Tuff to Kick - Rebuilt engine

Nigeldtr · Apr 17, 2014

Finally got my 850 MKII back on the road again today. After almost a year and total engine and gearbox rebuild the old girl burst back into life! On the road she flew along - was as keen as anything to “get up and go” - fantastic!! I managed to do about 40 miles this evening and will give the head bolts etc. a tighten tomorrow morning and re-check the valve clearances.

The problem I have is to kick her into life. She has been re-bored to +60 and I am really struggling to kick over compression even, with the full body weight/swing etc. she just seems to get stuck on the compression. This is a real killer – any tips?

I have standard pistons (compression wise) seriously skimmed head (previous owner) but compression plate fitted under barrels. The piston rings (especially the oil rings) are rather tight so I suppose this will improve and “free up” a little with more miles.

PS thanks for all the great advice and tips, really saved me a lot of trouble and helped me get finished. The idea of priming the crank via the rocker feed crankcase connection worked great, manged to pump in a lot of oil before it start to appear at the crankcase drain plug!

concours · Apr 17, 2014

Nigeldtr said:
Finally got my 850 MKII back on the road again today. After almost a year and total engine and gearbox rebuild the old girl burst back into life! On the road she flew along - was as keen as anything to “get up and go” - fantastic!! I managed to do about 40 miles this evening and will give the head bolts etc. a tighten tomorrow morning and re-check the valve clearances.

The problem I have is to kick her into life. She has been re-bored to +60 and I am really struggling to kick over compression even, with the full body weight/swing etc. she just seems to get stuck on the compression. This is a real killer – any tips?

I have standard pistons (compression wise) seriously skimmed head (previous owner) but compression plate fitted under barrels. The piston rings (especially the oil rings) are rather tight so I suppose this will improve and “free up” a little with more miles.

PS thanks for all the great advice and tips, really saved me a lot of trouble and helped me get finished. The idea of priming the crank via the rocker feed crankcase connection worked great, manged to pump in a lot of oil before it start to appear at the crankcase drain plug!

Inertia... Get it rolling as much as you can BEFORE compression. Start at TDC.

Eat more pasta? :lol:

acotrel · Apr 17, 2014

If you do the big swinging kick start, it can bounce off compression and even kick back. Stand on the kick starter until most of the compression is gone, then give it a sharp push over TDC. It doesn't need much momentum to start, even if it had a magneto. I once kicked over a Vincent which was on 13 to one comp. Just do it slowly.

Nigeldtr · Apr 17, 2014

thanks Guys, so do I keep my weight on until I can feel the compression weaken and then push or do I let it go just over TDC and get some swing in before the next compression stroke? I have an older Boyer, good charge and battery and was wondering when the spark occurs - before or just after TDC fully retarded?

Matt Spencer · Apr 17, 2014

Once everythings positioned correctly and all the switches ETC , you hurl yourself upward so as the crank has just started to move as you arrange yourself vertically upon it , thus your weight is used to maximum advantage . Kicking it buggers things . you ENGAGE it before cranking , at the top of its range . :mrgreen: , this will throw it over two compresions , just .

Nigeldtr · Apr 17, 2014

hmm I think I need to put on some more weight as I do as you say, let it engage, jump up in the air, straighten my leg and let all the weight come down on the engaged kicker. This usually gets her to turn and if I am lucky start, other times she just sits at compression and my knee screams at me. I'll try taking her to TDC, pushing off a bit of the compression and then do the swing.

PS concerning vibes etc, when do the isolastics cut in? Seems to be around 3000 rpm on mine - very impressive!

pete.v · Apr 17, 2014

2500 to 3000 is common. generally closer to 3000.

pommie john · Apr 17, 2014

Get some miles on the motor.
Mine was really hard to kick over straight after the engine rebuild but loosened up quite a lot after a couple of hundred miles.

Oh yeah, make sure it's not wet sumped, that can make it hard.

1up3down · Apr 17, 2014

you have a newly rebuilt motor, all is tight

I had the same stiffness with starting after my rebuild, patience, it will loosen up soon

tricatcent · Apr 17, 2014

Usually when the cylinders are still rough from the honing the bike will be stiff to kick over. The idle will be hard to adjust. After about 500 miles the idle will get faster indicating the cylinders are polished up for less friction.

frankdamp · Apr 19, 2014

Properly adjusted Isolastics shouldn't "kick in" anytime. There should be just a very slight shudder as the engine starts and it should be silky smooth from idle to red-line. The prototypes were like that even after a lot of hard miles, and those weren't the vernier adjustable types.

The only issue we had was with the original spacer tubes, which were just straight pieces of fairly thin-walled tubing which started to go "bell-mouthed" under the end load of the assembly fasteners. They were redesigned with flanged ends to eliminate the problem.

Tuff to Kick - Rebuilt engine

Similar threads