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Help Mod'n My 03 CRF450r

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Hey guys,

This is my first post but I have been trying to read and find out a lot about my bike becuase i know its dumb to ask questions that have been posted before, but ive been having trouble finding exactly what i need. I have an 03, it was barely riden and i knew the guy who owned it so its a pretty fresh bike. I'll post a pic here when i get home, but i want to start fixing and moding up my bike for the summer season. I dont really ride MX but id like to start hitting the track and i do a lot of woods riding but its full bore, I also go to Silver Lake Michigan to ride in the sand every year and would like more power for that. My bike is currently 100% stock besides a Twin Air filter kit.

I dont want to get crazy but from what ive been reading i can make it run much better and i dont want to just start buying stuff and throwing it together to mess stuff up. Basically i dont want to miss something or need something to go along with my mods and not know. I fix my own stuff and i know a decent amount about mods but not too specific really. So here's my ideas, your input would be awesome.

1. Id like to bump up the piston to a 13:5:1 - Can I do this? What else would i need?

2. Get 06 Heads - Is there a different head i should get? I know the 06 Cam is what i should get.

3. 04 Flywheel - Different Flywheel?

4. 04 CDI box and harness - Should i get a different year? I know there is a little splicing needed with that. pretty sure i can find thread again i hope.

5. Full exhaust system - Was looking into a Bills, I need the arrester for the sand. Any different recommendations?

6. Jet Kit.

7. 40mm Rads

8. Better Water Impeller.

9. Maybe an Oil Cooler.

Everything else i want to do is cosmetic, like new rims & hubs, red rad hoses, anodized red bolts, Hammerhead shifter/break lever/clutch lever, powder coat frame swingarm subframe black, but this stuff will be a slow process.

I plan on keeping my bike for a long time. I know its not the best year but i like it. With a few other things like new 20mm tripple clamps and stuff could be perfect for me.

Thanks for your help, I hope i didnt annoy ppl for asking previous questions, ill continue to search the site.

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No replies yet. but ill keep posting on what ive been reading and hopefully someone will chime in.

13:5:1 - Ive read pistons will work but there is a detonation problem at higher RPM's someone said, but someone also said that is only if it is jetted wrong. This true? I might just get the 12:5:1 so i dont have to worry?

04 Harness - Buy this. But the stator wires are different(easy to make work). You can buy an 05 stator and it will bolt right up and connect normally?

CDI - Ive read to get the 06 box. Somone mentioned the 250r box is better? This true, if so what year to get?

Cam Shaft Tensioner - I read that the 03's are a problem, to get an 05 tensioner.

04 Flywheel - It is lighter and will rev quicker, but you will need a 04-06 box so it wont choke at idle. but the 06 box is better because it is newer and timing gets better with new models.

Water Impeller - 03 run at a high pressure and cause the water pump seals to leak. I want the Boyeson Water impeller, maybe cover too.

Suspension - 49kg fr springs and 5.8 or 5.9Kg rear for 190-200lb rider.

Off set tripple clamp - 20mm will help you corner alot better, makes turning faster.

Exhaust - I read that procircuit is the best, Ill look into getting one of those if it has a removable spark arrester.

Havent found the thread i was reading on the 06 head.

Edited by Murarik35

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I have the 06 head with the 02 cam. The 02 cam is supposed to be comparable to a stage 2 cam.

I just did the 04 flywheel mod to my 02. I bought the 04 flywheel on ebay for $15.00. I then bought 05 electrics on ebay for around $90.00 - everything including the stator and it all bolted right up and no need to jump any wire's and runs perfect!

I too am looking into either the 12.5:1 OEM 08 Honda piston or an aftermarket (Wiseco probably) 13.5:1 piston and so far I am hearing it will be fine unless the crank has a lot of hours on it, which mine does not. Check this thread for more info http://www.thumperta...-gas-b4-boooom/

I found the FMF header/muffler was the cheapest aftermarket exhaust but it does burn leathers around just below the inside of the knee so I use a heat shield FMF sells and a little bit of aluminum heat tape on my leathers to make sure they don't get burn't.

