ninjette.org - View Single Post - Comparing the 250 & 300 motor/engine (Version 2)

TheKid760 · January 16th, 2016, 12:57 AM

Somchai,

Thank your for the link, it seems they make more aftermarket parts for this engine than I was aware.

I would love to share the details of my build, but its only in planning stages at the moment to see about the feasibility of my project within budget & hp/mph goals.

Initial plans are to go with somewhere around 10.5:1 CR and over 30psi boost. This is a dedicated race only Bonneville build. The air up there is thin and requires higher CR and boost to compensate. Spec fuels will either be leaded 117 octane or methanol.

My concerns are how good of a platform is the ninja 250 to use in this application vs another model 250? Obviously I will be asking way more than ANY 250 should be easily capable of, but if one platform isn't quite as durable (block, heads, etc) as another then I will obviously choose the beefier one.

One of the areas I will need to likely spend most of my budget will be the rotating assembly. It seems IMHO any of the readily available aftermarket parts (rods & pistons) will not be durable enough or are not suited for high HP and high boost. The piston pins are only .630" .120" wall thickness. this will have to be increased which will necessitate custom ordered rods and pistons, which have to be ordered in sets of 4.

Another area of concern is the heads and how much can the ports be enlarged before hitting a water jacket or other obstacle as well as the ability for larger valve springs.

Any how, enough ramblings for one night, Cheers.

January 16th, 2016, 12:57 AM	#141
TheKid760 ninjette.org newbie Name: Mark Location: San Diego, Ca Join Date: Dec 2015 Motorcycle(s): 2007 EX 250 Posts: 2	Somchai, Thank your for the link, it seems they make more aftermarket parts for this engine than I was aware. I would love to share the details of my build, but its only in planning stages at the moment to see about the feasibility of my project within budget & hp/mph goals. Initial plans are to go with somewhere around 10.5:1 CR and over 30psi boost. This is a dedicated race only Bonneville build. The air up there is thin and requires higher CR and boost to compensate. Spec fuels will either be leaded 117 octane or methanol. My concerns are how good of a platform is the ninja 250 to use in this application vs another model 250? Obviously I will be asking way more than ANY 250 should be easily capable of, but if one platform isn't quite as durable (block, heads, etc) as another then I will obviously choose the beefier one. One of the areas I will need to likely spend most of my budget will be the rotating assembly. It seems IMHO any of the readily available aftermarket parts (rods & pistons) will not be durable enough or are not suited for high HP and high boost. The piston pins are only .630" .120" wall thickness. this will have to be increased which will necessitate custom ordered rods and pistons, which have to be ordered in sets of 4. Another area of concern is the heads and how much can the ports be enlarged before hitting a water jacket or other obstacle as well as the ability for larger valve springs. Any how, enough ramblings for one night, Cheers.