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essarjayauto Group: Members Posts: 58 Joined: Dec. 2008 Posted: Mar. 03 2009,19:36 I recently stripped down my engine for a rebuild and now im having problem's with the reassembly. The gear box went together with out a hitch, but when i fitted the crank and the top casing i started to have problem's !! The casing seat's well and the crank spin's freely, but when i start tightening the 8mm and 6mm bolt's that hold it the crank become's tight and start's juddering. It seem's that the crank and balance shaft gear's have become too tight togehter and hence the juddering. It is doing this way before i even get close to the torque setting's. I did take all the bearing's out to clean out the gear box before and after blasting it, but i cant see how i could manage to fit any bearing's back in the wrong place !?! At first i thought i might have fitted the wrong bearing back on the balance shaft which may of forced it closer to the crank. I have tried to re-seat the top casing a coulple of times now and have the same result each time. Any help would be massivley appreciated as im losing the plot slowly !! Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: Mar. 03 2009,20:21 Never had any such prob's myself, but have you: 1. located/meshed the drive gear and baklance shaft gear correctly - ie: matched up the dots? 2. Located the main bearing 'pins' in the right place ie: in the little rebates along the upper edge of the 'main' crankcase? -------------- A garage overflowing with old stinkers... Back to top

essarjayauto Group: Members Posts: 58 Joined: Dec. 2008 Posted: Mar. 03 2009,20:28 Hi warwick, the dot's are lined up and the pin's are in their seat's. I am right in thinking that the dot's are only on one side of the gear's ? Although thinking about it, that should not make a difference. I do not remmember the crank being anywhere near as tight as it is now. Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: Mar. 03 2009,20:49 Yes, just on the outside of teh gears. Certainly something amiss there, but never having had such a problem it's hard to imagine what. The crank should run smoothly when it's all torqued up. Have you checked the seals are correctly located in their grooves, put the 'half moon' ring in the right place etc? Have you tried putting it together with the primary gear off to determine if the problem is at the crank itself? -------------- A garage overflowing with old stinkers... Back to top

Mr stinkwheels Group: Members Posts: 206 Joined: May 2006 Posted: Mar. 03 2009,20:55 All I can suggest is remove the mesh gears from the end of the crank, put crank in to position and tighten the bolts, starting from the middle and keep checking to see if the crank gets juddery. If all is well without the mesh gears in position you will know the crank is not the problem. Check everything individually as you go to eliminate each part. Of course you may have already tried this, in which case I would be as stumped as you. Warwick you beat me to it Back to top

essarjayauto Group: Members Posts: 58 Joined: Dec. 2008 Posted: Mar. 03 2009,20:57 That's the thing warwick, all the seal's and the half moon ring are in the correct place's. This is why it's doing my head in !! Once my dinner has settled, i'll give it another bash !! I'll do as you suggested, i.e remove the primary gear and see what happen's then !! Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: Mar. 03 2009,22:28 Quote (Mr stinkwheels @ Mar. 03 2009,18:55) Warwick you beat me to it Lol. Well there are so few things that it can be that we are fishing in a very small pool.   -------------- A garage overflowing with old stinkers... Back to top

essarjayauto Group: Members Posts: 58 Joined: Dec. 2008 Posted: Mar. 03 2009,23:59 update : i removed the primary gear's as suggested and the crank ran smoothly. I then removed the crank to check the balance shaft and again, all run's smoothly. All the bearing's are seated properly and in the correct place's and secured by the retaining plate's. Although now the screw that hold's the balance shaft bearing at the crank end has now sheared off   So now i've got to get that out !! Ever get the feeling someone has "been there before" ! I cant see that anything can be bent because there are no tight and loose spot's, very strange. Ah well, tommorrow is another day Back to top

jools Group: Members Posts: 1221 Joined: Oct. 2005 Posted: Mar. 04 2009,03:45 As long as ALL the locating pins on ALL the bearings are in place you should be ok. If they weren't and you happen to torque the case screws down its possible in extreme circumstances to twist the cases, but they ought to pull back down when everything is ok. Go carefully - has to be something basic ..... -------------- "The only thing worse than being talked about is not being talked about...." oscar Wilde Back to top

essarjayauto Group: Members Posts: 58 Joined: Dec. 2008 Posted: Mar. 04 2009,19:55 WOOOOOO HOOOOOO. Found the problem. Bloody stupid and bloody simple. The oil seal on the balance shaft was knackered ! When i first stripped it ( a while back now ) i noticed a bit of rust on the balance shaft and thought nothing of it. The oil seal had collapsed just inside and folded over. When i was trying to turn the crank around last night i was only doing it in the same direction as if it was running. Today i went the other way and after an initial jolt it spun freely. And stayed that way. I better check everything else now. No wonder the engine seized on the previous owner !! Are these oil seal's yam only or can i source them cheaper ? Bought a handfull of bolt's and a neutral light switch from local dealer and it all cost me over £60 !! Back to top

Warwickb Group: Members Posts: 1911 Joined: Sep. 2003 Posted: Mar. 04 2009,20:35 Good news! Never repalaced that seal so can't visualise it, but if it's just a generic kind of seal it'll probably have the dimensions stamped on it. If it doesn't, but is a simple type, you may still be able to get a generic replacement by measuring it up, either from an old school bike shop that still sells such things or from a bearing supplier - if going in in person take the seal with you of course to make life easier... -------------- A garage overflowing with old stinkers... Back to top

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