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micoulisninja · July 31st, 2014, 03:55 PM

Like I've told you already...
I expected sth like that would be the case with ARP... the thing is... will the casing hold that much bolting power ?? I mean is the amount of material around the studs enough if you drill it out ?? 250 cases are already somewhat fragile and opening up those hoes will not help its rigidity... helicoil might help but it will be all trial and error and we don't have that luxury...and what's more I think it will all be marginal around the head and especially the cyl block... we're not talking about an inline4 here with space between pistons and liquid flow...
the other 8mm solution is pretty close to factory as far as bolting power... so in that case why not stick with factory studs...
I am glad you are looking into it thorougly and so will I but it's vacation time here in Greece and it's kinda hard to get the info required... I am working on it though and as soon as I get anything interesting I'll be in touch with you...

oh and about the oil cooling thing....(is Bruce reading ??) I am going the way I did on my ZX-12... oil pump sprocket with 2 (probably 1 for the 250) teeth for extra flow... will aso give the water pump extra flow and I think that is critical... I will have it machine at a special machining shop for sprockets, axles etc... I highly reccomend you look into that too...

one more thing... I had a little chat with some mechanic who turbo-mods small bikes (single cylinder 100-150cc) and he told me that it will be much better and easier, as well as far more reliable to use the 300's pistons (and the cylinder block...)
reasons... numerous...
1. flatter crown will give you less compression without need for too many gaskets...will also give you better and faster flame travel so you can have less advance timing... all in one safer, with lower temps and less chance for any predetonation and/or lean spots of burning mixture...
2. they are lighter (both pistons and pins) and stress much less the rods which can give you a little extra "safe" boost...
3. they have a special design underneath to circulate more easily oil between the pin and piston bottom which results in even better heat dissipation (all that always in comparison to the 250's pistons and pins...)
4. the block has much better heat dissipation abilities as well but most important steadier meaning with less difference form top to bottom of "sleeve" (no sleeves of course, it's all aluminium...) meaning less chance of overheating points...
5. he claims that you can still use only the pistons since it is the block that has the clearance differences...pistons are exactly same size...

July 31st, 2014, 03:55 PM	#13
micoulisninja modaholic junkie Name: Nick Location: Athens, Greece Join Date: Sep 2012 Motorcycle(s): 2001 ZX-12R, 2009 ninja 345cc and plenty of others in the past... Posts: 438 Blog Entries: 2	Like I've told you already... I expected sth like that would be the case with ARP... the thing is... will the casing hold that much bolting power ?? I mean is the amount of material around the studs enough if you drill it out ?? 250 cases are already somewhat fragile and opening up those hoes will not help its rigidity... helicoil might help but it will be all trial and error and we don't have that luxury...and what's more I think it will all be marginal around the head and especially the cyl block... we're not talking about an inline4 here with space between pistons and liquid flow... the other 8mm solution is pretty close to factory as far as bolting power... so in that case why not stick with factory studs... I am glad you are looking into it thorougly and so will I but it's vacation time here in Greece and it's kinda hard to get the info required... I am working on it though and as soon as I get anything interesting I'll be in touch with you... oh and about the oil cooling thing....(is Bruce reading ??) I am going the way I did on my ZX-12... oil pump sprocket with 2 (probably 1 for the 250) teeth for extra flow... will aso give the water pump extra flow and I think that is critical... I will have it machine at a special machining shop for sprockets, axles etc... I highly reccomend you look into that too... one more thing... I had a little chat with some mechanic who turbo-mods small bikes (single cylinder 100-150cc) and he told me that it will be much better and easier, as well as far more reliable to use the 300's pistons (and the cylinder block...) reasons... numerous... 1. flatter crown will give you less compression without need for too many gaskets...will also give you better and faster flame travel so you can have less advance timing... all in one safer, with lower temps and less chance for any predetonation and/or lean spots of burning mixture... 2. they are lighter (both pistons and pins) and stress much less the rods which can give you a little extra "safe" boost... 3. they have a special design underneath to circulate more easily oil between the pin and piston bottom which results in even better heat dissipation (all that always in comparison to the 250's pistons and pins...) 4. the block has much better heat dissipation abilities as well but most important steadier meaning with less difference form top to bottom of "sleeve" (no sleeves of course, it's all aluminium...) meaning less chance of overheating points... 5. he claims that you can still use only the pistons since it is the block that has the clearance differences...pistons are exactly same size... __________________________________________________ If noone has tried it before, I will !!!