Minimax engine swap 503 for 447

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bebedriver

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As part of a general sort out of my Minimax 91 (UK version of 1600R). I'm fitting a 503DCDI. Here's the story so far...

So, the issues arising from this are as follows:

1. Its bigger! Not a lot but it is. Annoyingly the 4 mounting studs (8mm dia) are 8mm further apart than on the 447. In practice, this means that the rear pair of mounting holes in the engine mount plate are close enough to form a figure 8 hole! So a new plate is the neatest option - see photo 1.

2 The longer motor together with twin carbs requires a bit of surgery on the left side of the fuselage. 40mm to be cut back! Fortunately this is non-structural so it just requires some neat jig saw work and tidying up. See photo 2.

3. I had one of my M5 Starters fitted on the 447 and this did require further surgery in the form of cutting a pocket in the inner skin of the fuselage side. The extra length of the 503, actually eases this situation as it's further back and thus the fuselage is a bit wider, meaning less relief (if anyone was fitting one with a 503 from scratch) - Did I mention that I make the M5 Starters? :cool: - See photo 3

4. The overall size of the 503 means a tighter fit all round including the area of the cooling shrouds. The existing cooling system of the enclosed engine Minimax is (in my opinion) a bit random. Fan cooled Rotax 2 strokes require an adequate supply of cold air directed in through the rear facing fan housing where the fan forces it around the cylinders and over the heads and out over the carburettors. Cold air currently enters the cowling though a hole in the front and a small scoop. I'm going to make a scoop that fits over the fan housing and directs air straight in via an enlarged scoop in the top cowling (yet to be done). See phot 4 - this is just a quick piece of card in the rough position of the new cut out.

More anon!

Only 8mm longer between.jpg

503 twin carb clearance.jpg

503 with M5 Starter.jpg

Paper engineering scoop.jpg
 

bebedriver

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Hi Tuneturkey,
Yes I do. Best I quote you £ Sterling as the exchange rate keeps changing! £485.00 + carriage to USA (£40.00 last time I sent one at the end of 2020). What aircraft is it for? Delivery varies, depending on whether I'm waiting for machined parts etc. but never longer than 30 days between order and dispatch. Currently I would probably finish one within 14 days due to current component stocks.
 

bebedriver

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Here's a recent M5 I supplied for a Quickie Q1. It's a really tight installation and this was the only position it would fit, due to the engine mount. You can see that the coil plate will have to be moved (by extending the mounting plate) and the rear carb bowl will only come off by loosening the carb! However, you get to specify where you want the starter motor to fit :cool:
 

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Tuneturkey

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Here's a recent M5 I supplied for a Quickie Q1. It's a really tight installation and this was the only position it would fit, due to the engine mount. You can see that the coil plate will have to be moved (by extending the mounting plate) and the rear carb bowl will only come off by loosening the carb! However, you get to specify where you want the starter motor to fit :cool:
Engine is a 503DCDI, dual carb, mounted cylinders down on a Hi-Max
 

bebedriver

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Ah ok. I have a 'Max too (as you can see!) but the motor is enclosed and upright. Due to the width of the fuselage, that configuration requires a chunk of the inner skin removing (it's non-structural at that point). I've attached a couple I've attached a pdf of the backplate, which I normally send to potential customers so they can decide if/how it will fit their requirement. Just print it on some thin card etc. and offer it up to the mag end of the engine. Use the top center of the crankcase as 12.0'clock, and the virtual minute hand of an imaginary clock face, with the centerline of the template being the hour hand. We then drill the 4 mounting holes to suit.
 

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Mig29fuk

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Jan 19, 2021
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I have a M5 Starter on my Letov Sluka with 447 engine directly from Nigel in Devon. Great to install and wonderful action.
I've used a FullBat 170A Cranking Lithium Ion Battery weighing 10 ounces! It really turns the engine.
Well worth the investment. After hand propping an old Continental for 20 years its a luxury!
Regards
Gerry1638637-medium.jpg
 

Armilite

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Hi Tuneturkey,
Yes I do. Best I quote you £ Sterling as the exchange rate keeps changing! £485.00 + carriage to USA (£40.00 last time I sent one at the end of 2020). What aircraft is it for? Delivery varies, depending on whether I'm waiting for machined parts etc. but never longer than 30 days between order and dispatch. Currently I would probably finish one within 14 days due to current component stocks.
================

$450 BRITISH POUND = $676.44 USD. $40 BRITISH POUND = $55.77 USD. $732.21 USD TOTAL. XE - The World's Trusted Currency Authority: Money Transfers & Free Exchange Rate Tools

You would probably Sell A LOT more of these if you lowered the Price by using the Cheap Seadoo 580/587 & 650/657 Starters on eBay.

You have to compete with GPL, and Rotax Starters.
 

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bebedriver

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I appreciate the comments, but firstly the Seadoo is a simple bendix type, the same as the original Rotax starter. Both need to stick out of the back of the motor. The M5 is a development of the M4 which I designed in 1993 along with a guy called Don Law. I repaired an M4 the other day, it was still working 28 years later - I'd call that value for money! The M5 is lighter than a Rotax starter as well.
I can't comment on the the GPL weight wise but I'd pit mine against it from a quality or design point of view any day. The difference in price between the GPL and the M5 isn't so great when you compare the two.

I see from the link you provide that there is no stock. Ironically the whole M4/M5 development started with me becoming a distributor in the UK and Europe for the CPS 'Airdrive Starter' which was a total failure. CPS actually gave up as they couldn't sort the problems out. The M4 was the direct answer to that.

There are M5's in the USA, Canada, South Africa and Russia as well as most European countries. My biggest problem with sales in the USA are the additional shipping costs and the exchange rate, which hopefully will stabilise in the near future.

Of course a bulk order of say 10 units would see a significant reduction in price; anyone fancy becoming a US Distributor? :pilot:
 
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