I think all the tensioners Honda sells are Auto tensioners and the key is to get a manual tensioner. I am ordering this one

http://shop.thumpert...ng_tt_mcct1.htm

I have Excell/Talon rims/hubs but I got them for next to nothing new. If your wheels are in good shape you may want to save the $$ for other mods.

My water pump is stock and it does not have any issues but I may go to the Boyesen

I have 05X forks and I believe the clamps are stock

Edited by mrmoto35

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What was the benefit of the 06 head? Im still trying to find that thread.

I read to get the 06 cam because its lighter then the 04 and is compared to the hot cam.

How does the manual one work as far as maintence tho? do i have to check it often?

As far as the piston goes. My bike does have low hours and id like as much performance as i could get with the 13:5:1, but i dont want to worry of blowing it up if the crank n stuff isnt that good. So i might go with the 12:5:1 piston to be a little on the safe side.

Exhaust - I liked Bill's, i had them before on my old 2 stroke but i dont know how they are for 4 strokes. The one i was looking at was on ebay, complete one piece from header to silencer and it has a removable arrester, which i need to put in for when i go to the sand dunes.

The 05 450x shocks better? should i look into getting them?

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If youre going to change the head, you want the 08, not the 06.

You want the 05-06 ignition box and harness. You'll have to adapt your harness off the engine, no biggie. The wires are the same colors.

The cam chain tensioner is a problem. Dont bother with an OEM one, even the later ones fail. Get the manual one from TT.

The 13.5:1 piston is fine on pump gas.

The jetting is better with the 05-06 needle. No sense in throwing a ton of money at a good carb to start with.

I like the 03 flywheel. The 04 is 4oz lighter. You can tell a difference but not a lot. With the 13.5:1 piston and the 03 flywheel, lots of traction there.

Do a search on impeller mod. Its only a 3mm hole drilled in it. Do the search, there are pictures. All the hole does is pull a low pressure area near the seal lip.

Call MRD on the exhaust. Best bang for the buck going. www.mrd-racing.com

Youre going definitely want stiffer springs. .49's or .50's in the front and 5.7 on the rear. And get the suspesion serviced. The fork oil is probably original and the shock oil isnt that great stock either.

Ive got a 20mm clamp on my bike and it wasnt any kind of magic bullet by any stretch. You'd get more for your money by sending out the suspension for a revalve than you would the clamp by itself and it's cost is half of that of the revalve.

The radiators and oil cooler...I dont think its necessary unless your crawling through trees or something.

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What was the benefit of the 06 head? Im still trying to find that thread.

I read to get the 06 cam because its lighter then the 04 and is compared to the hot cam.

How does the manual one work as far as maintence tho? do i have to check it often?

As far as the piston goes. My bike does have low hours and id like as much performance as i could get with the 13:5:1, but i dont want to worry of blowing it up if the crank n stuff isnt that good. So i might go with the 12:5:1 piston to be a little on the safe side.

Exhaust - I liked Bill's, i had them before on my old 2 stroke but i dont know how they are for 4 strokes. The one i was looking at was on ebay, complete one piece from header to silencer and it has a removable arrester, which i need to put in for when i go to the sand dunes.

The 05 450x shocks better? should i look into getting them?

I think the 06 head thing came about before the 08 was available? If I replace mine it will be with an 08 like Shawn says.

I have not seens Bill's. Had I know about the FMF burning leathers thing I might have done more research but it is not a big deal if you take the steps to prevent it. I am going to have a look at the MRD now as well.

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Also, are you looking into a Rekluse clutch kit? Oh man I am dying to ride a bike with one. I am definitley looking into getting one. Not cheap but I am reading they are the best thing since condoms! Do a search you will find lots of info on it.

