Piston knocking sound after break-in

[kobermeyer]

Just drove a new 150cc single cylinder out of the shop- warmed it up first, drove it pretty slow in 1 and 2 gear around a few blocks, cooled down for 15 minutes or so and then took it outta town for 40km, varied gears between 2-4 a lot and gave it some 1/2, 3/4 and almost full throttle for a few seconds with down-shfting. Up to 80kmh max. in 4th gear, maybe 60kmh in 3rd. About half way home I noticed a knocking/clacking sound and thought it might be a bolt or something that didn't get tightened. When I got home, I gave it a close look/listen and it sounds pretty much like its coming from the engine. It happens at idle and every rpm. Seems to run well, but sounds not awesome. This is basically my first bike and I'm not a mechanic. Could this be from riding it too hard at the beginning? Everything I've read points to "no", but I'm still worried that I f-ed it up. It's got a 1 year warranty, but I can see them in the shop givin' me a hell of a time. Any advice, suggestions, what to check, would be greatly appreciated?

[SlickSix]

I don´t see anything wrong with your initial break.

Can you make a visual check of your engine oil?
If it came low from the factory, it can make the engine knock.

Is the gas around there of good quality? You might be hearing some pre detonation.

[Mongle]

Originally Posted by kobermeyer

Just drove a new 150cc single cylinder out of the shop- warmed it up first, drove it pretty slow in 1 and 2 gear around a few blocks, cooled down for 15 minutes or so and then took it outta town for 40km, varied gears between 2-4 a lot and gave it some 1/2, 3/4 and almost full throttle for a few seconds with down-shfting. Up to 80kmh max. in 4th gear, maybe 60kmh in 3rd. About half way home I noticed a knocking/clacking sound and thought it might be a bolt or something that didn't get tightened. When I got home, I gave it a close look/listen and it sounds pretty much like its coming from the engine. It happens at idle and every rpm. Seems to run well, but sounds not awesome. This is basically my first bike and I'm not a mechanic. Could this be from riding it too hard at the beginning? Everything I've read points to "no", but I'm still worried that I f-ed it up. It's got a 1 year warranty, but I can see them in the shop givin' me a hell of a time. Any advice, suggestions, what to check, would be greatly appreciated?

Hard to diagnose a noise over the internet...


I would start at the exhaust..make sure all bolts and fittings are tight. An exhaust leak can sound like a knock under some conditions.

After that...well, I would take it back to the shop and just give them the "whats going on here" and see what they say. Most manufacturers reccomend keeping the bike under a specific rpm for 500-1000 miles. I don't know about your bike. I will say if the engine is 'right' what you did should not have hurt it.

[mcma111]

Got Oil??

[mamm]

Well, it may be your first bike but you already did a great job breaking it in (you did what I do to my new bikes/cars, always with good results: lots of pressure on the rings, both accelerating and decelerating). So don't worry about the break-in procedure.

Which bike? OHV, SOHC or DOHC engine? Sometimes they have very distinctive valve/cam sounds.

Did the shop tightened all the right bolts in the pre-delivery inspection?

Did you listened to a similar bike to see if "they all do that"?

[kubiak]

i had a brand new 06 yamaha xt225 that did the same thing and i broke it in easy. it had a noise that sounded like piston slap at lower rpms. i sold it with about 1,000 miles and it always made that noise but ran great.

[cyclewizard]

Originally Posted by mcma111

Got Oil??

x2....check oil level.

[Attico]

For the si,plicity of the conversatio at the dealer, just tell them you followed the break in instructions from the manual. If you give them an out, they'll usually take it.

Might be normal. Check around. Ride it for a while. Change the break in oil at the latest according to the manual. If they say 1000miles, change it before. Keep receipts or have the dealer do it. Changing it too early sometimes isn't better either because of the zinc in some break in oils.

Check with the dealer if it is on your mind...hell you have a waranty....use it.

[mamm]

Originally Posted by Attico

For the si,plicity of the conversatio at the dealer, just tell them you followed the break in instructions from the manual. If you give them an out, they'll usually take it.

GREAT reminder!

[ping]

My bike dealer told me " the first 600 miles , use low r.p.m. , do not go over 45 miles per hour. After the 600 miles, I changed oil and oil filter and used the bike normal riding" .

[kobermeyer]

Thanks for the replies and questions. Answers:
-Got oil, check. Checked it before and after the first 40km, was a little low, but within the dipstick range. I changed it after 40km to Halvoline NON-synthetic. Noise still happens.
- The noise did NOT happen at first, during warm up in the shop, so I guess something went wrong after about 15-20km when I noticed the sound.
-Engine is SOHC
-Other bikes with the same engine (a friend has one) do NOT make the knocking sound.
- I have not checked exhaust bolts etc. and will do that.
- Gas here (Nicaragua) is unknown quality, but seems to work fine in other machines I have. I was thinking of adding an inline filter though.
- I will tell the shop that I broke it in as per manual. Since it runs fine and "is only a noise" I wonder if they will say at the shop, "it's not a problem". ??? The sounds makes me wince every time I start it up though. WHAT IS THE ACTUAL DOWNSIDE TO THIS PROBLEM IN TERMS OF PERFORMANCE ETC? DOES IT MEAN LESS POWER, FASTER ENGINE WEAR, HARDER STARTING DUE TO BLOW-BY...?

Anyway, I'm planning to ride it a while longer and then take it back when I get the chance (1 year, 10,000KM warranty).
Any other suggestions on what to check will be appreciated.
THANKS!!

[Bultaco206]

You need to be careful here if you think you may have a problem. If you feel there's an issue then get it taken care of now. Get it documented against your VIN number now...no matter how insignificant it may be. Just because you have a year warranty doesn't give you license to take what may be a problem and make it bigger one by putting it off.

The longer you wait, the more damage you could potentially do. And with more damage comes a greater risk of the manufacturer creating an out and turning it back on you in the form of neglect. Things that could be easy to deal with now can become more difficult as time goes on. Warranties aren't black & white. They are very gray.

Just my experience.

[mamm]

Originally Posted by kobermeyer

Other bikes with the same engine (a friend has one) do NOT make the knocking sound.

Well, there you go. Obviously, there is a problem.

Park the bike at the dealership and let them handle it. That's what warranties are for.

NO, it wasn't caused by your break-in procedure, and NO, it wasn't caused by changing the oil outside the dealership (I assume you didn't go back just to change the oil). You did the right thing on both accounts (lots of pressure on new rings, and an early oil change) - but that's the perfect out they might grab to, so it would be wise to not mention them at the dealership.

Just out of curiosity: which make/model?