im prettynew to tuning these.21 motors but need a little advice on how to tune i have a rossi p5(awsome powerfull motor) by adjusting the bottom end , how much does that efect the temp of the motor?motor is running around 200 to 220,after a 15 min, main but i wanted to know what does adjusting the bottom end really do????? thanks a lot


j.maggio

The LSN will cause the HSN to follow. I.E. if you lean the LSN out a bit, then the HSN will lean as well. So just make sure you compensate. On a side note, a great way to increase bottom end without sacrificing top end or temps, is to either get a heavier spring set for the clutch, or shave the shoes down so they require more travel to reach the bell housing. This only takes about 20mins and makes a very large difference.

thanks that helps

No problem bro - That's what the site is for.

Actually the tuning is the other way around, the LSN has no Impact on the HSN but if you lean or richen the HSN the LSN will also have reduced or increased fuel pressure..

If you are running too lean a LSN then the motor can appear lean all over and lean bog...

Set your HSN for clean running over the longest straight (or longer) then set the LSN for a clean pickup...

To check you LSN, pinch the fuel line just before the carb...

if the engine speeds up after a few seconds, races for a bit and then cuts, you were about right...

if the engine just dies you were too lean

if the engine speeds up after a longer period 4-5 seconds, and then cuts you were too rich...

I stand corrected. Sorry about that - been a long day.

I would still recommend shaving the clutch rather than leaning the engine out though.

the motor has plenty pick up as it is but ,i just wanted to know the real deal on tunning,was not 100% sure thanks for the advice