Piston replacement interval on a 2009 CRF 250

1. The factory service manual says to change the piston and rings every 15 hours-I realize that is based on a racing schedule, but I dont race, and that seems a little excessive. There is nothing in the manual about checking the compression; do you know what the compression should be? Not trying to be cheap, just dont like to fix things when they aint broke. I normally ride a 650R, so, well you know.....

 

2. I replaced the factory piston after about 30 hours-there was virtually no wear. Put a Wiseco kit in, ran exactly the same. It has always been hard to start cold. Put in the R & D powerbowl, did not have any effect on starting. Dropped the main jet to a 172 as Charlie C suggested some time ago, and that improved the cold starting dramatically. I am approaching 40 hours on the Wiseco-the bike runs great, doesnt go through oil.

 

So the question is, would you guys just replace it to be safe?

 

 

 

50 hours ish

That is more what I was thinking-thanks for the reply

You can go a lot longer than 50 hours if you aren't racing. Do a leak down test, and change your piston once you see an increase in leakage, or just change the rings every time, piston every other time.

You almost never see crfs with piston problems, might as well wait until you need a crank or a valve job before replacing it

yeah i was just giving what most shops recomend for some hard and not so hard riding, a medium level racer would be at 50 hours

You can go a lot longer than 50 hours if you aren't racing. Do a leak down test, and change your piston once you see an increase in leakage, or just change the rings every time, piston every other time.

You almost never see crfs with piston problems, might as well wait until you need a crank or a valve job before replacing it

You are right-I have not seen problems with the pistons on these bikes, or any other Honda, and I have owned several. The problem usually occurs with the crank(especially on the 4 strokes) or head, and that is usually because of poor maintenance(air filter, oil changes, etc).

 

I am sure this will get some comments.....right? :devil:

The only piston failure i've seen in a long time is the guy who cracked a CP piston from detonation on a high compression race motor, by running pump gas in it....

The only piston failure i've seen in a long time is the guy who cracked a CP piston from detonation on a high compression race motor, by running pump gas in it....

Yeah, I'm that guy. :banghead:  :naughty:  :cry:  :eek:

at least 50-60 hrs

 

 

here is how to fix the hard to start crf250

 

http://crfsonly.com/forum/viewtopic.php?t=21535

Interesting fix-I will try that today. Too bad I didnt see this before I bought the R & D powerbowl; that did nothing to help the cold starting. Dropped the main jet down to 172 as Charlie C recommended, and the starting improved dramatically, but still not as good as I would like. So I guess the question is, after doing this modification, should I put the old main jet back? I really does run good with the 172.

Thanks for pointing me to this

Yeah, I'm that guy. :banghead:  :naughty:  :cry:  :eek:

 

Don't worry, you aren't the first guy to blow up a motor trying to save a few cents....

 

Just hang that piston on the wall like a badge of honor!

Interesting fix-I will try that today. Too bad I didnt see this before I bought the R & D powerbowl; that did nothing to help the cold starting. Dropped the main jet down to 172 as Charlie C recommended, and the starting improved dramatically, but still not as good as I would like. So I guess the question is, after doing this modification, should I put the old main jet back? I really does run good with the 172.

Thanks for pointing me to this

 

stock 188 jet is to rich, leave the 172 in if the bike likes it right now.

 

The mod decompressor mod simply raises compression slightly when kick starting, has zero effect on how the bike runs. Another way to make the bike easier to start is a higher compression piston. 13:1 is stock, can go as high as 14:1 on ethanol free premium pump

 

is it the r&d powerbowl or powerbowl 2?

Edited by adam8781

I actually used a wiseco which bumped the compression slightly-it started better(I thought) after that. I need to be able to run on pump gas, and I use premium with that Startron additive; seems to work well.

It is the Powerbowl(Not powerbowl II, what is the difference?), and I actually used a 175 main because I had one in my toolbox. Just finished that decompressor mod, very easy, and it did allow it to start much easier. I even killed it after 10 seconds, and it still fired right up, no choke, and its only about 40 degrees out.

Thanks for all the input-happy riding.

Edited by pabrown

I have my two kids both on CRFs. Boy is fifteen and really uses the engine all the time - piston change every 15-20 hrs. And the pistons shows the wear by then. Engine get's  a full rebuild every 65hrs (max). (3-4 pistons) We have 95 hrs on this years bike and ZERO problems.

 

My daughter is fast for a girl but we can use the piston for 30-40 hrs due to here different rev level

 

It all depends on how you ride. But i would not recommend to run in longer than 50hrs - and remember if the pistons wears out and starts to tip over you damage your cylinder So spend the money early and wisely.

 

Oh and oil changes every 4-5 hrs.

Edited by spike1911

Yeah the skirts are scary short on these pistons. I will probably do the rebuild this winter. And yes, I change my oil every 4-5 hours as you do-I think the service manual states something like 10-15 hours, and I can tell you the engine oil is usually smoked by then. I think that is maybe the reason that you see a lot of people having crank problems.

Edited by Paco32

Engine/ trans oil every 2 hours. engine top end pulled and inspected every 12-15 hours and a new piston and rings installed.

I'm really mean to it. Nothing seems to last more than 10-15 hours on the bike racing it. Trail riding or basic track use for a slower rider you can get 50 plus hours easy.Run a clean air filter every ride and change the oil. It's all in how you ride it. Bikes in the past I never went through chains,brakes,tires,clutches,graphics,and engines til I got some speed. I can feel the engine power starting to go away after about 8 hours.

It's also peace of mind. When your riding pro level tracks with 4th gear jumps the last thing you want to do is have an engine lock up or something break.

I have had this happen before, now every little noise freaks me out LOL

Edited by limp1969

Engine/ trans oil every 2 hours. engine top end pulled and inspected every 12-15 hours and a new piston and rings installed.

I'm really mean to it. Nothing seems to last more than 10-15 hours on the bike racing it. Trail riding or basic track use for a slower rider you can get 50 plus hours easy.Run a clean air filter every ride and change the oil. It's all in how you ride it. Bikes in the past I never went through chains,brakes,tires,clutches,graphics,and engines til I got some speed. I can feel the engine power starting to go away after about 8 hours.

It's also peace of mind. When your riding pro level tracks with 4th gear jumps the last thing you want to do is have an engine lock up or something break.

I have had this happen before, now every little noise freaks me out LOL

That little noises that appear from time to time when something is not perfect is scaring the shit out of my boy too  ;)  He then refuses to ride until we find what it is. But is understandable! 

Had i known how much work, time and money i would have to spend when my kids grow up (we started as real gooners ) i'd have thought about going down that road...  :thumbsup:

But now it is too late - we are in full training for dutch and german SX now for the first time. on saturday we are going to pick up a brand new 2014 honda...

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