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Old March 12th, 2019, 02:54 PM   #1
awiertalla
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Name: Andy
Location: Oakland
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Motorcycle(s): 07Ninja 250, 04 h.d dyna, 71 cb750, 78 bigbore 750(970cc), 67 cl125a, 78 ds100

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2over pistons, will not run!

The backstory:

A friend rode her 2007 ninja 300 miles, and at some point she dropped the bolt that holds the lower coolant pipe to the case, which case drained all the coolant. Brought it to me to fix, and I told her it was a complete rebuild and she sold me the bike for 100. Had 90psi on one side and 65 on the other

I bought a deal from my buddy who owns a reputable shop, 3 nonrunning ninjas and buckets of parts for 500.

I took a good head, lapped the valves and checked for leaks. I then bought new stock rings, and honed a set of cylinders and reassembled, and it would not run. It turned over and wanted to turn on, but to no avail. I pulled and cleaned the carbs (very clean already), tried again, and got nothing. Using a "new' gauge off amazon, got 30psi

I assumed the cylinders were out of round and was tired of messing with it, so I bought a set of 2 over weisco pistons, and had it professionally bored and honed to spec. I then blended the combustion chamber between the valves in order to allow for clearance of pistons. I reassembled, and I am at the same point, turns over, get some pops like it wants to run but it will not actually turn over. Using the "new" gauge off amazon, got 30psi again. I think I have a ****** tester, or there is something really wrong.

Valves are adjusted (I will double check this)
battery is charged
spark on both sides
in neutral, kickstand down
starter solenoid making noise and turning the motor over
new base and head gasket
New plugs

After all that, what are the thoughts? Could the CDI be fried after riding with no coolant? Is there a coolant switch or circuit that could be fried after riding with no coolant?
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Old March 12th, 2019, 08:11 PM   #2
Z1R rider
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You are holding the throttle wide open while compression testing I assume. Even with the throttle blades wide open the slides are still closed and it takes 10 or 15 seconds of cranking to get a good reading. If the reading is really that low, I'd guess the lap job isn't holding or cams are not timed correctly. Try holding the cylinders at TDC and blow compressed air into the cylinders through the sparkplug hole (leak down test) and hear were the air is escaping, into the crankcase (past rings) or the exhaust (past ex. valve)or the intake (past int. valve). If you are getting spark the ignition box is working.

PS: welcome to the site!
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Old March 12th, 2019, 09:36 PM   #3
DannoXYZ
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I assume cam-timing on each cam is correct?
I usually just pull carbs for compression-test as it's usually part of bigger project.
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Old March 13th, 2019, 05:44 PM   #4
awiertalla
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Quote:
Originally Posted by Z1R rider View Post
You are holding the throttle wide open while compression testing I assume. Even with the throttle blades wide open the slides are still closed and it takes 10 or 15 seconds of cranking to get a good reading. If the reading is really that low, I'd guess the lap job isn't holding or cams are not timed correctly. Try holding the cylinders at TDC and blow compressed air into the cylinders through the sparkplug hole (leak down test) and hear were the air is escaping, into the crankcase (past rings) or the exhaust (past ex. valve)or the intake (past int. valve). If you are getting spark the ignition box is working.

PS: welcome to the site!

I am not touching the throttle during compression test. Should I be?

As for the cams. I set the timing mark to #2 cylinder with the white mark on the rotor, intake cam lobes are upwards and facing the carbs, exhaust was facing up, but #2 cylinder valves slightly open, lines on both cams are parallel with the case (cam chain tensioner is installed for this). Am I missing something here?
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Old March 13th, 2019, 06:44 PM   #5
Z1R rider
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Yes you should hold the throttle wide open while doing a compression test. I can never remember exactly how to do the cam timing, don't do it often enough and have to look it up each time I need to do it. Here's a thread that goes into it, or Google is your friend.

https://www.ninjette.org/forums/show...ght=cam+timing
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