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View Full Version : Yfz450 Starting Issue


Rohr397
12-20-2010, 09:19 PM
Okay so I just picked up this 2004 Yfz450 with a K&N filter, 13:1 High comp piston and Dr.D SS exhaust. I understand that these things are hard starters and all but this Yfz WILL NOT start. The guy claimed the battery was blown (which it was) so he used his Yfz450r battery to get it fired. Thing went right away and the engine was ice cold. I haven't messed with anything and temperature hasn't changed at all in the last few days other than putting the positive wire on the positive post and the negative wire on the negative post of my new battery. The whole starter motor turns over and all but the engine just won't fire. I've tried the choke and priming the engine four times before cranking on the starter. When I use the choke a large blue flame (about 4 inches long) shoots out of the exhaust pipe. I am gonna guess spark plug but I want to make sure I buy the right part before I go blow my money.

P.S Video might be processing within the first few minutes of posting.
yfzrider690
12-22-2010, 08:04 PM
The valves probably need to be adjusted.
XCRacer236
12-22-2010, 10:30 PM
although valves dont usually need adjusted on YFZ's, it could be that.

sounds to me like a jetting issue.
yfzrider690
12-22-2010, 10:32 PM
Originally posted by XCRacer236
although valves dont usually need adjusted on YFZ's, it could be that.

sounds to me like a jetting issue.

Where in the hell did you hear that. His quad is 6 years old. You don't think the valves need to be checked. If the vavles are out of spec it will make it hard to start. If it's jetting it might be a little hard but it will start but run like crap. Please don't give advice if you don't know.
west coast chop
12-23-2010, 12:09 PM
possible that it has jumped time....the cam and piston are no longer in time so the valves are not opening at the right time
Rohr397
12-23-2010, 12:36 PM
I think it might be the starting motor, when I bought it the guy said it needed a new battery. I put in the battery and a spark plug but thats all. I doubt that me riding it for 30 seconds in his yard would've changed the timing of the valves. However, the starting motor is making funny noises and randomly sputtering out so I think it's that.

The noise is high pitched and its a weird grinding sound.