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Marty d's CH-701 build log


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Hi Marty, a quick word on those doors:

My doors have the Lexan polycarbonate, I trimmed the protective film round the edges before fitting it...looks as though you've done the same.

When it came to masking, I then masked with regular masking tape and paper.

 

When I stripped the masking paper and the Lexan protective coating after spraying, the Lexan was lightly fogged in a blotchy fashion all over. Since the masking was tight, with the original protective coating still under, I can only think this was paint solvent penetrated in some way.

So I bought some sort of McGuires's auto product, and was very relieved to find that I could polish the fogging out.

 

Another time, I would make enquiries as to how to avoid this. A mate of mine is currently reworking a 185, and they seem to mask with foil, so maybe that's the trick?

 

(I should note that the Lexan was the same stuff in the same pack as the windscreen and roof, which are installed after painting, and which had no fogging, so I'm confident my Lexan was not 'pre-fogged'.)

 

Maybe someone here can add to this???

Hi Bob,

 

Thanks for the heads up! Yes I was just planning to tape the edges and trust the protective film to, well, protect.

 

I won't now - will add a couple of layers of something over the top - possibly the plastic drop cloth material or similar.

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It worked!!!!!   I just popped the lower cowl out of the mould.  It came straight out, no sticking, no lumps and bumps and divots.  (Well maybe a couple of minor divots!)   Decided

Quick update - I finished trimming the lower cowl today (apart from where the exhaust will exit), located it properly and did a 1/8" hole on each side so I could cleco it.     Unfortunately

Step one is to cut your mat to fit the inside of the mould - lay the pieces out so you know whit bits fit which curves. Don't try to do the whole cowl with one big piece of mat. After applying ha

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Hey Marty..what did you do for tanks?

Hey Mark, I bought a couple of the plastic Savannah tanks - a bloke was selling his kit including long range tanks, so I asked if he'd part them out.

 

I know they're heavier than Zenith ones (which are welded 0.025" aluminium) but I wasn't prepared to spend $1000 + getting them from the US and I doubt I could have found anyone prepared to weld ally that thin.

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These ones we just got made are 1.6mm. Roger a friend of ours has 25 thou tanks and has had a lot of trouble with leaking at the seams...just too thin

They must have an absolute artist at the Zenith factory. A mate of mine in Canberra got his welded up (building a 750) but the guy took it on as a challenge, spent months on them (around other jobs) and reckoned it cost him a lot more in time than the $500 he'd quoted to do the job.

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One of those days. I'd drawn up the jig for the exhaust runs, bought some framing pine from Bunnings, looking forward to a day in the shed building it.

...Then I decide to double-check the distances from one cylinder's outlet to the other, and how far the starboard cylinders are ahead of the port ones, and realised I'd got the measurements wrong by 14 mm.

 

So instead of a nice satisfying shed day, it was spent on Sketchup redoing the whole thing.

 

I also redesigned the back pipes which I think gives them a smoother run and looks more like the exhausts you buy for this particular muffler.

 

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where is your exhaust outlet Marty...if you dont have a baffle inside you would be best to bring it out half way along between the pipe entries. We have found major drama with the sav muffler as too less back pressure is on one side due to the outlet being close to one set of inputs. This causes one side of the the engine to run a lot hotter/leaner than the other

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Don’t forget the bend in the front left pipe to allow oil filter removal

 

Yes I have to actually take the filter off to see how much room it requires. Strangely, when you look at the pictures of commercially available systems, the front left pipe seems to be angled in the same as the other (example below from CPS Parts).

 

 

 

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where is your exhaust outlet Marty...if you dont have a baffle inside you would be best to bring it out half way along between the pipe entries. We have found major drama with the sav muffler as too less back pressure is on one side due to the outlet being close to one set of inputs. This causes one side of the the engine to run a lot hotter/leaner than the other

 

Mark, it's very similar to the one below with the outlet at the bottom of one end, it's reasonably weighty so I reckon it has a baffle.

It came with a stainless steel exhaust pipe that has an elbow like the one shown. Still a bit confused as to whether it should be welded straight down. Any advice?

 

1593081005544.thumb.png.a443b5f6875326350daec7545328f68e.png

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Yes I have to actually take the filter off to see how much room it requires. Strangely, when you look at the pictures of commercially available systems, the front left pipe seems to be angled in the same as the other (example below from CPS Parts).

