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First top end estimated time.

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I am at 35 hours on the meter, which didn't go on right away so I would say I'm 10 past that. I know I need to do a topend. I plan to order a JE 13.5-1 kit, but I have never done one of these before and really don't have anyone to show me. Going to the dealer is not an option either. I do all of my other maintenance and am up for learning anything. How long does one of these usually take for a beginner? I know it will be different for everyone, but I'm just looking for an estimate because it's fall, the best time of year to ride in my opinion(around here anyway) and I don't want to miss out on the fun. I have been riding every weekend and don't want to change that. Should I just go for it?

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start on a monday in case anything goes wrong.....

it should take you around 3 houres, it will go by fast, you might actually have fun. get your cylinder honed, just make sure to get cam chain on right and timed right, you should be fine as long as you take your time

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mxboy got me thinkin......if it were me i would wait untill next year, but thats just me.

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I do mine every 50-60 hrs. 35 does seem a bit premature. Aside from that to answer your question. It really depends on you. First of all make sure you have an oem manual for it. The manual is your bible with doing any major work to the bike. I would give yourself a weekend to do the rebuild and try to make sure you have all of the parts you need for the rebuild before you start. If your just doing the top end then here are the parts I would recommend you have. Obveously the piston kit you are getting (make sure it comes with the head and base gasket.), and the plate that mounts to the end of the decompression plate. The timing chain shouldnt need replaced at 35-45 hrs but the plate that attaches to the decompression weight is cheap and does break frequently Its about $3-$4.00. You dont want a piece of that floating around in the engine. Also follow the torque specs they give you in the manual. The camshaft cap is the most important one to torque correctly. If when you get into the engine you cant find help or get stuck just come back to TT and I am sure someone can help you through it. Good luck and just be patient when you do it. :D

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3 hrs is a normal amount of time if you have done it before. If it is your first time plan on around 5 hrs.

35 hrs is due for a top end.

With my JE piston (or any) I will re ring at 25 hrs and replace at 50. With the piston being stock, just replace it.

Make sure you hone the cylinder and do the dry rebuild method.

With the dry method the motor will run stronger and be cleaner inside, I have personally witnessed both of those on my bike.

Here is how:

Hone the cylinder (ball hone or brush hone) in soap/water. Clean out with break clean and paper towels until there is no black on the paper towels. I have a 3.5” ball hone in 180 grit.

Wash the piston/rings in soap/water, spray off with break clean and let air dry.

Install the rings on the piston. Use proper ring staggering - follow the manuals staggering method - Be really careful not to get any oil residue on the piston, rings, or cylinder. Keep your hands wahsed

Install one clip on the piston. - the right side one.

Install the piston on the rod, use a light coat of oil on the wrist pin only.

Install the other clip, be sure not to get any oil residue on piston/cylinder.

Install the piston in the cylinder. Compress the rings with your hands and very carefully install it. Be sure that the oil ring doesn't bend over.

With the motor together, and no crankcase oil rotate it 50 times. Then fill with oil and check all fluid levels

Do not start the bike until you intend to ride it. Start it up, let it warm up good, go ride it hard with engine breaking, this will ensure the ring seal.

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If this is your first time I would also order a left side cover gasket. Just in case you drop your timing chain off of the crank teeth. If that happens and you have to pull the side cover off, and if you tear the crap out of your gasket, you will be glad you had a spare around.

Get a Clymer or service manual, and take a look at the dirt rider article, link below.

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

I just did my 06 CRF250 last night - 103 hours, that was the third time I have done it. I try and replace the piston and rings every 35 hours. Stock valves are still doing fine. It gets easier each time.

As far as time, take your time, don't rush it. The first time I did mine I did the tear down one night, and the rebuild the next. I also took lots of pics with my digitial camera.

One other thing, get a plastic parts box with compartments to put all of the little parts in (shims, buckets, bolts) and keep them seperated so they don't get mixed up, and have a telescoping magnet just in case.

Good luck!

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I have 2008 250f and it has 40hours on it..

I was thinking to change the piston in next couple of hour or so.

What else i should do?

I'm gonna adjust my intake valves also, they are at minimum spec now.

Never adjusted so i was thinking to give it a try before spending big bucks on the whole new intake valve kit..

And yes, I am gonna do the dry rebuild!

Someone said not to use synthetic oil during break-in? Why is this?

What else should i do before there is more than 50 hours on the bike?

I really dont know that much of these bikes, first bike for me..

And sorry for my bad english.. from Finland

Thanks.

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If this is your first time I would also order a left side cover gasket. Just in case you drop your timing chain off of the crank teeth. If that happens and you have to pull the side cover off, and if you tear the crap out of your gasket, you will be glad you had a spare around.

Really? I knocked mine off the gear on the crank the other night and i got it back on there in seriously like 10 secs. Maybe im talented :p:lol:

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I always put a new timming chain on when i do a top end as well,there like $20.00 thats cheap insurance.

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