Edited by mrmoto35

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Thanks for the reply guys

Sounds like it'll get the 13:5:1 piston then!

And ill also get an 08 head. does that include the cam? Or do i have to get that seperate, i was looking to get the 06 from previous threads. I also prob want to get a new cam chain as well with the manual tensioner.

The harness adapt is to the stator right? So if i get the 05 harness, 06 CDI then id have to do the stator wires thing i found in a thread right.

For the impeller. i was just going to get the Boyeson one to improve flow to help cool.

Ill def look at the MRD exhaust! Does it have a removable spark arrester? Im sure ill know when i look it up.

The only reason i want the bigger rads and oil cooler is because i do ride the woods. Also when i was in michigan last year my bike got to hot and now i have a head gasket leak. This is why i want to start and make some changes since ill have it apart.

As far as the clutch system goes. I havent really looked into changing that. depending on the price and what performance gains ill recieve, i might have to get it. lol But ill def read up on that system.

Edited by Murarik35

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i have been building theses things and desighning heads and cams for them since they came out i also understand what it takes to play @ silver lake i use to spend a lot of time up there i did a ton of 2 strokes RHC dominated the flats and the drag strip for years building 3 wheeler and quad engines.

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The harness adapt is to the stator right? So if i get the 05 harness, 06 CDI then id have to do the stator wires thing i found in a thread right.
Yes that is the hook-up you will need to jump if you stay with the 03 stator. I personally did not want to do that out of being anal, I like that I have the 05 stator that plugs right in with no modification. Look for a stator on ebay if cost is prohibative. They stuff I found was a huge steal. I paid probably 80% less then retail and found stuff that was like new.

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Yes that is the hook-up you will need to jump if you stay with the 03 stator. I personally did not want to do that out of being anal, I like that I have the 05 stator that plugs right in with no modification. Look for a stator on ebay if cost is prohibative. They stuff I found was a huge steal. I paid probably 80% less then retail and found stuff that was like new.

Thats prob what im going to do. get a harness, stator, and pisten kit off ebay. Try to find and 08 head.

Does the 08 head include the cam? is that a good cam or should i get another year?

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Thats prob what im going to do. get a harness, stator, and pisten kit off ebay. Try to find and 08 head.

Does the 08 head include the cam? is that a good cam or should i get another year?

As far as the cam goes I am not sure what to go with. I don't know if the 03 is the same as the 02. Do some more searching and wait for someone with more knowledge then me to chime in. I am staying with my 02 cam as it is said to be one of the best OEM stock cams for 02-08.

As far as it coming with the head I think that just depends on what you order and/or what someone/place is selling.

Edited by mrmoto35

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What is your budget for modifications? I am the last guy to try and talk someone out of souping up their ride, but you are talking about about changes in the $700 to $1,000 range, and it won't make you bike worth a dime more.

My real advice would be to sell it and buy a 2007 with the money you are talking about throwing at it.

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What is your budget for modifications? I am the last guy to try and talk someone out of souping up their ride, but you are talking about about changes in the $700 to $1,000 range, and it won't make you bike worth a dime more. My real advice would be to sell it and buy a 2007 with the money you are talking about throwing at it.

There is no real budget.. lol.. but i want my bike to liven up and run mean. I know it wont be worth a dime more but id keep if for a long time. What would be the benefit of buying an 07? I would just be back to square one i imagine?

Edited by Murarik35

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There is no real budget.. lol.. but i want my bike to liven up and run mean. I know it wont be worth a dime more but id keep if for a long time. What would be the benefit of buying an 07? I would just be back to square one i imagine?

Yeah i am keeping my 02 because it is a California green sticker bike and I can ride it in any OHV park year round. 03 and up red sticker bikes you can only ride from Oct to May. You can still ride red sticker at private tracks year round though. If anything I would by a newer bike for the track and keep the 02 for the desert and mountains etc.

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What is your budget for modifications? I am the last guy to try and talk someone out of souping up their ride, but you are talking about about changes in the $700 to $1,000 range, and it won't make you bike worth a dime more.

