310 big bore kit

[TRX55]

Hey, I have a 95 kx250 and when i first got it it had well over 100hrs on the bike and the original owner of the bike never did a top end or anything else to it for that matter. The bike was pretty clean and never been touched. When i tore it down i noticed the plating was already coming off the cylinder wall around the exhaust port. Since then i have put probably three pistons in it and just about ready for another. The bike never really had a ton of power like other kx250's i've ridden and my compression was only around 120psi average each time i would check it a little after a rebuild. I've just been buying some time until i could get it replated. I am undecided whether to replate it stock or a little oversized, depending how bad the cylinder is or go for the eric gorr 310 big bore kit. I was wondering what i should expect as far as power, reliability and piston size availability if i went with the 310 kit. I really want to get a couple of more years out of this bike and wake this motor up a bit. I have a 12oz. flywheel weight, fmf gnarly with stock silencer and i run a 14-49 for gearing. The bike is pretty much stock other than that. I just need to know how much of a gain in the low to mid i should expect over a stock rebore and aprox. how much it would cost? Thanks for and info..............

 

[john stu]

i never did a big bore on a 250 but so far my kx144 big bore runs great and i would do it again in a second its been just as reliable so far (knock on wood)

 

[turboandy]

I put a EG 310 in my buddys 00 kx250 and it makes my 01 kx250 (ported,pro circuit exhaust, 2 stage reeds, power now, vortex ported carb) feel lika a 125. NO COMPAIRSOME it is brutal.

 

[bclapham]

i think the only con would be having to buy the piston from max power, but i bet the pistons last for ages in them things anyhow.

 

[cujet]

Make sure to use a reputable plater to re-do the cylinder. The original Kawi plating is not so good. I like US Chrome NiCom plating

Going larger will give the bike a really nice feel.

Chris

 

[TRX55]

Thanks for the info, I'am not 100% convinced yet but i'am getting there. Does anyone know if you have to mess around with the pilot and main and does it make the motor more suceptable to running too hot? Does eric send his bore jobs to US CHROME or does he do it inhouse and does anyone know the price to have this done? Thanks

 

[bclapham]

the big bore kit will probably change the jetting, just like any other modification does. there is more to doing a big bore than boring and plating- the bored cylinder must also be ported to make it run right and you have to grind the powervalves to clear the bigger piston and cut the head. i think for the 310 that the crank cases need to be clearanced for the bigger piston too. Eric does all the work and then has US chrome do the plating, your best bet would be to crate the entire engine and send it to him- his prices are the best going and all you will have to do is drop the engine straight in when it comes back. give him a call first since he is moving shops so he will have a bit of down time.

if you use the search in this or the 2stroke forum on "310" you will find a ton of people that love that kx310

 

[Senior KX Rider]

All the work on the KX 310 is done to the top end. I am one of the people that loves the 310, what a difference in performance. When you ride one of them for a while most other bikes feel weak. My KX has been a 310 for 3 years orr more and I have had no issues with overheating or reliability. There is a bit of a problem with wearing out rear tires a little faster :thumb:

 

[cujet]

Those that have done the Eric Gorr big bore kits really love them. He will set you up properly.

As far as jetting goes, there are folks here that can point you in the right direction and I am sure they will let you know what works for them. That should get you very close indeed.

Chris

 

[KX'er]

I have the 310 in my '00. I really like it. Much more power, while being more ridable as well (i.e. engine is very torquey).

 

['00kx250spode]

Mark me up as another that loves his 2000 KX310. The power is very smooth and predictable. I had to go a bit leaner on the main, pilot and clip.

For the difference in price between getting her plated or the big bore, the bore will be a steal.

 

[TRX55]

Hey, Thanks for all the info. It sounds like the kind of power i'am looking for. Now to call eric and get the ball rolling.......... Thanks again!

 

[motometal]

anybody comment on vibration?

 

[wormser77]

How much is the kit and what type of turnaround on getting the cyclinder back?

 

[Senior KX Rider]

Originally posted by motometal
anybody comment on vibration?

I didn't notice a considerable increase in vibration

 

[mtneufer]

In have used sevral of erics 310 kits on kawasaki.They run twice as long as the stock cyl.We did a hill climber a few years back on a 97 kx 250 and found runing a 99 kx 250 stock exhaust and leaner jetting really woke it up.It pulled like a stock cr 500.In my opion it is better to spend the money on one of his kits then to buy the junk Kawasaki is selling every one.

 

['00kx250spode]

I picked up a 2003 RM125 last month and the first thing I noticed is the difference in vibration. My KX310 vibrates much less than the stock 125 and no more than a stock KX250.

 

[Kx_God]

I put a EG 310 in my buddys 00 kx250 and it makes my 01 kx250 (ported,pro circuit exhaust, 2 stage reeds, power now, vortex ported carb) feel lika a 125. NO COMPAIRSOME it is brutal.

So it is worth it? And was it just bored or ported also with the 310? And what type of power characteristics does it have compared to yours I have an 03 kx250 getting mine done by costume kraft want to see if it's worth it