2010 yz 450f intermitant miss at low speed

Well back at it again trying to figure out what is going on. I still have that intermitant miss at lower speed. I have taken the fuel injector out and checked it for dirt and debris. No such luck. Air filter is clean. Checked the valves, right on the specs, I even replaced the stator as suggested. Does anyone have any other ideas? Will the yamaha programer show any codes for fuel? Do I need to take this to the dealer?

I havn't been keeping up or know the whole story but have you tried a different map?

I have not tried that yet. Just don't understand why it is doing it. It runs hard when you are on the gas.

Well I found out what I thought the problem was. The resistor was the wrong ohms in the sparkplug cap. It was reading 9.45 and I was told that it should be 5 ohm's or just under. Bought a new cap and sure enough just under 5 ohms. Fired it up last night, ran like a champ.

Went out today and it ran for 5-10 seconds then died. Would not start again, about every four kicks it would backfire out of the exhaust.

I have replaced the stator, checked the valves, sent my ecu to be checked and re-mapped.

Has anyone else had these problems, or suggestions for me to check something else?

I couldn't enjoy my evening just sitting there and wondering what the hell was going on with my bike. We started troubleshooting, check the plug, running a little rich, does it have spark, yes, disconnect the kill switch, good.

Check adjustment on the TPS. Out of spec. Adjust into spec, put back together and rip up the road. The blurble off the start of the throttle was gone, solid crisp throttle, from bottom to top. The bike sounds awesome.

I still had one or two little misses, hickups, as I was accelerating. I am going to get a couple new plugs, cr8e, and a cr8EIX and give them both a good test next weekend and see how they burn. Thanks Dan for all your help, my good buddy that is an ex-mechanic, an old two stroker with tons of knowledge.

I have been having a similar problem on my 2010. I seems to have a misfire at low RPM and does not want to idle. It goes away after I ride for 15 mins. or so. It has been happening for around 3 months but I have not got to carried away with trying to determined the cause. I have tried different MAPs, checked valve lash, and tried a different plug. I will test the resistance in the "spark plug cap".

Definately check the ohms on the spark plug cap resistor, mine was almost 10 and should only be 5. Oh and if you need a new resistor your local shop should sell an NGK replacement spark plug cap. It won't fit but you can take out the resisitor. It cost $4, the factory one is $75. Also the TPS is adjustable it is on the right side of the bike. Check your manual. Mine was way out for whatever reason. As soon as I adjusted it back in it purred like a kitten. I took it out last weekend and it was back to it's normal self, no hickup's. The only thing I want to change now is the map. I rode my friends 08, and WoW the power was frickin awesome, I want that for my 10. Next on the list, the programer.

i had probs the tps,the gytr tuner said, everything is all right. ( i changed the stock ignition to GET,with the GET the bike didn't run bzw it had prob from low to middle) but i changed it and the bike run. i think the tps was from the beginning not correct working...

I checked the spark plug end cap and found that the threaded part that holds the resistor in was loose. I did check the resistance of the resistor and it was 10.72ohms. I did not find in the manual the resistance specs for the resistor. I am gonna ride it this weekend and see how it does with the threaded part tightened.

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