Question for Brad and Doug on Four Strokes

Have been wondering if given the current thoughts of running a four stroke fast with a low pitch prop, do you think the YS engines might work for C/L now? I understand that poor luck was had in previous attempts, what about one more try? I have a couple of them in R/C applications and once you get them dialed in, they are super. I wonder if we are missing out?

thx,
Mel D>

LAST EDITED ON Apr-11-04 AT 06:07 PM (CDT)
 
Mel,

I would love a second try. However I dont have mine anymore.

The problem I found with the motor was slowing it down. At full throttle and a good setting on a 13X4 two blade APC it was sub 4 second laps. Slowing down 4s motors with needle doesnt work as well. It gives you a rich run that is inconsistant all throughout the flight. I setup a rig so I could adjust the carb easily and the needle. It doesnt work to well. You get it running then close down the carb some then lean it back up with the needle. Carbs dont work well and dont give you real true reading when setup like that. It is always either rich or lean once it gets in the air. The YS 63 I had wouldnt work without the carb so removal was not an option. I imagine getting one to work with a steady venturi it would be a great motor for stunt. All you have to do is figure out the starting point.

On the bench my 63 would spin the same prop I use on my PA 65!

12500 rpms with flatout. The PA spins it at 13300 flatout. The motor would have run that prop easily in the right range. Trouble with the carb is there is not real way to gauge the size of the opening like you can with venturis, or I just havent seen it yet.

If you have any ideas on how to figure it out let us know. Maybe I have tried them or maybe not.

>Have been wondering if given the current thoughts of running
>a four stroke fast with a low pitch prop, do you think the
>YS engines might work for C/L now? I understand that poor
>luck was had in previous attempts, what about one more try?
>I have a couple of them in R/C applications and once you get
>them dialed in, they are super. I wonder if we are missing
>out?
>
>thx,
>Mel D>

Basically, the new OS Max 70 is a close cousin to the YS. Because of the intake tube arrangement, we will be able to replace the carb with a venturi. There is a lot of extra stuff thown in to the carb design that is simply not necessary for our use. The fuel system must run at high pressure (via a check valve on the tank input from the crank) simply due to the fact that the fuel regulator in the carb needs it to function correctly. That high pressure stuff has got to go to make the venturi work, as there is no fuel shutoff at the carb anymore (as in the stock arrangement).

Also, the OS pump has no adjustment like a Perry pump (which sucks) and the delivery volume is somewhat critical. I have found ways to externally adjust the flow, so I do not anticipate not being able to make it work.

The OS will scream just like a YS 63 (much more RPM capable than a Saito). It also runs very dry (much better than the Saito) read that (no crankcase leakage). It is also very smooth, more smooth than a Saito.

As to whether it will work at all, we will see. I bet I can make it work. When it works we will have the manifolds for sale.