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LML125 gear ratios

Posted: Sun Sep 16, 2018 3:04 pm
by johnd
I'm reading in different places that LML 125 engines have slightly longer gear ratios than Italian px125 motors. Anyone know where the diffence is? Is it primary drive or a complete different gear set?
I'm in the process of doing a long stroke polini 187 on an LML 125 and was going to add a DRT 65 primary gear but don't want to over gear the engine.

Re: LML125 gear ratios

Posted: Sun Sep 16, 2018 4:37 pm
by johnd
johnd wrote:
Sun Sep 16, 2018 3:04 pm
I'm reading in different places that LML 125 engines have slightly longer gear ratios than Italian px125 motors. Anyone know where the diffence is? Is it primary drive or a complete different gear set?
I'm in the process of doing a long stroke polini 187 on an LML 125 and was going to add a DRT 65 primary gear but don't want to over gear the engine.
Obviously i could strip it and count the teeth but its still in the bike and running so i'd rather leave it in one piece until i'm ready to work on it.

Re: LML125 gear ratios

Posted: Sun Sep 16, 2018 5:41 pm
by gaz_powell
I believe, its 57, 42, 38, 34 gears, cluster 12, 13, 17, 21 and 68/21 clutch

Re: LML125 gear ratios

Posted: Sun Sep 16, 2018 6:01 pm
by johnd
cheers Gaz.

Re: LML125 gear ratios

Posted: Sun Sep 16, 2018 6:09 pm
by johnd
so it looks like 22/68 or DRT23/68 would be fine for a polini motor with those cogs. Would it be a good idea to throw a T5 fourth in to shorten the jump between 3rd and fourth do you think?

Re: LML125 gear ratios

Posted: Sun Sep 16, 2018 8:21 pm
by Juan
Don't know about LML gear stacks but the PX 125/150 4th was same as the T5. Only 200's were longer.

Re: LML125 gear ratios

Posted: Mon Sep 17, 2018 8:23 am
by johnd
It looks like the LML 125 has a 200 4th gear cog. I'll hold off buying anything for it until I've counted the teeth of the gears though as I'm getting conflicting info on it.
As a standard 125 you really feel the gap between third and fourth, feels tall.

Re: LML125 gear ratios

Posted: Mon Sep 17, 2018 5:59 pm
by Shaunbond
I can't tell you what 4th gear an LML has in but I suggest it's no different than a PX. I can say from experience that I run a BGM 177 on LML 150 reed cases with a DRT23 Cosa and it pulls lovely, great mile munch but a 22 would be better for town or shorter trips.

Re: LML125 gear ratios

Posted: Tue Sep 18, 2018 8:33 am
by johnd
Cheers for that shaun. I think it's going to be a case of teeth counting when I open the engine to know for sure. I'm leaning towards 22/68 or drt23/68 if my primary drive is in good condition and a drt65 tooth primary if I have to replace the Cush drive springs. So many options these days!!😜

Re: LML125 gear ratios

Posted: Tue Sep 18, 2018 4:50 pm
by johnd
Right, had a day off so I stripped Down my engine. Primary's are 21/68 and fourth is 21/35. The rest as gaz has said above.
So that's a px200 cog. According to scooterhelp's gearing calculator that's a final drive of 5.13 with 22/68 and I'm guessing something closer to 5.00 with a 23 clutch cog. I can live with that.