My real advice would be to sell it and buy a 2007 with the money you are talking about throwing at it.

Why an 07? If that was an option an 08 would be better.

The cam tower assembly will fit from 02-08 heads. The cams themselves are a little different as they changed the decomp mechanism. The 02 cam will bolt into the 03 tower assembly. The 02 cam is almost identical to what HotCams sells as a Stage 2. In 03 the toned down the cam a bit. In 04 the added some compression and lightened the flywheel. After 04 they really didnt mess with the cam grind too much I dont believe.

Now, the 13.5:1 piston and the 02 cam is a good combo. The 13.5:1 piston with the Stage 1 Hotcam is kind of a pain in the ass to get dialed. The stage one is a short duration cam that builds a lot of cylinder pressure right off the bat. When combined with the tall 13.5 piston...its a bottom end brute, but can be a pain to start sometimes and getting it jetted is a challenge too. It acts way rich on the fuel screw but runs lean...very odd. Like the Primary air jet needs changed, but they dont offer that for the FCR-MX. They'll say they do, but what you get wont fit. Not in the newer square body FCR-MX's anyway. I digress...

If you want the thing to haul ass, send the head to Tuff Racing and have it CNC ported. Send the carb to modified (taper bored) get an RHC 187 cam, get Dave at MRD to build you a top end pipe and with a 13.5:1 JE or CP piston and youve got something thats going to flat haul ass...

If youre trail riding it though, I wouldnt. Not with a light flywheel. Not in the woods. If your plunking around in the woods. that OEM 03 11.5:1 piston is what you really want. All the compression and HP will just be a handful to deal with on single track stuff. There's a reason shopping carts dont have 800 hp.

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I could go get an 08 or newer. I found a '10 for 5G if that would be a good price? But i really dont want to sell my bike to go get a new one. I ride fast through the woods so its not trail riding and want faster for the sand when i go out there, i do jump some dumb stuff in the woods and wrecking isnt out of the picture so i dont want a brand new bike for me to wreck and mess up and if i do ride a track, its just for fun on practice days. If i get an 08 or newer, then i have to buy exhaust and some other things which will just be more $$$. My '03 is in great shape and was barely rode. So i figured i can do some basic mods i found on this site. They all would be stock parts from different years ,mostly but it would run so much better and would be cheaper then buying a newer bike. No matter how much you put into a bike reguardless of the year, you never get close to what you put into it.

So if i get:

12:5:1 Piston - Id like the 13:5:1 but i want my bike to be reliable and not worry about too much compression or jetting to much to blow it up

05 Harness

06 CDI

05 Stator

02 Cam - So it will fit on my 03 head

An Exhaust

- My Bike should run pretty good

On a side note. A friend of a friend who use to work on bikes at a very good shop said he would not start taking parts from other years like this because it will blow up. Is this true? i dont see how changing that stuff with other stock parts would be enought to blow an engine. I dont believe him and trust what you guys say but figured id ask anyways.

How much is it to get your head ported from Tuff Racing?

How much to get my Carb Modified? Is that from Tuff Racing Also?

I want to start buying and modifying my bike now so it'll be ready for the summer season. Im from PA

Edited by Murarik35

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dude just ride your bike keep your money in your pocket its a old 03 450 if it blows it blows thats the cost of fourstrokes you never know when its going to go ive had them last from 3 years to 3 hours just the nature of high performance motors. No point in modding a bike if you cant ride it to its full potential

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I would just go with the 12.5:1 piston with a stage 2 hotcam. Leave the flywheel stock, you won't notice any difference in power from the 03 flywheel and the lighter 04 flywheel, other then it may flame out easier. Spend your money elsewhere. People are putting 12 oz heavier flywheels on the 05 and newer bikes and saying that they don't notice much difference in power but it doesn't flame out as much. You won't notice the difference when the change is so small.

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