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Engine broken in?


Discussion at Motorized Bicycle Engine Kit Forum in the 2 Stroke Bicycle Engines & Kits forum. Hey guys, I was looking through other posts but couldn't find the answer, I have been riding my bike for ...
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Old 11-29-2009, 06:45 PM
Motorized Bicycle Newbie
 
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Default Engine broken in?

Hey guys, I was looking through other posts but couldn't find the answer,

I have been riding my bike for about a tank and a half now, and all of a sudden my engine got significantly louder. I was not far from home so I immediately turned around and shut it off. Not positive what exactly happened and I was wondering how do you know when an engine is broken in? Does it get louder?

I did not ride it long enough to see if there was any increase in power. I would appreciate any insight!

Thanks,

Sascha
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Old 11-29-2009, 08:33 PM
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Default Re: Engine broken in?

The muffler assembly is loose.

Jim
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Old 11-29-2009, 09:24 PM
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Default Re: Engine broken in?

The muffler itself does not seem any looser than it was previously. It only has the one connection to the engine so could it be anything else?
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Old 11-29-2009, 09:34 PM
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Default Re: Engine broken in?

Quote:
Originally Posted by mystmaker33 View Post
The muffler itself does not seem any looser than it was previously. It only has the one connection to the engine so could it be anything else?
sounds like you have a exaust leak(blown gasket)Or the screw at the bottom of the muffler is loose....

John-John
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IF I CANT FIX IT,IT ISN'T BROKEN!....ummmmmmm so I thought....
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Old 11-29-2009, 09:38 PM
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Default Re: Engine broken in?

Quote:
Originally Posted by mystmaker33 View Post
The muffler itself does not seem any looser than it was previously. It only has the one connection to the engine so could it be anything else?
At the bottom of the muffler, there's a screw holding the end-cap on. Ensure that it's tight. (The end-cap isn't missing, is it?)
Double-check that your exhaust mounting nuts are tight.
At the same time, check the gasket where the exhaust flange mounts visibly for gaps/leaks.

If there was no noticeable change in power, there's not much else that it could be.

Hello Fall Down Stand Up, (like Reggae?), we're on the same track.

... Steve

Last edited by AussieSteve : 11-29-2009 at 09:43 PM.
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Old 11-29-2009, 09:48 PM
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Default Re: Engine broken in?

As an update, it is making a pretty loud popping noise when it starts up and then continues while I ride. Also it revs fast when I am idling. ( I didn't notice at first because I was in too big of hurry to get home and make sure it wasnt about to fall off! lol still a noob when it comes to this stuff)

I checked the screw at the bottom, I do not think that it is loose It may be the gasket, does this sound like a problem with the gasket?
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Old 11-29-2009, 10:12 PM
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Default Re: Engine broken in?

Just took the muffler off the engine and the gasket broke in half, so im going to guess that was the problem lol. Thank for the help guys

On another note though, how will I know when the engine is fully broken in? I was reading about a power increase. Is it gradual or sudden?
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Old 11-29-2009, 10:17 PM
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Default Re: Engine broken in?

Quote:
Originally Posted by mystmaker33 View Post
it revs fast when I am idling.
That's possibly the idle screw. But it might in your case be a lean mixture, caused by a leaking inlet gasket. see below.
To adjust idle speed, you'll find a screw with a spring on the LHS of the carby. Turn it clockwise to increase idle RPM and anti-clockwise to decrease.

Quote:
I checked the screw at the bottom, I do not think that it is loose It may be the gasket, does this sound like a problem with the gasket?
You do not think that it is loose. Did you use a screwdriver to see if it would tighten more?
If it's tight, then it sounds like a gasket.

First grab a 10mm open-ended spanner and check that the exhaust and inlet tube mounting nuts are tight and visibly check the gaskets on both for signs of damage/leaks.
If nothing looks wrong, start the engine and stick an ear near the exhaust mounting flange and see if you can hear a leak. Often, you'll feel the leak with your hand if it's bad.
To test for inlet leaks, spray carb cleaner toward the suspected leak while the engine is running, (Don't aim into the air inlet). You'll hear the revs change if there's a leak.

Update: The run-in process is gradual, following an exponential curve. It takes up to 500km to fully run in, but the process is most rapid at first, then gradually slows as time passes, like a capacitor charging/discharging, if you're familiar with electronics.
It only takes a couple of hundred kilometres to get close to maximum power.

... Steve

Last edited by AussieSteve : 11-29-2009 at 10:21 PM.
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Old 11-29-2009, 10:25 PM
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Default Re: Engine broken in?

It is normal for the engine to idle higher when there is an exhaust leak.

Once a new gasket is installed, the idle will return to normal.

Jim
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Old 11-29-2009, 10:29 PM
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Default Re: Engine broken in?

Great! Thanks for the info. I will see if the problems persist after I put in a new gasket, I was reading elsewhere on the site about using a cookie sheet as a gasket, would/could I do that for the exhaust, or should I order a specific type online?
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