First And Second Gear Cutting Out When Revving, Other Gears Fine. - 125cc Sportsbikes Forum

125cc Sportsbikes Forum: First And Second Gear Cutting Out When Revving, Other Gears Fine. - 125cc Sportsbikes Forum

Jump to content


Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

First And Second Gear Cutting Out When Revving, Other Gears Fine.

#1 User is offline   Lucas 

  • 125cc Sportsbikes Novice
  • Pip
  • Group: Members
  • Posts: 9
  • Joined: 05-February 20

Posted 24 April 2021 - 07:26 AM

Hi,

I have been wondering if how my 2004 Aprilia rs125 (fully derestricted, stock exhaust) is normal or is there something wrong with the jetting or something else. I've done all jetting procedures I could find and on high gears (3rd,4th, 5th and 6th) it runs absolutely great.

However, in the first gear if I give it a lot of throttle (over half) it sounds like the rev limiter is kicking it at way too low revs. It sounds like it cuts out at 7k, then immediately revs to 8k, cuts out, revs to 9k etc. If I give it full throttle and a little bit of clutch it seems to punch through that issue. However, if I simply accelerate in first gear without clutch it has this weird behavior at the beginning of the power band.

Same thing happened in the second gear, but in lesser extent. Other gears pull brilliantly. I have stock sprocket sizes BTW.

I learned to ride in a way that avoids the problem by using the clutch and throttle to skip over the problematic rev region on 1st and 2nd gear.

The key question is, is this how it should be due to the engine being tuned to behave best under lots of load, or is something not right?

As I said above I believe it happenes when lots of throttle is given under low engine load. "Lots" is anything that causes it to rev out, but Wot and over 75% seems to punch through the issue.

My jets currently are pretty much stock (for a derestricted bike).

#2 User is offline   Lucas 

  • 125cc Sportsbikes Novice
  • Pip
  • Group: Members
  • Posts: 9
  • Joined: 05-February 20

Posted 02 May 2021 - 08:30 AM

Well, turns out my main jet was too big most likely. It was 128. I tried removing it completely to see how it would work with too rich main jet and it changed very little for worse. So I fitted 120. It is much better, but still not ideal. For a derestricted bike I think anything smaller than 120 would be risky so I'll be trying a leaner needle setting next.

It is currently on 3rd clip (idle is 2 and a half out).

Share this topic:


Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

1 User(s) are reading this topic
0 members, 1 guests, 0 anonymous users