Polini 303DS

[Mountain Cat]

Thinking about selling my Polini 303DS, everything ordered from Chris. It might be too light for my purpose. Includes everything, the whole ball of wax. 304-847-5723

[LA F2 Flyer]

Has it been run in?

[Mountain Cat]

No never been started. But all polini's have been test run at the factory. The only way I can use it is talk Chris into building an engine mount that moves is forward another 8"-10". The problem is not the engine but, it's light enough to not let the CG move forward into the range. Only way to move the CG towards the nose is to move the engine forward. Without adding excess weight.

[Mountain Cat]

As it turns out, I was working with limited information that was 30 yrs old. I won't make ultralight weight, but that's OK. I have a PP license. The 303DS will take some minor adjustments but will work out I think as of now.

[LA F2 Flyer]

Good to hear. It simplifies things a bit for you!

[Mountain Cat]

I tried to make Pt 103 but just can't pull it off. Considering I need a bigger tail wheel, also have individual flaps plus ailerons, along with bigger tires, its just more than Pt 103 will allow. So E/AB it will be. Still fly it as a LSA pilot though.

[LA F2 Flyer]

How far past 103 are you, out of curiosity?

[Mountain Cat]

About 20 lbs. But registering it has some advantages. Can use bigger tires if wanted, more fuel cap if wanted. Downside is will require a BFR every two years. Around here, the FAA doesn't bother with experimental aircraft unless you do something stupid. And a BFR keeps you from developing bad habits.

[Mountain Cat]

Polini 303DS is just too light for my airframe. Putting it on Barnstormers. CG will not come in limits without serious rework.

[Mountain Cat]

Well, got tired of waiting on a new engine mount from Chris. Decided to reinstall the engine/mount and do whatever is necessary to bring CG into range if possible. When he does get it made, then this winter I'll change it out. This way I can get the engine dialed in and running good. Evidently he is covered up in work and has little spare time. Maybe supply shortages, backorders, etc. This day and time, who knows what will happen next.

[Mountain Cat]

Installed the new 303DS, run it for 20 min to verify everything was working (it was) and then removed it and put it back in the factory crate. If anybody needs one, $3000 for the complete package including prop, mount and gauges.

[LA F2 Flyer]

I might be interested in that engine. Did you happen to run it up to max static RPM and check the thrust? (As you know mine doesn't see to rev up to where it should be...)

Would love to see some pics.

And do you have any idea if it fits the same engine mount as the Thor 200?

Also, what does it weight all in (minus prop)?

[Mountain Cat]

I briefly ran it up to about 5500 and still had more throttle left to go. Checked both ignitions to verify they were working. Total time was about 20 minutes. The prop weight is less than 1 lb. Total engine weight(flying weight) was 65 lbs. According to Polini, the 200, 250 and 303 use the same mount. But I have all the mounts to bolt it to a Badland. I got the package from Chris ($7500) plus ordered the bleeder valves, and 90 deg thermostat housing. I also have the extra senders for EGT, CHT, and water temp. And the Polini gauge that Chris sent. But depending on where you are, shipping is expensive in todays world. You would be looking at 3 boxes.

[LA F2 Flyer]

I will say it's very tempting! My only concern is that it might put me over weight...my current engine (by itself, no prop, mount etc) weighs in at about 39 pounds. (When you say "flying weight", what exactly does that mean? Is that including the mount, bolts etc?)

The other concern is that you didn't rev it over 5500...probably pure paranoia on my part, but that's why I want to swap mine out - it won't rev over 5500RPM. But you did say it felt like it had more to give...

[Mountain Cat]

Flying weight is mounted on the airframe ready to fly w/ all fluids. If it don't sell, this fall I'll mount it on my trailer as a test stand and have it running. Easier to sell if someone can run it and check everything out before they buy it. I didn't go over 5500 rpm due to it wanting to pull the plane forward along with my ATV. But mounting it on a test stand means pick up only.

[LA F2 Flyer]

Oh, that makes sense about not going over 5500. I may need to re-weigh my plane and see how much leeway I have. I wouldn't mind the extra horses nor the watercooling.

