main bearing replacement

[Chris58]

After finishing a major overhaul of the storm (big bore, hi comp pistons, light flywheel, etc.) Ive had a KNOCK all summer! I found a loose main bearing with 0.005 of play at the flywheel... Im thinking the cases somehow didn't mate up perfectly.
Winter is back.. so its time to fix it up right.

Im curious if anyone has managed to split the cases without completly removing the engine?? Wouldn't that be easier??

[tony.mon]

Did you replace the mains when you had the bores machined?
And did you use new big end bolts?
Re splitting the cases, it will take longer to split the cases and leave the upper half connected to the frame.
Unless you have a really good reason it would be simpler to remove the engine and place it on an engine stand to work on.

Machine mart's stand is less than 50 quid.

[Commando77]

Mines upside down......sits well on the valve covers..

[Chris58]

Did you replace the mains when you had the bores machined?
And did you use new big end bolts?
Re splitting the cases, it will take longer to split the cases and leave the upper half connected to the frame.
Unless you have a really good reason it would be simpler to remove the engine and place it on an engine stand to work on.

Machine mart's stand is less than 50 quid.

I did replace all of the bearings in the engine, new strech bolts on rods. I didnt replace the big bolts around the crank holding the cases together, pretty sure the manual says you dont need to for those. or do you??

I plasti guaged everything as well..all was good, but it ended up loose on final assembly

[tony.mon]

No, all the crankcase bolts are reusable.
Perhaps one of the shells hasn't quite seated properly.
Anyway, it's a straightforward fix having done it once, just time consuming.
I'd still suggest pulling the engine out and using an engine stand, it makes it much easier than working at ground level.

[Chris58]

Yea, your probably right. Shouldnt be too hard even with taking it out, just time consuming. Usually trying to take a short cut doesnt work well

[mik_str]

bummer Chris. Hope the rebuild goes well. More importantly, I hope you don't end up beating my consecutive rebuild record (a frustrating and expensive accomplishment to be sure). While you have it apart, why not port the cases (improve internal airflow) and clean up the heads?

[Chris58]

bummer Chris. Hope the rebuild goes well. More importantly, I hope you don't end up beating my consecutive rebuild record (a frustrating and expensive accomplishment to be sure). While you have it apart, why not port the cases (improve internal airflow) and clean up the heads?

hahaha I dont know about beating the record. I may port the cases. Also still looking for cams Going to leave the heads on for this job though..

Did you manage to get those pistons in as well?

[mik_str]

yessir, and bike is awesome (had the cases ported and did a one-off cam set-up too - am running Yoshimura intake cams and OEM exhaust, gives me power right where I want it).