Other Airleak

jetfest

jetfest

Location
Prince George,BC
So i know i habe an airleak caused by the uncontrolable revving of my motor if i have 190 psi in both cylinders it means that the head cant be leakin righ and it has to be on the intake side of things i did notice when i pumped the primer lots fuel came out of the end of the shaft for the butterflys so maybe there but i just installed a primer kit and before i never had this problem and now i do so im wondering if that could have caused it i t'd the primer line on one of the fuel in lines is that correct. A side note is that i can clearly see air bubbles large ones in the fuel line so wondering if thats a problem and anytime i have the ski in water it wont rev past 3000 rpm before dying then as soon as its on the trailer and i start it it runs away on me very confused please help!!
 
Dustin Mustangs

Dustin Mustangs

uʍop ǝpıs dn
Location
Holland, MI
Cases dude! Prob where the two mate together or at one of the crank seals. Pump her up to 10 psi, spray it with soapy water and look for bubbles. Or just tear it down and put in new gaskets and seals cause that's likely what you'll have to do anyways.
 
jetfest

jetfest

Location
Prince George,BC
So do u mean where the jugs go onto the crank case and where can i buy a kit for doing a leakdown test and the crankseals u mean like the seals on the end of the crankshaft
 
jetfest

jetfest

Location
Prince George,BC
ya that would be awsome and if you have a list of the stuff i could buy cuz i would rather just go to the hardware store and purchase the parts than have to wait to get them shipped as summer is a very short season up here in canada. Thanks alot
 
jetfest

jetfest

Location
Prince George,BC
if anyone could help me with the building of this leakdown tester it would be awesome also with the carbs removed in order to do the test how can i tell if the leak is between the carbs and the intake manifold?
 
jetfest

jetfest

Location
Prince George,BC
also is there a certain gasket between the reeds and intake manifold i bought my reeds used and they did not come with a gasket so i am currently using a gasket the i got extra with my reed spacers i would put the stock metal one back in but the inside diameter of the gasket is much smaller than my new manifold kind of defeating the purpose of the larger manifold
 
Dustin Mustangs

Dustin Mustangs

uʍop ǝpıs dn
Location
Holland, MI
A leakdown tester is a pretty simple device and there are a number of different ways to make one. All you need is a controlled source of compressed air and a gauge to read what it's at. I use my air compressor and it's built in regulator. I've got something like this to hook up to it:

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I unscrewed the red hose just beneath the gauge and put on the second one shown here in palce of it:

651771_front200.jpg


You can find those available as an air compressor accessory. Then you can just hook that up to your pulse line and pump it up through that.

You will need to seal up your manifolds to do this. Intake somewhere before the carb, exhaust somewhere before the headpipe. I use sheet metal I cut to mimic the shape of the gasket I put it behind. Then I just torque the part down like normal. You can also find expandable rubber plugs used for plumbing to do this.

Do a search to find out more if you need, the info is out there. Also note this tester can be used for a number of different tests, like pop-off on carbs for example.
 
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A

aramis

Location
Rochester, NY
It sounds like your ski is running lean...but that does NOT necessarily mean an air leak. It could also be starving for fuel.

- do you have any pinched fuel lines?
- is the check valve on the tank working correctly (letting air into the tank)?
- did you recently open your carbs, and forget to put the clear diaphragm back into the fuel pump?
- are the jets clear?
- is the fuel petcock clogged?
- if you can get it to idle at all, did you try spraying a bit of ether near the crank seal and see if the ski revs up?

Those are the easy, quick things to try that I would do first...
 
jetfest

jetfest

Location
Prince George,BC
so i performed the leakdown test and after 6 minutes there was still roughly 2 psi of pressure in there so makes me think the leak cant be that bad i sprayed snoop a product designed to test for leaks and found a verysmall one on the reeds but not major so i tighted the intake down more one thing i did not do though was make sure the piston is a bdc not sure if that is to big of a concern as im sure it still will fill the crankcase full of air i was not able to check the crank seals though do i have to remove the flywheel cover in order to check the crank seal none of the fuel lines were pinched my tank is venting as i have a internal filler i pulled the cap off and no vaccum or nothing i rejetted the carbs before install and did not notice any clogged jets fuel petcock? not sure what this is but i did put a new needle and seat in the carbs prior to this and they were clear.any more suggestions
 
Dustin Mustangs

Dustin Mustangs

uʍop ǝpıs dn
Location
Holland, MI
You want to pump to just shy of 10pisi and see no more than 10% pressure drop over 10 minutes. Ideally you'll have none and that is typically what I shoot for when chasing a leak. A small one will not stay small for long so if you can find it, fix it. The flywheel cover should technically come off during this test but most don't do that.

So yeah, you got a pretty sizable leak going on there.

Oh, and no need to pinch fuel lines. Keep your spark plugs in, seal off the intake and exhaust, and plug the pulse line unless you are using that to pump through.
 
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jetfest

jetfest

Location
Prince George,BC
I found that on my carbs they were missing the seal at the end of the throttle shaft you can look straight down the shaft and see inside the carbs im guessing that cannot be helping at all?
 
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