Strange Jetting Problems

[MountainMax]

Hey guys, I have a strange jetting problem on my bike, maybe someone here can shed some light. I have done all the free mods, and boyseen fuel cover and storm fuel screw, jetting as per indys sticky thread and now a YZ muffler. While i drive my bike at higher speeds while cruising the streets she hickups every now and then while at light throttle, when i accelerate she seems fine. I tried to adjust the needle up and down a notch, same thing, she dont' backfire now when i let go of the gas as i turned out the fuel screw until it went away 2.5 turns, my next step was upping the pilot to a 50 and try that (on back order). But the biggest concern is last night i removed my sparkplug after going 80km on a road/trail averaging 100-110 km/h and when i check the plug the center electrode was nice and clean-tan looking. but the outter inside area of the plug was very black and sooty, what the hell could cause this? i have never seen this hapen before, it looks to me like my jetting is rich somewhere but where i drove last night was good enough just to keep the electrode clean, any ideas??

[clark4131]

Disconnect the TPS and see if that cures the "hiccup"...SC

[Thumper_Bloke]

Indeed. My bike is jetted perfect. Runs great, and air/fuel was checked on a dyno. However, when riding at steady state like on a 40mph flat road, it hiccups and sputters and misfires. I disconnected the TPS and it completely went away!

I still use the TPS offroad though.

[MountainMax]

Thanks for the tip, I will give it a shot, Im just afraid if i keep it disconected it may cause my bike to advance the timing too much and burn up a piston or detonate? or if not if it keeps my timing the same (not peak) then I will lose power, can anyone explain how disconecting it will affect timing??

[Dodjy]

Try going leaner on the needle (raise the clip 2 notches if necessary). This problem is usually caused by a rich needle.

[MountainMax]

Thanks, I did move my clip up one position already, no diff, then i tried the TPS trick, now that made her 90% good, still a little hickup every now and then but way, way better, Will I hurt anything with this left disconnected??

[Yamahondaha]

What about adjusting the Throttle position sensor? I was having the same problem on my 99 WR400 and after fartin around with a JD jetting kit I adjusted the TPS and it was kickin butt and takin names...

[MountainMax]

hmm, which way did you adjust it? is there info on that in the manual? i don't remember seeing any?

[comrade_yzf]

Why does the TPS mess it up for onroad?

[clark4131]

Why does the TPS mess it up for onroad?

These bikes were not designed for steady throttle riding. Off road you're on and off all the time with the terrain features, so the TPS hiccup is still there, you just don't feel it...SC

[comrade_yzf]

These bikes were not designed for steady throttle riding. Off road you're on and off all the time with the terrain features, so the TPS hiccup is still there, you just don't feel it...SC

Thanks for filling me in

[Thumper_Bloke]

Why does the TPS mess it up for onroad?

Me and my co-workers are speculating that with the TPS connected, there is too much advance and with the weak ignition system and very short spark duration, its just not getting the charge lit all the time.

Hopefully i can get some advance curves from the stock ignition and share them here.

[Indy_WR450]

My Vortex X-10 CDI does not miss a beat and uses the TPS without steady throttle surge or hickups. Biggest issue with our bikes is the stock CDI unit.

[OneToGo]

My Vortex X-10 CDI does not miss a beat and uses the TPS without steady throttle surge or hickups. ? Biggest issue with our bikes is the stock CDI unit.

Interesting Indy..

I thought my bike was cured of this but a recent stint on the road / highway proved otherwise. Maybe my jetting was/is not spot on but at around 70kmh (with absolutely steady throttle on the flat) I got the dreaded surge. As soon as I shifted the throttle slightly it disappeared. It was more apparent at the lower speeds and no sign at 90kmh +. Otherwise perfect spark with Vortex - agreed!

BTW, I reckon Vortex returns better fuel consumption - could that be so? I got 19km/litre mixed dirt road riding with a heavy hand (168MJ/Red #4, 31C and 90 R.hum) - gee a 165MJ would probably give me over 20km/l, ie. over 55mpg (imperial not USA!).

CDI Map 4 and 1 used - and I did not have the time to disconnect TPS to check any changes.

Just for info guys and a little OFF Track I know - but useful for someone?

[Matty05]

Vortex!Vortex!Vortex!Vortex!Vortex!Vortex!Vortex!Vortex!Vortex!Vortex!

Get one!