too much squish

[peter357bikes]

what are the symptoms of too much squish on performance? I have fitted a lth reed valve on an early mugello 200 which I ported as per threads here. Low down pull is ok but when trying to rev higher it seems to struggle and the noise is outputting. set up is 26 deli b race stealth expansion main jet is 110 av264 atomiser x13 needle 2nd clip 53 pilot 60 choke

[dapper]

Firstly, you don't say exactly what squish you have Generally, no less than 1.2mm. is recommended.

[camel]

im running something similar,a 225 mugello,30 dellorto witha shorty reed valve manifold and an ads 3 pipe
the performance on mine is amazing,on the dyno its getting 21 bhp with 19ft,lbs or torque and the ride is better than my ts1.
i would like to add the exhaust port looks more like ts1 spec and i had to add a 1mm packer to get the transfers to line up at btc.my squish is nearer 1mm which is a tad tight with a head that sits slightly into the bore..
i take it you have cut holes in the piston for the reed valve to work?the exhaust port height needs to be bigger with a reed set up...and the tranfers on big block mugellos are hit and miss so hence my 1mm packer...it certainly wasnt a straight forward conversion

[Avantone]

what are the symptoms of too much squish on performance? I have fitted a lth reed valve on an early mugello 200 which I ported as per threads here. Low down pull is ok but when trying to rev higher it seems to struggle and the noise is outputting. set up is 26 deli b race stealth expansion main jet is 110 av264 atomiser x13 needle 2nd clip 53 pilot 60 choke

Area or gap?

Area: Too much area probably means the combustion chamber is too small and therefore the compression ratio will be too high. 50/50 seems a benchmark. High compression = detonation, pinking, excess heat, holes in piston, empty wallet.

Gap: Too much, means potential detonation depending on compression ratio. Too little (<0.8mm) could mean piston kissing/hitting/smashing cylinder head. General damage to top end.

[peter357bikes]

yes I should have said 1.8 mm squish and what would sound and feel like the power bandits the strained part

[peter357bikes]

I also cut the skirt of the piston and 2holes to boot like my imola piston

[dapper]

Then I'd say your squish is too big and you need more like 1.2mm to 1.5mm max.

[camel]

did you cut a boost port into the barrel?is you stator/coil known to be good?i agree the squish is a little big on your set up and could lose performance but it still should rev out which makes me think its related to something else...what head is on it?...i got rid of the muggello head as the bowl was massive and reprofiled an indian one to suit the piston

[peter357bikes]

I cut a 20mm wide boost port up to the transfers. Its a variatronic ,,,but I haven't had the flywheel off yet to see the stator condition. The scooter was stood for 3 years at least before I got it and had only done 300 miles in the previous 5 on the early mugello kit. In fact before I messed with it it would drone/boom as it accelerated...not a pleasing sound I put it down to vibration/exhaust resonating (Gori 50 race)

[camel]

sounds like youve done a lot of things right then so i would certainly persist in trying to sort it,maybe get that squish down a bit as youve suggested,and maybe mess with the jetting,if you had the 110 main running as the piston port set up id maybe go to 120 with the reed set up as they do require upjetting quite a bit....