william hanshaw

Hello, Jack. I saw your post today, after just receiving a new CS replica of the .75 Mills. I turned it over and like my other CS diesel (1.3cc Mills replica), it seems rather tight.

Could you further describe the "TLC" you gave your CS Mills to get it performing well? It certainly looks much better than my two Aurora Mills, so I hope it'll perform better. Thanks for any help you care to give me on this before I try to start the CS Mills replica.

Bill Hanshaw, Fort Worth TX

william hanshaw

Guys, I acquired a MPJet Classic 040 several years ago and have had much difficulty with it. I took it over to an experienced diesel man to run it, and It wouldn't run despite swapping another MPJet carburetor off an engine which ran very well. We used the same fuel...everything. Its contra-piston is poorly fitted, even slides up and down while starting! I've emailed the factory to get a spare cylinder/contra/piston, with no answer as yet. Ed Carlson says he's trying to get these parts from the factory, but they are also slow to him.

So, does anyone have a handle on where I can find a new assembly? I agree that it appears to be well made, except for me it has been a problem since I first got it. Ideas anyone?. Bill

steve111

Hi Bill, you could try David Owen - he carries a pretty good range of MP Jet parts. [email protected]

(Sorry, can't get the email link to behave. The bit after the '>' is what you want.)

Cheers
Steve

mike109

G'day William.

I bought the MPJet 040 from David Owen. Mine was the opposite of yours. I could not get the contra piston to go back up. David serviced it for me and it is now fine. He is worth knowing about.

More recently I bought a PAW 40 from him. I have just put it in a Kadet Senior for its first flight. Possibly tomorrow.

Cheers

Mike in Oz

AMB

ok group in our classic design diesels the contra is sometimes an issue, too loose and its a no fix need a new one or new matched set, too tight with patience
easily fixed , I have been lucky my MVVS 15s and 09 on the money, PAWs ditto, My sharma 15 was not movable in the upper third of the cylinder used my dremel
with the polishing pad and toothpaste as a lapping compound took it slow I could finally get it up and down with a light tap of a wooden dowel done goes down and bangs up on running against the screw , no leaks, these will last for decades with no further issues well maybe a new rod after many hours of running but so far so good on all mine martin

Pe Reivers mentioned on his site if the MVVS15 contra too tight he will lap it in, my 3 from him did not require it

maxtenet

If its too loose you can always sit it on an anvil and give it a whack with a hammer. This is what Eric Clutton suggests and I've done it myself. It is an inexpensive (free) and effective solution.

Max

AMB

Maxtenet sounds simple I would have suggested heating it with a torch to expand it, the bang on the anvil great idea, the old adage " if it does not fit hammer it"

applies martin

earlwb

The bang on the anvil is dangerous if the contra-piston is made from iron. They tend to shatter like glass.
Same thing for the piston too.

AMB

Earl how about the heat thing to expand it ??? martin

HOW ABOUT THE CAST IRON it could be ductile or brittle ??

earlwb

Maybe, I have read of people that say it works. I think Adrian Duncan of Model Engine news mentioned it somewhere but he wasn't fond of it though.
Usually all the engine guys make new contra-pistons and fit them to the engine they are working on.

fiery

My Feedback: (2)

An extract from an engine building article on the "Model Engine News" site.

This builder wound up with a piston in a prototype Taplin Twin replica which was slightly undersize. This is what he did. Text is directly from the article:

"I decided to try an expirement on the pistons before making completely new ones. Fellow Motor Boy George Aldrich knows a LOT about speed engines and tells me he "grows" cast iron pistons a couple of thou by heating to red heat and oil quenching. On the theory that this pair was stuffed anyway, I gave it a try on the worst one (the front). "Before" measurements gave a diameter of 0.5044". The piston, held on a piece of soft iron wire was brought at a bright orange in a propane tourch and quenched in chain saw oil. The "After" dimension measured 0.5060" with no appreciable out of roundness. A little honing soon removed the scale and produced a good fit in the front cylinder. The piston is still not as polished as I'd like indicating just how under size I'd turned it (and how blunt the tool had been). Reassembled, the front pot would now "pop" on a prime. With this encouragement, the back piston got the same treatment with similar results: growth of 0.0016" and no distortion. Simply amazing. With both pots a-poppin, I just had to try for a run."

[email protected]

Bill Hanshaw, I just saw your 10/1/2011 post today. The CS Mills .75 cc diesel would not run the fuel tank dry. My flying buddy had the same problem. His fix was to do a fine taper of the needle valve. He put the needle valve in a drill press to do the taper. Then the engine would run the tank dry. I gave my CS Mills .75 cc to SAM for their engine raffle. My MP Jet Classic has me spoiled so no need for the CS. Last few years my R/C diesel flying has been with Oliver Jaguar/Panther 2.5 cc reproduction and the GB 5.4 cc I got from David Owen. The GB is in an Airborn 810 sq. in. wing area model. Both the Jag and GB are sort of high quality big Mills. Jack

[email protected]

Airborn with the GB 5.4 cc diesel. Jack

Recycled Flyer

Gotta love that extra engine mount clamp!

fiery

My Feedback: (2)

MP Jet .040 classic. Superb design and execution by Czech craftsmen.

