20 Most Recent 2004 Yamaha WR 450 F Questions & Answers

Could be your regulator over charging battery,

Valves could be sticking closed or open causing (good or bad compression) that or de-com-lever if faulty somehow.. And you need to do a compression test

Something in the decompression mechanism is obviously broken or jammed and you will need to diagnose further and find out what.

Sounds like a fuel problem, too rich in the midrange. You said that it idles good but I'd still check the float level. If that's right, check the position of the needle. The needle has about four or five grooves in the top end of it. There is a small clip that clips into one of these slots. By putting the clip in a slot closer to the pointed end of the needle, you raise the needle making the midrange mixture richer. Moving the clip to a slot nearer the blount end of the needle, leaner mixture. Your needle should have the clip in the middle slot if there are five slots. The second or third slot if there are four. Make sure the needle is installed correctly in the slide so that it does not not raise up. If you get it too lean, it will start to surge when you're trying to cruise.

I would inspect the slip rings on the armature/rotor first to see if they are clean and not burnt. IF the brushes are in the regulator unit ok but if separate check condition of the brushes

Hi mate have you checked valve clearances they may need adjusting on the intake side your describing a issue of either a leaking intake valve due to clearance to tight or worse case valves are to old and not sealing correctly. hopefully they just need adjusting as is cheap and easy to do... if need replacing then its pretty big job with getting the seats re cut and buying the valves etc. Happy to do the work for you if you anywhere near Perth wa ww.motoxpartsonline.com

10.5 volts is enough; the problem is more likely in the contact switch, too high of a resistance. Find out which wire gets the 12V on the cdi and make a temp wire direct from the battery. If it starts then the contact switch is the problem. Solution is a relay in between to feed the cdi directly from the battery or a new contact switch. Start is while jumping the battery from a car battery, makes sure it indeed starts. If you need further help, I’m available over the phone at https://www.6ya.com/expert/robert_573a00ba7e399076

almost certainly the battery, needs to be fully charged to be effective.

having same problem, but i only left it for 5 months. Did you get it started? if so, how? or what was the problem? Thanks

maybe the started is bad, try having it tested, and also, check all wiring connections for the starter, see if anything is grounding out, or has a dirty connection, as that will cause you to lose electricity

The filler is on the side cover.

your water pump seal and oil seal have failed on the water pump shaft. Replace both seals noting which way the seals face. replace the water pump shaft if it is scored. Chaz- Moto DC