Jockey Journal Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
317 Posts
Discussion Starter · #1 ·
Kinda O/T, but I thought I'd give it a try anyway. I've got a 1982 Honda Urban Exress moped(vintage by most moped standards :) ). 49cc, 2 cycle, miniture CV carb, centrafugal clutch, etc. Problem is it tops out at 23-24 MPH(30 downhill with a tailwind). Being that slow, I'm always in the way of other motorists(not good). Are there any cheap and easy things I can do to get more top speed out of it? I tried a velocity stack instead of a filter, that didnt help. I fiddled with the jetting a bit to no avail(went slower with both more jet and less jet). I turned the mixture screw 1/2 turn at a time, and it made almost no difference. Any tips would be appreciated. Thanks.
 

·
Registered
Joined
·
500 Posts
Ya need a smoothbore. Look in the MB5 world. I think they are the same mill. I believe the Europs had a 80cc big bore kit fer these but you'll hafta dig. Good luck!
 

·
Registered
Joined
·
3,991 Posts
not sure how you would do it on an express but general wisdom on hopping a 2 stroke is increase the compression (top and bottom), rework the port timing, use a bigger carb and add a tuned exhaust. The japs are pretty good (excellent actually) of max tuning their stock shit right out of the box. however the japs also have a racing gene that puts ours to same. them little bastards will hop up and race ANYTHING! so, i wouldn't be suprised to find a japanese website that covers how to hop up an express.
 

·
Registered
Joined
·
581 Posts
lilbill said:
not sure how you would do it on an express but general wisdom on hopping a 2 stroke is increase the compression (top and bottom), rework the port timing, use a bigger carb and add a tuned exhaust.

Right on target but all involve some more work than you may want to do. Pull a few teeth off and stretch the flex it will give you more on the top without killing the bottom
 

·
Registered
Joined
·
317 Posts
Discussion Starter · #6 ·
Craven Moorhead said:
lilbill said:
Right on target but all involve some more work than you may want to do. Pull a few teeth off and stretch the flex it will give you more on the top without killing the bottom
Thanks for the info. I'll keep you posted on my "Results." :)

What do you mean by "pull a few teeth off and stretch the flex"? Have anything to do with the clutch governer under the primary pully?
 

·
Registered
Joined
·
581 Posts
Bugman said:
Craven Moorhead said:
Thanks for the info. I'll keep you posted on my "Results." :)

What do you mean by "pull a few teeth off and stretch the flex"? Have anything to do with the clutch governer under the primary pully?
You said you were running out on top end, If you take a few teeth off of the rear gear and increase the header or flex length you should be able to get more out of the top end. You can also increase the intake tract length for more bottom and conversley shorten it for more top. I was just looking at the lowest cost ease of use options. There is a ton of shit you can do to a two cycle to gain performance most involve machining and parts.
 

·
Registered
Joined
·
317 Posts
Discussion Starter · #8 ·
Thanks for the info.
 
1 - 8 of 8 Posts
Top