Ignition Timing Adjustment?

My 426 pings between about 4000 and 7000 RPM, under any load/throttle opening on the best available gas here; 91 pump posted octane...Is removing the flywheel and slotting the pickup coil's mount to slide it counter-clockwise, the only way to retard ignition timing? How about adjusting the TPS or disconnecting it?

You could buy one of those expensive CDI's with multiple settings. Wolf and Vortex I believe. Strange it pings on pump gas. Have you actually looked at the pickup to see if it can be slotted? I'm interested in doing the same thing, but for other reasons.

Are you sure that's gasoline, not moose piss your using? :) Just kidding...I haven't heard of anyone having detonation problems on the YZFs as long as the compression is stock. Is the jetting stock, 162 main, 42 pilot, needle clip in the stock position?

...under any load/throttle opening on the best available gas here...

Does it also ping in neutral (i.e. zero load) at that rpm range? If so, I would say you are not hearing pinging. It would be darn near imposible for the motor to ping with zero load -- unless you are burning a ton of oil or have a completely wacked out ignition system that is advancing to something like 80 degrees or so btdc at 4000+ rpm.

Could you be having some other issue that just happens to sound like pinging? Maybe a clutch vibration problem that produces a nice, high-quality ringing sound? Or, could it be a valve lash issue or something?

Anything weird ever happen to the bike: run it out of oil, burn up the clutch, crack the crankcase?

Yeah, I'm sure it's pinging, plus I never had any problems; valve lash is still perfect and it never burns any Amsoil... We had 92 octane available till last fall on which it had a slight and acceptable ping just at the beginning of the power band. They then downgraded to 91 octane just before the end of our riding season when the pinging worsened. It was then impossible to accelerate through the about 4000 to 6000+ RPM range without pinging too much for my taste, which is what I meant by "any load/throttle opening". It doesn't ping at idle or cruising. Our gas really does suck here.

I'm taking the bike out this Saturday, 1st time since last fall and I will start by trying backing off the TPS adjustment, and hopefully have less ignition timing advance...

Have you tried using some octane boost to see if the pinging goes away afterwards? Octane boost is relatively cheap considering that you probably are only burning 2-3 gallons of gas a week, right?

The manual specifies 95 octane fuel for the bikes. Mine runs fine on 93, but if you are at 91 or 90, maybe some race gas mixed in or some octane boost would help.

As far as the TPS goes, I don't think it controlls your advance curve -- well, at least it doesn't make the timing advance; I think it actually retards the timing from the stock profile. People that have disconnected their TPS are reporting a performance increase most likely from the TPS not retarding the timing. I'm not sure though....

If you want to try retarding you,re timing pop off the flywheel,mark you,re stator plate to the case so you can go back to where you started from,loosen the 3 bolts holding the stator and turn it counter clockwise to retard the timing. When I installed a lighting coil on my bike the stator was in the fully advanced position.Ther is not much adjustment in the bolt holes but it should be enough.The idle should go down a bit if you retard the timing due to the slight power loss.

Hope you get it worked ouy. :D:)

Cool...For further possible ignition timing adjustment, my Baja Design's stator modification instructions' pics also reveal 2 phillips screws holding the pickup to the stator. I've backed out my TPS as much as I could; from 850/4030 ohms to 350/3520 ohms and I'll test that 1st this weekend. If it's not enough, the counterclock stator/pickup shift will definitely retard ignition timing. :)

Carbonbody; If additional adjustment is desired, the stator/pickup should be slotted in the same radius point as the stock holes, in a circle orbiting the crankshaft.

Thanks guys! Now time to mount up the turbo. :)

Speaking of turbo which has nothing to do wtih the conversation, what if someone bolted one up a very small turbo with maybe 3 lbs of boost wouldit work and how much power gain? Does anyone have the guts to tri it? they make turbos that are palm size maybe slightly bigger i think someone shoul try it be brave and differnet.

It worked! Backing off the TPS from 850/4030 ohms to 350/3520 ohms was just enough to eliminate pinging. I can only manage to emit a light ping or two if I snap it open at beginning of power band...It's even much better now on 91 pump octane than it was on 92. I actually had to reduce idle a tad, and it now runs smoother and is more tractable.

TPS was already close to maximum clockwise setting, so I removed its bushings, filed the holes a bit bigger and even filed away top threads on screws and used larger fitted washers. I also matched and polished my exhaust port outlet and seal, so there is no apparent power loss. :)

Speaking of turbo which has nothing to do wtih the conversation, what if someone bolted one up a very small turbo with maybe 3 lbs of boost wouldit work and how much power gain? Does anyone have the guts to tri it? they make turbos that are palm size maybe slightly bigger i think someone shoul try it be brave and differnet.

I'm working on it. :)

Will let you know in a few weeks.

What do you mean by 350/3520 ohms? Is that the open/closed values?

Yes, 350 ohms is the TPS's resistance at off throttle idle position, and 3520 ohms at WOT (wide open throttle). Normal spec is between 4000 and 6000 ohms at WOT allowing maximum ignition timing advance. Disconnecting the TPS results in infinite resistance, so the mapped ignition advance curve is relying only on RPM input and is not retarded at any throttle opening.

The lowest achievable TPS resistance allows a stronger ignition control input signal resulting in more retarding effect on the mapped curve...

How do you adjust the resistance? I've also noticed the TPS has slightly slotted bolt holes where it mounts to the carb. Does it make a difference if the TPS is rotated to either extreme when mounted?

Turning it clockwise lowers resistance, and turning it counter-clockwise increases resistance. This can be verified with the engine off. Using an ohmmeter set at 'K ohm X 1'; tester positive lead on TPS yellow lead, and tester negative lead on TPS black lead. Chapter 6.8 (Step 3: TPS coil variable resistance.)

Thanks. I figured the slots were there for something. I never really paid attention to how I screwed that thing back together after I reassembled the carb after a thorough cleaning. Can't say I've noticed any adverse effects though.

It could be to much carbon on the top of the piston.

I guess you could fool it easy with a 3500 ohm resistor pluged into the harness.

The manual specifies 95 octane fuel for the bikes. Mine runs fine on 93, but if you are at 91 or 90, maybe some race gas mixed in or some octane boost would help.

Actually I believe the manual states the RON not the pump octane which would be (RON+MON/2 if I recall correctly). For a stock bike the 91-92 octane usually will work if the jetting and timing are correct. Now, to figure out if my new 250 with Wiseco piston will need race fuel due to higher compression...

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