 

 

 

[ATTACH type=full" alt="1593079813098.png]54276[/ATTACH]

 

 

 

 

 

Mark, it's very similar to the one below with the outlet at the bottom of one end, it's reasonably weighty so I reckon it has a baffle.

It came with a stainless steel exhaust pipe that has an elbow like the one shown. Still a bit confused as to whether it should be welded straight down. Any advice?

 

[ATTACH type=full" alt="1593081005544.png]54277[/ATTACH]

Every second oil change you need to remove the muffler and apply kopper Kote to lube the joint so not a real biggee if you don’t have the bend.

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Marty a genuine rotax muffler has a trumpet style baffle for the outlet which creates the backpressure leveling inside the muffler. I will find the pics of the one I extended of the internals

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The exhaust for the rotax muffler is out one end but there is a trumpet in the expansion chamber that levels the pressure inside gets forced into the trumpet then out the exhaust pipe on the end

 

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Hi Mark,

 

I think it's the same as yours - number stamped on the end is the same anyway, 973 674.

 

I took a photo down the end as best I could, from this end you can't see the trumpet flange, it's at the other end by the looks of your pics.

 

This is a new muffler kit thrown in when I bought the engine, when the bloke put in his new Rotax he kept the same muffler setup in the plane so he had no use for the new muffler.

 

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Yes thats the genuine muffler...its a keeper. And Mick is 100% about the oil filter too...mine was a pain in the bum as well had to undo the exhaust to get the oil filter off. The pipes were supplied in the kit

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You can often purchase oil filters of the same type of thread and diameter, with an identical seal - but with a shorter body on the filter. Not only Rotaxes have problems with filter accessibility.

It pays to scout through the filter cross-reference numbers, then check the dimensions of the filter body with the manufacturer, until you find one with a shorter length that allows fitment without removing other components.

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I don't know how the pipes are arranged for the Rotax muffler, but FWIW the Sav pipes allow easy access (room to spare) to the standard Rotax oil filter without any major offset. The initial swept bend out of the head sits perpendicular, after that the pipe is angled inward.DSCF1950.thumb.JPG.09fe8c5bb9f9e15a48875dc4302d24a8.JPGDSCF1955.thumb.JPG.74e7417a56c1ca8dba939a645b79b98b.JPGDSCF1953.thumb.JPG.38f93082f7325291144033ea2958e94b.JPG

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Lots of plumbing. Is the front radiator for oil or cylinder head coolant? The Zephyr that landed in a tree recently had coolant leaking in to the cockpit & those ribbed metal clad pipes seem to go all the way to the rear. I still don't understand why you would route coolant pipes through the cockpit.

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The front radiator is oil.

We figured if there was a problem with the ribbed pipes we'd have heard about it by now. The downside of them is that each end is connected with a piece of hose and 2 hose clips. The upsides are that they are compact and light (not having the wall thickness of hose) and that you can form them to shape that they hold, including very tight bends where a conventional hose would flatten and collapse. So they do lend themselves to very compact installation. I have been careful to secure mine to minimise vibration.

The oil and glycol circuits on the Sav are confined to the engine compartment.

And I had a problem with my front RH pipe, Mark, which ran too close to the coolant elbow there. Turned out to be an incorrectly manufactured pipe.DSCF1943.thumb.JPG.9d7e7282d23e532caf00050ca68a737d.JPGDSCF1948.thumb.JPG.c3dc9c1d2472456ff4624e2bb6047b6d.JPG

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It's a very neat looking installation Bob - you should be proud.

 

One day when this is all over I'd love to come to NZ and see your pride & joy!

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Thank you, Marty. I was just following the instructions. For this part, I also got a lot from the pics that Reg Brost supplied when I bought the kit.

I need to do more recent pics, as these are missing the throttles, also I went through a heap of cable ties moving the wiring around until I was quite happy with it. I figured I could save someone else some of the cableties and a lot of the time that went into that.

 

Yes, it'd be great to see you over here, come see us! And certainly if I find myself over there, I hope to visit some of the many people whose work and posts I have enjoyed on here...)

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Those ribbed metal lines are now supplied by ICP in the Sav kit they also use it for fuel....I have to say I am not a big fan of it

 

Are you worried about the stainless steel work hardening?

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No Hank...they are super thin and if they were hard alu lines them maybe ok but you have a lot of vibrations in and around the engine....I dont know Hank it just doesnt sit right with my brain about using that...give me the correct rubber style lined reinforced hose any day..also for ICP its a way or further reducing build weight too

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