Indeed. Very often someone shows me a cylinder head pointing into the corner telling me this is the squish. Hmm no. The squish is exactly what Mista FreakMoPed is showing in this video. You need to know the squish in order to bring the piston into a healthy distance from the cylinder head because the piston shall not knock into the cylinder head. Sometimes I heard even from experts that the squish has the task to keep the explosion away from the piston rings in order to save the rings from braking. If this is right, why does the mega squish in the original px200 cylinder exist and why there are no stories in forums of broken piston rings? For an effective deployment of the combustion energy the ignition timing is adjusted so that the highest combustion pressure at all speeds deploys about 10 ° to 20 ° crankshaft angle after top dead center (TDC). The focal point of combustion, that is the time at which 50% of the fuel mass burned are then at about 5 ° to 8 ° after TDC. Lets say we have the highest pressure at 14 ° after TDC in a malossi 210 with a stroke of 57 mm and a squish of 1,2 mm. The squish at 14 ° after TDC will be 5,6 mm. My experiance is that you will get problems with a too high compression ratio but not with a high squish. If the compression ratio ist right you can go down even to 0,8 mm squish. I had to go down to 0,8 mm squish in my malooser because I wanted to reach a compression ratio of 11:1. Reason: I need to get more torque in lower rpm to solve the low power in the beginning of the 4th gear with 57 mm stroke. No problems with compression ratio of 11:1 and no problems with 0,8 mm squish. Next step will be 0,6 mm squish *evil smile* how how how .... nice vid .... liked.
its quite common pratice that you have on a 2 stroke a low squish of around 0.7 0.75mm is what i reccoment for good performance 0.6 sir i would not advice you can get away with it deppening on the poort timings in the cylinder but your piston will be running to hot also its bad to chance the cilinder heads unless your aiming for high pressure head cause the squish should be adjusted with the base gasket and not the cylinder head!! cause the squish as i mention also has to do with the durations of the poort timmings !!!when they open and the duration of them as wel wich both of you did not mention :P
Squish height,PBT, base gasket, head gasket,skimming top/bottom side cylinder,machining head , overlaps eachother, very interesting problem in my head 😖 nice video btw!
@@FreakMoPed8 I have looked for information on the squish that it should have as in other cylinder manuals and I do not find anything. For example in the VMC 177 the manual indicates 1mm squish. I would like to know if Piaggio really advises some measure or as you say, I can sand 1 mm of the cylinder head with ease.
dont think of piaggio as a highend 2stroke engine. its a tractor engine. power is low, cylinder timings and intake timings as well, exhaust port also small, squish huge = low compression. Etc
Hi. I am fitting a Pinasco vespone 190cc kit to my px 150. It has a 60mm crank. The kit comes with a 1.5mm spacer. When I use the spacer the squish is around 2.7mm. Without the spacer the squish is 1.5mm. What is the correct amount of squish and nearly 3mm seems far too much. Thanks.
@@FreakMoPed8 Yes I have gone without the spacer. Ports align so much better. At BDC piston is level with intake ports and sits around 1mm below the exhaust port. Squish measured at 1.5mm when all torqued down. Squish is a bit on the high side but safe. Thanks for youre reply.
I just changed the piston size to 60mm. what is a good squish size and degree for a cop head. please tell because I don't understand how to count, thank you
No, no need. Its about HOW TO MEASURE IT , cause its mostly done wrong I dont provide more details cause i dont talk about things i just read, but dont have enough OWN experience.simple a s that.
Hi Great video by the way Which squish value do you recommend for a yamaha mate50 (50cc) has a cast-iron cylinder (bored to 45mm)and aluminium head(also 45mm) with central sparkplug Ps : i'm new at this and might learn something
Hi brother nice content by watching your video I think you have very deep knowledge about engines of vespa so kindly help me I have vespa SXL 125 there is a problem with my scooter that is when I do self start or kick start it wont get started & when i showed my scooter to mechanic he told me that there is an issue with the engine head i.e. your scooter is facing starting issues so could you plz help me to fix this problem.
it will work. it will not fit as the pistons are different BUT anyways, not sure if polini or pinasco ever designed their heads onto the specific pistons ;) so just do it.
