Musings on Yamaha Design

[boscoe99]

Speaking from the top of my head;

Virtually every Yamaha two stroke uses one carburetor per cylinder.

Virtually every carburetted Yamaha four stroke uses one carburetor per cylinder.

Of the early Yamaha EFI models, the smaller models used only one mechanical throttle body whereas the F115 ~ F225 models used one mechanical throttle body per cylinder.

My guess as to the use of multiple carburetors or throttle bodies was to produce more power.

All of the later Yamaha EFI models using electronic throttle bodies use just one TB.

In keeping with Yamaha's propensity to use multiple carburetors and multiple mechanical throttle bodies, I am wondering why no Yam models use multiple electronic throttle bodies. i. e. one per cylinder. If there was a benefit to use six mechanical throttle bodies on the F225TXR, why not use six electronic throttle bodies?

Is anyone aware of any motor that uses multiple electronic throttle bodies?

[zenoahphobic]

Multi carbys gave better draw of liquid fuel and better control of the mixture, throttle bodies only need to regulate the air.

So the only need to have multi TBs is if there is a need to get more air in which doesn't seem to be much of a problem, only if the space is limiting.

All engines use tuned inlet manifolds that can be made to curve to wherever and one TB is convenient to plumb with one hose to one filter, saving on linkages in the deal.

Yes there are motorcycles that use one TB per cylinder, that I think is done to fit into the very tight and limited space available, not for performance gain (that only comes from an increase in the sum of the cross sectional area. Air flow resistance doesn't come into the equation at all, because TBs are simply chokes.)

Yes maybe individual TBs may disperse the injector spray behind it a bit better but that is a marginal gain if at all.

[99yam40]

Speaking from the top of my head;

Virtually every Yamaha two stroke uses one carburetor per cylinder.

Virtually every carburetted Yamaha four stroke uses one carburetor per cylinder.

Of the early Yamaha EFI models, the smaller models used only one mechanical throttle body whereas the F115 ~ F225 models used one mechanical throttle body per cylinder.

My guess as to the use of multiple carburetors or throttle bodies was to produce more power.

All of the later Yamaha EFI models using electronic throttle bodies use just one TB.

In keeping with Yamaha's propensity to use multiple carburetors and multiple mechanical throttle bodies, I am wondering why no Yam models use multiple electronic throttle bodies. i. e. one per cylinder. If there was a benefit to use six mechanical throttle bodies on the F225TXR, why not use six electronic throttle bodies?

Is anyone aware of any motor that uses multiple electronic throttle bodies?

I have the remains of an old Yamaha 30HP that has 2 cylinders and one carb.
I would think the crankcase pulses could interfear with a single carb with multiple cylinders motor, but the engineers got it all worked out in just 2 cylinder ones plus the reeds help

[pstephens46]

I still say much of this is due to their organizational structure. Different teams, at different times, doing different things. Sometimes redesigning the wheel in the process.