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2002 CRF 450R Problems

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Posted by: GRat86---------------------

I purchased a 2002 crf 450 about 6 months ago. i got a pretty good deal on it because it was in parts and missing plastics, chain, sprocket, etc. Once i got the bike put together it ran, but i started having serious popping when i would let off the throttle. I torn the carb out and rejetted it for the altitude and temp... problem still exsists. I've been reading up on this bike and i've heard that valves can be a real issue with this particular year. Any thoughts on what might be going on? Also, the throttle sticks open. As you can assume that is pretty scary. i replace the throttle tube and cables and it got worse. now i can hardly twist it. I've looked over the throttle components on the carb and they appear to be working smoothly. Any thoughts there? I'm starting to get pretty frustrated with this bike and i'm outta ideas.


Posted by: Matt90GT---------------------

Okay. 2 problems here.

First some history on the bike. The 02 is the first year of the bike. Great bike, but they did have airbox sealing issues that cause motor problems. make sure the airbox intake has been resealed, had the honda update or aftermarket product to cure that problem.

It would not hurt to check the valve clearances, but most likely not your problem.

Popping on decel can be 2 things. First check for exhaust leaks from the head to the tip of the muffler. Second, the hotstart can be stuck open or have the cable holding it open. You need slack in the hotstart cable. when open, it causes a lean condition in the carb. If both those items are good, then adjust the fuel screw and if that does not help, up the pilot 1 size then adjust the fuel screw again.

For the throttle sticking, check your cable routing. Once verified, split the cable housing on the bars there. There is a plastic divider between them. Most likely the cable is not in the groove on one side of this divider causing the problem. After it is solved, then adjust the slack in the cables.


Posted by: IndyMX---------------------

Throttle housing could also be too far down on the bar, binding against the end of the bar.


Posted by: GRat86---------------------

Thanks Matt90. I'll try it all out. I know for a fact that the airbox is not sealed, but i never made the connection that it could be the problem, or at least contribute to it.


Posted by: GRat86---------------------

Quote:
Originally Posted by IndyMX
Throttle housing could also be too far down on the bar, binding against the end of the bar.

i chopped the end of a billet throttle tube with a dremel to inst. bar end handguards.


Posted by: IndyMX---------------------

Quote:
Originally Posted by GRat86
i chopped the end of a billet throttle tube with a dremel to inst. bar end handguards.


Make sure the grip isn't binding against the hand guards.


Posted by: Matt90GT---------------------

here isa writeup:

http://dirtbike.off-road.com/dirtbi...l.jsp?id=331289

MXBonz:

http://www.mxbonz.com/cnc_airbox_fix.htm


Posted by: GRat86---------------------

Quote:
Originally Posted by IndyMX
Make sure the grip isn't binding against the hand guards.

its not. i think my routing is screwed up, but thanks


Posted by: whenfoxforks-ruled---------------------

What size leak jet is in it?


Posted by: GRat86---------------------

Quote:
Originally Posted by whenfoxforks-ruled
What size leak jet is in it?

whatever stock is. i havent messed with it... should I?


Posted by: Matt90GT---------------------

So how did we jump from sticking throttle to a leak jet? only mess with that once you have the bike running without a sticking throttle. The leak jet helps with quick throttle twist and problems such as bogging. IT is part of the Accelerator pump circuit.

Fix the stocking throttle. as suggested inspect the white plastic seperator piece in the throttle housing on the bars. Also make sure the throttle cables did not slip off the throttle tube.


Posted by: GRat86---------------------

Hey Matt, I just swaped the pipe and header with a full white bros system and its still popping. Starting to narrow it down.


Posted by: Matt90GT---------------------

did you put in a new copper gasket at the head? if not, get a new one.

Second check the mid pipe for leaks. IF any, fix.

What is the jets in the bike right now?



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