'12 250F need new piston & pipe ...recommendations?

It's time for a fresh top end on my '12... 44hrs since new. These never-ending midwest winters REALLY cut into my riding time!!!! :banghead:

 

Everything stock so far, need a cam chain and piston. At this point the crank is staying stock ( I'll look at an aftermarket con rod and possibly a cam & porting at a future date)

 

+50 Vet, 185lbs  riding mostly outdoors (Red Bud, Sunset Ridge, Byron, Mt Carroll) and I enjoy a bit of over-rev from all my years riding well-built 125's...

 

Looking for some recommendations on options...Wouldn't mind something with more compression but not thrilled at dropping $200 for a top tier piston, unless it's a complete no-brainer, total waste of money to go with anything else. Isn't there an OEM piston from a different year 250F which has slightly higher compression? I keep VP C12 on hand for our built 2 strokes so if higher octane is needed to mix with 93 octane pump, I believe that will suffice. Not really interested in getting setup to use exotic fuels for daily use, as I'm budgeting for 3 other riders in my family...

 

Will also be looking at aftermarket exhaust (either slip on or full system,) along with a remap, as my overall goal is to try and pickup 2-3 HP in the midrange and up, without losing much bottom end. I've tried searching older posts for exhaust comparisons, plenty of conjecture but most folks agree the Honda really needs at LEAST a slip-on to liven things up. I'm wondering what's the real world difference between a slip on (say yosh or fmf) vs the complete system? I've read the MXA test from '12 but that didn't provide any data on a slip-on only comparison.

 

 

Thanks!

 

Mark

 

I may start another thread on just the exhausts to try and get some more feedback

 

I put the oem 14' piston in our 2013 to bump the compression up a couple points. I like the price of the oem piston and Stage 2 hotcams helped the mid and top-end  out. Bottom end was still good according to my rider. For the price these were very good mods. Also running Yoshimura complete exhaust with spark arrestor screen removed and the Yoshi box. You could just get a remap to save some dollars. You can still run 91 octane fuel with that piston but we usually mix 2 gal of race fuel in a 5 gallon can.  

Edited by WrenchDaddy

I put the oem 14' piston in our 2013 to bump the compression up a couple points. I like the price of the oem piston and Stage 2 hotcams helped the mid and top-end  out. Bottom end was still good according to my rider. For the price these were very good mods. Also running Yoshimura complete exhaust with spark arrestor screen removed and the Yoshi box. You could just get a remap to save some dollars. You can still run 91 octane fuel with that piston but we usually mix 2 gal of race fuel in a 5 gallon can.  

I agree, the oem piston price is pretty competitive. Good to hear I can use the '14 parts

we put a full rocket exhaust and had sisneros remap our '13 and it was a completely different bike, much better power overall. at the next interval for a piston we then put a 13.8:1 je piston and a rhc cam in and wow, another huge leap in performance, much stronger and pulled longer on top with plenty of over rev. no race fuel needed! I recommend just using the 14 or 15 oem piston and a remap with at least a slip-on. that should suffice.

rocket header.jpgrocket <a href='https://thumpertalk.com/link/click/4478/' rel='nofollow' data-ipsHover-target='https://thumpertalk.com/index.php?app=autolink&module=links&controller=content&id=4478' data-ipsHover target='_blank' data-autoLink>exhaust.</a>jpgrocket can.jpg  Rocket makes some very good pipes imo, this came off our 2013 with about 50 hours on it...no dents anywhere and the  anodizing still looks excellent.

I put the oem 14' piston in our 2013 to bump the compression up a couple points. I like the price of the oem piston and Stage 2 hotcams helped the mid and top-end  out. Bottom end was still good according to my rider. For the price these were very good mods. Also running Yoshimura complete exhaust with spark arrestor screen removed and the Yoshi box. You could just get a remap to save some dollars. You can still run 91 octane fuel with that piston but we usually mix 2 gal of race fuel in a 5 gallon can.  

Just want to confirm, I can run the '14 oem piston in my '12 without issue?

You can run the 2014 piston with good results  you can also purchase a .005" copper base gasket from cometic that will boost your compresion a bit more closer to 14-1   an RHC 34 cam and valve spring kit  will put you where you need to be the stock exhaust is capable of suporting 42 hp up from the stock 37 the yosh or fmf will make about the same peak but will help the power between 5000 and 9000 rpm i have made 42 hp on my dyno with this cam and light porting and the stock exhaust this is 3 more hp and more torque than the new yamaha 250 

How's valve life with your cam and springs with stock seats ron?

theres no problem ask walent they have been running for a season

How's valve life with your cam and springs with stock seats ron?

50 hours with no valve adjustments ...period....fast socal novice rider!

And that is with stock valves and seats...we got 100 hours on valves without having to adjust.....then sold the bike....it's all about the maintenance intervals and good oil and clean air filters...

I built a 250 for a local pro with a" different" cam and stiffer springs and the valves and seats chipped in 10 hrs

Poor cam design, perhaps... And/or too loose on the valve clearances.

I have built a few CRF250R motors with Ron's biggest cam and his full porting. One was hammered for a full mx season by a national pro, sold to a Canadian pro for another season, then the bike was sold again. The only did top ends on that bike, valves never moved from 004/009. 46hp on the dyno too.

I built a 250 for a local pro with a" different" cam and stiffer springs and the valves and seats chipped in 10 hrs

Edited by Eddie8v

How long are oem cranks good for when you port/cam these engines to do ~40hp?

How long are oem cranks good for when you port/cam these engines to do ~40hp?

Yes that's a major considerationconsideration when contemplating a mod

Yes that's a major considerationconsideration when contemplating a mod

Are you being sarcastic?

Are you being sarcastic?

Nope, serious comment/question...see my first post, I'm running an original OEM crank, need to use it rest of the season so I don't want to get into something this crank can't handle for another 25-30 hours...

You can run the 2014 piston with good results  you can also purchase a .005" copper base gasket from cometic that will boost your compresion a bit more closer to 14-1   an RHC 34 cam and valve spring kit  will put you where you need to be the stock exhaust is capable of suporting 42 hp up from the stock 37 the yosh or fmf will make about the same peak but will help the power between 5000 and 9000 rpm i have made 42 hp on my dyno with this cam and light porting and the stock exhaust this is 3 more hp and more torque than the new yamaha 250 

Thanks for the tip about the Cometic gasket...

I called them and they are going to ship me out a set

by the way, in case anyone else wanted this info,

that part number is B1005005C

the last 4 places indicate the  thickness and material, in this case 005 thick and C for copper   005C  presto!

Thanks for the tip about the Cometic gasket...

I called them and they are going to ship me out a set

by the way, in case anyone else wanted this info,

that part number is B1005005C

the last 4 places indicate the  thickness and material, in this case 005 thick and C for copper   005C  presto!

thanks

Poor cam design, perhaps... And/or too loose on the valve clearances.

I have built a few CRF250R motors with Ron's biggest cam and his full porting. One was hammered for a full mx season by a national pro, sold to a Canadian pro for another season, then the bike was sold again. The only did top ends on that bike, valves never moved from 004/009. 46hp on the dyno too.

is it better to set the valve clearance to 004/009 than the manual spec of 006/011? I have also had porting done and been told to put a je 13.8.1 piston in to suit the set up or would it be better to use a newer model piston instead?

( Still learning )

Thanks

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