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Should I do my own first rebuild?

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I just blew my 2010 crf250. i bought all the parts i needed and a service manual. My dad used to race for factory KTM so he has a lil insight. but ive never torn apart a motor before and im afraid im gonna mess something up then have to pay even more. I have a guy that can do it for me but he says 40/hr for labor. Is rebuilding my first motor on this bike a bad idea?

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$40/hr for labor is dirt cheap. Most places are twice that.

But to your original question.. With a service manual, the proper/needed tools, and a little imput from your dad, you shouldn't have any problems. Don't get in a hurry, and pay close attention to your manual and what your doing. If you need some info between the lines, you can probably find it down in the CRF forum.

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If your dad and you get together on this i am sure you can do it. Also go on line and check out the video 's on rebuilds at Rocky Mountain site.

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http://www.dirtrider.com/tech/141_0409_honda_crf250_dirtbike_rebuild/index.html

I just rebuilt my CRF 250. I've rebuilt my RM125 but that was my first time tearing into a 4 stroke engine. It really wasn't that bad, just do a ton of research. The best tip I can give is as you disassemble the bike put the parts in baggies and label them as well as number them in the order you take it apart. When it comes time to put it back together just start with the bag with the highest number and work your way back.

I went with a JE 14:1 Piston, Tokyo mods carb, FMF powerbomb header, 2008 Cam, ported/polished head from bigborethumpers. Just broke the bike in last weekend and it's an animal now running on VP C-12 race gas. Go for it! Just make sure you use a torque wrench to reassemble and be extremely careful not to drop anything into the bottom end (stuff rags everywhere).

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The first time i ever took a wrench to a motor I did a complete rebuild/buildup on a 1959 Chevy 283. Was running 2MPH off the National Record in class before I moved on. If you are mechanically inclined, a bike is a lot easier. Just take your time and make sure you understand why and what you are doing every step of the way.

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Yep, entirely possible to DIY. As mentioned before, take your time and do it right, then you won't have to do it again.

I take a piece of cardboard, punch a hole through it with a screwdriver and stick the bolts through the hole. Use a sharpie to write where the bolts go. That cardboard shouldn't have any leftovers when you finish.

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Yep, entirely possible to DIY. As mentioned before, take your time and do it right, then you won't have to do it again.

I take a piece of cardboard, punch a hole through it with a screwdriver and stick the bolts through the hole. Use a sharpie to write where the bolts go. That cardboard shouldn't have any leftovers when you finish.

That is probably the best thing to do when rebuilding an engine. Screw putting parts/bolts into baggies, then you have the headache trying to decide where all the bolts go. It is most valuable when taking out the cover bolts, inner cover bolts, stator cover bolts and case bolts. Everything else, like shifting components, throw those into baggies. Also, invest in a torque wrench.

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Give yourself credit. You can do it. Maybe before you start, work something out with the $40/hr guy to assist you if you get stuck. My first rebuild a few decades ago went fine until it was time to place the tranny back in...... I did need some help with that. Otherwise the manual, dad, and common sense will guide you.

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Got wrenchin' on mine this weekend.

Went from riding on Friday...

DSC06035.jpg

to a real lightweight bike with parts on the bench....

DSC06082.jpg

...and other parts in the kitchen sink.

DSC06090.jpg

Had to stop by the bicycle shop to pick up a chain breaker small enough to fit on the cam chain. And it helps to have a friend that's done this sort of thing before. But all in all it's gone pretty well; nothing unexpected so far.

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Use a digital camera or camera phone to take pics as you disassemble also.

Great memory jogger and you have a record of what it looks like and where it goes.

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Thanks for all the insight. I think i might take a look into doing it myself now. I mean im no dummy. I used to build bombs and rockets in the Marines so im pretty sure i can handle this

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Well look at it this way. When you are done with the bike you will either have a rocket (if done correctly) or a bomb (if done incorrectly). You can do it!!! Take pics and post them if you have questions. You have your dad behind you plus thousands of other people here on TT that will gladly give you their opinion, whether you want it or not.

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You can definitely do it! However, YOU NEED TOOLS.

The ones you need specifically:

- 1/4" Torque Wrench in inch pounds

- 3/8" Torque Wrench in foot pounds

- Flywheel puller

- General sockets/ratchets etc

Once you get the motor apart to find out what is wrong, I would suggest starting up a thread in the crf section for suggestions on repair methods.

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its really kinda simple. the cylinder head is the worst part. if your valves and guides are messed up, take it to the mechanic. it they're ok youll be fine doing it yourself. the head isnt really hard, just a major pain in the butt

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yeah buddy, no biggie to rebuild these 4 ticker motors....they are super simple....

plenty of threads out there to help you...

just a couple reminders/tips:

replace all gaskets you take apart

have the bike surgically clean before ripping it apart

take pictures along the way

when putting in new piston, check ring end gap

rebuild can be done without taking the engine out...

replace anything worn while you're in there, ie cam chain!!!!!

a clymer manual should be able to tell you all the clearances to check

if youre head is out of whack, leaky valves or not flat or out of spec, you can have your whole head basically rebuilt to OEM specs for 150 bucks +- 50....which i highly recommend as most homegrown mechanics dont have the machining tools available to do it or the precision instruments to measure cylinder/piston clearance, etc

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