Sasha Rudolfski

Leak down test questions

16 posts in this topic

I want to do a leak down test to verify all is well with the top end on DRZ.  The instructions on TT by Erik Marquez say to hold the engine at TDC I can use a flywheel holding tool.  Can I put the bike in 5th gear to hold engine at TDC?  There must be a reason the instructions said to use a flywheel holding tool - but I would like to know why before I go out and buy one.  Thanks!  

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I want to do a leak down test to verify all is well with the top end on DRZ.  The instructions on TT by Erik Marquez say to hold the engine at TDC I can use a flywheel holding tool.  Can I put the bike in 5th gear to hold engine at TDC?  There must be a reason the instructions said to use a flywheel holding tool - but I would like to know why before I go out and buy one.  Thanks!  

You need to hold the flywheel so the crank doesn’t move when you pressurize the top end.putting in 5th wont work.i use a breaker bar on the crank nut.

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Just now, mickeydee said:


You need to hole the flywheel so the crank doesn’t move when you pressurize the top end.putting in 5th wont work.i use a breaker bar on the crank nut.

Why do you use a breaker bar instead of flywheel tool?  Do I have to further disassemble to use flywheel tool or only need to remove the inspection plug and crank plug to use flywheel tool?

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Why do you use a breaker bar instead of flywheel tool?  Do I have to further disassemble to use flywheel tool or only need to remove the inspection plug and crank plug to use flywheel tool?

Using a flywheel tool you have to remove the flywheel cover.using a breaker bar and 17mm deep socket, all you have to do is remove the generator plug.
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What method do u use to hold the breaker bar in place at TDC?  Do you physically hold it or just place it on the ground so that it can't move?
I've done it without a tool, but you have to get it at perfect tdc, took me a few tries, but it will hold on it's own if it's perfect.

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What method do u use to hold the breaker bar in place at TDC?  Do you physically hold it or just place it on the ground so that it can't move?

Either I tie the breaker bar to the foot peg or have someone hold the breaker bar

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18 hours ago, Sasha Rudolfski said:

I want to do a leak down test to verify all is well with the top end on DRZ.  The instructions on TT by Erik Marquez say to hold the engine at TDC I can use a flywheel holding tool.  Can I put the bike in 5th gear to hold engine at TDC?  There must be a reason the instructions said to use a flywheel holding tool - but I would like to know why before I go out and buy one.  Thanks!  

You can use the flywheel bolt, IF you have the crank at least a degree or two past TDC, so that air pressure in the cylinder is trying to push the piston down, and crank normal rotation direction.
If you have the piston before TDC or even dead on at TDC the crank is likely to rotate backwards and the torque of the crank spinning backwards and your breaker bar/ socket holding the bolt in place,,,,will loosen the flywheel bolt.

If you don't want to risk loosening the flywheel bolt, you can remove the stator cover, and use a flywheel holding tool as described in the article.

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9 minutes ago, Erik Marquez said:

You can use the rotor holding nut, IF you have the crank at least a degree or two past TDC, so that air pressure in the cylinder is truing to push the piston done, crank normal rotation, ..if you have the piston before TDC or even dead on at TDC the crank is likely to rotate backwards and the tq will loosen the rotor bolt.

 

If you don't want to risk loosening the rotor bolt, you can remove the stator cover, and use a flywheel holding tool as described in the article.

Thanks for the details.  Can you send a link or details about what flywheel holding tool you're talking about?

Removing the cover on that side require new gasket? I have a spare.for the clutch side but not the stator side...

Edited by Sasha Rudolfski

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28 minutes ago, Sasha Rudolfski said:

Thanks for the details.  Can you send a link or details about what flywheel holding tool you're talking about?

Removing the cover on that side require new gasket? I have a spare.for the clutch side but not the stator side...

Stator side is almost always reusable, it is a fiber and metal sandwich

Tool is in the FAQ

 

 

 

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The tool in the FAQ - how is that being held in place - by hand physically? or one end on the cast hex and other end on the floor?  Will a double deep offset wrench 26mm fit like the custom made tool in the FAQ?  I have butane torch but no vise to hold the wrench while heating and bending.  I really want to get this test done but have to postpone until I can properly hold the flywheel in place with engine at TDC.  I am trying to figure something out to be able to get it done by tomorrow.  Also I would really like to be able to confirm TDC and hold it there in the future so trying to get the right tools and method so that I can repeat when necessary...Thanks for all the help!

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I've allways used a breaker bar on the flywheel nuts/bolts though the center plug with a breaker bar tied to the footpeg ,never had a nut/bolt come loose . Turning the air pressure up gradually helps but it doesn't put enough pressure to break one loose .

 

 

.

Edited by jjktmrider

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9 hours ago, Sasha Rudolfski said:

The tool in the FAQ - how is that being held in place - by hand physically? or one end on the cast hex and other end on the floor?  Will a double deep offset wrench 26mm fit like the custom made tool in the FAQ?  I have butane torch but no vise to hold the wrench while heating and bending.  I really want to get this test done but have to postpone until I can properly hold the flywheel in place with engine at TDC.  I am trying to figure something out to be able to get it done by tomorrow.  Also I would really like to be able to confirm TDC and hold it there in the future so trying to get the right tools and method so that I can repeat when necessary...Thanks for all the help!

Holding the end of the rotor holding tool is limited only by your imagination.  If the motor is on my bench, then the tool end is resting on the bench.
If the motor is in the frame I use the foot peg to hold the tool end. 
I rarely use the rotor holding tool when doing a leakdown.... only if the flywheel is not on the motor.
To lock the crank for leak down testing I use the flywheel bolt, have the crank a few deg past TDC (as long as all 4 valves are closed it does not matter on crank position) I use a 3/8"  breaker bar and socket on the flywheel bolt and put the end of the breaker bar on the foot peg.

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8 hours ago, jjktmrider said:

I've allways used a breaker bar on the flywheel nuts/bolts though the center plug with a breaker bar tied to the footpeg ,never had a nut/bolt come loose . Turning the air pressure up gradually helps but it doesn't put enough pressure to break one loose .

Then you have been lucky is all.
There is more then enough TQ from the crank with 100PSI cylinder pressure to loosen a flywheel bolt...

And yes, like you suggest, add pressure slowly no matter how your holding the crank... good idea.

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9 hours ago, Sasha Rudolfski said:

 I have butane torch but no vise to hold the wrench while heating and bending.

Then skip the custom tool and use the flywheel bolt.... just have the crank past TDC a few deg..... anything past TDC will work for the tool and a few deg past TDC , the valves are still closed so no issue with the leakdown test

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2 hours ago, Erik Marquez said:

Then skip the custom tool and use the flywheel bolt.... just have the crank past TDC a few deg..... anything past TDC will work for the tool and a few deg past TDC , the valves are still closed so no issue with the leakdown test

Please bare with me, I open the crankcase inspection plug, and the timing window.  Use a socket and breaker bar to turn the crank (CCW) a few degrees past TDC.  Cam lobes a few degrees past 10 and 2.  

When I apply pressure thru leak down tester / air compressor compressor the breaker bar which is resting on the foot peg will stop the motor from turning?   

Using this method am I risking loosening the flywheel bolt?

My compressor is rated at 90psi - will that suffice?  

Should I be using an in-line water/oil filter on the air line or not necessary? 

I appreciate your patience and thanks for taking the time to help!

 

Edited by Sasha Rudolfski

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