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Leakdown Tester


docjcwatson

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Tell you guys what...

I just got one from my buddy at RB Racing, and I found leaks I didn't know I had.

The intakes were leaking were the rubber meets the metal.

I don't know if they just started, or possibly were leaking all last year....

 

These kits are absolutely worth their price in gold...fo sho.....

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in regards to the 2 into one question, this is the type of guage i use for my leakdown tester.

 

Gas_Test_Pressure_Gauge.jpg

 

it gets rid of the seperated pressure side and guage side issue. you can use a 3/4" thread by 3/4" slip (1" outer diameter) fitting for a stock intake. i also use a short piece of 3/4" pvc with a 3/4" pvc cap (1" outer) to plug the opposite side. for a 2 into one you need to use a 3/4" thread by (i wanna say) 1" slip. i'd have to go to the shop to confirm this.

 

as for the cleaning the exhaust port to keep the plugs in, i've had problems before with shoddy port work and carbon build up leading to leaks at the exhaust ports so i've went to using a trick i learned a while ago...

 

if you have access to a pair of stock front rubber hub caps you can slip them over your exhaust ports and use a couple hose clamps to clamp them down. if you dont have access to a set of hub covers then you can always get a pair of rubber fernco caps that work just as well.

 

61014090.jpg

 

these are just the methods i use myself, i thought it might give everyone else some ideas of different ways to go about doing your leakdown test....

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i lied...

 

i looked at my set today while doing a leakdown on a 2-1 setup.

 

i'm using a 3/4" thread by 1"slip with a 1" coupling (so like 1 1/4") to go into the intake for the 2-1

 

for stock i'm using a 3/4" thread by 1" slip to go into the intake...

 

some crappy phone pics of my set up for a 2-1...

 

56dba906.jpg

a83b099f.jpg

2a1397f8.jpg

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  • 1 month later...

6 pounds in 6 mins.

just a few ???'s

 

Does it matter were the pistons sit in the cylinder I.E. top or bottom dead center?

Should i perform the tesk with the tranny fluid drained? Well i guess the tranny seperate so that dont matter.

Also DONT put more then 6 pounds yes?

I have a 1978 yz250 i just got all my final gaskets im going to put them in and am going to do a test. Is 6 pounds a good number for this motor? It is only one cylinder and only a 250cc.

 

After i perorm leakdown tests on by shee and the 250 i want to do compression test i have the guage with the correct sparg plug thread hose, does anyone know the prpoer way to do the test/or know a link? I test the shee cylinders seperate yes? If the cyclinders areant seperate via the crank how will the comp test read per cylinder? and for the single cylinder how many times to turn it over?

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6psi for 6 min is the recommended test.

 

For compression, take out both plugs, turn ignition and gas off, hold the throttle wide open and kick until the gauge quits climbing.

 

 

sounds good.

6psi for single cylinder?(all engines?, i have klx110 and eventually ill test it)

Just kick until stops climbing 3 kicks or 12 kicks it wont matter?

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kick it over till it doesnt climb anymore. If you are not sure it's done climbing, kick it over some more. You wont hurt it.

For stock carb intakes I use 1" Sch 40 PVC pipe.

I measured mine today. The ID of my stock rubber intake boots were about 1 7/16".

Edited by RagunCajun
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  • 1 month later...

Are the reeds in when you do this? If you have the pressure tap in one intake and the gauge on the other, The reed valve should stop the air from entering into the other intake boot right? That is what a reed valve is a one way check valve?

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  • 3 weeks later...

what do you guys do if you find a leak??

 

i have all brand new gaskets all torqued correctly and am going to do the leakdown test tomorrow.

 

was just thinking if i find leaks do i then take it off and add some high heat gasket silicon between the gasket to seal it properly??

 

what are your reccomendations to fix an air leak?

 

sorry if its a silly question, was just wondering how to correct the air leak without over torquing the bolts.

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If your bolts and gasket were properly installed to Yamaha's specs. You shouldn't find any leaks.

 

Over tightening the bolts will get it to pass the leakdown test, but will later on cause more problems.

 

If you find a leak coming from the cases, then you will have to take it back apart. (Your leakdown SHOULD be done with both side covers off. That way you can see if you have a case leak.) If the leak is in your intakes, you might get away with some RTV. If the leak is in your tester (Very common), just use some more Yamabond to seal the caps.

 

So, I guess to answer the question...It depends on where the leak is.

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If your bolts and gasket were properly installed to Yamaha's specs. You shouldn't find any leaks.

 

Over tightening the bolts will get it to pass the leakdown test, but will later on cause more problems.

 

If you find a leak coming from the cases, then you will have to take it back apart. (Your leakdown SHOULD be done with both side covers off. That way you can see if you have a case leak.) If the leak is in your intakes, you might get away with some RTV. If the leak is in your tester (Very common), just use some more Yamabond to seal the caps.

 

So, I guess to answer the question...It depends on where the leak is.

 

 

thanks man!

 

i will let you know how it goes. tester is made, i just need to get the freezer plugs or something to seal the exhaust side.

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  • 3 weeks later...

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