weimedog

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Damn Yankees
Nov 21, 2000
959
2
My son came home on leave from the Navy...for a week. He really wanted get some riding in before going back to the Carrier for another typical Navy Cruise...so he bought a used 2004 Honda CRF450. It was a race beater is my guess and we replaced the wheel bearings, Chain & Sprocket, air filter, oil & oil filter etc. Oil come out really dark as the prior owner didn't change it often enough..my guess.. but it was clean and so were the oil plugs. Overall it looks healthy. AND he got some ride time in. So it has served its purpose I guess. And he loves it to death.

Couple of questions.

1) It starts, idles and runs really strong. A really snappy power band and doesn't use any oil or have any other bad habits...but it does have what sounds like a valve rap at LOW idle that emanates from the very top of the motor, almost the valve cover and emanates loud thru the frame. A stethoscope probing shows the motor to be real smooth & quiet right until you get to that top part of the cylinder head/valve cover area..I can't decide if its a valve or a cam chain slap. The rap goes completely away as soon as the RPM's pick up. What typically needs maintenance on those things up there that will "rap" at idle when out of adjustment?

2) The power is SO abrupt, almost explosive. He loves it..I think he would be better with a better transition from no throttle to explosion! Any idea's how to calm that monster down a bit? Its perfect for a track but rough in the woods.

3) What else should we look at on those '04's to get ahead of the wear & tear maintenance curve?

4) How much difference is there from the 04's to 07's?
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
An 04, I would at least pull the valve cover and have a look at the cam and buckets for wear, cam journals, and check the valve clearances. The cam chain adjusters would make noise further down, but are a wear item. The 04 to 07, got smaller valves, they detuned it, made the power band more usable. The bike is just crazy fast, detuned or not. This is why I believe the trend will go to making 350's, and no more 450's in the future. Vintage Bob , ps Good to hear your son is doing okay, stay in good health!
 

weimedog

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Damn Yankees
Nov 21, 2000
959
2
Thanks for the advise..I will do exactly that. As far as 350's are concerned, my kid just loved that power. He spent his time finding corners to blast and played that hit for the time he was here. Like and accelleration junky. Its me who had issues with it in the woods, my kid didn't care..but he's a kid. To be young again!
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
2
Merrillville,Indiana
Look into a throttle that opens slower, has more range. I can not think of the company, but they have different cams for slower and faster throttle opening. Vintage Bob
 

Rich Rohrich

Moderator / BioHazard
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Jul 27, 1999
22,838
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Chicago

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
Awesome Rich, I have been wanting a quicker turning throttle for another bike. There is all kinds of things to mellow out the 450f, but I kind of get the picture he really enjoys the power. I am pretty sure a few more months on it and he would be fine. Are you going to tear the motor down and give it the once over? That model can be a real lot of fun, and it can come apart and cost a but-wad of money to fix, when things poke holes where they should not be. Its the easiest bottom end to take apart ever. Do you have a service manual? Vintage Bob
 

weimedog

~SPONSOR~
Damn Yankees
Nov 21, 2000
959
2
We have the manual supplied with the bike, I can "ebay" a service manual I think. The kid works on F-18's for his job and really likes spinning wrenches so I think a tear down will happen as a natual turn of events. He's back for leave in March I think. Too wet to ride...but not to wet to work on motors. I may "spike" the deck a bit and get one of those throttle cams & just have it in before he gets home.
 

mxwm464

Member
Mar 8, 2009
2
0
weimedog said:
My son came home on leave from the Navy...for a week. He really wanted get some riding in before going back to the Carrier for another typical Navy Cruise...so he bought a used 2004 Honda CRF450. It was a race beater is my guess and we replaced the wheel bearings, Chain & Sprocket, air filter, oil & oil filter etc. Oil come out really dark as the prior owner didn't change it often enough..my guess.. but it was clean and so were the oil plugs. Overall it looks healthy. AND he got some ride time in. So it has served its purpose I guess. And he loves it to death.

Couple of questions.

1) It starts, idles and runs really strong. A really snappy power band and doesn't use any oil or have any other bad habits...but it does have what sounds like a valve rap at LOW idle that emanates from the very top of the motor, almost the valve cover and emanates loud thru the frame. A stethoscope probing shows the motor to be real smooth & quiet right until you get to that top part of the cylinder head/valve cover area..I can't decide if its a valve or a cam chain slap. The rap goes completely away as soon as the RPM's pick up. What typically needs maintenance on those things up there that will "rap" at idle when out of adjustment?

2) The power is SO abrupt, almost explosive. He loves it..I think he would be better with a better transition from no throttle to explosion! Any idea's how to calm that monster down a bit? Its perfect for a track but rough in the woods.

3) What else should we look at on those '04's to get ahead of the wear & tear maintenance curve?

4) How much difference is there from the 04's to 07's?
Raise the idle. It is the decompression weight rattling back and forth. You do not want it to do this. By raising the idle you will save the wear and tear and get rid most of the noise. It is worse on the '09's.
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
How many times did he kill the engine in the corners? I know my son had the idle turned up faster than a lot of C class riders ride. Not because of top end rattle, killing the bike can be a really bad experience re-starting, especially in a race! Vintage Bob
 

Matt90GT

Member
May 3, 2002
1,517
1
Also replace the cam chain tensioner. They are known to fail on the pre 06 models.

It also could be the piston rocking in the bore. They are a short skirt design and factory schedule is 15hours on a piston.

For less abrupt power, loose 2-3 teeth on the rear sprocket. Easiest way to do it.

For changes from 04-07, they are many. 05 is the next gen frame, much better and narrower frame. Pulled the axle back 2mm on the forks, new intake, new plastic. 06 got everything lowered 5mm, and then 07 has a 41mm carb and smaller exhaust valves for better power. Also 07 has a new decompression cam system and new front brake master cylinder. 04 is the last of the first gen bikes.

Maintenance, LOTS of oil and air filters. Change the engine oil every ride or every other ride, tranny every 5th ride, and air filter daily. Also a Hinson clutch basket is a must in the bike as the stocker is pretty soft.
 

weimedog

~SPONSOR~
Damn Yankees
Nov 21, 2000
959
2
whenfoxforks-ruled said:
Have you rode it? Vintage Bob

Yea..its violently fast and has a seriously abrupt power delivery vs. what I usually ride. Its the Hit vs. Pull thing for me. My 503 VOR actually stays with it up the longer "technical" 3-4-5 gear pulls and across the bigger fields & up big hills..just coming out of corners the burst of power that Honda has is for racing for real..I just like my tractor better. I actually have a hill out behind the barn where there is a 200+ft elevation change..probably 12% & few hundred yards of hill; and My VOR pulled that one starting with 3rd gear rolling thru an "off camber" corner into the hill & I gained a few feet vs. my kid.

My kid only stalled the bike once, maybe more I didn't see; in three days in the woods and he really enjoyed that "hit". He just would kick it up a gear and carry his speed when things were tighter & slick. Just when we were digging around he would loose ground putting power to roost vs. to ground. Especially on the uphills and wet grassy stuff. Where there were berms & solid traction he was ...gone...

My feeling was as much as he had a... BLAST..he would be more efficient if the power went towards forward motion vs. throwing rocks at the old man. A philosophy thing I think.

(Be more fun to follow as well.)
 
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