Who's a 2 stroke Cylinder head Guru ?

[micko]

Thanks anyway Ross much appreciated. Lozza the standard 78 head has the same offset dome and squish as I have now, got a few things to try that may eliminate it or get close to being rideable for now.

[micko]

Thanks for all the suggestions, mostly by PM's. As well as having an inefficient cylinder head (fix that later)It was suggested my stinger pipe may be to small (28mm) was told that I needed to go to 32mm as that was the size of the outlet on the Pro Form pipe. So bent up some new 32mm pipe and matched it to a Pro Form muffler, set ignition timing back to standard setting and off I went to Dyno Time (thanks Russell)
We'll blow me down, no more pinginggggg ! And runs cooler too.Loaded it up, ran it hard etc and sounds so sweet !!! ? did I say no more pingingggggg ! ?
This is what this forum is all about, lots of guys with real world experience all willing to share there tips and tricks. Cheers Micko.

[vandy010]

ahhh... the old "stinger" enlargement trick...

[FourstrokeForever]

Thanks for all the suggestions, mostly by PM's. As well as having an inefficient cylinder head (fix that later)It was suggested my stinger pipe may be to small (28mm) was told that I needed to go to 32mm as that was the size of the outlet on the Pro Form pipe. So bent up some new 32mm pipe and matched it to a Pro Form muffler, set ignition timing back to standard setting and off I went to Dyno Time (thanks Russell)
We'll blow me down, no more pinginggggg ! And runs cooler too.Loaded it up, ran it hard etc and sounds so sweet !!! ? did I say no more pingingggggg ! ?
This is what this forum is all about, lots of guys with real world experience all willing to share there tips and tricks. Cheers Micko.

Great stuff..... Isn't it amazing how 2 stroke pipes work (or don't work)?

Yet another case of start with the simplest thing and work from there!

[Lozza]

Thanks for all the suggestions, mostly by PM's. As well as having an inefficient cylinder head (fix that later)It was suggested my stinger pipe may be to small (28mm) was told that I needed to go to 32mm as that was the size of the outlet on the Pro Form pipe. So bent up some new 32mm pipe and matched it to a Pro Form muffler, set ignition timing back to standard setting and off I went to Dyno Time (thanks Russell)
We'll blow me down, no more pinginggggg ! And runs cooler too.Loaded it up, ran it hard etc and sounds so sweet !!! ? did I say no more pingingggggg ! ?
This is what this forum is all about, lots of guys with real world experience all willing to share there tips and tricks. Cheers Micko.

32mm is wwwwaaaaaaaaayyyy big for a 400cc  would help with spread of power though

[Momus]

Was the stinger changed to 32 OD or ID micko?

[micko]

32mm od, 1.5 wall thickness. It slips straight into the end of the chamber,my old  stinger was  off a late model KTM 250. Anyway will try it on the track tomorrow and see how it feels.

[Momus]

Thanks Micko.

My 370B has a GMC pipe with the 1.25" 16 guage stinger finished by a DG muffler with the same perf bore; so the same sizes as your new one.
I have a  400C cylinder with Boyeson reeds and the  offset combustion chamber 370 head. It runs the std .5 mm? gasket.  When I fitted the 400 bore it I increased the chamber volume slightly to maintain the compression ratio and left the main jetting alone. Timing is standard and I have never had it pinging even in some deep sand slogs.

[micko]

Should be all good now, was sweet on the dyno couldn't get it to ping. Didn't ride it last Sunday, was having to much fun on the 250,I'm sure it will be good now, see you on the weekend.