`03 Honda CR250R Strange "knocking" sound!

[Jacob Hansen]

Hey.

I just bought a `03 Honda CR250. I discovered that it has a strange "knocking" sound. sounds like a piston rattle, or really bad timing/detonation. But the piston is only 4 hours old, so it shouldn't be the piston.. right?? The "knocking" sound is loudest at idle, if it was bad timing/detonation it would be loudest at hard pull.... right?? so my question is.... what the H... is it.. The bottom shouldn't make that kind of noise after only a year should it. The problem doesn't go away with the clutch engaged/disengaged. It also feels like it running lean in the top end, is there a connection with my "knocking" problem..
PLEASE HELP! :ugg:

Best regards Jacob Hansen
Denmark

 

[marcusgunby]

The pistons on the crs are really loose, if it goes away when riding its a loose piston, if it doesnt then it maybe detonation.

 

[Jon K.]

You shouldn't have detonation at idle.

Pistons don't knock, they rattle.

Maybe you have a nod rockin'.

Pull the cylinder pronto and check it out.

Pull the flywheel cover and shake the crank as well.

Or just run the heck out of it, soon enough the problem will become much more easy to diagnose! :p

Lean on top is very bad, by the way.

 

[uts]

My old cr has a weird sound too. It's more of a rattle and is quite loud. I had the whole engine rebuilt (top and bottom end)when I bought it and it rattled when it came back from the shop. So I took it back and showed them and asked them to re-check it. They did and said there was nothing wrong and some hondas just rattle. One of them said his 01 model did it too. I was not real happy with that outcome but what could I do. Anyway I have done 2 top ends since then and there has never been any sign of trouble, and the crank checked out fine both times.
Go figure.

 

[killerbeez 75]

My 02 cr250 does the same.2 seasons and still running strong.Im glad you guys posted this because I thought it was just my bike. :yeehaw:

 

[Jacob Hansen]

Hey John K. See im from Denmark.. and not all words are familliar to me.. Nod rockin`. I actually dont know what that is :rotfl: .. So please explain, but it does sound a bot like its the honda sound??! due to the other answers i got in the thread.

Jacob Hansen DK

 

[Fly-n-High]

Rod Knocking.....

 

[Crash 142]

I may be way off here, but I used to have that bike. Let it idle, when you hear it knocking, hold the radiators - mine made a kind of 'knocking' sound when they vibrated/rattled.

 

[viking20]

Hej Jakob !
Jeg er også Dansker , som du ser....
Dont really know about the 250´s , but the 125´s has had a really noisy clutch after a redesign for the 02 model , I think.
On top of that the 125 has a real bad rattling OEM piston , Again , I really dont know , if these things are an issue with the 250.
If the engine has been rebuilt recently , I would check if the marks on the stator line up with the correct ignition mark. While you are in there , I too would suggest grabbing the rotor and check for up-down play in the main bearings.
The " caveman" method of keep riding , untill it gets worse , could actually work , but I would certainly check the easy things first !
Godt at se flere Danskere herinde ! :yeehaw:

 

[viking20]

Oh , yeah , I forgot: If you are new to this , the Honda uses aluminium plates in the clutch , makes the gear oil dirty real quick.
Most people change it every or every other ride...

 

[marcusgunby]

If you use a vertex or wiseco piston they tend to be alot quieter.

 

[Jacob Hansen]

HEY VIKING!! ;)

Ja det er da rart at se en anden dansker herinde.. I went to the garage last night because i wanted to find out about the strange "knocking" sound. I wanted to rejet the carburettor for the cold weather in Denmark now. I took of the carb. Then i thought, lets just inspect the reeds now where at it! when you take out the reed block it leaves a great inspection hole into the cylinder.... AAAARRRGGHH ! :bang: Now i could see some large grinds/tracks in the piston.. Off with the cylinder.. same grinds/tracks there so know im looking at my new christmas present for myself. A new cylinder and pistonkit. :ugg:

Og viking... Kender du forresten nogen der skal køber en `03 Honda Cr250 med kun ca 35 timer på bagen. Med helt ny cylinder og stempelkit fra j.ø- service?

 

[john3_16]

Sounds like you're running lean....Is it cold where you live ? This time of year as it gets colder will put your jetting out of spec...

Try turning your air screw..Should go away.

 

[dubious]

It could be a bad rod bearing, loose piston(too much clearance).
A friend of mine has a03'cr 250 with the rc valve and when he did his top end he over tightened the cables , and broke the rocker plate which the cables attach to on the power valve.
The exhaust valve would not open and needless to say it had no top end power.
Check your exhaust valve linkage. Often the exhaust valves are over looked when a top end is done, when in fact some parts are worn out!

 

[NO HAND]

My bike would detonate like crazy at 1/4 throttle. This bike comes stock with a very lean pilot jet.