Dirt Bike guys step in, carburetor guys too... Backfire/startup issue (also stalling)

NYSpeed Automotive
21

Your pilot jet really only controls idle and when you first get on the throttle. So your main jet and needle are fine from pics of the plug and you don’t notice it any other time.

22

Are you saying you still think it’s carb or timing?

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23

I’ll be honest, this bike has been ridden hard since the day I bought it. Stoppies, wheelies, and high revs every time I ride it. Always warmed up and oil changed every 600 miles or so.

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24

I still think it’s the pilot jet. I would try the fuel screw first just to see if it helps.

25

Will do. Tomorrow am… Any other ideas are appreciated…

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26

I would check the valves second, expecially since you ride it hard. I know drz’s are bullet proof but yours is modified pretty good.

These are just my opinions from my experience and what I would check first. Hope it helps, but I could be wrong. Haha.

27

:tup:

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28

I agree with the pilot jet being partially plugged. If you don’t want to pull the carb you can try adding half a cup of Seafoam to the fuel on your next fill up. I have had very good luck with this carb cleaner.

29

You might be able to cheat on the carb. Rather than fully removing it. Loosen the clamps and turn the bottom one way or the other. I honestly don’t Remember if there is room to do this or not. I did it on the ktm trying to dial the jetting in.

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30

As said check pilot and valves. Tight intake valves will cause hard starting and can backfire when the cylinders fill with fuel from cranking it. Based on the plugs the needle and main jet look pretty good. Popping on decel again points to pilot.

31

That’s how I normally do it, but like you said I have no idea how that bike is setup. It’s an old design so I’m sure it would work.

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Also he said when he cracks the throttle open it starts. That’s why I’m going with the pilot and 2nd choice will be tight valves.:tup:

32

dick bag steel frame makes it hard on these

33

Did nothing to bike, cold started flawlessly. Added seafoam to tank, drove for 10 min, parked it, restarted flawlessly 10 min later, added more seafoam, rode around for an hour, refueled and drove home. Bike seemed to backfire less on completely closed throttle when at high rpm, so no complaints there. Actually felt great all day.

I took it out again a few minutes ago, to get more gas, grab coffee, etc and each time I started it, it required me to twist the throttle to get it to fire. Another symptom I noticed is the starter sometimes seems to catch (feels almost like a dead battery for half a second) then she cranks normally.

I did replace the stator and rectifier not long ago with an aftermarket unit that seems to throw 15ish volts… Not sure if that’s an issue or not, but figured I’d just mention it.

I hate the long starts. (no backfires on startup today though)

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34

Stator and rectifier were done at same time 600 or so miles ago.

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35

Did these issues start around the time you changed the stator? Just wondering if it’s possible you got the ignition timing too far advanced. That would cause every one of these problems and she would go like hell too.

36

Yes… Not immediately, but I noticed them afterward. How is this remedied?

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37

What burns my as is this bike has almost every mod possible and my Buddy who owns the same bike with similar mods minus the big bore and cams (he has the thin head gasket, cams, 39mm carb, and exhaust) he’s damn near as quick as me and he’s geared for Highway use too… My bike should be raping him at 48 whp

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38

When you installed the new stator did you use locktite on all the bolts holding the stator and pick up coil to the stator cover? It’s possible that the pick up for the ignition has come loose and is vibrating around.

39

Not if jetting is off. I would walk all my friends raptors with same parts but I spent the time tuning mine. Mine would power wheelie in 5, they had trouble in fourth.
I won the grass drags they weren’t even in the top 5.

You didn’t say anything about the stator before lol. Make sure that’s all good also.

40

I lock tighted everything when I installed th e stator… At least I’m pretty sure I did.

I’m just giving you guys each symptom and each thing I’ve done to it.

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