Scooterotica

For information to anyone interested...........

I have puchased one of these kits as they are brand new..................

The kit comprises of:
An aluminium nicasil lined barrel with 4 transfer outlets in the barrel and a 'boost? port?
An aluminium cylinder head recessed to allow fitting without a gasket.
Lightened type gudgeon pin.
68mm Asso two ring(thin) piston with port cut for 'boost'?
Two base of barrel gaskets in differnt thicknesses to adjust squish
Inlet/exhaust studs (no nuts/washers)
Piston circlips.

Spent a pleasant few hours fitting the studs to the manifold and giving a smoother finish to the inlet/exhaust ports and installing the kit.

The kit is in every way akin to it's smaller brother, the 185 kit,which I have fitted to an SX150 engine casing (not fiited to frame yet so untested).

The inlet manifold studs are spaced for a small engine case i.e. 125/150/175 even though the kit fits a 200 casing. I have had to use a GP150 inlet manifold to continue using the 22mm Dellorto(fits smallblock studs but allows fitting of 22mm Carb).

Apart from that all seems to be 'plug and play'.
I am at present experimenting with jetting but 125 main and 48 idle seem to be in the right direction.
As far as I can determine squish seems to be about 1.3mm but compression is very high but am not able to calculate this.
I am planning a test run of a few miles tomorrow so will report any incidents.
I don't have access to a Dyno in this area to finalise carburation so everything will have to be trial and error.

arr right,whats the cost of one of these kits?

Cost of kit £395. But factor in that this kit was intended as a 'change head, barrel and piston retaining your existing carb/exhaust.

Today following advice from Scootopia, upjetted to 128 main and 50 idle. Have covered about 30 miles around town. Engine pulls very strongly but has developed a metallic sort of tinkling, (especially when accelerating and when engine hot) sound. Possibly head leak as engine has heated cooled etc....or pinking?....or chain rattling. will check all of these out.

Report back later

Maybe it's piston slap or your piston is hitting the magflange ?
Seems they may not have done a very good job on the R&D of these kits - a bit like the launch of the RB22 eh !
Have a look here for a thread over on the LCGB site.

rog60 wrote:... a metallic sort of tinkling sound...

sounds like pinking ?
ignore at your peril. i know i have...
what's your timing set at ?

Sounds like a perfect description of pinking to me, as Byron says ignore it at your peril!

Timing set at 19DBTDC and checked with strobe. Before final assembly I turned the engine over by hand to check for piston skirt fouling the mag flange but could see no evidence of it. The 'rattling' as stated before doesn't occur before engine starts to warm up, disappears when backing off the throttle but seems reminiscent of that slight squeek we used to get when a gasketed head leaked slightly. The cylinder head, by the way, has a central combustion chamber.

As I have not had to deal with pinking for such a long time, would some kind soul remind me on what to check for and solutions to those conditions?

Timing >>advance the timing till pinking can be detected, then retard the timing by a degree or so, I know it sounds rough but its the best method,

the only variable is how good you are at detecting an engine that is not running at its best, do a spark plug test.

If you can see any grey on the plug, then the timing is still a little advanced.

Thanks for that and all input so far. Was planning to do a plug test but had it in my mind that it had something to do with weak mixture.

I think the best plan at this stage, after the plug test is to recheck the timing and then strip the kit down to see if anything untoward can be spotted. Just an afterthough, the engine was pulling like a train at about 2200 last night on my way home so could the ambient temps/humidity be a factor here?

Pinking is caused by a weak mixture and/or timing. Since it was ok and now isn't, it's probably the mixture.