2012 CRF250R rebuild questions

mxrider28
Edited Date/Time 3/8/2013 4:12pm
Hey guys I have a 2012 crf250r with 95 hours on it. So far the bike has been great but I think it is time for an engine rebuild. I had a new piston put in at 50 hours already. My question is though at 100 hours what all should be replaced? I ride/race mx at a fast C level pace. I change the oils/filter every 5 hours and clean the airfilter every 1-2 rides.
I plan on a new piston/rings but do I also need a
crank
crank bearings
water pump rebuild
valves/valve springs. Only 1 valve moved at 50 hours but the valves have not been checked since then.
I plan on just giving my bike to a mechaic and have him order all the parts. So what should I have replaced. I really appreciate any help. Thanks
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mxrider28 3/7/2013 8:32pm
3/7/2013 8:32pm Edited Date/Time 3/7/2013 8:32pm
Anybody?
RACESTHILAIRE 3/8/2013 5:58am
3/8/2013 5:58am
At 95 Hrs, I would replace without question:
-Crankshaft
-Piston, rings, wrist pin
-Valves, Valve Springs, cotters
-Cam Chain
-Main Crank Bearings
-Oil seals
-Water pump bearing and seals (Your bike requires a special tool to install the water pump mechanical seal)
-Clutch springs
-Clutch plates and fibers

We would thoroughly inspect for wear:
-Cylinder
-Valve seats and guides (Valve seats will need re-cutting anyway)
-Transmission and shifting mechanism
-Transmission bearings
-Camshaft
-Lifter Buckets and rocker arm+shaft

If you are in the New England area and need an experienced shop that does 100+ MX engines a year, give us a call. Many people outside of the New England area also ship their engines to us.

We offer discounts to vital guys as well Smile
slipdog
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slipdog 3/8/2013 6:02am
3/8/2013 6:02am
I usually recommend rebuilding the whole motor at 100 hrs. Can you get more out of the bottom end, yes people do, but a lot of people don't. Even at a "C" level I would be very concerned about the valve springs with that many hours. As they wear they loose seat pressure and the valves begin to float. This can be one of the first steps to engine failure.

Your mechanic should inspect all the major parts against the manufacturers service limits, but how do you inspect a rod that is going to break in 5.5 more hours. The play in the big end could measure out with in limit, but sometimes a rod lets go for no appearant reason and destroys the motor.
RACESTHILAIRE 3/8/2013 6:29am
3/8/2013 6:29am
^^^Slipdog is right on point. Don't let skimping on $500 extra to replace all recommended parts cost you $2000 when your rod snaps and blows through the transmission and cases.

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JCollins762
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JCollins762 3/8/2013 1:10pm
3/8/2013 1:10pm
As the previous replies said, gaskets of course, Valves (Getcha' some SS valves while you're at it), springs, Piston, rings, circlips, wristpin, crank, seals, crank bearings, and check your shift forks, drum, shafts, and gears for wear or warping.

And PLEASE, PLEASE, PLEASE, if you're going to do it yourself get a SERVICE MANUAL, valve spring compressor, case splitter, and flywheel puller. Do not be another goondick with flat heads ruining your cases.

Oh, and let me reemphasize one thing..
SERVICE. MANUAL. SERRRRRVICE. MANUAL.
mxrider28 3/8/2013 1:32pm
3/8/2013 1:32pm Edited Date/Time 3/8/2013 1:33pm
RACESTHILAIRE wrote:
At 95 Hrs, I would replace without question: -Crankshaft -Piston, rings, wrist pin -Valves, Valve Springs, cotters -Cam Chain -Main Crank Bearings -Oil seals -Water pump...
At 95 Hrs, I would replace without question:
-Crankshaft
-Piston, rings, wrist pin
-Valves, Valve Springs, cotters
-Cam Chain
-Main Crank Bearings
-Oil seals
-Water pump bearing and seals (Your bike requires a special tool to install the water pump mechanical seal)
-Clutch springs
-Clutch plates and fibers

We would thoroughly inspect for wear:
-Cylinder
-Valve seats and guides (Valve seats will need re-cutting anyway)
-Transmission and shifting mechanism
-Transmission bearings
-Camshaft
-Lifter Buckets and rocker arm+shaft

If you are in the New England area and need an experienced shop that does 100+ MX engines a year, give us a call. Many people outside of the New England area also ship their engines to us.

We offer discounts to vital guys as well Smile
Just wondering why do the valves need replaced if there still in spec? Same with the clutch. Thanks
xnationalwrench 3/8/2013 2:28pm
3/8/2013 2:28pm Edited Date/Time 3/8/2013 2:30pm
mxrider28 wrote:
Just wondering why do the valves need replaced if there still in spec? Same with the clutch. Thanks
That would depend on if you are following a service time limit on your clutch and the other components and carefully inspect all other wear parts also. In another words cheap insurance, well somewhat cheaper lol.
RACESTHILAIRE 3/8/2013 4:12pm
3/8/2013 4:12pm
RACESTHILAIRE wrote:
At 95 Hrs, I would replace without question: -Crankshaft -Piston, rings, wrist pin -Valves, Valve Springs, cotters -Cam Chain -Main Crank Bearings -Oil seals -Water pump...
At 95 Hrs, I would replace without question:
-Crankshaft
-Piston, rings, wrist pin
-Valves, Valve Springs, cotters
-Cam Chain
-Main Crank Bearings
-Oil seals
-Water pump bearing and seals (Your bike requires a special tool to install the water pump mechanical seal)
-Clutch springs
-Clutch plates and fibers

We would thoroughly inspect for wear:
-Cylinder
-Valve seats and guides (Valve seats will need re-cutting anyway)
-Transmission and shifting mechanism
-Transmission bearings
-Camshaft
-Lifter Buckets and rocker arm+shaft

If you are in the New England area and need an experienced shop that does 100+ MX engines a year, give us a call. Many people outside of the New England area also ship their engines to us.

We offer discounts to vital guys as well Smile
mxrider28 wrote:
Just wondering why do the valves need replaced if there still in spec? Same with the clutch. Thanks
Clutch plates are one of those items that I feel are not worth reusing if I am rebuilding an entire engine. At 95 hrs, you have gotten more than a fair amount of life out of that clutch.

For example, you could measure the piston that is in your bike right now and its possible it is within spec for reuse, but you have no way of testing when a part is going to catastrophically fail. This is why you have to trust the service intervals that Honda gives you.

You also stated one valve moved at 50 hrs, basically if your valve tightens up any more than one shim size...the valve is worn beyond reuse. Now beyond that point you've added 45 more hours. Again not only has one valve shown wear, but your valves have been in use more than 4 times Honda's recommended replacement interval.

Hope this helps

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