$25! Yikesā¦. but thats USD, equivalent to $120 CDN 
and it has longer hoses than mine.
and it has longer hoses than mine.
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Leak down test - stopping at TDC
- Thread starter bosco659
- Start date
they do tend to want to sit just a little way to one side. can't remember if it's before or after.Ponderin' a 360Ā° twin.... valve openings (cam) on the other cylinder might not allow you to set the crank on TDC.
Dunno.... never tried it. Now I'm curious.
Remember the compression numbers moving around at annual on an io360 but slowly dropping til I put in new Superior jugs. numbers still would move around a bit. shrug
Some coca chewin'... leak down test, why? Just polish.
Had an embarrassing mishap many years ago, so I follow this drill. Put the bike in gear, chock both wheels, lock the crank with a big old breaker bar braced against the floor, tie back the front brake lever, and run down the rear brake adjuster hard (drum type) or tie down the rear brake pedal (disc type). Overkill? Probably, but it's easily done. Don't worry about staying exactly on TDC, what counts is that the valves stay closed. You have some slack there, and you can get more by backing the valve adjusters off all the way.
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Thx for the advice. Iād rather go āoverkillā than have a mishap of my own. The bike is on a lift with the front wheel in a chock so the rear brake and breaker bar should be sufficient. Iāll post test results.
Got out to work on the bike today. First was a compression test. I was disappointed with the results as the right cylinder was 120 psi and the left 115 psi. When I picked the bike up both cylinders were 125 (using the poās tester). didnt get a chance to do a wet test with oil in the cylinders, maybe tomorrow.
Then came the leak down test. I used a breaker bar (holding the rotor nut) to hold the motor just past TDC and it worked perfectly. Kept it in gear with the rear brake on too. The right side tested at 8% leakage at 100 psi and the left 10%. It sounds like most of my loss is through the valves. Nothing seems to be leaking into the crankcase so rings might be ok. The reason for this test was to see if my head gasket had become compromised by the loose fasteners. Under full pressure (100 psi), I sprayed soapy water all around the gasket and no leaks were detected.
Even though the valves may need some attention, I think Iāll leave the motor in and keep an eye on it after a bit of run time and another head retorque.
Then came the leak down test. I used a breaker bar (holding the rotor nut) to hold the motor just past TDC and it worked perfectly. Kept it in gear with the rear brake on too. The right side tested at 8% leakage at 100 psi and the left 10%. It sounds like most of my loss is through the valves. Nothing seems to be leaking into the crankcase so rings might be ok. The reason for this test was to see if my head gasket had become compromised by the loose fasteners. Under full pressure (100 psi), I sprayed soapy water all around the gasket and no leaks were detected.
Even though the valves may need some attention, I think Iāll leave the motor in and keep an eye on it after a bit of run time and another head retorque.
Well done!
You've made a good decision, bosco. 10% or less is the standard for street motors, so yours ain't broke and doesn't need fixing.
Thx grizld1. Really didnāt want to pull the engine if I didnāt have to. Itās just a second bike so if it runs ok, thatās good for me.
How many miles you put on it so far?
Iāve only run the engine 10 minutes tops. Rebuild was done over 3 years ago (2 p.o. ago). The guy I bought it from never rode it or ran the engine. Considering how loose the head was, if it had been run, the engine would have been soaked in oil. Motor was clean as a whistle and the guy I bought it from never cleaned it.
Cool do all the usual checks and ride it for at least a couple hundred, Well you know come spring. LOL
Don't be too concerned about those compression numbers. Compression readings will be much higher on a warm engine, and they'll probably rise even more with some use.
With the amount of time it's been sitting; I might be tempted to use a chemical crutch, spray some pb blaster in cylinders, valve spring areas.
