CRF 250 2005 Knock

[bobdriver]

Hi. when I push the kick start by hand just after the compression stroke I get a knock noise, there is no knock noise on the intake and exhaust stroke and no knock when it runs it runs fine. Could it be something to do with the decompressor any ideas....

[biker boy]

i have the same bike... just its an 04 and it does the same thing... i think it is normal... if its not, i have a problem to lol

[bobdriver]

Im sure its got something to do with the decompressor as that opens the exhuast on the compression stroke, I need to know how the decompressor works, its buggin me biker boy.........

[bobdriver]

Do you ride your bike alot and how long have you had it......

[biker boy]

i have had it like 3 weeks lol... it only had 25 hours on it when i got it thou, still on original rubber... and i ride it every day that i am home

[bobdriver]

I think it must be normal then, I still think its something to do with the decompressor though. I used to ride a 2003 crf 450 but on the track it sucks the energy out me so I got the 250 which it more fun and flickable too with better air on the jumps. Cheers biker boy...................

[rob450thumper]

Guys its the decomp kicking over you can hear it when you turn it over slowly.Nothing to worry about. My brand new 07 does it as all of the 250's I've had do

[bobdriver]

That's a relief, I thought it was the decomp, Cheers...........

[Honda_250f_rider]

yes, its the auto decompression... Just make sure you stay on top of oil changes and airfilter cleanings and the bike will last... Change oil every 3-4 hrs, oil filter 15 hrs, trans oil 6-8 hrs, airfilter after every ride...

[bobdriver]

does anybody know how the decompressor works. Whats stops it from working when bike is running or is it only when the kick start is kicked.............

[kelstr]

does anybody know how the decompressor works. Whats stops it from working when bike is running or is it only when the kick start is kicked.............

its a spring loaded governer assembly, ------when the enging is spinning less than 750 rpm ( kicking over with your foot is about 500 rpm ) the spring keeps the decompressor activated and the cam has to roll over the hardened pin and open the exhaust valves way eairly so you kan kick it through the stroke , -----and this "snap" you are hearing is the cam dropping the exhaust fork off the steel pin extra eairly lift , ---when the engine starts and obviously is running more than 750 rpm , the spring is overcome with centrifical force and it deactivates the decompressor and the pin goes down into the cam and just sits there untill you turn the bike off again .

real simple deal ----decompressors have worked like this for 100 years ------just normal governers with a set weight spring !

its just that honda had the patent for many years for this type of set up for bikes ----and the first 2 years of yzf 4 strokes had to have the manuel lever because they had to wait until hondas patent lapsed before yamaha could use this set up on bikes ------now they all use this set up !

[Veccster]

I always thought the decompresser made a 'click'ing noise...not a knock!

[moto_x2005]

yes, its the auto decompression... Just make sure you stay on top of oil changes and airfilter cleanings and the bike will last... Change oil every 3-4 hrs, oil filter 15 hrs, trans oil 6-8 hrs, airfilter after every ride...

u must have to copy and paste it... everytime i look at a new thread you hav this posted hahahaha:ride: