Help I dont know whats wrong?


Today was out riding my 99' wr400 when the "push" throttle cable broke. I rode the bike home and adjusted some of the freeplay out of the pull throttle cable so it felt ok to ride. Anyway about 3 hours later I had been riding around this sandy track with my bike working perfectly. I stopped to get a drink. When I started it again, the exhaust sounded louder and when I tried to rev it in neutral it would bog down as you twisted the throttle but then rev smoothly as the revs got high. When you let go of the throttle it would also backfire. I could not visually see what was wrong. I inspected all the carby hoses to see if one was off, nothing, I also drained the carby bowl to see if there was fuel, there was. I dont know what is wrong... It seems to be maybe a fuel or ignition problem because the bike starts easy and idles nicely, so I am trying not to think an mechanical problem.

So what do you guys think? I am going to strip down the bike tomorrow and see if any ignition wires have chaffed or broken. I will also pull the carby bowl off to make sure no jets have come loose but apart from that I have no idea. Could riding the bike with a throttle cable missing damage anything. If you have any ideas please help!!.

Thanks Jason


I am having a real difficult time thinking that it is connected to your throttle cable. I think disassembly of your carby is

a good idea. Be sure and check the accelerator pump. Be careful when you remove the accel pump cover, there is a small o-ring that has a habbit of falling out. Work over an area that if you indeed drop any parts, you can see them. Also, be aware you will have fuel in the bowl and pump, so don't work on your new sofa, otherwise it too will smell like petrol. Work the throttle linkage to see if in fact your push cable could have any detrimental effect on your carb.


99 WR, all YZ mods, de-octopused, OEM YZ tank and IMS seat, jetting by Clark/James, got forked by Pro Action, DSP airbox, PB Header, Stroker SX-1 SA, Thumper Rad Guards, Acerbis Hand Guards. Moab, HERE I COME!!

Check for a vacuum leak at all the rubber hoses on the side of the carb and make sure the hot start button is seated all the way in.


MotoGreg - The voice of absurdity

'99 WR400 - 'Cause thumpers rule and two-strokes drool!

'92 GSXR 7/11 (But I wanna get a dope 916)

I might let you visit my photo album for $3 - ENTER AT YOUR OWN RISK - DANGER LURKS WITHIN

Throttle Position Sensor?

If this isn't working or is not adjusted the timing may be off. What you describe sounds like it COULD be an advance curve problem.

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