Can a Lean Condition Cause Loss of Power?

[scottinscotty]

2000 elite sr50
polini contesta kit
uni filter
variator
100 jet... my plug looks to be light sandy brown and feels slighty low on power
what are good ways to read a 2 stroke spark plug?

[bakaracer]

Yes a lean condition can be the cause of low power. The plug read on 2 strokes with a new plug is that your looking for a smoke ring at the base of the porcelain. You won't get a smoke ring if your out riding around the block for 5min. It will disappear. If your out riding around than the color is going to be a cardboard color slightly rusty

[scottinscotty]

i think i'm running somewhat lean then... i'm gonna try the stock air box or see if i can upjet to maybe 110 or so.. what's the chances that over 110 jet is too much? i have the stock carb on also...

[Wheelman-111]

Greetings:

A couple more thing would be good to know: what spark plug? What pipe? What RPM are you hitting when you go WOT? OK that's three things.

Assuming your 100 is a bit small - I ran a 105 with the LeoVince pipe on a 65cc Contessa - you should consider another thing: a bigger Main might help, but plug reads will always Appear to be leaner than your actual conditions due to the too-small fixed Pilot in the stock carb.
You do your WOT run, and then close the throttle to stop. What happens? Your engine coasts down for 5-15 seconds running on the equivalent of a 15 Pilot jet. Head temps soar, cooking off what might be a chocolate-brown coating on your porcelain until it looks white by the time you stop and unscrew the plug to examine.

For that reason, a stock carb may be difficult to tune, and. CHT gauge would be a big help. With the stock carb or the wrong pilot, mine jumper to 450 or even 500 whenever I shut down the throttle.

[bakaracer]

the 100 will be to large with the airbox. if you have a 88 or 90, try that with the stock airbox

[Bear45-70]

Greetings:

A couple more thing would be good to know: what spark plug? What pipe? What RPM are you hitting when you go WOT? OK that's three things.

Assuming your 100 is a bit small - I ran a 105 with the LeoVince pipe on a 65cc Contessa - you should consider another thing: a bigger Main might help, but plug reads will always Appear to be leaner than your actual conditions due to the too-small fixed Pilot in the stock carb.
You do your WOT run, and then close the throttle to stop. What happens? Your engine coasts down for 5-15 seconds running on the equivalent of a 15 Pilot jet. Head temps soar, cooking off what might be a chocolate-brown coating on your porcelain until it looks white by the time you stop and unscrew the plug to examine.

For that reason, a stock carb may be difficult to tune, and. CHT gauge would be a big help. With the stock carb or the wrong pilot, mine jumper to 450 or even 500 whenever I shut down the throttle.

Don't close the throttle.

[bmccaffry]

I'm running a 110 jet with my stock carb and 50mm BBK. I had needle on bottom clip but that was to rich on takeoff. Now I run it on middle clip. I also run stock pipe and airbox.110 jet seems to be perfect.105 seemed a little lean.

[scottinscotty]

I'm Running a 72cc Contesta kit
Stock Exhaust and Carb
Drilled 100 jet
b9hs spark plug
1000 center spring
Uni air filter
8:44 gears
oko variator
I'm Looking to get alot more low end power out of my scoot, it seems like it's not pushing the rpm's, and or lack of
power, i thought about changing my variator weights but i don't know if that would help out all that much?

[bakaracer]

fix the jetting issue first. thats where your loosing alot of power. Just make sure you run the stock filter in the airbox witha 88 or 90 main jet. I ran a 50mm bore with stock carb and exhaust with a 88 main. punch out that extra tab out the inlet on the airbox too. what clutch shoe springs are you using?

[scottinscotty]

all stock, but the center spring is the blue 1000...

[scottinscotty]

seems like all my friends are running high with there jetting from what you are telling me... my buddy has a 66cc kit on his and he's running a 110 jet.. with stock carb, uni and a stock exhaust

[bakaracer]

seems like all my friends are running high with there jetting from what you are telling me... my buddy has a 66cc kit on his and he's running a 110 jet.. with stock carb, uni and a stock exhaust

anything other than a stock airbox you will need to run bigger jets. If your using the stock airbox with the stock aifilter in it, a 90 will be about the biggest your going to need. change that clutch shoe spring to at least a 1000 or 1500

[ZMUD]

seems like all my friends are running high with there jetting from what you are telling me... my buddy has a 66cc kit on his and he's running a 110 jet.. with stock carb, uni and a stock exhaust

And it fly's!!!

bigger jet or bigger carb!

[scottinscotty]

umm... well now i'm at 105 jet with a uni air filter and it seems to run perfect.. with a cardboard to sandy color plug

[bakaracer]

umm... well now i'm at 105 jet with a uni air filter and it seems to run perfect.. with a cardboard to sandy color plug

keep in mind that the stock carb uses a very small pilot jet(38) so when your blasting down the road at full throttle and you have to let off, you risk seizure from heat spike and not enough fuel and oil from to small a pilot jet.