crank shaft primary gear problem

[magg]

Cannot regrind cranks as Honda does not make oversize bearings, although the Chinese do apparently. Wear on gear and crankcase faces looks more than on the two sets I have on the bench at present. You should be able to turn the crank and pistons by hand using the alternator flywheel. Agree with Luke, better to split the cases and check for other damage.

[rigsby]

Hi,

Just an update my fears where realized, split crankcases crank obviously has lateral movement now as you move the crank the gudgeon pins will slide though the con rod eyelets and it seemed to be over to the one side hence the dragging primary gear, the mains are worn but probably with new shells passable, but when i removed the con rods, big end failure was evident on two of the 4 cylinders.

Back right cylinder had failed not sure if the shells had been spinning as they are mashed the side of the shells have ground away where it sits up against the neighbouring con rod and the big end crank journal is ground away on the slant as if the conrod was running out of true, front left also has blued shells and journal so basically its buggered, the crank is scrap so are all the shells and two rods, not sure if the crank had been pulled over due to the big end failing or whether the crank was not centralized before the crank case halves were reassembled. My current engine in my race bike also has possible crank woes so i have one more engine that was out of a running road bike but unsure of millage i was told no funny stuff was going on before it was removed from the bike. So another complete engine to strip hopefully the crank is usable.
Can i use the crank from the road engine in the cases from the race engine and then select shells or does the original crank have to stay with the cases the only reason is that the bores from the race engine were honed and new piston/ rings fitted so i would like to use those cases but with the crank and rods from the road engine hopefully.

[lukemillar]

Yep, you can transplant the crank but make sure the rods come too. There are 3 different weight codes for the rods which are chosen based on the crank so they have stay together. Otherwise you have to get the whole thing balanced! (Don’t ask me how I know this....)

TBH the biggest hurdle will be finding new shells. Last time I looked OEM green codes were still about but yellows and browns had dried up. Mike Norman was looking to have a large batch made but not sure where in the process he is at.

[rigsby]

Yeah this is also a concern iv checked fowlerspartsuk they have some of the different shells but dont stock all options and the same goes for CSMNL in holland they have some in stock but not all, so either i hit the jackpot and between both suppliers i can get what i need or carry on hunting, graeme france has them listed on his website but it states to contact for availability so presume its gonna be the same scenario. Ill strip other engine if the crank is usable i will compile a list and start shopping, fingers crossed, i have 5 months before the start of next season.

Cheers for your advice much appreciated if you do find a supplier of shells give us a message.

Thanks

[gavins]

Mike norman of G-Force is supplying new shells: http://mngforce.typepad.com/nc450vdev/2 ... rings.html. I think they're also available through Rick Oliver.

[Neosophist]

At least you've found the cause of your problems.

Perhaps it was hastily rebuilt (worst thing to do!) and something wasn't installed properly, who knows.

I've seen engines been painstaikingly rebuilt only to have too much liquid gasket used which blocked up the strainer in the sump and killed the engine rather quickly...

Already been answered but Mike and probably Rick O have new bearing shells avaialable.

Hope you get it running again!