XS650 kicks like a mule

[surfer]

Anyone help with this one please?

I have an xs650 engine that I have just put into my bike to replace a broken one. When I kick it over it kicks back like a mule crushing my ankle and launching me over the bike. I'm not enjoying lying in a crumpled little heap with a stuffed ankle. I've done this a few times now and I can hardly walk. It sounds like it wants to fire up and has a few back fires. What am I missing so that this doesn't happen?

Ignition timing is set ok with points beginning to open at correct place on F mark. Points gap is ok and valve clearances are ok. Kick starter works fine with no power turned on as no kick back.

I don't have a tester to see which piston is firing. I haven't swapped the ht leads on the cylinders yet either. I also haven't looked inside the engine or taken it apart as I wanted to see how it ran to get an idea of what needed looking at before I stripped it.

Cheers

[paturoa]

Symptoms sound like it is still firing before TDC, hence the kick back ....

Check the advance retard mechanism is free and working.

If it is then retard the ignition by 5 degrees and see what happens.

Edit - and if still does it then keep retarding till it stops and see what happens then.

Have you got a timing light?

[kevfromcoro]

i had an xr 6 hundy.. kicked me back one day.. 6 weeks of work..
shit it hurt........
not to sure whats wrong with your bike.. sounds a bit like timing.............
iam sure someone will be along.. and able to help......
Whiskey is good for twisted ankles......
Trust me .. i know......................................

[jim.cox]

Ignition timing is set ok with points beginning to open at correct place on F mark.

Remember that the piston passes Top Dead Centre TWICE in each cycle.

On some bikes (eg, Notrun Commando) its easy tio get the timing 180 degress out - DAMHIK

[surfer]

Thanks, the 180degree out makes sense. How do I get it so itsnot180 degree out? Is it as simple as swooping the ht leads over? I'm loath to try kicking it over and end up on my arse again, is fkn painful. Cheers

[jim.cox]

. How do I get it so itsnot180 degree out? Is it as simple as swooping the ht leads over?

Yup, thats the quick way

[Motu]

Back to basics for a start,and make sure which cyl is firing - hold you thumb over the spark plug hole as you kick it over to find compression stroke.They have problems with the advance unit - advancing too far,retarding too far,weak springs,sticking of the advance shaft which runs on needle rollers through the camshaft.I presume you are setting it statically....full advance or retard? Do both to double check the wear in the advance unit.If you are setting on full retard,and the springs are soft...it will be overadvancing as you kick.

[Supertwin Don]

Make sure that the "correct" set of points is feeding the "correct" side - I can't remember which is which, but one set of points is a "lead" set and must fire first.

[surfer]

Yaaaaaaaaaaay... the beast roars into life and doesn't kick like a mule any more, my ankle and sanity are saved.

Cheers for your replies people, very much appreciated. It was a timing issue, and it was only a few degree out, so good input and great diagnosis.

Took the points, governor rod, backing plates apart. Carefully put them all back together. Checked on the F mark on the stator and the points were opening just a fraction too early. The backing plate for the points was hard up against the adjusting screw, there was no adjustment left to make. Having carefully put the points back together there was no way the problem could be anywhere else. So shaved a bit of the backing plate to allow for more adjustment and it worked fine.

I'm going to take it for a spin and see how it runs in the daylight so if anything does need tweaking I can see to put it right. Cam chain needs replacing, not sure what else at this stage

Massive thanks to Psyguy for helping pull stuff apart and going through everything with me to sort it out. Cheers.