June 5th, 2015, 03:23 PM | #1 |
ninjette.org newbie
Name: br1ckd
Location: Hawaii
Join Date: May 2015 Motorcycle(s): 07 EX250 Posts: 6
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Damage from loose cam chain?
Last weekend my 07 EX250 started making a lot of noise. I figured out the cam chain was really loose and I was able to tighten it by resetting the CCT. I also checked the cam timing and it looks like it didn't jump a tooth. It's still making some noise around 5k rpm, though, and I'm having trouble starting it and it won't idle (the RPMs slowly drop until it shuts off). I just did a compression test and only got about 90psi in each cylinder, but when I put some oil in the cylinder I got about 140psi. This probably isn't related, but I adjusted the valves a couple weeks ago and did a bench sync on the carbs (I tried to do a dynamic sync but wasn't very careful and had to do a bench sync just to get the bike to start again, and never got around to doing a dynamic sync again).
Here's a video of the sound it was making before I cleaned and reset the CCT: https://drive.google.com/file/d/0B2n...ew?usp=sharing Here's a video of how it sounds now: https://drive.google.com/file/d/0B2n...ew?usp=sharing Edit: When I did the compression test I let it crank 4-5 times, and had a spark plug in the other cylinder (disconnected from the coil). Last futzed with by br1ckd; June 7th, 2015 at 04:03 PM. Reason: fixed video link |
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June 7th, 2015, 10:08 AM | #2 |
CPT Falcon
Name: J.Emmett Turner
Location: Newnan, GA
Join Date: Apr 2009 Motorcycle(s): '08 CP Blue EX250J, '97 unpainted EX250F, 2nd '97 unpainted EX250F (no engine), '07 black EX250F Posts: A lot.
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Second link appears to be just a picture. My J-bike makes a sound like this until I reset the tensioner but it keeps coming back. I'm pretty sure I need a new tensioner.
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June 7th, 2015, 02:44 PM | #3 |
Daily Ninjette rider
Name: Hernan
Location: Florida
Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot.
MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16
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Welcome, br1ckd !!!
I see that you have three different issues ............ or just one producing three related symptoms: 1) Noisy cam chain. 2) Difficult start / excessively low idle. 3) Low compression results. Did all those manifested at once? Have you been feeling reduced power? Did you fully open the throttle for the compression tests?
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Motofool .................................Never ride faster than your guardian angel can fly "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí |
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June 7th, 2015, 04:11 PM | #4 | ||
ninjette.org newbie
Name: br1ckd
Location: Hawaii
Join Date: May 2015 Motorcycle(s): 07 EX250 Posts: 6
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Quote:
Quote:
I had almost no power when the CCT was really loose. I've only ridden it up the street and didn't get the engine above ~6k RPM since I tightened the chain, so I'm not sure if it's got less power than before the chain got really loose. I forgot to open the throttle when I did the test, I'll redo them with the throttle open. |
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June 9th, 2015, 08:40 PM | #5 | |
ninjette.org newbie
Name: br1ckd
Location: Hawaii
Join Date: May 2015 Motorcycle(s): 07 EX250 Posts: 6
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Quote:
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June 9th, 2015, 08:58 PM | #6 | |
Daily Ninjette rider
Name: Hernan
Location: Florida
Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot.
MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16
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Quote:
The compression test with oil indicates that the rings are worn; unless you have used too much oil and the chamber volume has been reduced much. If that is the case, you have low compression with or without oil helping seal the rings. If that is the case, the low compression reading may be due to a leaking valve. This is how to test that: http://www.dansmc.com/leakdown.htm If positive, the leak may be due to the cams being out of synch with the piston due to a jumping cam chain. The tensioner's spring is not strong enough to keep the chain with no slack during the four cycles, it needs the help of the the one-way ratcheting mechanism. If the balls are not perfectly round, the mechanism may go back enough to induce slack: http://faq.ninja250.org/wiki/Cam_cha...sioner_removal
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Motofool .................................Never ride faster than your guardian angel can fly "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí |
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June 9th, 2015, 09:08 PM | #7 |
Down Under
Name: Linkin
Location: Sydney, Australia
Join Date: Jun 2014 Motorcycle(s): Kawasaki ZXR250C Ninja Posts: 296
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Higher compression when you squirt oil into the cylinders means that you need new piston rings, or the piston ring end gap have all been lined up straight. Ideally all the end gaps should be 120 degrees apart from each other.
As for the cam chain and tensioner. Reset the tensioner and then reinstall it. Run the bike, then check how far the tensioner extended. If it extended all the way and the bike is noisy, you need a new cam chain. While doing all this, you should check the valve clearances and change any shims that are out of spec. |
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