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2002 crf450r Major help Needed

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I just got to tearing down my bike and found some real problems.

1st) I need to replace bottom end

2nd) They JB Welded the right side inner case (directly behind the kickstart)

3rd) The top end looked good and was within specs

I just need some insight on what I should do!

1.)Yes get a new bottom end but should I replace everything if I am replacing the bottom end?

2.)Should I replace the valves if I replace bottom and top?

3.)If I am replacing the bottom end should I replace right side case?

4.)I have seen people on here that has sent their stuff out to be done by someone else, what would I be looking at in price if I did that and who would you recommend for price and quality?

5.)What brand of parts would you use If I do it myself?

Please help me get a better grip on what my options are here.....!!!.....

Thanks in advance!

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Just rebuilt my 2003 (top and bottom) with one of the Hot Rods kits from an eBay vender. Ordered the complete kit with main bearings, gaskets and seals (arrived in 3 days). Kit was very complete, took the new crank to a local shop and had it checked and it was spot on. Replaced all the rest of the bearings from a local bearing supplier for 1/3 the price of the dealer. The only bearing that they did not have was the left side balancer bearing. Also replaced cam chain, cam sprocket and added a manual timing chain adjuster. Head was recently done so complete job for under $900 bucks

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The case is an expensive replacement. Really depends on how its broken but while its apart is the time to make the decision; leave it, have it welded or simply replace the case half.

The way Motor87 went about it is a good way. if youve got access to a bearing house, the bearings arent special. Just walk them in there and see what they got. The numbers on the bearings are standard. The OEM just reboxes the bearings and sells them to you at a pretty significant mark up.

If its the 02 crank, its got some miles on it. You could possibly save some money and have it reworked at Crankworks in AZ. All they do is put a new rod on it and a new main on the one side. The alternator side of the crank is the part you cant rebuild. It runs right in the bearing so if the crank pin is worn...its replacement time. The HotRods crank is fine. The OEM crank isnt much more (if any) expensive if you shop it.

As far as replacing everything in the bottom end...Bearings...ya, why not? They're relatively cheap. The gears? Nah...Just look over the engagement dogs really well and if you find a set thats rounded off more than you like, replace those individually. Look at the sides of the shift forks for wear. If one side is worn, could be bent a little...those are fairly cheap too.

A new cam chain is a good idea. The sprockets dont normally wear much. The cam chain tensioner should be replaces and manual one is the way to go. The 02-03 design was known to let go. The later ones were better, but still fail occasionally. For the price and peace of mind...manual is the way to go there.

The real question is do you want to sink that kind of money into a 10 year old dirt bike?

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This is going to be expensive and allot of work. maybe check ebayto see if you can find a used complete engine somewhere. You will certainly save yourself some headache, and if you are lucky, some money...IMO

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See if you can have the case welded by a competent machinist. If so, then rebuild that thing.

You can buy a used bike, or a used motor, but when you rebuild it, you have essentially a new motor, and you know exactly what it in it.

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Just rebuilt my 2003 (top and bottom) with one of the Hot Rods kits from an eBay vender. Ordered the complete kit with main bearings, gaskets and seals (arrived in 3 days). Kit was very complete, took the new crank to a local shop and had it checked and it was spot on. Replaced all the rest of the bearings from a local bearing supplier for 1/3 the price of the dealer. The only bearing that they did not have was the left side balancer bearing. Also replaced cam chain, cam sprocket and added a manual timing chain adjuster. Head was recently done so complete job for under $900 bucks

Thanks I definately check into that and see if I can save money that way.

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The case is an expensive replacement. Really depends on how its broken but while its apart is the time to make the decision; leave it, have it welded or simply replace the case half.

The way Motor87 went about it is a good way. if youve got access to a bearing house, the bearings arent special. Just walk them in there and see what they got. The numbers on the bearings are standard. The OEM just reboxes the bearings and sells them to you at a pretty significant mark up.

If its the 02 crank, its got some miles on it. You could possibly save some money and have it reworked at Crankworks in AZ. All they do is put a new rod on it and a new main on the one side. The alternator side of the crank is the part you cant rebuild. It runs right in the bearing so if the crank pin is worn...its replacement time. The HotRods crank is fine. The OEM crank isnt much more (if any) expensive if you shop it.

As far as replacing everything in the bottom end...Bearings...ya, why not? They're relatively cheap. The gears? Nah...Just look over the engagement dogs really well and if you find a set thats rounded off more than you like, replace those individually. Look at the sides of the shift forks for wear. If one side is worn, could be bent a little...those are fairly cheap too.

A new cam chain is a good idea. The sprockets dont normally wear much. The cam chain tensioner should be replaces and manual one is the way to go. The 02-03 design was known to let go. The later ones were better, but still fail occasionally. For the price and peace of mind...manual is the way to go there.

The real question is do you want to sink that kind of money into a 10 year old dirt bike?

Thanks, I look at it like this I can sink 1000.00 in it and know exactly what I have or I can buy another bike for about 1500 - 2000 and have to end up doing the same thing to it or I can buy an engine for about 700-1000 and again I am in the same boat.

If I could by an engine from a reputable company that says they just rebuilt it bottom to top or bored out all new for 1000 - 1500 I would consider it?? Maybe...

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This is going to be expensive and allot of work. maybe check ebayto see if you can find a used complete engine somewhere. You will certainly save yourself some headache, and if you are lucky, some money...IMO

I dont really like the sound of that idea, you never know what you are buying even if they say its all new. I wish it was the world I grew up in where your word meant something!

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See if you can have the case welded by a competent machinist. If so, then rebuild that thing.

You can buy a used bike, or a used motor, but when you rebuild it, you have essentially a new motor, and you know exactly what it in it.

I like that idea, Ill check and see if it can be welded properly before replacing it..

Thanks

Does anyone know someone that does this kind of work here in Indiana that is reputable?

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I ended up rebuilding the whole thing from bottom to top. Everything is new. Hot Rod Crank Kit, Felco Full engine gasket kit, Water Pump, Head redone and new valves and springs and new Cam Chain Tensioner. Replaced all bearings for swing arm, linkage, wheels and had front and rear suspension rebuilt. Also had to replace rear brake caliper and new pads for front and back.

Essentially a brand new bike accept for the bling...2125.00 was the total bill for everything and that includes labor. I figured I would prefer to pay someone to do it than try it for the first time myself and have to spend the money for the proper tools to do such a detail job and the time and frustration of going through it.

Thought it was a great deal..

Thanks for all the help and insight you guys offered!

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