can somebody give me some advice my evo 250 could do with a top end re build i have a little end rattle nothing major but its there and sometimes after high revs a fairly quiet clack noise (only way i can describe it ) my question is would you change the piston or just the rings the gudgeon pin as well as the little end or not head gasket for sure but ive been told not to order a base gasket money is an issue so i dont want to waste any

the bike is an 09 i have only had it about 6 months it has been well used but very well cared for by me and the previous owner

thanks

neil

Edited December 31, 201213 yr by nelly1

Sounds like it`s pinging. It happens just after you chop the throttle? Could be a little lean on the pilot, or just the fuel. Another cause/cure would be to clean the carbon buildup off the top of the piston. Did it just start? Or did you notice it when the weather became cooler?

about 12 weeks ago when i first heard it and it doesnt happen all the time and i dont ride it hard

Try some octane booster or super unleaded to eliminate pinking as a source.

if it does need to be opened up its probably best to put in a new piston kit including little end bearing.

this should not be too expensive and should last along time.

ben

I had same problem and it turned out to be my fuel/oil mixture, cheaper option to try first!

its deffinately got a top end rattle so it has to be done anyway

That`s about when the temp changed. It`s pinking as you folks say! I would go one step larger on the pilot jet and run better fuel. Cheap solution, but you might still need to de-carbon your head and piston.

I Agree with Lineaway - the pilot and fuel/air screw circuit maybe too lean for the cold & dry air of winter conditions. Its worth a try to clean the pilot jet and adjust the fuel/air screw for your winter conditions. Most carbs rely on the fuel/air screw circuit to provide fuel during throttle chops - (The slide is closed) and its very common to hear "pinking" if too lean. Another tell tale sign of a lean condition on the pilot/air screw circuits would be a lean bog condition when the throttle is opened full very quickly.

Pilot jets can get partially clogged and create what you describe as well as the colder temps - so a good cleaning is always recommended when suspecting carb issues.

thanks guys il give it a go happy new year

I've known a few evos which rattled and turned out to be piston slap, if go up a size with the piston.

thats interesting how many sizes are there

ok,

if your going to do it..do it right, buy a standard bore piston and ring, and have the cylinder replated, they will need your piston to match it , and follow the heat cycle instuctions from who ever you have replate the cyclinder.

it will be worth the extra money to have it done right.

Nelly, rob had the same issue with his evo..... Lampkins advised him to change pilot and main jet and use super unleaded..... CURED IT. Coincidentally, we went nant urcha today, could only get normal unleaded from the garage in Chester..... Guess what...... Yep, started with a little pinking again.....

Try this before you try anything else.

Take your carb off and see what size the main and pilots are..... Standard is 48 pilot and 125 main jet.

Robs runs on 45 pilot and 110 main..... And yes, when I tell most people that they look at me like I've got two heads..... It runs sweet as a nut mate.

thats interesting how many sizes are there

beta has 4 size pistons a b c d which is stamped on the piston that is in your bike ie if there was a a in there you can fit a b thats what iv been told iv got a small piston slap in mine now and for the parts piston kit base gasket and head gasket its not far short of 200 notes