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-   -   Roto motor 35FS (https://www.rcuniverse.com/forum/gas-engines-142/10039457-roto-motor-35fs.html)

MKnutson 09-30-2010 09:46 PM

Roto motor 35FS
Has anyone out there that has one of these engines run it yet? I'm on the fence about this engine, it looks pretty nice and it would go in alot of different planes.


shosho 10-22-2010 09:17 AM

RE: Roto motor 35FS
Hi here is one.


AmishWarlord 09-16-2011 06:24 PM

RE: Roto motor 35FS
I looks good but I don't know about the specs.

They say this is an 3.5 HP engine.

Then go on to say, "20x10 6,000 RPM"

A 20x10 at 6,000 RPM is only 2.3 HP

Plus this is only 15 pounds static thrust at 56 MPH.

Since a lot of 30cc two strokes put out 3.5 HP I'd be inclined to believe the Roto 35FS only has 2.3 HP

davidgeorge212 09-16-2011 08:19 PM

RE: Roto motor 35FS
I have one. I can not call it an excellent engine based on my experiences. It took me about a month and a half to finnally get my engine to run (long story). From what I can tell, it sounds like the ignition boxes that come with these engines are just not reliable at all. My original ignition that came with my 35fs would not run at all, it just had no spark. I contacted the seller and manufactuerer and sent it back and a month later they sent me another ignition box and I installed it on the motor again. The second ignition box ran for a total of 1 time for about 15 minutes and then it quit giving out spark. I then bought a dle 55 ignition box and hall sensor and installed it on the the roto motor 35fs and It has ran well ever since. It sounds great, but I agree its not a super powerful motor. Another thing the manual does not say but the manufacturer does is to use either an 18x8 or 19x8 for break in. That will help get a little higher rpm. I didnt know that and broke mine in on a 20x10. With a 20x10 prop I was only able to get about 5300 RPM's.


pilotarix 09-20-2011 06:00 PM

RE: Roto motor 35FS

I am also looking for information about the RotoMotor 35FS, I thought it could be a good engine for my TC Piper (22 pound 110 inch wing span). I like the sound from those 4 stroke engines, but unfortunately your experience sounds not like the best experience you ever made with an RC engine. This engine is simply to expensive not to be the BEST.
But maybe you were simply unlucky and after the problem with the ignition is solved now the engine will be perfect.
However, I will also check for other engines, befor the final decision will be made.


davidgeorge212 09-20-2011 06:37 PM

RE: Roto motor 35FS
Back when I originally posted my problems here on RCU, I remember one other guy who mentioned he had issues with his spark box as well on his rotomotor 85fs twin. I think he said he got tired of messing around with his engine and switched it out for some other engine. I dont have any regrets going with a four stoke engine, but, I think now I should have probably gone with the Saito fg36.

Yellowfeathers10 09-23-2011 04:58 AM

RE: Roto motor 35FS
Hi David,
Looks like you might be new with the gas engines. I have 2 roto motors. I even crashed twice and my ignition box still works perfectly. Maybe you used high or low voltage which could have burned your ignition box.. If you use the right battery with the gas engines, they will last for 2 or 3 flies. A lot of guys recharge after every flight on the field. Be sure your battery is charged all the time. I doubt there is any problem with the actual ignition box. The engines are working great for me.. I'm very happy with them.

Flugmax 09-25-2011 04:08 PM

RE: Roto motor 35FS
They will soon be available, they are running smooth

my 50cc CMPRO Zero wingspan 2,10 meters has 11 Kgs now and it flys powerfull with that one:


Greetings Martin

davidgeorge212 09-25-2011 04:56 PM

RE: Roto motor 35FS
Ive been flying gas for a few years now. I have a DA 100 and an OS 55GT and a DLE 20 and my last engine was this roto motor. I have had great success with everyone of my other gas engines and especially havent had any problems with spark boxes. I installed the roto motor spark box just like all my other engines and it was just sent from the factory deffective without a working spark. I know that for a fact because I sent it back to the distributor for them to try out and he told me I was correct. He sent it in for repairs and sent it back to me and It ran, and good like it should, but only for about 15 mintues. If it werent for the shipping costs to czheck republic and month and a half turn around time, I would probably send back my second spark box and have them replace it as well. I had a DLE ignition and decided to try that and it has worked great ever since so I figure why even try to fix the roto motor spark box.

AmishWarlord 09-25-2011 11:03 PM

RE: Roto motor 35FS
how is the sound on that motor?
Dose it sound better and really different than your other two stroke gas engines?
It's hard to tell by the videos on Youtube.

davidgeorge212 09-26-2011 08:51 PM

RE: Roto motor 35FS
The sound is unbelievable. Of course I like it the sound of it the best when it is at a low idle where its just ticking over. I think the sound of the gas four stroke is much better than a glow four stroke because they have a deeper and realistic quality. When I first got my engine running I put it on a test stand and brought it out to the feild one saturday just to run for everyone to hear. I can fill up a 10 ounce tank not even all the way full and it will run the engine for well over an hour. It is increadibly fuel efficent compared to an equivilent sized two stroke engine.

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