Help diagnosing metallic sound

[thejaredhuang]

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

[Ghostt]

Sounds like a valve adjustment, and also I noticed a manual cam chain tensioner, which is probably not adjusted properly.

Personally get rid of the manual tensioner, and double check the valve adjustment.

[thejaredhuang]

Originally Posted by Ghostt

Sounds like a valve adjustment, and also I noticed a manual cam chain tensioner, which is probably not adjusted properly.

Personally get rid of the manual tensioner, and double check the valve adjustment.

Thanks for the suggestion on the valves, I will recheck it today.

I've cracked 2 OEM cam chain tensioners probably due to my fault. I do not like the design of them OEM one though and I'm going to stick the manual one. I know what an improperly adjusted one sounds like and I'm sure this one is adjusted adequately for now.

[Ghostt]

Originally Posted by thejaredhuang

Thanks for the suggestion on the valves, I will recheck it today.

I've cracked 2 OEM cam chain tensioners probably due to my fault. I do not like the design of them OEM one though and I'm going to stick the manual one. I know what an improperly adjusted one sounds like and I'm sure this one is adjusted adequately for now.

How did you break two OEM cam adjuster

I'm not a big fan of manual adjuster for common street use, track use only maybe? Often times people over tighten. True you should rebuild OEM adjuster every so often, but it's a self adjusting unit.

But if you know how to adjust it properly then it's all good.

When adjusting the valves make sure your using the proper scale mm or inches

How to mess up your valve adjustment[edit]

There are two main ways that the Ninja 250 valve adjustment gets screwed up:

Wrong feeler gauge size[edit]
Some people make the mistake of using standard (inch) .10 gauges in the mistaken notion that that's what is called for. One quick way to tell if the gauges you are using are the proper ones is if the gauge is as thin as a piece of paper. If it's as thick as a dime, that's the wrong size.

Measuring the gap when the cam lobes are actuating the valves[edit]
What happens is that you align the timing mark on the crank, and then take the measurement, or try, and don't realise that the cam lobe is currently pushing the rocker arm down onto the valve. There is no clearance at this point. You need to turn the engine one more full turn until the mark lines up again, and the cam lobe isn't touching the rocker arm.

Basically, the engine is in the proper position when the exhaust (front wheel side) cam lobe is pointing toward the triple clamps, and the intake (rear wheel side) cam lobe is pointing towards the rear seat. That's when you can take the measurement on that cylinder.

Remember, you need to rotate the engine again when you are lining up the other cylinder. You can't do both cylinders without rotating the engine at least once.

http://faq.ninja250.org/wiki/How_do_..._the_valves%3F

http://faq.ninja250.org/wiki/What_is...t_procedure%3F

http://faq.ninja250.org/wiki/Hints_%...lve_Adjustment

Also if your planning on keeping the Ninjette for awhile I recommend picking up the Kawasaki tool, I found one on eBay for less than $20.00

http://faq.ninja250.org/wiki/Is_ther...this_easier%3F

[thejaredhuang]

Originally Posted by Ghostt

How did you break two OEM cam adjuster

I'm not a big fan of manual adjuster for common street use, track use only maybe? True you should rebuild OEM adjuster every so often, but it's a self adjusting unit.

But if you know how to adjust it properly then it's all good.

When adjusting the valves make sure your using the proper scale mm or inches



http://faq.ninja250.org/wiki/How_do_..._the_valves%3F

http://faq.ninja250.org/wiki/What_is...t_procedure%3F

http://faq.ninja250.org/wiki/Hints_%...lve_Adjustment

I didn't have the adjuster seated all the way before I started to tighten the bolts that go into the case. The tensioner housing cracked on the aluminum part that holds the tapered tube.

I'm using .003in for intake and .004in for exhaust. I'll update hopefully tonight.

On a side note I listened to the video and it sounds different in person. In the video it sounds high and light but in person its lower and louder. Its almost like a hammer hitting metal.

Thanks for the suggestion Ghost, I'm doing just fine with a screw driver and socket though and I'm trying to save $$$ for other projects.

[Ghostt]

It's worth checking into, just in case, and helps eliminate a variable.

The factory clearance specifications are .08 - .13mm (0.003-0.005 inches) for the intake valves and .11 - .16mm (0.004-0.006 inches) for the exhaust valves. It is easy to accidentally use an inch gauge instead of a mm gauge, so make doubly sure you're looking at the right numbers. The feelers should be thin and flexible, not thick and stiff.

Also if your need of carburetor services PM @ducatiman

Custom Carb Service

Ducatiman Carb Service

[thejaredhuang]

Checked the timing and valves. Intake cam was off by one tooth, cylinder #2 exhaust valves were a little loose. Put it back together and it sounds almost the same.

New video below, I think the sound is more accurate on this video. Beware of the first 3 seconds the starter sound is kind of surprising. It sounds a little bit like an exhaust leak but I'm pretty sure it isn't.

http://youtu.be/NJunGAX8ISI

[thejaredhuang]

Just recorded a new video, the sound is pretty spot on in it. Any suggestions or ideas are welcome.

http://youtu.be/Aet5jdHYrvc

[choneofakind]

Grab a piece of vinyl tubing that's pretty good sized and start listening around the bike to isolate where the noise is coming from.