stuessenhigh Posted March 30, 2009 Report Share Posted March 30, 2009 Hi folks, Some of you may have read my post about 10 days ago about scorched reeds on my 02 Rev3 250. Well...after checking what I thought was everything..(to try and cure the awfull blubbing I was getting) I put it all back together, and on starting the bike I sheared a woodruff key...and then another one after reasembling. I dont have a torque wrench so the third time I did the nut on the flywheel up tighter than before and all seemed well. Did a trial on it, and it ran fine after the first lap....(still had the bad blubbing for the first lap)..but then, as if by magic it was suddenly clear and ran like a dream for the rest of the trial. Then, a week later (yesterday) had a little practice and within about 2 mins the woodrufff key sheared again. If any of you have any ideas as to what I'm doing wrong, and if this problem might be connected to the blubbing problem I would appreciate your ideas. Thanks in advance for all your help. Quote Link to comment Share on other sites More sharing options...
technowaldo Posted March 30, 2009 Report Share Posted March 30, 2009 before refitting flywheel get some valve grinding paste and put it on the end of the crank that the flywheel fits on and fit the flywheel without woodruf key and turn it back and forth until the 2 surfaces are a nice light grey colour all over and perfectly mated to each other ,clean off paste fit key and torque it up and you wont have any more trouble Quote Link to comment Share on other sites More sharing options...
stuessenhigh Posted March 30, 2009 Author Report Share Posted March 30, 2009 Thanks technowaldo. I tried to do that before, but..(you're probably all gonna laugh now!!)..I used autosol, which I thought would be abrasive enough, but not too much. Hope that wasnt TOO much of a stupid idea. Anyway..I will try again with the proper stuff as soon as I can get some valve grinding paste, which I assume I'll find in a good auto shop Quote Link to comment Share on other sites More sharing options...
stuessenhigh Posted March 30, 2009 Author Report Share Posted March 30, 2009 When I say I used autosol...it wasnt I hasten to add, to work the two surfaces together, it was just to clean the surface of the shaft. Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 30, 2009 Report Share Posted March 30, 2009 When I say I used autosol...it wasnt I hasten to add, to work the two surfaces together, it was just to clean the surface of the shaft. Well it probably works better than anusol Quote Link to comment Share on other sites More sharing options...
dan williams Posted March 30, 2009 Report Share Posted March 30, 2009 (edited) I'm not saying you've done this Hugh but if you're three keys in then... It's been said before and I'll say it again, it's virtually impossible to hold the flywheel tight enough to put the flywheel nut on by any method that includes holding the back wheel. Not to mention that it puts tremendous twisting torque on the crank. A proper flywheel tool is the best and safest bet. A lot of guys in the know use air drivers which I suppose do the job but I'd be more comfortable with a holding tool and a torque wrench. This comes down to do it right or do it over. A sheared key could throw your timing off enough to scorch the valves. Hmmm. Edited March 30, 2009 by Dan Williams Quote Link to comment Share on other sites More sharing options...
jse Posted March 30, 2009 Report Share Posted March 30, 2009 before refitting flywheel get some valve grinding paste and put it on the end of the crank that the flywheel fits on and fit the flywheel without woodruf key and turn it back and forth until the 2 surfaces are a nice light grey colour all over and perfectly mated to each other ,clean off paste fit key and torque it up and you wont have any more trouble That may help if the taper surfaces are chewed up, but the real reason that the flywheel hub "sticks" to the crank taper is that they do NOT match perfectly. One taper angle is slightly different and it's called an "inteference fit". Mating the surfaces can allow a tighter fit than the rough surfaces, although not quite as good as the original fit, but one thing you'll have to watch for is the crank taper nose fitting too far into the hub. When you lap the crank stub into the flywheel hub, it will cause the stub end to end up farther inside the hub and sometimes the flat end of the crank stub protrudes out beyond the inside of the machined flat area where the washer and bolt go. This will allow the washer to contact the stub end and no matter how hard you crank the bolt down, it will not pull on the crank taper any further (it would be like putting the washer/bolt on the crank end without the flywheel hub and tightening it down, it "bottoms out" on the stub and won't go any further). You might consider using a larger ID, thick washer or short spacer underneath the bolt/washer so the nose of the taper can protrude slightly out but does not bottom out against the washer. Jon Quote Link to comment Share on other sites More sharing options...
stuessenhigh Posted March 31, 2009 Author Report Share Posted March 31, 2009 Thanks everyone for your comments. I will investigate if that is happening to me Jon. Might be a few days untill I have time, but will check it all out again anyway. Cheers Quote Link to comment Share on other sites More sharing options...
nzralphy Posted March 31, 2009 Report Share Posted March 31, 2009 Just to add another 2cents. If the faces are 'picked up' with a burr - do NOT lap them together with paste...... until you stone off the burr. As said check for bottoming out nuts (christ there is an image) then go to the auto store and buy a cheep air impact wrench. Quote Link to comment Share on other sites More sharing options...
stuessenhigh Posted April 2, 2009 Author Report Share Posted April 2, 2009 Thanks everyone. Had a bit of free time today, so took it all apart ...did the lapping..put back together and did up the nut with an airgun thingy...bike started fine, and all appears to be OK...for NOW!!!!!!!! thanks for all your help folks. Quote Link to comment Share on other sites More sharing options...
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