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does anyone know where the combustion chamber is??? the reason i ask is there is a loud knocking noise coming from the engine. i bought the service manual and it said it could be due to carbon build up in the combustion chamber. does anyone else have this problem or know if it is carbon build up???

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im not sure if it is that, may be due to some other issues...weather, bad/old gas, maybe the ignition system???

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does anyone know where the combustion chamber is???
I'm not trying to be insulting, but if you don't know something that basic about engines, I think you would be better served by taking the bike to a mechanic.

The combustion chamber is the area inside the cylinder between the dome of the piston and the head at Top-Dead-Center where the trapped fuel/air mix is compressed and ignited by the spark plug.

the reason i ask is there is a loud knocking noise coming from the engine. i bought the service manual and it said it could be due to carbon build up in the combustion chamber. does anyone else have this problem or know if it is carbon build up???
Carbon build-up can only cause noise in the engine if there is a lot of build-up, a significant enough amount to raise the compression and cause detonation (pinging). A "loud knocking" is not likely to be detonation (pinging). Pinging in our small engines typically sounds like a handfull of BBs or marbles bouncing around inside the engine, and will usually only occur when the engine is under a heavy load, not continuously. Knocking is going to be a much more serious problem, like a rod bearing that has given up the fight. It's time to tear into the engine.

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im 15. ive had a bike for a year now, theres not one person in my family or friends that knows anything about motorcycles or engines or anything, so im completely on my own, the only thing i have to go by is the manual

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Even with a manual, opening up a four-stroke MX bike engine can be a daunting task for a mechanical novice. It can be done, though, if you are patient, well organized, and follow the directions closely.

I'm sorry to say that you are going to have to start dissassembling the engine to find the problem. Loud knocking means something is broken.

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Hey tbs, some knocking is normal when the bike is first started and not warmed up. It may be that the piston has not expanded enough to "fit" the cylinder. Warm up the bike to operating temperature and the knocking should be quite a bit less or not at all. Before taking apart your engine, well, don't do it by yourself, you will need special tools and help with it. Find someone who is in your area willing to help you with it and more importantly, someone who clearly without a doubt knows what they are doing. The best thing you can do for your bike is make sure you change your oil and filter frequently and use a good full synthetic oil like Castrol Superbike, Mobile 1, Rotela, Belray, etc. Full synthetics are probably going to cost you about $10 a quart. You get what you pay for. Clean oil and filters, air filter also is the best thing you can do for your bike. Again, some knocking when the bike is cold is normal on most bikes. Warm it all the way up and check it then.

Hope this helps.

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Hey tbs, some knocking is normal when the bike is first started and not warmed up. It may be that the piston has not expanded enough to "fit" the cylinder. Again, some knocking when the bike is cold is normal on most bikes. Warm it all the way up and check it then.

Hope this helps.

Knocking is not normal, even at startup, except for engines with hydraulic lifters that need oil pressure to pump up the lifters. If you can hear piston slap, whether the engine is hot or cold, the piston and/or cylinder is worn out. If something is making a steady knocking sound, that part is worn beyond it's service limit and is failing/has failed.
Sometimes it due because your valves are tight.
Would you care to explain how tight valves could possibly cause a knocking sound? Loose valves can cause a light tapping noise, but tight valves are going to make any sound at all, especially if they have lost all clearance, because then the engine won't even start.

tbsrider9, if your engine knocks, don't keep running it, you're just going to do more damage. You need to start tearing it apart to find the problem. If the sound is from something like a loose rod bearing or wrist pin bearing, and that bearing finally lets go completely, you're going to have a $$2500 repair bill, when it could have been fixed for much less if repaired before the engine finally grenaded.

Just a thought, you do have oil in the engine, right?

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trust me when i say take it to an experienced professional mechanic or just an experienced engine builder (someone like a friend at the track or something, that has done this successfully before). someone who has experience with kawasaki motors preferrably. a service manual alone cannot do this for you. you will need special tools for some parts of the motor which can be anywhere from $50 to $100 for each tool. i have had lots of experience rebuilding four-stroke top-ends but i wouldnt even go down into the crank and transmission part of the motor without an experienced buddy's help.

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im 15. ive had a bike for a year now, theres not one person in my family or friends that knows anything about motorcycles or engines or anything, so im completely on my own, the only thing i have to go by is the manual

Trade for a 2-Stroke, less maint, way more reliable and durable.

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yeah, but they do smell and sound terrible. And they are so annoying to just have it pinned all the time.

Try to pin a RM250 or YZ250 all the time, you would win a lot of races if you could. I doudt you could keep a 125 pinned for most of a race. Most 4 joke racers become lazy.

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sounds pretty bad 2 me . . . one of my mates 06 kxf starting making a loud knockin sound from the motor .. he took it in 2 get fixed. . .they replaced the whole top end but it was still there . . they then went further down n his crank had cracked or sumthing similar . . it cost him $1800 after 15 hours on the bike

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that happened to me once, turned out my piston was warped

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well you wont have to worry about it being a bad wrist pin bearing since it doesn't have one. bring it to a shop or your dealer. how many hours are on the motor. does the noise pickup as the revs come up or does it stay constant. the more you run it the worse it will get so bring it in now

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