O.S 91 C-Spec pumped
 

Hey guys,

Have recently purchased an os 91 c spec with pump for the hirobo ec-135 but have got warning from some people that the engine will vibrate way too much and will shake the heli to bits, They recomended the YS 91 ST. Which is basically out of stock everywhere.

Just to double check is the engine too rough for this heli?

and does anyone have a YS 91st lying around?

Thanks

RE: O.S 91 C-Spec pumped
 

I dont have experince with that motor in a chopper (or anything) but a boddy has bought one and has it one a break in stand...it runs very smooth from my perspective, but thats on a stationary stand too...so i wouldt knwo how it will act in a heli

RE: O.S 91 C-Spec pumped
 

hmm well spoke to some more people and getting very different views so i guess ill use the O.S and see how it goes.

RE: O.S 91 C-Spec pumped
 

Make sure you take apart the carb and clean it out good, the manufacturing of some of those left some plastic bits in the jet and caused somewhat erratic runs. Or atleast if you have problems keeping a needle setting then take it apart and clean it.

RE: O.S 91 C-Spec pumped
 

shall do, i will post some pics of the mechanics soon.

RE: O.S 91 C-Spec pumped
 

Once run in the motor is extremely smoothe! It will also depend on your muffler/pipe a little wether it will be super smoothe or not though. In the beginning you might have some vibrations but it will be because of the very rich running motor during the first 3 gallons or so. After that it doesn't vibrate any more than other motors. The YS has been reported to be a little smoother than the OS BUT you are not going to get quite the same amount of horses out of the YS. Stick with the OS and just make sure you keep an eye on things the first 3 gallons with the very rich settings as you'll have some vibrations then. IMHO though if you're worried about a little engine vibration shaking the heli apart I'm not too sure I want to be near that heli when it spins up? :)

RE: O.S 91 C-Spec pumped
 

lol yeah im using a hattori muffler which should give it a kick, the only thing hirobo havent got spot on in these mechanics is the wiring, its all over the place!!! i hate messy wiring even when its wrapped neatly, its all over the place.

RE: O.S 91 C-Spec pumped
 

I run a CY MP2 on my machine but I've heard rumours that the Hatori is a little smoother but I can't confirm that with personal experience. Good luck on the machine! I don't know it at all as the only helis I have been fiddling with is the JR machines. Have fun with it! :)

RE: O.S 91 C-Spec pumped
 

thanks!! posting pics really soon now just charging my phone.

JR helis are quite expensive right?? i expect they are good performers

RE: O.S 91 C-Spec pumped
 

Don't know about the really expensive part but as with any heli their definitely pricey. :) The JR supplier in South Africa is really on the ball though so the prices are excellent for their stuff. And well the quality of machine you get does justify the price by all means. Seeing a JR machine in SA is not an uncommen thing but mostly due to the importers. The prices compared to other machines here is more than competitive. I am currently flying the JR Venture .90 which I chose firstly because of its great price and looking at what you get. I'm moving into F3C though and this heli was a great all rounder for me to also play a little with the 3D manuvers but I soften up the head with other dampers and I have a decent F3C heli as well. And yes this heli is an awesome performer for sure. Even though it is probably a little heavier than the high end 3D helis like the new JR Vibe it can still do everything I want to like piro flips etc.

RE: O.S 91 C-Spec pumped
 

sounds good, might try a JR heli one day...when my wallet grows :D

This heli is by far the nicest thing I've ever built or attempted anyway!

RE: O.S 91 C-Spec pumped
 

o yeah and sorry about the messyness, havent found a place for everything quite yet