Kdx200 An Even More Technical Question

[PZR]

My guess would be that either the flywheel or the crankshaft on your bike has been swapped out.

I suspect that this (modified) flywheel came off a bike where the keyway in the crankshaft had crapped out. So someone had a new keyway machined, in a different place on the crankshaft. Then had to modify the flywheel to match. Later either the modified flywheel has been switched onto your (unmodifed crank) bike, or a new crank has been fitted to your (modified) bike.

Does the modded flywheel line up correctly on your SPARES bike (on the long shot that that one might have the modded crank) ? Why can't you use the flywheel from that?

Yeah that makes sense (probably why I hadnt thought of it)
Though (and I havent looked at it yet) the spares bike magneto is welded in the same way but I have not checked it to see if it will work yet. Im onto that this w/end. Good thoughts guys. See why this is a great place to air ones mechanical problems

[F5 Dave]

I had thought that someone had welded a weight to the flywheel as some aftermarket ones do. Then I thought that maybe the rivets were so loose that they welded it to stop it rattling.


Irrespective I would not lose any sleep over it. If the flywheel gets loose it will break the woodruff key in a nanosecond. It doesn’t seem right, but the woodruff key is not what holds it in place. The taper does, just as it does on other machinery, your drill-press for instance.

The key is only there for assembly purposes & I know several people who run with no key & have no problems. I am just about to run a bike like that.

If you really want then the easy option is to machine a new keyway in the flywheel & put some araldite in the old one so it can’t be used accidentally. Yeah, yeah I know. . . .fuckin brilliant.

[Motu]

That's right - the old British bikes always used a plain taper with no key for the magneto,and modern Euro engines have plain tapers with no keyways on camshafts.I reckon the flywheel is original,the hub not.Find TDC and see how it all lines up.

[PZR]

Today I checked where I thought everything should be like TDC and marked it out. I then cut the welds and when I dismantled then reassembled it I found that two of the original holes lined up, so I rechecked it and welded it there. It started ok after putting it back together and when I put a timing light on it it looks like its running about 5 - 10 deg before TDC. I will dial that up a bit more accuratly tomorrow if I get time. I am unsure what sort of advance/retard if any it should have. Any thoughts anyone?
I took Ixion's advice and checked the spares bike and like I thought it was EXACTLY the same. It had to have been done by the same person. It was even the same amount away from the keyway like the going bike. So maybe they are an adaption off another bike, cause if they went to that much trouble then why in hell didnt they line up the keyway to make assembly accurate. I appreciate the comments F5 and Motu as I did not realise that the keyway was quite so unimportant. I thought it did more to stop side movement but what you say makes sense. But at least now it will be easier to assemble accuratly. I'll let you know how I get on with timing it