I am looking for the best .90 size 2 stroke, all info says stay away from the OS 91, what else is there? I saw the Jett 120, but for $375, I dont think so, what does everyone suggest? for a 60" 7lb profile, dont really want to go 4 stroke this time. What about the new super tigre 90s? price is cheap, maybe one of those with the performance speciaties muffler. Any ideas?

All WHAT info?????

reports show inconsistant runs, carb probs. How does it compare powerwise to the ST 90?

The power is very simular between the two. Both like a 14-6 at 10,500. I have two ST G90's and a friend has two OS 90's with one being of the problematic batch. He put a remote needle valve from another brand of engine on it and it turned into a very reliable , trouble free engine.

The Super Tigers had some problems too in that the very last ones produced in Italy had 40 type carbs. They would only turn 10,000 with a APC 14-6.

Enjoy,

Jim

The redesigned version of the OS 91FX has supposely fixed the reliablilty problems with this engine.

Take a look at the Magnum 91XLS. I have one and I think it is great.

Hey y'all, where is that Compare Feature that we use to have available here ? Yer know, where you could compare enginge specs side by side ? Is that still available at RCU ?

You might try comparing those to the new Evolution 100 NX ?

The ASP engine can be had very reasonably, and should be a good bet.

FBD.

I second the Magnum. Almost a carbon copy of the OS without the carb problems. Though I don't have any experience with it, the GMS 1.20 looks pretty good, and they're only $125 from Tower. Or, for a really good deal, go to www.mecoa.com. They have it for $119.99, and if you have an old engine from .10-.61, they'll give you $20 trade in. $100 for a 1.20 size engine, heck, it would almost be worth trying, even if it turned out to be a piece of crap!

I had an ASP 1.08 a long time ago, but cant find a NIB one now, or thats what I would get, any ideas where to get one?

AviatingBoarHog:

The 1.08 engine has been discontinued in the ASP/Magnum line, they still offer the 91 and 1.20 sizes.

Bill.

what about the mvvs 91 with mini tuned pipe? I wonder if a 90 will be enough for a 6.5lb profile

There's one on the "big auction site" right now....hurry 18 hrs left.

Dave.

well, maybe a saito 100 or ys 110 is a better choice for this project

MVVS 91 is a great engine if you do NOT use that rubbishy square "silencer" thingy it comes with. The MVVS is also very light for a 91. Use a decent short or full pipe and you will not find fault with this engine.

Also the ASP/Magnum 91 is excellent, very powerful and absolutely consistent. These Chinese engines are SORTED! The four strokes are quality motors also.

Well, I ended up ordering an mvvs 91, and going with the jett engineering muffler for it, hope it turns out to be a good one

Good choice. I doubt you'll be disappointed. These engines are honest workhorses, not show ponies.

Be careful with fuel though. MVVS engines like to run on nil nitro fuel. If you use nitro, add extra head shims and use a cooler rated plug. Or do what I do with my MVVS .61. I use FAI fuel (nil nitro, 80% methanol, 20% oil), enjoy the engine and save on fuel costs. Make sure your lube package has at least 5% castor in it as well.

Personally, I use 10% synth and 10% castor for lube, and my engine still goes like it did on the first day after 10 years of use.

fiery

Thanks, I can get fai fuel here, would that be better than the 5%? what plugs are you using in yours?

razorback

If the .91 is like it's smaller brother, the .61, I can say that the engine should not be fussy on plugs. Recently I have used K&B 1L's in mine. They seem to work well and are readily available. MVVS also make a "cool" plug which works well, but is only seems to be available from MVVS dealers and agents.

I have also used Rossi 5's, but they are hard to find and expensive.

It seems they like a standard long reach plug that is just a little cooler than your usual OS A3's, 8's, or Enya 3's.

I found that with Nitro the engine would not peak (pre-ignition at wide open throttle), and that when started by hand (as I prefer to do) it would fire and run backwards.

These are my experiences, others may have had no problems at all with standard warm rated plugs. Try whatever plugs you have on hand (I seem to have a fair collection after many years in the hobby) and see what works best for you.

Another tip - a little loctite thread lock on the muffler hold- down screws works wonders. Apply when engine is at temperature, and let cool. That should stop any tendency for the screws to come loose in flight.

Check out the neat clear "O" ring on the carby intake spigot, and the positionable cylinder for side or rear exhaust. I found them to be nice engineering touches on a well thought out, robustly constructed, engine that sells for a very fair price.

fiery

FRB,

Could you give me a link to that Jett silencer for the MVVS 91. I'm using a Weston throttle pipe at the moment, but it's quite long and gets in the way of the leading edge when inverted.

I have been running this engine on a 14 x 6, 15 x 4 wideblade and a 16 x 4. It pulls big props and doesn't need high revs.

Just buy a Super Tigre 90 and be done with it. Stop stressing over which one is best, has the most power, etc. An ST90 will haul your airplane around just fine.

I thought of the super tiger 90, but, its 7oz more than the mvvs, and I am trying to save weight, and also looking for the best power to weight, and didnt want to go 4 stroke this time, so bought an mvvs 91, price was right. Its for a 6lb profile, dont want marginal performance. www.jettengineering.com has the pipes, he recommends the 90 size muffler for rpm and the 120 size muffler for torque. They are $85 with the adapter for mvvs. I plan on going this route unless someone can convince me the mini pipe works very well.