Phantom neutral?????

[Richo]

howdy. .

Ive got an 87 GPX750 .. first bike in like .. forever ...

Anyway, it seems to have a phantom neutral that pops in rarely, but very un-announced .... I think between 3rd and 4th ...

It simply is a NO GEAR realm ..

What causes this? .. and no, it aint the real neutral .. .

Its no biggie .... but would like to shed some light on the matter ...

Richo.

[Slow and wobbly]

Worn gearbox. Selector fork or drum or dogs. Start simply and change the oil. Next the chain and sprockets - both of these can make a difference to gear shifting. Lastly spend a weekend and the GDP rebuilding it.
Or just accept it as it is and make sure every shift is done positively and slowly.
Worst thing I see often when someone hits a false ( or even the real ) neutral is that they immediatly pull the clutch and and slam the lever up to try again. When you do this you make an even bigger mess of those poor suffering parts. Best to take your time and attempt to match your RPM to road speed to ease the strain on the gnashing gears trying to tango together. Just like driving a nonsynchro gearbox in a car or truck. Get it right and it works a treat, force it and all you get is mechanical abuse.

[chrisw]

exactly what i was going to say but got there quicker than I...

what was said was true though, ride it like a postie bike (weak gearboxes with temperamental changes) do a slower, firmer and longer (shutup) , deliberate change at the right RPM.

if its a problem of popping out of gears too, what i was taught was hold the gear lever until you take the clutch off again, to kinda 'safeguard' it in.

[Smitty]

Worn gearbox. Selector fork or drum or dogs. Start simply and change the oil. Next the chain and sprockets - both of these can make a difference to gear shifting. Lastly spend a weekend and the GDP rebuilding it.
Or just accept it as it is and make sure every shift is done positively and slowly.

as a previous GeePeeX7fiddyR owner
I have to agree with some of S&Ws comments

the 750R is oil sensitive....
I tried Shell Advance(the GPX HATES IT with a passion..a whole box of false neutrals )
then Motul..not bad..but still lots of false neutrals

Castrol seems to be OK....as is Silkolene
and
under NO circumstances use a car oil (might be cheap but shags the gearbox on teh GeePeeX)

If there is wear (gotta be with a 20+ year old bike) yeah..a sprocket/chain change can help

plus
you have to adjust the shift lever so you boot it into position otherwise
a half arsed upshift attempt will give you ...no gears at all

on a final note..there is no bad history that i am aware of with the
GPX750R gearbox...apart from oil sensitivity they are fine
but of course you don't know what the previous clowns who have ridden
the bike have done...clumsy gear changes can phark the dogs and gears quick smart


hth

Smitty

[Rossi]

I have also had similar problems with an older bike ......... strip & clean/ grease the gear change lever pivot points..........I shit you not, it solved the problem

[Richo]

Thanks fellas ..

Tried simply making some more "firmer" changes on todays ride and didnt slip out once .... will continue that until I got some time to pull it appart ..

Thanks again, nice to know theres a world of knowledge in here