Top speed no wind MZ Rt125

[jojo]

Hi guys i just wanted to check what is the your top speed on the rt or sm 125 as mine struggles past 60mph. everything is stock and i have a windshield installed but didnt help much.
PS i weight 65kg

[DAVID THOMPSON]

with about 8000 miles on it mine would do almost 70
i changed the gearing it will do 68 mph flat out with a 52 tooth on the rear 49 was stock
its at 23,000 it does 55 ok but its weak in the area from 55 and up and 60 and up is hard on it
putting the 49 back on is a joke it loads it down and and its hard to do 55
Dave

220 lbs and 5f 11in some times called "ton of fun"

[stephendacosta]

I have a lot of MZ 125's. The most often successful corrections to lack of power are jetting (using a 105 main jet) and retiming the cams to be spot on. --Steve

[jojo]

@Wow that's pretty poor Dave. With 15bhp I was expecting something more spectacular. I could barely keep up with a cbf125 the other day. Annoying as it is 4bhp weaker than my Rt125.

@Steven is rejecting really going to make a difference? Current seeing should be the best right?

[DAVID THOMPSON]

factory setting is to keep the EPA HAPPY and not get over 15hp

some location did and still have HP limits for a 125cc 15hp power limit for beginners

if its less than 350cc and 30 hp
its just a big MOPED
Dave

[vicar]

Dave your 350/30 hp comment is wrong a 250 Mz is not a moped !

[DAVID THOMPSON]

It must have more hp than any 2 cycle bike i have ever owned..
But you need to understand the hill country i live in there
steep and your always climbing one any time you
Leave the house
Dave

[jojo]

Update.
Thanks for the replies guys. So after considering the option of a bigger jet I decided to first check my air filter.
I cut it out and changed to a a foam type from Ramair (only cost £3 for a large sheet of 20x30cm)
Takes a little bit of patience and sharp cutters but I managed to do a decent job.
Performance: still same top speed of around 62mph but I get there so much quicker
Also the gears seem to pull stronger too. The bike is overall slightly qieter which is a little strange
...
Im more thinking of reducing the rear sprocket to 47teeth to gain top speed. Any other suggestions?

[DAVID THOMPSON]

if it has over 10.000 miles i will be surprised if you gain any speed
when i want to go fast i get out the Saxon Tour rotax powered 500

[jojo]

Hi Dave,
My bike is 25000 on the clock do maybe it is as you said
I live in London so I don't really need blistering speed. I just want to be able to keep up on 70 mph A roads.
I was struggling between this amazing little bike and a cb400 Honda, suffice to say this a much better looking and practical bike. It also so easy to ride pity I cant have it all

[DAVID THOMPSON]

where i live most posted speeds are 45 mph a few ai 55 , 1 at 65 and 1 at 70
so mine is rt125 stock front and 52 tooth sm sprocket on rear
requires an adaptor made from the center of the old 49 tooth sprocket
with longer bolts the 49 had an offset so use center of 49 as a spacer to keep chain aligned

it is almost perfect for what i do
over here most 125 cc
street bikes are found dead at 8 to 10 thousand miles as there abandoned it the barn
as the riders feed the need for speed with something BIGGER

cb400 is badly abused over here most are toasted out at 30 thousand as the owners flog the hell out of them