Hitchcocks Forum

Well, I've finally discovered why my bike was running very rough, and what those metal bits were which I discovered in the sump. Just split the crankcase a moment ago, and the cage of the NU 305 roller bearing on the drive side had pretty much disintegrated. I can't see any other damage with my untrained eye. I will have to buy new main bearings, big end and rod, thrust washers, spacers and oil seals. Have I forgotten anything in this list that anyone can think of? Thanks for any advice!

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Hi Robin. Just a thought. My mate has an Electra X and has had to dismantle it for various reasons. He's an engineer and found that the crankcase halves didn't line up properly, and were actually manufactured out of alignment. If your main bearings have gone prematurely it might be for the same reason. I think it was Les-H on here that said around 50% of Electra Xs were made that way. Might be wise to get them checked whilst the engine is in bits. Cheers.

Hi Riggers..I think it was Norm who commented on the Electra X crankcases, I don't think it was me. BTW. Robin, check the oil pump drive parts carefully as if the drive side has been slopping around a bit the timing side would also have been running with some extra radial movement and possibly hammering some of the parts on that side too. Obviously replace all the crankshaft bearings and seals at this opportunity.

Hi Alan R - I keep a 50mg Diazepam in my tool kit for when working on the bike. Didn't need it this time though, as it all came apart without incident, which is just as well, because I've never split cases before. I only hope it all goes back together again just as easily! Thanks for your input Riggers and Les H! There was very slight damage to the oil pump worm and shaft, and I will replace those. I believe, that when I have the new rod and big end bearing, I will have to take the crank assembly to a specialist who will remove the old big end and press in the new one and balance the fly wheels. Is this correct?, and would this person also have the equipment to check for any misalignment of the crankcase halves?.

The crankshaft won't need rebalancing just re aligning very accurately. One way to see if the crankshaft is in line with the top of the crankcase mouths is to assemble the crankcase without crankshaft and push a long steel shaft through the bearings and use a straight edge across the crank mouth then measure either side down to the shaft and check for a difference. Or measure down from the crankcase mouth either side down to the tops of each flywheel...maybe Norm knows a way, but if you do have a crankcase that is mis aligned main bearing wise, It would be even more difficult to measure if there was fore and aft misalignment! If there is a problem I don't think there is much you can do about it apart from buying some new cases. I personally would just assume my cases were perfect (one of the good 50%!)and rebuild the engine regardless.

Hi Robin. Any decent engineering firm should be able to check alignment - it's done using something called a mandrel. However I agree with Les-H - it's one thing finding out they are misaligned, but it's another sorting it out! It's a 50 x 50 chance - do you enjoy a bet?!!!

Hi Les, we have had to do a few sets of cases, made up a dummy shaft to fit through the bearings, put it in the mill square it up then you can check fore and aft and up and down and we are able to get them to within a few microns and then you can mill the deck square to the shaft and also run the mill down the throat to make sure the barrel will sit down square. Once done we have had no probs with them. Bloody annoying on new motors with only a few thousand ks on them. We have also used this procedure on missmatched cases to make sure they are true.

Well, thanks guys! I don't know if this means anything, but piston was flush with top of barrel at TDC. I will nevertheless see if I can find a firm capable of checking for any misalignment. In the meantime the bullet is in bits, my Norton Navigator is a non runner, and I've been forced to fish a rusty, Chinese made 125 out of the shed to get me to work and back!

Robin even though I am a relative newbie on this site ,do check that the bearings have not rotated in the housing causing wear in the crankcase housing and more metal bits,if you are going to an engineering firm get them to check for any end float in the bearing housing and sleeve or re cut and fit sleeves to take the appropriate bearings.