Sunday, April 29, 2012

A 998S motor showing it's bits

I had a 998S motor in bits recently and the owner asked me to take some photos of the process.  I found the photo taking process quite intrusive to my flow initially, but must have settled into it in the end.  I thought I'd post a few of them showing what happens along the way.

As it arrived, on the pallet of its sturdy box.

Crank and gearbox in to check shimming (without LH case on).

Measuring crank end float to set preload.  The original main bearings were retained and I reduced the shimming by 0.20mm to give 0.20mm preload.  I was surprised how noticeable the extra 0.05mm was over the 0.15mm preload that I usually use (998 spec is 0.20mm) in terms of turning the crank by hand.  And at 0.40mm, as it would have been, you can hardly turn the crank by hand when grabbing it by the LH snout you can see below.  I'm often amazed how much preload I take out of these late thick shim motors.  At a training course at the factory in 2002 I was told there was a spec in the manuals for checking the runout on the RH (primary drive) end of the crank to tell if it is over preloaded - ie, how much the webs being forced together by the preload is bending the big end of the crank, but i've not found it in any that I've looked in.

I laid some white paper down on the floor, and with the doors shut and me up a ladder took some shots of most of the bits required for a 998 motor.  The heads came complete from Biggelaar in the Netherlands, and the crank and gearbox had been reshimmed and the rods refitted to the crank prior to this photo being taken.  This was 10:18 Friday morning.

Crank, fitted with the std Pankl Ti rods and balanced.  It had weight welded in during balancing.

Clockwise from top - primary drive, starter drive, timing and starter intermediate gears, supplied lightened by owner.

Crankcases joined and left hand side components assembled, ready for alternator cover to go on.  You can see the red painted hollow screw that feeds oil from the RH to LH cases for piston squirting.

Moved from laying RH case down on the bench to a stand through the engine mount holes at the back of the cases.  Primary drive gears and oil pump in, reading for primary drive cover to go on.

Vertical head on.  This was where I finished Friday afternoon.  I am required to be home by 6pm, which is not a bad thing either.

When I'm overrun with work (most of the time) I come back after the little man is in bed and work from 10pm to 1am-ish to catch up.  So Friday night the horizontal cylinder, head and ancilliaries went on.  Saturday night I got into the cam timing, set to the usual 105/109 with belts at running tension.  I know this is more advanced than many people run the inlets, but it doesn't seem to hurt them at all power wise and certainly fills out the middle nicely.

And, 12:20am on Sunday morning, it's ready to go back in its box Monday morning for a truck ride across the country.

Back in the bike it made 146hp on a dyno in Perth. Prior to the work it had made 131hp on the same dyno.  This bike was the one featured in the 998S report when owned by the original owner in Melbourne, when it had made 133hp on the old Dynobike dyno.


ThisGuy said...

Thanks for posting. I wish I had the tools/knowledge/skills to do this kind of work.

What were the main mods that resulted in the increased power? The heads and the Ti rods?

Brad The Bike Boy said...

The power is mainly in the heads, it always is. The pistons were around 13:1 I think, which helps too. Ti rods are std in the S model motor. The rods and other lightened bits and machining will help it spin up faster in the bike, but don't make any power as such.