Installing the MA Air Filter

[bigrcr]

When installing the Miniature Aircraft #125-120 (-120,-122, -124), make sure that the bolts that mount the assemblies are not too long.

The stock Zenoah supplied bolts may need to be trimmed off a bit to be able to be tightened down fully without an air leak occurring. These bolts pass through the filter back plate, the carb, the primer bulb heat shield and into the insulator mounting block.

The reason is that the stock filter box is much thicker than the base plate for the Miniature Aircraft air filter. I had mounted my filter unit without giving any thought about having to shorten the bolts. Several pilots have indicated a possible problem with surging at idle and operational problems as well. If these bolts are too long, they will bottom out against the motor lugs and push the carb and plate off of the insulator. This will lead to an air leak causing surging and poor motor operation.

Later,

[Dash]

I was just checking the seal around where the insulator mounting block connects to the engine. I was noticing some oil residue under the insulator. Sure enough the screw where pushing the insulator off of the engine. Thanks for the heads up. I love this forum

[Fredrik aka. mrNoodles]

Hmm guess its time for me to put another pair of washers under the bolts

That surging at idle sound terrible familiar

[Fredrik aka. mrNoodles]

Oops, did put 2 washers under the filter, but I just took a look at the stock plastic air cleaner and realized that 2 washers wont be enough.

Tried it today, runs ok at start of the flight, but after a while (when the engine gets up to its work temp) it starts to surge at idle.

More washers, will let you know how this ends.

[bigrcr]

If you have a Dremmel with a cut off wheel you can mark the bolts then cut them off shorter and dress up the ends. This what I did to mine (I forgot to tell folks about it though ).

Later,

[Dash]

Well I cut the bolts and added an extra washer. Started it up and am getting the surging at idle once the engine has warmed up I just want to clarify that the problem occurs if the bolts protrude out past the back of the insulator and start pushing against where the insulater mates to the engine? I don't think my screws are hitting anymore. I hope I didn't tighten the screws to much and possibly cracked the insulator. Would this cause surging at idle?

[bigrcr]

What pushes the carb out from the motor is the bolts hitting the ears on the intake flange of the cylinder. If the bolts are short enough so they are back within the insulator, this cannot happen. If the bolts in the insulator or mounting the carb are too tight, then the insulator can crack and this will cause surging as well.

Later,

[Fredrik aka. mrNoodles]

2more washers will give a try tomorrow, if it still surging tomorrow I´ll borrow a insulator plate from my friends TRM. :?

[Freakinflyin]

Another thing... if you still have a surge and still think it's to do with the isolator, check that the isolator isn't warped...check it with a straight edge and or lightly sand it with some 220 grit on a piece of glass, wife's favorite mirror works well for this, lol.

Cheers

[ddavison]

I just installed my air filter and measured the bolts ,they are app. thousand's too long. They can be cut off 2mm to 2.5mm and will definitely clear. I was using Vario air filters and velocity stacks on my Graphite gasser and frond out about the bottoming of the bolts and warping the insulator. I you have the carb go ahead and remove the insulator and as mentioned before sand it on a frat surface to make sure it is true, don't over tighten the bolts. Thanks John for the reminder.

[ddavison]

Spell check did not work to good.

[Fredrik aka. mrNoodles]

Hmm maybe mine is warped as well :?

[bigrcr]

As long as the insulator is not cracked, you can use the Zenoah(Walbro) gaskets between sections. I have even used a bit of FormAgasket in the past on the gaskets. Just a thought :wink:


Later,

[Fredrik aka. mrNoodles]

I did remove the insulatorplate and sanded it on a flat surface, before sanding it felt like I could wiggle it slighty when having it on a flat desk, and after the sanding it feels more stable.
No cracks or anything so I guess it sucked air there once the engine got heated up.

Will try it tomorrow, thanks for all the good ideas! :cool:

[r/c_outlaw]

is there any reason why my air cleaner rotates while i am flying around...lol...the bolts are all tight and the filter element seams tight..but it turn slightly in between the to carbon plates?

[bevoduz]

rc outlaw mine is spinning too, anyone got a fix for this? or does it matter? it looks sorta cool!

[bigrcr]

You can add a small bead or drop of Zap Goo, Shoe Goo, silicone, etc. to the element against the carbon. You can also take a wee bit off of each stand off inside of the filter if you wish.

I would think that if the filter element is spinning, it is not sealing as good as it could. Does this matter, probably not a bunch... :wink:

[rchelinut01]

I have just installed my airfilter and it fits fine. I belive MA have reconized this and added a thicker spacer to the kit.

Cheers Jeff