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OS70 FL exhaust problems

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andy watson28/09/2008 18:39:00
1942 forum posts
20 photos


I recently paid £105 for a 4 stroke OS70 FL.

The exhaust header pipe which leads to silencer screws into both the cylinder head and silencer.  It has a bend of about 45 degrees in it.  Unfortunately this will mean I have to cut huge holes in my cowl- something I really don't want to do.  I would prefer to keep the exhaust inside the cowl and drop it through the floor of the fuselage- in effect a 90 degree bend pointing straight down.

OS sell a replacement header pipe, but it looks to have an external thread on one end, and their flexible pipes look perfect, but are about £25 each- a quarter of the price of the engine!!!

Does anyone have any alternatives? 

frank killan29/09/2008 20:07:00
55 forum posts

Hi Andy,                   Just Engines have exactly what you need , cost about £12 I think expensive for what it is though.   Visit the 4 stroke exhaust section of their website                          good luck    Frank killan

frank killan29/09/2008 20:58:00
55 forum posts

Sorry Andy I gave you the Email address ,the website is  

andy watson30/09/2008 20:09:00
1942 forum posts
20 photos

Hi Frank,

Not sure what you were refering to at £12.  I was thinking about needed either a 90 degree knuckle (JEN price £18.95) or their flexible exhaust @ £22.50.  Both prices know

frank killan30/09/2008 22:14:00
55 forum posts
Hi Andy,  I was refering to the 90 deg. knuckle joint and you are right I got theprice wrong I think I was confusing it with the manifold adaptors. I do know what you mean about the prices but I suppose some people are prepared to pay and thank them profusely  for the privelege.  Oh I know its a minority market and they have overheads but really.....                                 Good Luck.  Frank Killan
Bob Cotsford01/10/2008 11:22:00
8152 forum posts
449 photos

so how much labour do you think your £18-20 will pay for?   Remember this includes the cost of transporting it from Japan (or more likely China) and the cost of the UK supplier storing it until you want it.  

I know from experience it will take more than an hour for me to procure materials and tools, then make an equivalent adaptor, which probably wouldn't look or work as well as the commercial item.  It does seem expensive compared to mass produced items, but I don't think it's that overpriced for the convenience offered.

You want expensive, look what you get for your £100-200 or more car servicing bill!

Back to the original question, I think Mick Reeves sells all sorts of flexible metal exhaust tubes and adaptors, might be worth trying a Google for his web site.

andy watson01/10/2008 16:40:00
1942 forum posts
20 photos

I accept your argument to a degree Bob, but when the £20 price of a header pipe is compared to the price of a complete engine (£105) then there isn't really much argument about it being expensive.  Especially when the engine contains the same part (albeit at a different angle).

I was planning on ringing Mick Reeves tomorrow!

andy watson05/10/2008 18:56:00
1942 forum posts
20 photos

Bought a piece of flexible pipe for a fiver, which I will solder onto the screw fittings of the header pipe.

Got it from Mick Reeves

Steve Hargreaves - Moderator06/10/2008 11:14:00
6731 forum posts
191 photos

Silver solder I hope Andy.........soft solder will melt....

Or you could try Easyweld from Durafix here ......fantastic stuff. Have used it to fabricate an exhaust based on some B&Q ally tube & an aluminium box from Maplin....starter kits are just over a tenner & if I can use it anyone can!!!

Bob Cotsford06/10/2008 13:09:00
8152 forum posts
449 photos

Andy, I don't like the pricing on spares either, but the way I look at it is that manufacturing a production item on a machining/assembly line is cheap up until you need to change something in the production setup.  Hence SC/ASP engines are such excellent value as they are reported to be made on the same lines in the same factory and using the same machining process and materials.  I don't know what p[oduction volumes we're talking about, 1000s I'd bet rather than 100s.

Optional exhausts will always be made in much smaller batches, so more manual intervention is needed to set up the production run in comparison to the number of items produced. Even more importantly, tunrover of these items is lower making individual packaging, transport and storage relativeley more expensive.

If the item costs less than I could earn in overtime in the time it would take me to make an alternative, then to me it's worth buying, unless I really want to make it myself for kicks.

Dave C06/10/2008 14:34:00
2 forum posts

I recently built a Blackhorse Chipmunk with an FL 70. In order for the exhaust to fit in the cowl and exit underneath the fuselage I needed to replace  the exisiting manifold with a 90 degree knuckle. I purchased one from Just Engines and it was perfect. Quality and service excellent.  It solved my problem perfectly, well worth the price in my opinion. These are low volume high quality parts that when you consider the machining/labour costs involved is reasonably priced. Sure I could of done it cheaper if I wanted to spend the time and effort to cobble something together. The part provided a quick and neat solution that I'm more than happy with.

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