thx for nice words
The kit for auction came with carbon reeds, a kit a friend of me bought came with fiber reeds. I thought the carbon reeds will give better top end and fiber reeds better low down power. How wrong. The carbon reeds topped the fiber ones in the best case (cold engine vs cold engine) nearly 1 bhp over the whole rev range. In the last hmm maybe 400 revs the fiber reeds were a little bit better, but not really affecting the performance.
Next on the agenda was a swap of heads. Gravedigger from MMW did two heads for the kit. I tried the one from these two with lower compression first. See pics on FB site for comparisation of the heads, they are 50% squish area - more squish area, msv and higher compression then the standard head as well. Power kicked in a tad earlier than the SM head and torque is now 37,7 Nm or 27,29 lb/ft @ 5950 rpm. Power also raised to 35,5 bhp @ around 6500 rpm - hold on - this run was with the 30mm carb
and L+S Tourist exhaust. On the downside, the band was shortened a bit.
Just because it was on hand and without big interest to the public, I tried a Genesis Big Air CNC carb from US-based sled tuners PSI. This carb has a triangular venturi, making it behave like a 30mm carb at low throttle opening and a 38 mm carb on fully opened slide. I was in fact VERY impressed by the performance from this carb as it added 1 bhp+ over the whole rev range. It is a carb with no jets, main jet is an adjustable power jet type, the needle can be raised/lowered with an allen key from the outside, I love it. Downside is the price of ~1100 USD, making it maybe a choice for racers when everything else is tried and done.
I will post both graphs asap.
Trying to remove the head for the next swap, one of the short bolts on top was loosening it´s threads, so now I know why CE changes them in the UK sold kits
Tightening the short bolts at the bottom is not an easy task, but we got around it now. With the kit comes a spanner with narrowed sides, so you can get into the very tight place. maybe. Step one: bin this spanner, it will break
Go for a quality (!) ring spanner (hope this is the right word) with narrow sidewall, check that both studs are drilled deep enough (or you won´t get it out after tightening) and that´s it. It´s just a bit tricky, but if you can properly fit a TS1 kit you will also have no problems with the SM. Squish clearance with the original head is advised to set at 1,1mm, for this head design this is safe. As is the jetting suggestion for the 30mm VHSA CS carb, even without an airfilter this is very safe, i would run it leaner on the road. Saying this, I don´t like the term "safe jetting" as this usually translates into "too rich setting", which it is at my altitude anyhow.
The kit, as it comes supplied and if you follow all suggestions should be quite reliable - as far as I can say without testing it on the road for many many miles. But the whole picture, from head design, ignition setting, carb jetting and big exhaust flange diameter makes this kit (and i think this is the intention) "fool proof" IF you follow everything (!)
Fine tuning without doing modifications to the kit will affect power and torque positively without changing the tractor-pulling performance, but you will need more feel for your engine.