[Mountain Cat]

The fuselage ready to fly, wings, tail, instruments, and all your goodies needs to be under 180 lbs. That would leave you 70+ lbs to play with.

[mrpilotron]

Where are you located? I'll be shopping for an engine in the near future.

[Mountain Cat]

Peer has already (stolen LOL) errr, I mean bought it. You might ask him if he is in the market to part with it.

[Badland-F5 Pilot]

Peer has already (stolen LOL) errr, I mean bought it. You might ask him if he is in the market to part with it.

With an appropriate mark-up I'm sure he'll sell – oh wait, I've already seen pictures of it mounted and the fun he's having with all you included, plus orders from Aircraft Spruce & Specialty Company and Amazon arrived today. Ah, maybe he won't sell it after all. It was an excellent deal.

[Mountain Cat]

I hope it's just what he wanted. I could not use it for my bird so why keep it. It is a powerful engine. I didn't change anything in the carb so it's just like it came from the factory. I am sure he will have to adjust, re-jet for his conditions. I thought it might be running a little on the rich side but didn't run it but only 20 minutes or so. It would be hard to tell in that time period. I am at about 2500' MSL here at home and 2 strokes are finicky anyway. It's supposed to have an alt adjusting carb but that is what Polini states.

[LA F2 Flyer]

Now that the "theft" has been completed, I have indeed started the installation! Hoses arrived from Amazon, a nice selection of nuts and bolts (and Adel clamps) arrived from Aircraft Spruce, and the fun has begun!

The radiator location has been determined and the hose install has started. I've also bent an aluminum bracket for the battery, which will end up between the rudder pedals. The throttle cable has been installed and confirmed to return to idle. That's as far as I've gotten. The biggest struggle will likely be finding a location for the starter/ignition box. It's a pretty big bugger.

I'll still need to buy more aluminum flat stock to make the radiator mounts, and a remote (cable) choke for the carb. Once the cowl is back in place (assuming I can make it fit) I won't have easy access to the choke lever.

Allen answered a question I was going to ask - what is your current field elevation? I'll definitely need to rejet as I am about 2000 feet below you.

Hopefully I'll find some time to work on it again soon! I will say, it's been nice to have a new and intensive airplane project!

Needless to say, I won't be selling this engine just yet.

One question for the group - how critical is it to get the expansion tank WELL above the cylinder head? I don't have that much room to work with, so my fill line on the tank may only be an inch or two above the top surface of the cylinder.

[Mountain Cat]

Looking at the picture, 11;00 O'CLOCK IS WHERE i had installed it. Looks like you might have room. Of course that will require an access hole in the cowl.

[LA F2 Flyer]

Thanks Allen. Did you just have the cap protruding? I don't want to go too high over the firewall.

I am actually going to need a few extra holes in the cowl if I intend to use the one I currently have.

[Badland-F5 Pilot]

Now that the "theft" has been completed, I have indeed started the installation!

I love it!

[Mountain Cat]

No, the cap was about 3/4- 1" below the cowl. I used a fabric inspection hole cover, those 4" alum disc, to cover the hole. easily removed and put back and can be painted to match. Very very good, last long long time, as my friend Ho Ching once said.

[LA F2 Flyer]

And Ho Ching knows his stuff, I'm sure. haha

I just wonder if it's really necessary to hang quite as high above the rest of the cooling system as Polini suggests. (If I were to do so, it would be five inches above the cowl.) As it stands now, my fill line (middle of the reservoir) is likely to be about an inch below the top coolant hose.

Do you think there's any harm in my current placement?

[Mountain Cat]

The expander tank is basically a relief tank for over pressure. The main cause for concern is bleeding ALL the air out of the system. Failure to do so is a cooked engine. The only air in the system should be in the expansion tank (1/2 full). With no leaks, the little tank will take the excess fluid due to heat expansion of the fluid and then when cooled allows it to return to the engine.

[Mountain Cat]

Didn't get any calls on the SkyRaider/Mountain Cat from Barnstormers. So I suppose I'll make a new cowling, add some mountain bike brakes and find an engine. Also will get my PPL current. Or with the new rules, or just drop to a sport pilot license. And go thru the airworthiness Insp. Got to have something to do this winter.