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Pressure testing a 2 stroke engine


Airhead
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It is important that a two stroke engine is pressure tight and to check my DT175MX I made a a test rig and did some testing today. This is the test rig I made, it fits nicely in the inlet manifold where the reed valve is,

EngineLeakdownTester_1.jpg

So I removed the silencer and blocked off the exhaust using the original connecting rubber from exaust to silencer, I bunged the end up using a copper piping stop end.

100_0767.jpg

and then fitted the test rig into the manifold and pumped the engine and exhaust to 10 psi

100_0766.jpg

And bugger...it leaks

so the only place I can test is the right hand crank seal, to test this one put the engine breather pipe in some water

100_0769.jpg

No bubbles here so the leak is elsewhere, It could be on my blanked off exhaust, the exhaust manifold, cyl head or base joint, my test rig, inlet manifold or left crank seal.

All I know is it drops from 10psi to 5psi in just over 3 mins, so I'm going to have to get some leak detector spray, I suppose I could use soapy water but I have the real thing at work so abandoned the job for now.... :)

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Impressive. I would be too worried to do anything like that with mine at the moment.

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orrr it mght grow to be a 250... :D

now your "over boring" us :lol:

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now your "over boring" us :lol:

Haha prepare for som more boredom!

Well i got the soapy spray and found a leak at the end of the exhaust, I hadnt made a good enough job here

AirLeak1.jpg

So having cured that one I soon found another at the intake manifold,

AirLeak2.jpg

these things have an in-built O ring that has become a bit flattened after its 30 ish years of life, so having priced one up at £48 (Thats not dear...said the man at Granby's) I decided to buy some silicone gasket goo from my local car spares shop...£5.00 . A ring of the stuff around the manifold and hey presto, my engine is air tight, held 10 psi forever. Peace of mind if nothing else, i had the engine completely in bits not too long ago so it had new crankshaft seals which are obviously good but now I know that the crancase halves are sealed well too, ..

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Haha prepare for som more boredom!

Well i got the soapy spray and found a leak at the end of the exhaust, I hadnt made a good enough job here

AirLeak1.jpg

So having cured that one I soon found another at the intake manifold,

AirLeak2.jpg

these things have an in-built O ring that has become a bit flattened after its 30 ish years of life, so having priced one up at £48 (Thats not dear...said the man at Granby's) I decided to buy some silicone gasket goo from my local car spares shop...£5.00 . A ring of the stuff around the manifold and hey presto, my engine is air tight, held 10 psi forever. Peace of mind if nothing else, i had the engine completely in bits not too long ago so it had new crankshaft seals which are obviously good but now I know that the crancase halves are sealed well too, ..

The killer question OG, does she run any better now you have got rid of the leak at the manifold. Thats a bit of a critical one.

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The killer question OG, does she run any better now you have got rid of the leak at the manifold. Thats a bit of a critical one.

Thats a good one, I dunno yet havent started her up let alone been out, The wifey is in bed been on nights, also havent ridden this thing for almost a year now so ive forgot how it was anyhow...And Ive thoroughly cleaned and re built my carb so that might also make some difference... :rolleyes:

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also havent ridden this thing for almost a year

Shame on you........

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cheeky old bugger! :P

... swap it for a Jawa? :D

Thats like swapping a meal at the Ritz in Mayfair with all the trimmings for a Kebab with salad.

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