i've bough a beta rev 3 250 2002 off my brother partially stripped, he couldnt get it started so took the head off for inspection (not sure why), i have now rebuilt it with new piston rings, gudgeon pin, clips, little end bearing and spark plug, the reason it wouldnt start was the woodruff key had sheared. ive given the bike a service and ran it in gently, it ran fine for roughly 4 hours on friday, on staurday it seems to have a kind of loose bolt rattle coming from the exhaust manifold (if you use a screwdriver as a stethascope), only present at mid to high revs, ive taken the front pipe off and the piston and rings all look clean and well and refitted the exhaust, ive also checked all the bolts are tight everywhere and the water pump impellor is ok, the bike runs ok and the noise isnt loud but this rattle is concerning me. could a new little end bearing have failed from new?. any ideas would be aprecieated. p.s the noise is present when cold or hot, in gear or neutral.

i've been reading the search functions and i dont think this is plinking as the piston was decoked before refitting and is still clean, also the piston fits snug in the barrel and the compresson is very good. is there anyway this could be caused by something loose in the clutch as it grabs untill the engine is warm and then its ok, and the noise is there from cold. i can only describe the noise as the water pump impellor wobbling/catching when running fast/mid to high revs but ive had the pump cover off and impellor off and ran for few seconds when cold with noise still present, any ideas anyone?

Edited September 23, 200817 yr by benj

Hi there ,when you replaced the woodruff key did you torque it all up correctly ,have you checked the magneto has not come loose ......

thanks for the reply, when the woodruff key was replaced i took the engine with me to the shop and asked them what the torque should be and they did it with a air drill which appaently is the standart practice so im guessing its tightenough, i'll remove the flywheel tomorrow to check the stator is still tight, how should i know if the timing is set right, is this correct (its the picture of the stator in the faq link). i've listened to it again tonight and im sure the noise is from the engine head, if the piston was to 'slap' what measurments should i be making to know if its faulty and what i need to order a new piston, as it seemed a tightish fit. p.s i only changed the little end, rings etc for peace of mind while it was apart, my brother bought the bike as a none runner, thanks again

thanks for the reply, when the woodruff key was replaced i took the engine with me to the shop and asked them what the torque should be and they did it with a air drill which appaently is the standart practice so im guessing its tightenough, i'll remove the flywheel tomorrow to check the stator is still tight, how should i know if the timing is set right, is this correct (its the picture of the stator in the faq link). i've listened to it again tonight and im sure the noise is from the engine head, if the piston was to 'slap' what measurments should i be making to know if its faulty and what i need to order a new piston, as it seemed a tightish fit. p.s i only changed the little end, rings etc for peace of mind while it was apart, my brother bought the bike as a none runner, thanks again

Slightly off subject, you may want to re-check the torque of the flywheel fastener. It's standard practice for good mechanics to remove fasteners with an air wrench, but not for installing them on a motorcycle engine, especially one as critical as a heavy Trials flywheel nut/bolt, which is far different from a small, light MX flywheel. Final torque result will vary in a WIDE range according to pressure, wrench setting and how long wrench is operated. Inappropriate torque setting is one of the main reasons keys shear.

Jon

ok thanks mate i'm gonna remove the flywheel to check behind it, what is the correct torque i should tighten it to or/and could you point me in the direction of any online manuals for 2002 beta which contains info such as. most apreciated

ok thanks mate i'm gonna remove the flywheel to check behind it, what is the correct torque i should tighten it to or/and could you point me in the direction of any online manuals for 2002 beta which contains info such as. most apreciated

I'm sure someone out there can give you the exact Beta spec.'s, they generally are around 30-32 ft lbs/40-42 Nm +-. If you need to hold the flywheel, take the plug out, get some, maybe, 3/8th inch cotton or plastic woven rope, move the piston up past the exhaust port (you can poke the rope in the plug hole to feel it come up) and stuff some rope into the combustion chamber and then lock the piston up against the rope inside, in the direction you need. It won't hurt anything as it's soft, and then just back the piston down a little afterwards and pull out the rope and throw it in your toolchest for the next use, it's easy to store and foolproof.

Jon