Alien Exhaust

[builtone]

Is this a good pipe for a jet and 150 upgrade for 125 SM? I'm also going to change the sprockets and I'm curious what might be good for San Francisco with the hills and all.

[witttom]

[DAVID THOMPSON]

i am running a 52 rear in place of the 49 ori
on my rt125 and it was a big improvement
here in my hilly town
in sf i mite go 54 or 56 but it will kill top speed on a freeway
my top is about 68mph with the 52
so 52 is ok and it runs sweet up to 65 then the rpm's get a bit high
ar dave

ps do you have spoke or alloy wheels on your SM

also with the 52 your chain will be 3 or 4 links longer than stock

[witttom]

[DAVID THOMPSON]

it is the stock one for the SX and i used a adaptor made from the center
of the 49 tooth as it is not offset for the alloy wheel like the 49 tooth

i can do the adaptors here from your old 49 tooth if you have the alloy wheel as i have the lathe to cut it down to make the offset spacer
then use the 52 with with longer bolts to mount to the hub
this works on the alloy wheels i have not seen the setup on the
17inch spoke wheels
goood mod this winter in the fowl wx of january


THIS IS FROM A PAST POST OR LETTER TO SOME ONE LAST YEAR
Installing 52 tooth SX sprocket on RT125

You can install a 52 tooth SX sprocket on a rt125 in place of its
49 tooth
You must cut the center out of the old 49-tooth sprocket
Just above the mounting holes so it can be used as a spacer
It will cut very easy with a hacksaw then have a machine
Shops trim the edges so it's round on a lathe with a three-jaw chuck
This spacer is used to get the offset so the front and rear sprockets
Line up as the SX sprocket has no offset but has the same bolt pattern
Longer bolts will be required
Also it is required so the original snap ring will work to hold the whole
Unit together

This will make the bike perform better at speeds up to about 70mph
And give you better pulling power on hills at 55 and 60
It steals some top end but this bike is only 300 LB and much too
Light to be going over 65mph any way

Rpm to speed equals 150 rpm in 6th gear per 1mph
Example 30=4500 40=6000 55=8250 60=9000 65=9750 70=10500 or wide open
This bike is only 300 LB and much too light to be going over 65mph any way
Engine power is peak at about 8700 so 55 to 60 is a good cruise
Have not been enough miles to tell what it does to gas mileage will update that later this summer

GETTING 68 TO 70 ON TRIPS IN AUG 2004 WITH 16 /52 16/49 WAS ABOUT 73 75 MPG

[witttom]

[DAVID THOMPSON]

this page shows sprockets

http://www.ksportmotorcycles.com/mz125_kit.html

yes there in ca but probbly have then in stock

52 runs nice 54 would make top speed about 66 mph
52 letts me wing it at 65 on a flat freeway with touring load me 220lb
and about 70 to 90 lb of camping gear

while your at it order these parts
9015059000 engine chain sprocket
3746030000 sleve behind sprocket (if damaged this will cause down time)
3746032000 sprocket lock ring
3746033000 sprocket nut
these seem to be MZ PARTS only i searched a local mc atv shops stock
and could not find any thing like them
i carry them as road spairs on long trips if the nut falls off your hauling it home

also these items
clutch cable rt and sm 3923006000
gas cable rt and sm 3923012000

you will need a short piece of 428 chain and 2 master links
to make chain longer
a note on top speed this is a very tight engine mine did not get loose
and start to wind up till it had above 4000 miles on it
and i saw an indecated 78 mph befor i changed the sprocket
as i needed more low end grunt
it will probbily be next summer befor you see and hear it really sing

[builtone]

So is the alien the best or most afordable option? BTW I'm getting the stock spoke 17" wheels. I'm not really concerned about top speed, I won't be driving on the freeway anyways. I just want something good for city use and trails.

Thanx for all the help guys.

[DAVID THOMPSON]

builtone

i would not worry about a pipe till the motor is broke in

if your going to be using it on roads posted 55 mph or less

52 tooth will make it run nice but a 54 will turn it into a hill
climber but top end will suffer
in SF i would go for the 54 tooth and stay off freeways posted over
55mph
with a 54 this thing will EAT most street 250's a new ass up to 60 mph
unless the have had the same mods

but don't rev it up tooo hard till its got at least 3000 miles on it
because if you blow it at high rpm i will here the noise from here in WV
and also hear the flying parts landing on my roof

[builtone]

Well it's a toss up between this used one that has 1000k and a new one. Prolly gonna get the newey. Plus the new one is black lol.

[mxsteven]

that is in ur RT.... how about for 125SX? what is the best macthing?

[DAVID THOMPSON]

on the SX 52 is stock but rear wheel is an 18 so a 54 would
make it pull better but 56 mite make it a bit slow on the
freeway
with the SX you will have to be the expermenter

[mxsteven]

thanks for your comment.... anyway i will try to experiment it...