mark89v

Member
Jan 9, 2006
4
0
i recently removed my ignition cover to look for the source of a rather loud knocking sound in the engine. the flywheel weight (13oz steahly) was loose and came of with little resistance. the nut was apparently left off during the last bottom end rebuild. my question is, what damage could this have caused, if any, and would it have changed the ignition timing. should i just replace the nut and forget about it? i rode the bike about 5 hrs in this condition.
 

pesky nz

Member
Sep 13, 2010
296
0
you need to remove anything that was rattling and clean it and even a light rub with 800 grit wet and dry and reassemble it and then listen and hope the noises stay away. It could have damaged all parts that were rattling. The timing will only alter if the flywheel key has sheered off or the backing plate (with the wires and windings) has moved.
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
Put the stock rotor back on, no extra weight, please? There are more sound methods of detuning that bike. Trails, put a Forestry approved muffler may do! Dragging a boat anchor works too, but does hang up on trees! Not recommended!
 

mark89v

Member
Jan 9, 2006
4
0
thanks guys, i had planned on removing the weight anyway. on visual inspection there doesn't seem to be any damage. bike runs fine aside from some jetting issues which i'm addressing today. boat anchor ? haha....
 

mark89v

Member
Jan 9, 2006
4
0
farmer john, you are correct sir! to expound on what ~wff-ruled~ said, these weights put unnecessary heft on a place where it wasn't really meant to be. hanging out there on the end of the crankshaft could potentially cause abnormal bearing wear. they also, because of the design, have a tendency to come loose. if you do run one,you really have to keep a close eye on it.
 

julien_d

Member
Oct 28, 2008
1,788
1
whenfoxforks-ruled said:
Put the stock rotor back on, no extra weight, please? There are more sound methods of detuning that bike. Trails, put a Forestry approved muffler may do! Dragging a boat anchor works too, but does hang up on trees! Not recommended!

Strange... Almost all enduro models use much heavier stock flywheels than their MX counterparts. 'Splain me? I mean, I know the OEM's are retarded sometimes, but I don't really think this is one of those times. I do suppose some bolt on weight could not be properly balanced. Balancing the weighted flywheel would prolly be smart? I'm all for using one though, they really do work.
 

pesky nz

Member
Sep 13, 2010
296
0
julien_d said:
Strange... Almost all enduro models use much heavier stock flywheels than their MX counterparts. 'Splain me? I mean, I know the OEM's are retarded sometimes, but I don't really think this is one of those times. I do suppose some bolt on weight could not be properly balanced. Balancing the weighted flywheel would prolly be smart? I'm all for using one though, they really do work.
If you put an rm250 crank next to an rmx250 crank you find a thicker shaft to mount the larger flywheel on (not 100% sure but you probable find a larger main bearing on that side also).
 
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