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thejaredhuang · August 17th, 2015, 11:57 AM

Story:
Bought the bike with a seized engine. I put a ratchet on it and got it to spin relatively easily. Cleaned the carbs and it just barely started but wouldn't idle without full throttle. It had low compression in the cylinder #2 and an exhaust leak I don't remember if it had the same metallic sound.

I dropped the engine to check the piston ring gaps. The bores looked fine, ring gap was a little loose but well within tolerance. valves did not leak, basically nothing was wrong with it when i opened it up. I only got it down to pulling the barrels off I did not check the crank or con rods. Put it back together and checked the timing and it will start it right away but with this horrible sound. It is firing on both cylinders but the cylinder block around #1 is very hot compared to cylinder #2. I tried unplugging one of the coils but the engine will not idle with either one of the coils unplugged.

The engine will rev a little and the tapping noise gets faster. I've adjusted the cam chain tensioner and it wasn't any better. The engine will easily idle for a long time but I've only had it running for 20 seconds due to the sound.

Video 1:
http://youtu.be/8YUr1axV1IA

Video 2, little more accurate sound:
http://youtu.be/NJunGAX8ISI

Video 3, best sound:
http://youtu.be/Aet5jdHYrvc

August 17th, 2015, 11:57 AM	#1
thejaredhuang ninjette.org member Name: Jared Location: Socal Join Date: Sep 2012 Motorcycle(s): none yet Posts: 37	Help diagnosing metallic sound Story: Bought the bike with a seized engine. I put a ratchet on it and got it to spin relatively easily. Cleaned the carbs and it just barely started but wouldn't idle without full throttle. It had low compression in the cylinder #2 and an exhaust leak I don't remember if it had the same metallic sound. I dropped the engine to check the piston ring gaps. The bores looked fine, ring gap was a little loose but well within tolerance. valves did not leak, basically nothing was wrong with it when i opened it up. I only got it down to pulling the barrels off I did not check the crank or con rods. Put it back together and checked the timing and it will start it right away but with this horrible sound. It is firing on both cylinders but the cylinder block around #1 is very hot compared to cylinder #2. I tried unplugging one of the coils but the engine will not idle with either one of the coils unplugged. The engine will rev a little and the tapping noise gets faster. I've adjusted the cam chain tensioner and it wasn't any better. The engine will easily idle for a long time but I've only had it running for 20 seconds due to the sound. Video 1: http://youtu.be/8YUr1axV1IA Video 2, little more accurate sound: http://youtu.be/NJunGAX8ISI Video 3, best sound: http://youtu.be/Aet5jdHYrvc Last futzed with by thejaredhuang; August 18th, 2015 at 09:41 PM.