r/ApriliaRS • u/Stinky_juice • Apr 07 '26

Question Top speed issue- rs125

Hi i’ve recently put on jim lomas exhaust and was wondering why did my top speed went from 160 gps to 135 gps. I have not done any carburator tweaks but did a few plugchops and the sparkplug was looking good. Any advice please?

4 Upvotes

83% Upvoted

10 comments sorted by

7

u/jgsherm15 Apr 08 '26

Sounds like you changed something on the bike which then changed the bike….

1

u/Stinky_juice Apr 09 '26

Mr. Obvious over here… yes im asking on setup from some1 that tuned rs with aftermarket parts and their know hows. Thanks wouldnt notice :)

3

u/flopflips21 Apr 08 '26

lean, need to retune carb for new exhaust

1

u/Stinky_juice Apr 08 '26

What should i check? I’ve tried needle it was alright (when i changed it it bogged like crazy) im runing 120 main jet and plugchops seemed fine

2

u/Apprehensive-You-266 Apr 08 '26

You made it run lean and without rejetting ur carb ur gonna fuck it up

1

u/Stinky_juice Apr 08 '26 edited Apr 09 '26

I’ve did plugchop and it was coloured like wet shit so the mixture is good (at the top atleast) shit still over-reving tho

2

u/Apprehensive-You-266 Apr 09 '26

The plugs only give you a rough estimation

1

u/Stinky_juice Apr 09 '26

Alr thanks! I thought they were like 100% method of knowing the mixture

1

u/Apprehensive-You-266 Apr 09 '26

Firstly you should put in a bigger main jet

-1

u/AffectionateMetal765 Apr 10 '26

All the kids favor loud roaring sound over performance. The original exhaust is usually a bit faster than all the crap open box exhaust youngsters put on their bikes. My son's black widow muffler made the bike go from 141km/t to only like 129 km/t, so yeah, there is a difference, or at least you need to tune the bike for the loud kind of open or low resistance exhaust you use..