Engine rattle

insomniac_32

Quick question:

Ive a cbr250 and in the last few days its developed a rattle that sounds like its comming from the engine.It seems to run in time with the engine.Its loudest when I let go of the throttle and the revs are dropping but its there when accelerating aswell.Anyone any ideas as to what the most likely cause is?I havnt noticed any drop in power and it still revs fully but I want to sort it before/in case, it becomes something worse.

Krusty_Clown

Did you check your oil levels?

Pigeon Reaper

Does the rattle increase decrease with the revs when in neutral? Check the oil and valves. If after adjusting the valves you still have noise leave it to a bike shop as something may be loose inside the engine. I lost an engine due to something similar a few months ago.

Gurgle

insomniac_32 wrote:

Its loudest when I let go of the throttle and the revs are dropping but its there when accelerating aswell.

Does a CBR250 have a timing chain?
If so, might need tightening.

Wossack

you could try (if you havent already) asking over on cbr250.com

madrab

sounds like the cam chain to me, though could be the valves need tightening

spiggotpaddy

the cbr 250 does'nt have a cam chain it uses cam gears,thats where it gets that nice whirling sound from. your rattle could be a loose or dry drive chain

bushy...

Yup, it has no camchain ( btw be careful removing clutch basket , it transmits drive to camshafts )
If it was something like loose valve clearance , it would usually make the same noise regarless of LOAD ( not revs )
Since it sounds like it is load dependant , it is probably a bit more serious.Do not ride it at all until you know what it is. Plenty of them blow cranks afaik , starts off as small rattle , then gets louder a bit more rapidly.Unfortunelatly the cylinder head near #3 is a bit weak , so if the shell goes on that cylinder , the piston hits the head and puts a tiny crack in it....leading to much post rebuild fun if you don't know.

insomniac_32

The thing is that the rattle isnt there between 4k-6k revs or if I accelerate slowly.Someone mentioned that it could be the cam chain but if it doesnt have one then thats that cause out of the way at least.Thing is ive to drop it out to a garage on tuesday to have it sorted but I need some idea of what it could be so I dont get shafted.I checked the cbr250.com forum and someone else posted a similar problem the cause turning out to be that one of the cam gears had shed 26 teeth.Would a rattle from a dry drive chain dissappear betweem 4k-6k revs?

insomniac_32

Also when I was riding the bike today the rattle wasnt nearly as bad as earlier in the week!?

faceman

Could be the pistons, but hopefully not as its pricey to replace.

insomniac_32

faceman wrote:

Could be the pistons, but hopefully not as its pricey to replace.

Turns out its a bearing on the way out in the cam gears.

Pigeon Reaper

at least you got it sorted before it failed.

Gurgle

insomniac_32 wrote:

Turns out its a bearing on the way out in the cam gears.

keep an eye on it - that sounds a lot like a 'quick, make something up' diagnosis.