p2 t5 4th gear

hi all havint bin on in a while, how is everyone? anyways problem, during the anual rebuild, seals clutch rings etc etc,tryin to put a t5 4th gear in a p2 motor as havin a bit of trouble pullin revs in 4th with the old scorpion.its an OLD p2 motor not a px,seems to need some sort of a shim, i no the t5 4th while fit straight on to a px motor with no worries but havent come across this before.the t5 seems to be just brushin the prim drive,and needs lifted up.wen assem measured with feelers a gap of around 1.6-1.7 between 1st gear and the top shim, anyone come across this and can the shim be got, cheers folks,

the reverend stubbs[I)]

Yeah best to fit the right gear.

I can think of better things to do than stripping engines to replace cruciforms, like drinking!

mmmmmmmm BEER!


hello stubbsy,long time no hear.the t5 4th is for px-efl.if youre fitting it into an „old style“ px you need the px125 4th gear.how many do you want ive got 10 to choose from.reverend eh? not the u.l.c by any chance

stroud valleys(midnight hour)sc est 1984

the problem with shimming the t5 4th stringy is the cruciform wont go into the shaft deep enough for the gear selector to locate into 4th position so it’ll keep jumpin out

stroud valleys(midnight hour)sc est 1984

yo doc, if you have afew 125 4th gears to do the job would u part with one? ive got an add on scooter trader so if u can get in touch that way,

the reverend[I)]

stubbsy,while stringy is getting lashed up if you look in the profile section on this board you will find my e-mail address,chop me a line,sorry,drop me a line and i’ll sort you out

stroud valleys(midnight hour)sc est 1984

Sorry guys & girls I know its an old subject but did Stubbsy ever get his 4th gear sorted out?

I had the same problem with a late Rally engine. I ordered a T5 gear from PM. I also found it was about 1mm too narrow. Also it would not of been possible to shim the gear outboard as the spacer would have to run on the internal machine Rad on the shaft shoulder. PM had never encountered this problem before.

Checking through alll info here it appears if if you have an early P2 or a rally with a shouldered output shaft then you have to use a P125 4th gear from an early engine not a T5 gear.

SIP do sell an early px125 4th gear but before I buy one can anyone confirm this please?



To lower the gear ratio in fourth gear you either need to use a T5 fourth gear or an old PX125 fourth.

It depends if it is an early or late engine as standard P/PX200 fourth gears are different widths:

Early gears are 4.85mm Wide
Late gears are 6.43mm Wide

A difference of 1.58mm, this seems to be about the figure you are measuring.

If you look at page 79 of the SIP Catalogue they list the gears you require.

I suppose you could shim it up with a couple of standard gear shims but then the position of the gears will move in relation to the pre-set movement of the gear selector.

Hope this helps!


I thought I heard the word BEER, OK you got my attention, not in the slightest bit interested in px boxes but BEER, well STRINGY, now we’re talking. Just like to add tho that Scooter center koln, were doing complete late type layshaft, four gears inc t5 4th, cruciform, and selector shaft all shimmed and circlips for £79. which means no more jumping out of gear either, and a new lay shaft means a better fitting rear hub. you can use with your xmas tree with this. SIP may match price if you ask nicely!! BEER.

fukkit,sorry stubbsy.it came out of my rally so thought it was good.if youve got no circlip and washer on the bottom thats early early p series.if youve got a new style shaft itll do it??as for the ported p2 well now,im getting a lob on! if the ports are polished i presume youve raised the exhaust port by 5mm(if not do it or the rest is a waste of time)and widened it by 1.5mm each side you will need main jet around the 125-128 mark especially with that pipe.another tip is where the inlet port goes into the housing file out the front of the port by 3-5mm giving you longer inlet.i ran the above with the sip pipe and the old girl screamed the tits off herself through all gears and standard p2 4th!!(my main jet was 130 though) with the above even if you want a bog standard p2 in future it wont cause any probs to go back to it.the longer inlet timing will help a bit .soz to have held you up mate

stroud valleys(midnight hour)sc est 1984

yo doc, got your parcel today, no good my friend is exactly the same as what i sent you., new as soon as i opened it up, the problem is the depth of the gear in the centre. if you can picture my shaft, in the motor of course;D ,there is no shim or circlip at the bottom, ie hub side,(as there is at the top> where 4th gear rests is part of the shaft it self. maybe give it up as a bad job, itchin to get her back on the road,o got a mate to to all the cylinder ports for me, ano u like that portin stuff[:D] [:D] so what set up with standard p2 with scorpion and polished ports? up a plug or 2 and maybe a 120 main? < non lube carb>