) 2.86 lbs. Gear ratio 14:15 14:15 Fuel Regular petrol Min. 86 Octane Regular petrol Min. 86 Octane Fuel tank capacity 2.3 Liter / 0.6 Gallon 2.3 Liter / 0.6 Gallon Fuel mixing ratio 30:1 30:1 Weight 92 lbs 92 lbs Transom height 11.2 inches 13.5 inches Ignition timing 0.200" to 0.250" B.T.D.C. 0.200" to 0.250" B.T.D.C. Compression Ratio 8.6 8.6

[joejohn44]

I am pretty sure the transom height on the 321 is a misprint. I think it is the same as 302

[Hutch06]

The chart that Wayne posted is accurate. There is a slight difference between the 302 and 321 transom heights from experience in setting up. From setup of a 302 to a 321, there is definitely a height change. Should not be anything crazy that shims can't fix however.

[joejohn44]

The chart shows 2.3 inches in transom height difference...that is more than just a couple of shims!!!!!

[ZUL8TR]

Tom

There are comparison photos as well as the 321 manual here:

http://www.yamatoracing.co.uk/model-321/4587843953

Pete

[champhotrod]

How can a ratio be one number??