I have posted the pic to explain a minor update of this particular type of engine mount on my first build a few months ago.
Never mind the roughness at the time, it is not a picture of the finished job, but I want to show the thinking behind the concept when the picture was taken.
If you rev a car's engine, it will torque/twist to one side.
If you ever get the chance, drive your car with no engine hood, put it in gear and drive the car, slow down by taking your foot off the pedal and speed up several times, and you notice an immense amount of stresses being taken care of by the engine mounts.
The same in principle applies to these HT bike builds. When you twist the accelorstor handle and slowdown, speed up, slowdown countless times, it naturaly has stress points the bike is not built for.
Can you then imagine this stress point is taken up by a single bolt or bolts day in day out as you ride your bike ?
It was by accident I discovered to leave my wooden measuring tool I made to align where to drill the centre bolt hole, after 2 weeks the engine had shifted, downwards.
I simply loosened the bolts, re-fitted the original wooden tool to bring the height back up, and this time left it there while tightening up the front centre bolt.
The force was then placed on the wooden tool and I thought this might be a good idea and see what happens.
I got smoother ride, there was less vibrations and by less I would say 75% and that is no joke and no exageration. It's a pleasure to ride this 27" steel frame motoredbike with the wooden support underneath the engine.
I only used a angle grinder and a bench grinder to cut and shape it, so it's easily made to suit your requirements.
Has the wooden tool under the engine lasted ?
Yes, it has only slipped a bit due to some softening from fluids, but it is still holding the engine strong and steady.
My point is this, that from my own expirience and observations, I will not take the kit's engine mounting methods for granted.
Think beyond the square with some commonsense that these HT engines mean business on your bike frames and some sort of added support may need to be considered.
Try making a wooden support as your template towards more durable material for later on.
BTW, the black piece on the rear mount is leather, advice from this forum to not use rubber.
Good advice, the leather is Ok up till now.
BoltsM.