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Old 04-28-2014, 10:55 PM
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Default 03 crf 450, runs hot, kicks easy, hard start

     

Have had a 03 crf450 for maybe 3 months. Never done maitainence on it besides oil and filter change. 1. its super easy to kick over I can almost do it with my hand, low compression? 2. its full on anti freeze but seems to get really hot, what's normal running temp? Has ti4 exhaust. 3. my bike takes for ever too warm up, if I tohtouch the throttbefore its warm it'll die and take forever to start back up, I have to let it warm up for around 5 mins even after I have been riding it and come in for like a 5-10 min break. Please help, anyd input is much appreciated thankss
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Old 04-29-2014, 01:08 AM
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Ok I think you need to kiowbthatbuou are dealing with a bike that already has a weak valve train... This leads me to think a few issues are at hand, carburettor and engine wise.

Let's look at the engine-more importantly the valves and piston. I'm betting bottom dollar that a/the valve(s) are hanging, meaning they are not closing properly and causing low compression-especially once the engine is warm! The second thing would be the piston and rings which, judging by the year of the bike and the fact that you've not mentioned the last time a 'topend' was done, I'm guessing that also be affecting the compression.

If I were you, I'd think about taking the head off and inspecting the valves-more than likely they are at their limit and need replacing. If they are ok you can re-shim an carry on....BUT valves that have an unknown service time are risking serious damage if they let go............
Piston and rings, it's probably time for a new piston kit... Barrel measurement/potential hone etc
DONT leave the piston for long!!!!

As for the carb, this will be your sorce of overheating ( I'm guessing it's boiling over ). A blocked jet or incorrectly set carb for the pipe might put you in a dangerously LEAN condition, I would ask for a plug reading to CONFIRM what I'm think though. An air leak is another possibility of a lean condition.... Now of corse I'm assuming that your at least getting so air through your radiators ( riding ) otherwise they will boil in short order ( it's just the way they can be...)

I'm sure I've left something out.... And get a MANUAL

---------- Post added at 03:38 PM ---------- Previous post was at 03:36 PM ----------

On the contrary, your carb may not have ever see a service and I'm guessing the float needle and seat should be checked and float height set ( fuel LEVEL ) and jets cleared....
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Old 04-29-2014, 04:17 PM
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Ok, check valve clearances including the auto decompression arm.
Shim them to:
Intake .006"
exhaust .011"
Decompression arm at .015"
While you do that also check the timing of the cam as if off by only a bit it will be hard to start. THe timing must be set to perfection as per the service ma nual. This can be caused by a worn cam chain.
If it is not set correctly you will have a very hard time starting it.
Also checked for a plugged pilot jet and starter jet.
Check you fuel screw setting.

Paw Paw
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Old 04-30-2014, 03:31 PM
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That was my thoughts. Check valve clearance.
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Old 04-30-2014, 04:45 PM
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Also...The bike may not really be running hot, but could be loosing coolant via a leaking water pump seal or most likely the radiator cap is weak. I see the weak cap on may bikes, even new ones. The owners are sure the bike is running hot, but all that is wrong is a weak cap.Your bike came with a 1.1 cap. You can pick up a 1.6 cap for cheep and stop the lose of coolant.
A lean condition due to plugged jets, float height set too low or poor fuel flow, will make the bike run hot however.

Paw Paw
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Old 05-27-2014, 07:36 PM
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Default 03 crf450r

I 're shimmer the valves which didn't really seem to help much. I just did a compression test and it's around 35 psi after like 5 kicks. Not leaking coolant but I am running straight anti freeze I believe and I'm assuming that's bad?? What are your thoughts guys? Thanks
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