Leak Down Test

[Strummer10]

Apologies, I know this thread has been covered in the past but just a few queries from my observations on testing yesterday. Sorry my first leak down test ever lol and it was a disaster lol....but unfortunately I'm looking to follow the new science we have all be landed with to ensure i'm 'leak free' :-

1/ I have a pressure kit with a scale that reads in mmhg, but anyone know what I should pressure the cylinder to in mmhg ? If i'm right I did it yesterday at 5 PSI (which google converted to 248 mmhg) ?

Should it be more ?

2/ What should the test duration time be and what is the accepted fall off in pressure ?

3/ Yesterday's test showed the spark plug was leaking. Is there any way of air tighting this ?

4/ With the mammoth head you cannot see the seal made to the cylinder head because it wraps around the cylinder, any thoughts on how to do this.....I could separately flood with soapy water as a separate test I guess and listen for the 'hissing'.

Thanks

[garry inglis]

hi strummer10 here is a pic of mine 5psi is fine make sure your piston is at bdc and leave it under pressure for 5 minutes you can have a slight drop but try for no leaks if you can't see the joint for the head you will here it if it's leaks

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[holty]

hi strummer,
i made my own leakdown test kit using a blood pressure kit just like you, a cheap way to make one, i built my last engine and used 3 bond on all gaskets apart from exhaust manifold on which i used exhaust silicone, and the head on which i used studlock, all new bearings and seals, at first it wouldnt hold pressure but i soon found the innertube i sealed the exhaust downpipe with was leaking, it was realy obvious as the needle dropped quickly, i fixed the tube better and no more leak, needle still dropping so out with the soapy water, i thought the mag flange or inlet manifold would be leaking but no, it turned out to be the spark plug just like yours, all i did was tighten it up a bit more and problem solved, needle stayed put, i left it for a few mins and was happy with that, them mmhg gauges are very sensative and any leak will be seen by the needle dropping, so fix your leak so needle dosnt drop and you will be fine, you could always use a new crush washer on your plug to see if it will stop the leak, if you stand your engine on its head you should be able to get your soapy water in behind the vanes to check for a head leak as well,
good luck,
holty

[Strummer10]

Cheers both..........Garry thanks for confirming the 5 PSI......incidentally it drops off within a minute and bottoms out to 40 mmhg.

Just changed the silent blocks on the engine case (another story, the engine bolt not greased and split rubbers on other silent blocks getting it out). I will now whip off the chaincase and flywheel next and give the leak test another go. I sealed the spark plug crush nut with red sealant (like you use for the engine gaskets from another post suggestion) and that seems to do the trick but the needle on testing kit is still dropping like before.

Incidentally i'm not using the bicycle inner tube method, although this does look more straightforwards. I got a proper kit for testing so wondering if i'm doing it properly firstly, its got a bulb and tube into the inlet (like Garry's in the photo above but has two ends to it) there is one end that goes to the inlet like Garry's and another section of the pipe goes to the pressure gauge. However, it must be working because when I put my finger over the valve hole on the internal face (where it would sit inside the inlet manfold rubber) the needle on the gauge doesn't move and I move my finger it drops.

[Muppet]

Cheers both..........Garry thanks for confirming the 5 PSI......incidentally it drops off within a minute and bottoms out to 40 mmhg.

Just changed the silent blocks on the engine case (another story, the engine bolt not greased and split rubbers on other silent blocks getting it out). I will now whip off the chaincase and flywheel next and give the leak test another go. I sealed the spark plug crush nut with red sealant (like you use for the engine gaskets from another post suggestion) and that seems to do the trick but the needle on testing kit is still dropping like before.

Incidentally i'm not using the bicycle inner tube method, although this does look more straightforwards. I got a proper kit for testing so wondering if i'm doing it properly firstly, its got a bulb and tube into the inlet (like Garry's in the photo above but has two ends to it) there is one end that goes to the inlet like Garry's and another section of the pipe goes to the pressure gauge. However, it must be working because when I put my finger over the valve hole on the internal face (where it would sit inside the inlet manfold rubber) the needle on the gauge doesn't move and I move my finger it drops.

pm sent

[holty]

I made my adaptor to fit in the inlet just like the one in Garry's picture, and I blocked the exhaust down pipe as I wanted to be sure the exhaust flange didn't leak as the port is quite large, I just stretched some inner tube over it and put a jubilee clip over it. If your needles still dropping it could be either drive side seal or flywheel side, I would check flywheel first as it's easier, if your using soapy water you should soon find the leak, mag housing inside and out and inlet manifold are prime leak areas, did you manage to test the head ?

[garry inglis]

As hotly says mag housing is probably the culprit I always seal that with three bond or any silicone based sealant try spraying around mag and centre seal around crank

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[Strummer10]

Cheers...........i gave up today, it can be deflating (excuse the pun). i will strip out the stator next and test the mag flange better.

Head's difficult to test, but sprayed where i could and no hissing, mind you, no hissing anywhere tbh....I used the red sealant (600 fahrenheit) stuff the mag flange gasket, aluminium base and head gaskets too......

IF i had stuck the engine straight into the bike i'm sure i would have ridden it for the next 5 years trouble free but with adopting the scientific approach i now feel compelled to get no leaks lol.


Garry i now know how you felt with the issues you had it can be quite negative which is why i pulled out the garage lol ........

Good thing is i noticed my first gear had a few chips on it (i think i left it like that) so thinking might change the box now. A question what's best touring box for TS1 225 (sure i might have asked before) and is it worth changing the now 47 years old layshaft and what's the best out there ?

[garry inglis]

its always best to have a brake you will suss it out next go lol on gearbox ive fit an italion li150 at 4.9 and its great but most go for gp200 indian because of the closer 3rd to 4th and even better is afs close ratio box on layshaft if there is nothing wrong with the threads use it as it will be better than whats out there i no casa has a new layshaft with more splinds

[Strummer10]

Garry.....yes came in, shower and dinner and a bit of TV whilst i ponder next moves. Will give it another go in the week, there's no rush. Yes i have an Li.box and do like the GP indian 200 one, got that one in my Avanti and nice ride.