Tuned up engine gearing disagreement ! Please help

[getsomegetsome]

Hello

Right I’m stuck in the middle of a disagreement between my parts supplier and my scooter shop. Both are saying that they are right and the other is wrong.
Now none of this is my area of expertise and I’m stuck in the middle. Not knowing who is right. But it’s rapidly heading to the point where each is going “ well go on do what they say and see where it gets you !”. ………. Each wanting the other to fail. 
now I obviously don’t want this as I’ve already spent a fortune on parts and if I’m totally honest I’m now flying on vapours. So I need to get it right first time round.
So it’s come to me either choosing one over the other or saying “ look just fit this “.
But I’m not going to lie I don’t have a clue about gearings on hotted up motors.
I’ve tried to look it up but I’m not getting anywhere.
I hate these situations as both people are nice and I’m going to have to choose one. If I choose the wrong one the other is just going to say “ ha see “. 
I want or can afford that.


In the interests of world peace I’m not going to mention any names. As that’s not fair on either and we all make mistakes. I would rather we were on the same team.

Hopefully someone has done a similar build , with wanting similar results, who can say this is what worked for them.

Here are the details

i have a ‘07 Vespa PX125 ( Disc )

These are the parts I have about to be fitted . Sent to me by my supplier after a lengthy chat about what I wanted my ride to do. My mechanic was like get the parts and I’ll do it. So at that time no advice from him.

BGM 177
BGM 60 stroke crank
BGM Bigbox exhaust 
24 carb
23 tooth banded clutch PX200 coda
BGM 36 tooth 4th gear
12 spring Cush drive primary repair kit

ideally what I want my scooter to do is be nice and torquie ( as torquie as possible ) but still give a higher top speed late 70s-early 80s if possible. 
But I also will be doing a lot of twos up.

now I chatted to a very helpful bloke about short 4ths to give a smoother powerband and really liked the idea of that. So told my supplier and these parts are what he recommends and they were purchased.

Now the parts are here and there is a dispute. This is what I’m being told by the mechanic 

That a 23 tooth clutch is wrong for this set up ( 125 )
the Cush repair won’t work unless cog is changed.
the px125 comes with a 36 tooth 4th as stock so why buy another.

I’ve tried looking up this stuff but can’t get a straight answer. I’m at a loss here.

if you’ve done this build or something similar and you wanted the same results as I’m after then I’d really appreciate your advice ?

cheers

[getsomegetsome]

If I had to choose between torque and top speed . I think I’d put more importance on torque. But obviously a higher top speed would be nice too

[shaunbond]

That a 23 tooth clutch is wrong for this set up ( 125 ) - Correct, a standard 23t 200 clutch centre will not mesh with a 125 primary, however company's like BGM do a version which will. I have one fitted to mine.
the Cush repair won’t work unless cog is changed - As above
the px125 comes with a 36 tooth 4th as stock so why buy another - Correct, commonly known as a T5 4th, they are fitted to 200's to shorten the gap between 3rd and 4th.

[shaunbond]

My setup is the same but with a standard 57mm crank, so probably less torque that the 60mm set up. It's fantastic, plenty of pull and I'm confident it would pull standard 200 gearing

[scooterbooter]

Yes I kind off agree with above. T5 4th is the same part as a px 125 4th. The t5 bit just makes it sound faster. 23 tooth primary needs a 200 xmas tree. You could have just gone 22 tooth clutch in real terms there's little difference if you have the torque and it sounds like you will. Fast acceleration and huge top end is very difficult with 4 gears . Good luck. I hate it too when good people give bad advice it very subjective and everyone's vision is different. Don't forget to smile. People will think your enjoying it. 😉

[ironsloth]

As above really. My job is a parts supplier, and I’m constantly getting approval from our mechanic. The way I see it is he’s done it enough times, some parts guys are not mechanics. Also had a similar chat with my usual scooter shop. Although the conversation was one sided, with a lot of ‘stupid t**t’’ and ‘what do you wanna do that for, waste of money’… Always go back… 😎

[scooterbooter]

Unless you've bought a drt 23 toother. Apparently they fir a 125 Xmas tree. But a normal one don't it's close but no cigar. I've tried it myself the dealer I got it from mislead me , not on purpose and was happy to exchange. I've had this shizzle meself.

[gpowell]

Quote..
ideally what I want my scooter to do is be nice and torquie ( as torquie as possible ) but still give a higher top speed late 70s-early 80s if possible.
But I also will be doing a lot of twos up.

You will not see high 70s - early 80s...being realistic this set up will achieve mid 60s to 70 at best on a good day...unless you have a tuned speedo..

You have also factored in two up riding...

Ive built plenty of kitted 125s, (though never used BGM and never will for vespa or lambretta) without major casing and cylinder work there is a limit.

I ride tuned P200s that will not achieve 80mph

My TS1 225 wont do much more than 80 on the road, its a "standard" set up that is tried and high mileage tested.

GPS quashed many pub claims....

Doing a genuine 70mph on a px is an achievement and very difficult to main for long periods on motorways

[scooterbooter]

Yes well yesish I kind of (only sort of) agree. You do need to put in major surgery for a px to do 70+ for long periods. They are not comfortable at that speed anyway. Part of the fun. Major heart ache.

You are expecting a bit too much top end I think he's right to manage your expectations.

[scooterbooter]

How fast you go top end depends on what the wind is doing more than what kit you got. Mother nature, a real bitch.