Rev Counter Drops To Zero...

[exuprob]

Gave my old 4xv R1 a bit of love yesterday due to having done 3 trackdays and hardly been looked at. Refitted the dynojet kit, K and N filter and fitted a new 4 degree ign advancer plus all the usual oil and filters.

Apon riding its spot on, actually its alot better than it was.... apart from the rev counter drops to zero at anything over half throttle. Ive re checked the TPS and did have to recalibrate it but it still does it.

If you slowly twist the throttle back it only does it at full throttle but whip it back and it does it pretty much straight away.

Could this be a knackered TPS or could the ignition advancer cause this?

Any help greatly appreciated.

[gsxr renegade]

Does it jump to another number on the tacho, then back to zero/normal revs, or does it just drop to zero and stay there?

[exuprob]

Nope, sits at zero until you close the throttle. I performed the tps reset (ign on, unplug tps and replug it in and rev counter goes to 5k which is correct) but still does it.

[Superdunc]

Is there a crank sensor near the ignition advancer? It won't be anything to do with the tps.

[exuprob]

Yep, the ign advancer sits right next to the crank sensor. Suppose I could have got some crap on the sensor or the bike just doesnt like the advancer. Might swap it back to std and see what happens.

[exuprob]

Ah right, thanks for that.

Any ideas why would it be sensitive to throttle position then??

[porter_jamie]

Try taking the advancer off. I thought about getting one for my mine but ivan from ivans performance says you are better off without. I dont know either way but if it fixes it, it must be that

[exuprob]

Yep, thats my next job. Need to order the timing chain cover gasket though, wheres best or is it a yamaha only job???

[MonkeyJim]

I only ever used genuine gaskets on my 4xv, and never had any leaks.

the timing cover one is a fiver maybe IIRC?

I found that a good smear of grease on both sides of the gasket meant it could be re-used many times, without any problems at all.

[gsxr renegade]

Does it always happen at the same point on the tacho?

As silly as it sounds, the tacho needle on one of my 4xvs needed pressing back onto the face of the tacho after it used to swing about wildy with revs, turned out it had come slightly loose. Probably won't solve it, but it could be worth a shot?

[exuprob]

Cheers for that Millemille. I suppose it could be corrosion has got into the white multi plug that feeds the dash so I'll check that too.

Cant see how its the advancer but may remove it anyway and return that to standard just to eliminate it from the fault.

Still weird that it only happens with the throttle open more than half way though.