Yellow Bullet Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
88 Posts
Discussion Starter #1
ok on the dyno today started with 4 50 jets and 4 41 jets in a victor jr kit showed rich went down to 50n and 35f cleaned plug up some went down to 50n 29f lost 50 hp and showed way richer than even with the 41f jets so went to 50n 32f still showed way richer but gained 10 hp so went back to 50n 35f gained my other 40 hp cleaned plug back up but still shows a little rich af showed 13 with this jet with the 32 show 14 made the most power with the 41f jet but shows rich can someone enlighten me ??
 

·
First round fodder...
Joined
·
3,602 Posts
somethings wrong.....14 is on the lean side, you added fuel jet and it leaned the motor?
 

·
First round fodder...
Joined
·
3,602 Posts
mine runs on the lean side as well, he started with a black plug at 14, added fuel and the plug cleaned up.......:|
 

·
Registered
Joined
·
1,908 Posts
I'm sure that he leaned it so much that the cylinder lost temperature and that's why the plug got dirty. Most people never see the plug get dirty from being lean because most people have too much timing in and it hurts the motor first...lucky for him, sounds like he didn't.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #11
yes i stayed very very conservative on timing till i got the plug cleaned up and i just took it dead ass lean not enough heat to clean the plug so added fuel and it cleaned back up now can creep some timing in to it i just did not think about that i have 8 jets in the plate and that going from a 41 to a 35was a fuck ton of fuel out of it was a brain fart on the new plate but with being conservative on timing 4 .050 jets put out 310 to the tires so im happy with that will see what the timing will do fer her
 

·
Super Moderator
Joined
·
12,136 Posts
Looks like you saw something we talked to guys about all the time. Going to lean and taking away to much fuel takes power away as well.. As I have said many times before, it's a balancing act to proper N/F ratio's to get the best power return...

Also depending on fuel pressure and flow, yes going from a .041 to a .035 jet is a pretty big move.. Could easily be around 40-50 pounds and hour of fuel..

Another thing to think about as you got it to lean and saw the plugs get dark and ugly. When you start to detonate and engine and un settle the rings, you'll let oil start to get in the chambers as well and it will make the plugs look nasty.. Just a little food for thought.. Thanks, SJ
 

·
Registered
Joined
·
2,427 Posts
Another thing to think about as you got it to lean and saw the plugs get dark and ugly. When you start to detonate and engine and un settle the rings, you'll let oil start to get in the chambers as well and it will make the plugs look nasty.. Just a little food for thought.. Thanks, SJ

So what is your theory behind lean being reason behind oil getting into cylinder? Cuz me personally I would think phat would cause this not lean
 

·
Super Moderator
Joined
·
12,136 Posts
Another thing to think about as you got it to lean and saw the plugs get dark and ugly. When you start to detonate and engine and un settle the rings, you'll let oil start to get in the chambers as well and it will make the plugs look nasty.. Just a little food for thought.. Thanks, SJ

So what is your theory behind lean being reason behind oil getting into cylinder? Cuz me personally I would think phat would cause this not lean
Fat or lean both can be a cause. Bottom line is when you start to detonate an engine the rings will un settle.. SJ
 

·
Registered
Joined
·
32,419 Posts
496 15 to1 bb1 head hurricane intake 1050 prosystems dom 308ar cam plug readings and afr on dyno by the afr on dyno went to 14 afr and plug was black add more fuel jet brought it back to 12.5 13 and plug still had color but less color and cant get a good pic of plugs
If the AFR is “lean”, in the high-heat zone a few % richer than stoichiometric, near 14-14.5/1, the black on the plug can be the piston metal alloys’ vapors distilling out of the piston.

Ask any snowmobiler that has played with the 4+ HP per CI two-strokes. As you lean it and it picks up power, greed for more power encourages another jet leaner and the plug turns black. Run it for very long with the jet that made the plug black, or change one jet size leaner again and the metal vapor becomes chunks and some piston goes out the exhaust, then you wish you’d brought your snowshoes.:confused:
 

·
First round fodder...
Joined
·
3,602 Posts
the lean detonation steve is refering too can cause some ringpacks to deform or roll the edge causing a similar oil in chamber issue as a rich/ pinched ring condition without the fuel to somewhat help slow it down, usually results in a major failure though instead of just a loss of power....too little timing is something i didnt think of.......
 

·
I kill parts
Joined
·
10,216 Posts
Anything near "stoich" (14.7:1) while at WOT is too lean to be making good power. A wideband is far from the end-all tool, but @ WOT you should be seeing somewhere closer to 12.5:1.

Sounds like being too conservative on timing meant needing to go "too lean" to try to get the plugs cleaned up.
 

·
Registered
Joined
·
885 Posts
Steve, do you have a certain or about N/F ratio you start at for a dry nitrous, fogger setup?
My dry fogger likes a 7to 1 ratio maybe start a little fatter at first what jet you starting with and how many lbs per hr
 
1 - 20 of 21 Posts
Top