250EX Big Bore Kit

[250ex>Civic]

Okay, I own a 2002 250EX and want to do some upgrades, and I dont want a 400 or 300. I already have nerf bars, skid plates, spacers, and an armadillo bumper, so those areas are fairly covered.

Performance wise, I have a T4 Complete Exhaust, K&N Jet Kit, K&N Filter.

I want to custom fit a K&N PowerLid (I fiberglass alot), and a Powroll Big Bore Kit with Upped Compression. (2mm over and 11.0 compression.)

The question is, will my stock transmission handle this? I dont powershift or drop it in gear ever.

Thanks for your help

[bwamos]

It should, no problem.

However, you may need to look at the auto-clutch for some upgrades, IMHO.

[newts250ex]

if you put parts on you might want to go with an aftermarket clutch. the stockers have truble handling the increase

[ex_fan]

it souldnt be a problem but i would change it n e way just to be sure. have u ever thought about puttin a clutch kit on it?

[250ex>Civic]

Yeah I figured id have to get an aftermarket clutch at some point because with my pipe and such its already very torquey and with a big bore kit it should be sweet.

Thanks for your help

Anybody know some good clutch kits?

[250ex13]

http://rockymountainatv.com/productDetail.do?prodFamilyId=4495&navTitle=Engine&allVehParts=true&pageLinkUri=&webCatId=17&vehicleType=&webTypeId=38&navType=type

[250rider1]

i think barrnett might have stuff for the 250ex.

[BlasterEaten250]

I would also get sport tires.

[250ex>Civic]

I knew about the ebcs but i heard great things about the barnetts, thanks I couldnt remember their names.

I ride lots of rough trails so sport tires wouldnt help me.

[coolex]

get holeshot h-d then there really tuff

[ex_fan]

dont go with EBC clutches cuz they suck!!!
i bought some for my lil blaster and in 2 weeks they were bad. dont go with EBC on anything.

[XCRACER26]

dont get H-ds because they will suck the power right out of the bike. get some holeshot xcr-03 20-11-9. I dont see why you would bother with that 250ex:huh ??? Your just going to start dropping a piss load of money into something that cant get over 65 mph. Take some of that money and get somthing faster.

[cudaman1973]

I just completed my motor upgrade. I first looked into the big bore kit from powroll. Thought it was over priced. I purchased the .5mm Oversized 11.5 to 1 Domed piston from JE. The kit comes with everything except gaskets and man it's nice. I CC'ed the stock piston and head before. Stock static compression measured 8.8 to 1. It is a large compression jump and so far I'm very impressed with the response and the major problem I have with keeping the front wheels on the ground when trail riding. I know with all the people out there that just trash the idea of hopping up this little 229cc motor this could seem like a waste, but I've played with the jets, filter, modified the exhaust etc etc. They don't even come close to this mod. Best under $200 mod I've done yet. For anyone who has worn out there motor.... this is a no brainer to do.

[250rider1]

how much power increase can you get out of the 250s?

[cudaman1973]

I'll find out next week...I'm going to a dynojet dyno to see.

[heavyd119]

I love my big bore kit, made it a new bike

[cudaman1973]

Well I went tailriding today........ The JE piston is great.... man I could jump over logs and hill climb like never before..... before the auto clutch started to go. The more I rode the worse it got. I am now delaying my dynojet trip to find a good balls to the wall clutch. Being mine is a 2003 I will not be replacing it with a stock unit. Any clutch experiences?

Thanks and man you guys have to get this piston if you were thinking about a powroll kit. The JE piston kit will still give you enough money to buy a pipe over the powroll kit. And that money for the pipe I'll be now using for the clutch.