Warbird Tom

Ok Ive decided to go with the 91 surpass 4 stroke, but this is offered with or without a pump. What do you guys suggest? Thanks in advance for putting up with my questions.

mimoore67

My Feedback: (51)

Hey, there are no dumb questions!

I too was wondering what would best for me too. After doing some research and talking to other people, all I could determine, was that the new Surpass 91's weren't as affected by tank location in relationship to the carburetor. Also, these newer style don't have a choke, which really turned me off, even though it probably works just as well as the older orginal Surpass.

So, what I did, was some research and ended up buying a ASP/Magnum XL91 RFS four stroke. It's basically a copy of the orginal O.S. Surpass 91. Tower sent me a coupon for $20.00 dollars off, with a purchase of $150.00, plus you get free shipping. When I bought mine last month, it was listing at $149.99 (Cheap)

I have used and still have a O.S. Surpass in my Midget Mustang, it runs great. This was my main motivation to go with the ASP/Magnum, as it's a proven design.

So, may be you might want think about this option.

Also, was I correct in my understanding on the newer Surpass II 91's??????

gnirwin

My Feedback: (25)

I just recently bought a 91 surpass with pump used. It's a wonderful running engine. It's a little harder to start than my other 4 strokes due to the pump (The engine starts fine, there are a few things you have to do prior to starting and it has to be started with an electric starter). I am also really impressed with the over all quality of mine. Now the pump issue, I happened to buy mine as a package deal , the engine came with the plane I bought and the engine is indeed a pumped engine. From what I have read, it my be cheaper to buy a non pumped version and add one of the after market pumps to it. I understand that alot of the OS replacement parts that deal with the pump can't be purchased very cheaply and it might be cheaper in the long run to go after market. If you feel that there might be problems with the mounting of the fuel tank in relation to a good fuel flow to the engine then by all means go witha pumped engine.

Warbird Tom

Thanks for the good info guys, I'll have to mull it over and make a decision.

mimoore67

My Feedback: (51)

The number one reason and I forgot to mention this in my initial post was that you have to start the new pumped 91 with an electrict starter.

I don't like to haul all that stuff with me and I really like start all my four strokes by back spinning the spinner or if you like bouncing the pistion off of the compression made by the engine. Every four stroke I have every owned, no matter what the brand, as started very easily this way, and I might add very safely.

For me, haveing to have a starter and a battery, is just one more thing, I would probably forget to bring to field. We've all done it, drive all the way to the flying sight and forget your transmitter, wing, plane, etc........

2BFlying

Hey Tom
I have the OS 91 Surpass II pumped and I really like it. It started the first time I tried it new out of the box. I just followed the instructions, and I couldn't believe how easy it started. Actually, I didn't know it was running because my starter made more noise than the exhaust. It is my only 4 stroke and starts easier than anything else I have. I really like the pump system because fuel pressure is constant regardless of the plane's attitude.
RWCherry
Mt Sterling KY

hookedonrc

I have a 4*60 with an OS91 surpass - no pump. It runs very well and starts quite easy. I too, considered the differences and went without the pump mainly due to the cost. I guess it depends what type of plane you are using and where the tank is going to be. I haven't had any problems with mine so far and it's 2 years old now.

gnirwin

My Feedback: (25)

The engine is more difficult to start not because it "doesn't want to start" but because of needing to start with an electric starter. If you look at how the manual suggests you start the engine is to apply the starter for several seconds to get fuel started into the engine, add glow igniter, then re-apply electric starter and it will fire up.

garch 22

My Feedback: (7)

I have a .91 pumper on a vintage 60 size Ultrasport and find it a perfect match. I agree with GNIRWIN that if it is first primed w/o igniter per the mfr instructions, it will fire up easily with a starter, which is no problem for me.
The best aspect of this engine is it's reliability in all attitudes. I have tried to flame it out with just about every neg. G maneuver I can impose, and it has yet to quit. If I had a large amount of time and money invested in a warbird I would probably go for a pumper, which is cheap insurance when the total cost was considered.

Rocketman612

My Feedback: (85)

I have both and both run well. The pumped 91 is in a Kaos and the tank level is off from the carb. Runs strong with no issues.

Pete

Harry Lagman

That's the aspect of the OS .91 pump that is really important to me too. They are one of those engines that rarely if ever deadstick.

Mine's mounted inverted. The trick to handstarting these engines when they're inverted is to use a tee junction between the pump and the clunk for fueling. Set the throttle to full when you fuel up. The pressure of fueling forces a little fuel past the pump/reg and into the carb - just enough to prime the engine for a backflip. I just flick the spinner clockwise and up she lights!

There are another couple of advantages to the pump engine:

1) You are not compromising your state of tune. Rather than tuning for peak then richening back a few hundred rpm for reliability, with the pump you just tune for peak, then back off slightly until smoke output slightly increases. RPM drop is minimal, and she'll hold that tune for at least the rest of the day, if not for weeks or until the climate changes significantly.
2) because you don't need exhaust pressure on the pumper, you can fit the EX503 straight pipe to the engine. It makes a very quiet engine only slightly louder yet adds 200-300 rpm. That's a significant increase and it only gets better once the model is airborne and the engine unloads. With the free flowing header, it seems to run cooler too

The OS .91s I've seen without the pump have also been good runners.

RDonovan

I've had a Surpass II with pump for 5 years. It is currently in a H9 P-51. It has performed flawlessly. The pump allows inverted mounting even where the fuel tank is too high. I have never tried starting by hand. OS recommends using a starter. I spin the engine over for a few seconds to prime it before lighting up the glow plug. Always starts. Priming usually is not required after the first start each day. As far as I can remember, I have never dead-sticked with this engine for any reason other than running out of fuel.