• Ian Watts

Mounting the motor

Updated: May 31, 2019

Once the cylinder head was removed, the swingarm was next. I found it easier to leave the swingarm attached to the scoot for the major kit removal as it helped support and hold the crankcase etc during the work. After that, it was the turn of the oil pump, the starter motor and the ignition system.

I'll need to design some covers / blanks for the holes. I intend to route the motor cables through the square, oil pump hole so will make a blank specifically for that purpose.

Once the cylinder head, oil pump, starter motor and ignition system were removed I began to 'play' with possible motor positions; the crankshaft was 'annoying' me though - it seemed to always be in the way and I knew it'd have to come out for re-working or... something...

Anyways, below are some images of me removing the crankshaft with use of a trolley jack - I tried but couldn't move it any other way. The trolley jack did the job in a couple of minutes - live and learn, I guess !

The swingarm was placed, upside-down, on the trolley jack and 'tied' down with tie-straps all the way around the outside of the jack. The crank shaft was located centre of the trolley jack 'saddle'. The jack was slowly and pressurised, the 'saddle' extended BUT the swingarm itself was restrained by the tie-straps. Slowly, very slowly, being careful so as not to distort the swingarm itself, the crank shaft popped out - as per the centre image above. The whole lot was then cleaned up.


There simply wasn't enough space to mount the motor within the engine casing - even if I had the mind to attempt it ! Looking at the various 3Kw motors available I don't think I can get one much smaller regardless of the amount I'd be willing to pay and even then, the mechanical / machine shop re-work would be extensive (and, therefore, expensive !).


In the end I began to see that the motor could be mounted in lieu of the cylinder head if I designed a suitable bracket. Out came Sketchup and then the 3D printer and in an afternoon I had an ABS bracket knocked up (in pieces - much as I would eventually need in aluminium) and welded them together with an acetone/ABS slurry. Effective !


Once I'd determined that the the bracket was correct for the motor, I went about mounting it to the 4 threaded holes vacated by the cylinder head studs - all the time being very careful not to break my template ! And, once I'd done that and noted the correct positions of the 4 x slots in the back panel for the new cylinder head machine screws. I say 'slots' - these are 4 x horizontal 20mm x 5mm slots allowing the bracket to be mounted to the crank case in a way that there would be 20mm +/- of lateral movement to enable future alignment of the motor pinion with the rear, gearbox, sprocket.

I then cut out and welded the same pieces all over again BUT, this time, in some 'scrap' 5mm aluminium I re-tasked from the skip at the local scrapyard.

Now I had something like the images below. I actually began to feel pretty pleased with myself... starting to believe the whole crazy idea might just work !!

The three holes in the bottom strengthener / spacer are to enable any water to drain more easily.

The motor is held rigid by the two pivot bolts at the bottom bracket and then the short arm at the rear of the motor (left hand side in the images) to help prevent twisting. The long arm on the top of the bracket, at the pinion / drive side of the motor allows the whole motor to rotate forwards / backwards (in relation to the scoot) and thereby enable the chain to be tensioned - much like an alternator adjuster-arm.

To be fair, after a wee bit of filing some rough edges, the whole system mounted up in 15 minutes.


Motor mounted to the crank case and aligned with the rear wheel sprocket

My job with the motor was almost done. All I had to do now was blank off the old / no longer used crankcase holes for the starter motor, crank shaft and oil pump etc being careful to route the motor cables through the now empty, crankcase and up towards the back of the scoot where I planned the electrics & controller would go !

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© 2017 Ian Watts