Leak down test

7 replies to this topic
  • kijen

Posted November 20, 2012 - 05:35 AM


Ok, I'm building a leak down tester, and I have read the many posts about them, but what are you guys using to plug the exhaust port? the 99-13 YZ250's have a weird shape and I'm not sure the plugs everyone else is using on the CR's and KX's will work, thinking of a cap vice a plug, so what do you guys use?


  • rjpjnk

Posted November 20, 2012 - 06:35 AM


On my 125 I used an expandable plug from an auto parts store. It looks like a big rubber cork with a bolt in the middle to squish it and make it expand. They sell many different sizes. Not sure what they are called or what their intended use is, but they make perfect exhaust port stuffers. :thumbsup:

  • GMO397

Posted November 20, 2012 - 09:22 AM


Just buy a rubber pipe cap with hose clamp. Slips over the exhaust flange like the exhaust does, tightens down with the hose clamp. Doesn't need to be much, leakdown shouldn't go over 8 psi.

  • kan3

Posted November 20, 2012 - 09:24 AM


Not sure what they are called or what their intended use is, but they make perfect exhaust port stuffers. :thumbsup:

Expansion plug

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  • GCannon

Posted November 20, 2012 - 10:43 AM


Check the size you need and get one of these
I picked one up at the local Hardware store

  • kijen

Posted November 20, 2012 - 10:54 AM


yep cap makes sense...thanks for the replies...

  • BDubb106

Posted November 20, 2012 - 04:42 PM


Another vote for the expansion plug... be sure to post back with results for your test.

  • pk6n

Posted November 20, 2012 - 05:17 PM


You can't use an expansion plug in a newer bike. the exhaust port is oddly shaped(like stated). I used a 2 inch rubber plug for sewer pipes. I think an 1 3/4 might fit better but the 2" still did the job. On the intake I used a 1 1/4 X 3/4 pvc bushing. Wrapped it with a few layers of eletrical tape and it fit perfect. Then I just got a gas pressure tester. 3/4 female by male adapter, a 3/4 45 and a stick of 3/4 pipe( best if you have a small piece laying around). Glue it all together and use Teflon on the threads.

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