************************************************** *****

This one was in poor shape as received.

A new contra piston, piston, liner and conrod set were installed. My thanks to David Owen for his kind assistance.

************************************************** *****

After two choked primes, it starts in two to four flicks. Every time. Hot or cold. A Master Airscrew 8x3 propeller is fitted and suits it perfectly.

earlwb

Actually that extra mounting clamp might have resulted in a little more speed or power out of the engine.
Years ago several engine manufacturers used high speed cameras to film their engines at WOT. They were surprised to find that the bolt on front engines flexed and vibrated a lot, so they went with one piece crankcases built more strongly. The same thing happened with the small spindly like front ends on engines too where the front end would flex too much from the vibration as well.
I know it was one reason Fox manufacturing quit using the Eagle II design with the multi-piece crankcase design when they saw what it was doing from the high speed camera movie.

william hanshaw

Howdy Derek,

Your pics are great to see! BTW, I've never seen a Blue Master Airscrew prop! Every one I've ever seen is plain black! No big deal, but I suppose that their export props are colored differently for some reason. Anyway, it's very good to see the little MPJet performing so nicely. I hope that my little VA "Mini-Mills" will do as well...it's very small and should be a challenge to redo.

Thanks again for the very nice pictures!

Bill

[email protected]

The story behind the extra clamp on the GB 5.4 cc replica diesel started with an Oliver Jaguar/Panther 2.5 cc replica diesel I got from Rustler Engines in the UK. This 2.5 cc diesel vibrated severly when using a plastic motor mount. So I went to an aluminum motor mount with less vibrations but still unaceptable. I remembered seeing Team Race Diesels such as the PB TRD from 1985 with extra mounting lugs up fron behind the prop. So I had a fellow make up an aluminum motor mount that clamped the front of the Jaguar and problem solved. I did get a bit more RPM. The bigger GB does not vibrate as bad as the Jaguar but had a similar motor mount made up. Acturally, the GB does not need this special mount. Jack

[email protected]

Two more team race diesels with mounting lugs just behind the prop. Jack

fiery

My Feedback: (2)

A cautionary note about setting up these little side-port diesels.

The engine shown below is my own example. I recently set it up to run it for the first time.
The intake tube was screwed on and lock nut tightened. I fueled it, primed, and flicked.

I noticed the piston was very tight, I could only get a 'pop'. No joy. Perhaps a factory error?

I asked the Australian MP Jet agent, David Owen, to look at it. He diagnosed the problem immediately. The intake tube had been screwed a little too far in, in order to get the tank bowl parallel to the cylinder. This put pressure on the liner, causing a tight spot.

David unscrewed the intake a turn, and the problem disappeared. He test ran it for me. Luckily for me all was well.

The fits are excellent. It now starts and runs like a champ.

PWF63

I have my MP Jet Classic in this FF Scrambler converted to 2 RC assist.
Has no trouble running a 8x3 Master GF prop.
A delightful little engine.

Fredo

Ployd

Like Fredo I have never seen blue 8x3 Master airscrews, can only get black ones. It would be nice if they did a few more colours to brighten up a model.

I use an MP Jet 040 with an 8x3 prop in my Tomboy; got the engine from Dave Owen and had it running in 3 flicks...better than a Mills.

Re: T/R diesels, you will find that the extra lugs just behind the prop driver are not put there for vibration purposes but to hold the crankshaft housing rigid so that it does not flex or distort from prolonged running. Early high preformance T/R diesels had screw-in steel crankshaft housings to solve the problem in addition to extra lugs.

Ployd in OZ

fiery

My Feedback: (2)

Lovely aircraft.

ffkiwi

I rate them the equal of any Mills as far as starting and handling goes-and a little bit superior for power......and I've got half a dozen of the wee fellers in the stable-four in current use, and the other two will eventually wind upon the front of something suitable............... all mine have been very tightly fitted in the bore when new, and needed a good 30 minutes to free up. The 40% castor specified for run in [which I freely admit I thought was grossly excessive when I first saw it-in fact I thought it was a transposed typo error!] turns out to be bang on the money for the first 10-15 minutes running-you can then switch to a conventionally proportioned fuel mix.
As Peter and PWF63 have said-they're very happy on an 8x3 Master.....though I tend to run them on DC or Cox nylon 8x4s, since I have a small supply of them.

ChrisM
'ffkiwi'