What does too lean feel like?

[turbowrenchhead]

My bike reacts different to my friends new bike. Mine just seizes and then I need a piston. I have mine dialed in now after 3 pistons and lots of jetting. My friend just picked up a 01 blaster that's modded pretty good. Its has 170 psi compression. Running a 48 pilot and a 180 main and a 34mm keihin. I have 182 and 185 main ordered. We had to move the needle one slot lean because he was getting bog and dark brown on the plug at half throttle. I thought I had it dialed in real good. We had 75 degree weather when we had the chance to run them and changed the jetting. We took them to a friends field yesterday and mine ran real strong and feels great. His bike was experiencing a power loss at half to 3/4 throttle and the temp was 15 degrees lower. If the temp drops then your engine is leaner due to denser air. So does a lean condition feel like a loss in power? I ran out of new plugs to do chops so I didn't know what a plug chop would look like.

 

[sicivicdude]

A slight lean condition will feel very "surgy". Like the quad wants to take off and then stumble. I've heard it described as "zingy" like a small 125 cc dirtbike but unless you've rode a 125cc dirtbike, I'm not sure how to describe that.

If it's REALLY lean (which, with a 180 main @ 170 psi I would hope not) it will just bog when you get to a certain point.

 

[turbowrenchhead]

So both a too lean or too rich condition you will get a bog. To me it felt like a rich bog condition but I'm inexperienced so I cant be for sure. If it ran great in warmer weather with no bogging you would have to think its too lean then. It was fine at wide open. In fact I want to put the 182 in it to see where its going to bog at wide open to find the sweet spot. I don't want my friends piston melting down due to being to lean.

 

[sicivicdude]

Too rich is descrbied as a sputter (if extreme) like a fouled out spark plug or just a lackluster performance. No real hit coming onto the power band....

Rich bog is easy to identify with the spark plug too. Yank it out of there and see if it's black as night.

 

[Blaner]

have you considered the effects of humidity in your jetting? im not sure what your humidity is at with 75 degree weather but its worth considering....

Humid air is LESS dense than dry air.

Check http://www.blasterforum.com/engine-13/effects-elevation-air-pressure-how-jet-accordingly-39872/ for the full story, it may help you pick up afew things you dont yet know.

 

[Blaaster]

So both a too lean or too rich condition you will get a bog. To me it felt like a rich bog condition but I'm inexperienced so I cant be for sure. If it ran great in warmer weather with no bogging you would have to think its too lean then. It was fine at wide open. In fact I want to put the 182 in it to see where its going to bog at wide open to find the sweet spot. I don't want my friends piston melting down due to being to lean.

A motor will seem to run extremly well with a mild lean condition, but can cause damage.

A lean bog can be explained like BLAAAH
Too rich is like a babble, motor picks but never seems to get to speed.

If you are not able to do a plug chop, jet it on the rich side, then come back in main jets until it pull well.

But really it is a wise idea to do a plug chop to make sure it is just right.