Hello Thumper Talk Community,
I am reaching out and in need of some advice and help.
Some background on the bike:
2011 YZ450F that I purchased used, I am the second owner. The bike was claimed to have 15 hours on it. It does have strong indications of sand dune use as well as the original owner said he had run it out there. It does have stock chain and sprockets but chain was stretched to max setting when purchased. They have been replaced.
It seems as though poor maintenance has been practiced by the original owner. Air filter was extremely dirty and sandy, some sand found in the fuel injection and even inside cam cover. Everything has been cleaned thoroughly with new air filter and all new fluids.
Bike has started well while cool since I purchased it but seems to be troublesome while warm. Otherwise the bike seems to run perfect while motor is running.
The bike jumped timing while at the track recently. It was running fine, had it parked on a stand. When kicking it over to go back out the intake cam jumped about 6 teeth after further investigation. It never ran while missed timed. After inspection of the piston and valves, they seemed to have avoid psychical damage.
Took the bike apart and could not find anything that seemed to stand out as a problem. Cam chain did have some slight kinking it, it has been replaced. I believe that is why it jumped timing. I replaced the chain and reset the timing. Valve clearances were inspect but on the tight side of the range after reassembly. Did a compression test. Performed a homemade leak down test.
After putting it back together it starts up pretty well while cool, but it a beast to start warm. Hot starting now seems to be worse.
I then re-shimmed the valves to put them at the loose range of the spec. Did not seem to help anything.
I am not sure what to do and this is my first fuel injected bike.
Any advice or help would be appreciated!