NSR250 MC18 Crankshaft disassembly

Yesterday, Sunday 20 June 2010 I disassembled my $300 SP engine.

I could not easily get the gudgeon pins out, or get the flywheel off.

So I stripped it down until it was just an assembly of:

Upper and lower crankcase halves

Crankshaft

Pistons

Flywheel and alternator coils

I then took it around to Colin's and he had some large spanners with which to apply more torque to the wheel puller. After a bit of grunting, the flywheel came off.

So then I unbolted and seperated the 2 crankcase halves and pulled the crank out.

However, because the 2 pistons were still on, the upper crankcase half was still loosley attached to the crankshaft.

I then went around to Wobbly's and, as we now had better access to the pistons, punched out the gudgeon pins.

Wobbly then pressed the 2 outer crank webs off the crank. These were fine.

However, the 2 inner crank webs had stuffed big end pins and both conrods had stuffed big ends.

See the attached jpeg. Items 2 and 4 were stuffed.

Paul's crank was similar to mine, items 2 and 4 stuffed.

Dave Spin's crank had 1 good conrod and only item 4 was stuffed.

I need to get a good single pin crank web (item 4) and a good dual pin crank web (item 2) and 2 good conrods. Then I can make a complete good crankshaft assembly.

Actually, Paul has 2 good conrods spare I think.

Last night I spent a few hours creating the picture (you see here) of the crankshaft components. I figured it would be helpful to refer to when emailing people about the various parts that make up the crank. I am happy for this picture to be used/reproduced by anyone for their own purposes.