Mallosi 172 skiming head

Hello

Does anyone happen to no the offset of the spark plug hole to the sealing o ring groove location.

Thanks

 

Not sure on that one. air cooled or L/c ?as you know the plug is angled to make it a centre plug type, what are you wanting to do apart from skimming head ?

 

Sorry I should have been way more clear the bike is an Italjet Dragster.

I have had my LC mallosi 172 kit sent out to Germany for porting and matching to the exhaust upon getting it back I have been told to run a 1mm base gasket to raise the port timings.

Obviously by doing this it will raise the squish band also... this is where it gets tricky so I have to skim the head back down to a 1mm squish band I'm unsure about this do I need to reinstate the o ring groove depth or could i get away with using a good quality sealant in that area?

Also by skimming the head would it then mean I have raised compression because I cant work the combustion chamber easily due to it being offset by an unknown amount. I have been thinking though would it raise the compression at all with skimming the head because I have only technically moved everything up rather than just removing material and making the cylinder volume smaller.

Would a compression test be accurate enough to check compression after skimming or would I have to do the syringe and measure the volume of the combustion chamber I have never done this method before so a little worried.

 

You have some big questions there, are you in the UK ? I have never heard of raising the hole barrel, I just raised exhaust port. Try WILKINSON RACING here in the uk, he seems to be one of the UK's best piaggio 2t tuners. You can find him on facebook as he's on the Gilera runner owners rorum !

 

Yes I'm in the UK I have actually just got in contact with him seems like a good guy.

Yeah seems a strange one raising the barrel on a standard 52mm crank perhaps its a way to be lazy on the porting side of things I'm not sure as its starting to get out of my knowledge zone.

I'm a machinist by trade so ideally I wanted to do it all myself by I have to remember I'm not a engine builder or two stroke expert from what i gather the mallosi head isn't actually any good for this type of tuning due to it being offset where as moving over to a pm tuning head its all concentric.

 

It does help having a dead centre spark plug, it feels crisper, possibly better combustion !

 

Yes I think your right about the centered spark plug I imagine the flame could reach to the outer edges of the combustion chamber quicker than an offset type head also the chances of detonation should be reduced with a centered plug....but then a counter argument could be an offset spark plug away from the exhaust would make the engine run cooler as the exhaust side will all ways be the hottest.

Im new to all this as you can tell I was always led to believe a two stroke engine is very simple which I suppose it is looking from the outside but when you really start to break it down its very complex luckily there is a lot off good books out there !!

 

I love my 2t' typhoons, it is a dark art tuning them and I'm a bit conservative when porting barrels. I mainly due std nowdays as I like ease of them running, not light switch power !