Hi All

I've recently put a MVVS 160 into a Katana 140. I encounted my first problem when pointing the noise upward the motor would always lean out regardless of needle settings and attempts to increase back pressure from muffler. I then fitted a perry fuel pump which sorted the problem out. However I now have a problem ( in flight only ) when inverted the motor splutters and looses power. On the ground the motor runs perfectly. Does any one have any suggestions. All manufactures installation recommendations where followed for motor and pump ie. tank location, pump orentation ect.

G'day Mate,
How much running has this motor had, sounds to me like it needs a lot more. Will it run without the pump or muffler pressure on the ground, & in level flight? If not it needs more running.
As the motor runs in, the seal between the piston & the sleeve improves, this increasing crankcase suction which will draw more fuel/air mix into the engine, that is why, as engines run in, they go richer at idle & need to be leaned out some to run smoothly.
By the way, muffler pressure & back pressure are not the same thing, muffler pressure is used to pressurise the fuel tank to allow more consistant engine tuning during aerobatics.
But back pressure is caused by the shape of the muffler, it allows the exhaust gasses to be more efficiently removed from the engine.
4 strokes don't need back pressure, thats why they have small straight through exhaust pipes.

Not much running, about 2 liters ( about 1/2 gallon ). Will run on the ground without pump and muffler pressure. In level flight runs perfectly even when I pull vertical its fine. Only INVERTED its not happy - thats the weird thing.

Warrend,


Allan is right about the break-in.
This engine has strong parts that need more than a few minutes of break-in.

It will take several running hours until it begins to behave perfectly.

With the low-end mixture setting too rich, this engine has a strong tendency to load-up and upon throttle-up, to back-fire and to throw the prop!

With the Perry pump, this tendency is increased, so you must both lower the pump pressure somewhat and close the low-speed needle, until it runs well and transitions reliably from low-throttle.
The instructions that came with your Perry pump explain the extent, to which you should adjust these control.

Thanks for the info. Will try the advice.

Regards
Warren

Hi!
Are you using 0-5% nitro! (you should) . A good glowplug is the Enya 3.
Prop : Menz 18x6. Not APC or any other heavy plastic prop.
Tank: 500cc Tettra "bubbleless" or the usual Du-Bro or Sullivan set up with "Uniflow" set-up!
Try it!

----------------


Is this the needle bearing equipped glow 1.60? Just curious. Using fuel with too much oil in the needle bearing equipped engines can cause problems with anomalous behavior(s), or so I've heard.

A stiff fuel tank clunk line is something to watch out for, but I agree with everyone else that the engine will improve a great deal with more running.

How about air flow problems through the cowl? If the engine is using a Walbro carb, you may have to install a "static line" into some dead air (fuselage) like that gas boys do. I have seen so many variations of MVVS engines that I'm not sure which one yours is - if you know what I mean? <G>

Please come back to this thread and report your findings. TIA


Ed Cregger

Jan,


The Enya #3 is the hottest plug there is, together with the OS A3...

It needs a much colder plug. The Novarossi C6-S it comes with is equivalent to the Enya #4 and it is too hot!

It need an Enya #5, or an equivalent.

The plug I'm using is a Rossi C6, ( the plug that came with the motor) and which is also the one that is recommended to be used for the 160 by MVVS. As far as I know it is a cold plug for use with nitro. ( see http://www.scootworks.com/rdrc/gloplugs.html ) I use my own mix of 5% nitro, 10% cool power, 5% caster oil. Also using a 18x8 wooden prop. As far as I know my motor has the roller bearings on the conrod, because thats what the exploded view shows on the documentation that came with the motor. Although I hav'nt actualy opened the motor and checked. I'm tending to be thinking along the same lines as Ed Cregger about air flow through the cowl. ie in flight the airflow is different as compared to on the ground. MVVS actualy make a fitting / static tube that goes over the carp air intake. I think I will try it. Will try the sugestions and let you know on monday how it went on the weekend.

Regards
Warren

warrend,
I would try a smaller prop 17x8 or 18x6 for this new engine running on a muffler.