| Author | Message | ||
     Sgthigg |
     Changed my plugs today. I thought it was weired the REAR plug was the Darker one. Any suggestions why this happens this way? | ||
| Btb |
my XB12s same this. why? please help | ||
| Bombardier |
This cylinder gets hotter and so will run richer. The front gets more cooling air and will require more fuel. | ||
| Id073897 |
... and gets more fuel. Enrichment differs between 102% @ 170 degC and 104% @ 240 degC (for a 2005 XB12X). Regards, Gunter | ||
| Bombardier |
Gunter, How does the o2 sensor manage the mixture for the front cylinder? It must just guess as to the difference as far as I can work out. | ||
| Id073897 |
The O2 sensor doesn't manage the front cylinder. That might be the main reason for just give it a little addon. Regards, Gunter | ||
| Blake |
Looks like the result of burning some oil to me. I'd check compression and leakdown of both cylinders. Be sure engine is good and hot when you do. | ||
| Bombardier |
So the hotter the climate and the hotter the rear cylinder gets the leaner the front cylinder will get? | ||
| Id073897 |
Why? | ||
| Bombardier |
There is a set percentage in the fuel map between the front and rear cylinder I am led to believe. As the rear cylinder gets warmer it will adjust the amount of fuel it needs to get to the best air/fuel ratio 14.7 to 1. If the rear cylinder gets more than 104% hotter than the front would this not mean that the front cylinder will start to run less than 14.7 to 1 to the lean side of the equation at the same rate as the rear cylinder heat increases? | ||
| Id073897 |
At 170 degC the front cylinder is enriched by 102% (based on the front fuel map entry) and enrichment increases up to 104% at 240 degC. The rear cylinder is either in closed loop, and the mixture gets adjusted, or in open loop and the mixture will not be adjusted. | ||
| Btb |
 No service shop in thailand Harley of Bangkok say NO! Harley OK Buell No service | ||
| Bombardier |
So once the rear cylinder gets more than 4% hotter the front cylinder gets leaner? | ||
| Id073897 |
Sorry, don't understand your question. Enrichment usually means the mixture getting richer. Regards, Gunter | ||
| Blake |
That plug turned black is likely not from rich fuel mixture; more likely it is from oil. | ||
| Bombardier |
The fuel map allows for a further 4% of enrichment to the front cylinder based on the temperature of the rear cylinder. If the rear cylinder goes outside that range of temperature you mentioned then the front cylider mixture should become leaner as the O2 sensor in the rear in conjunction with the cylinder head temp sensor will start to remove fuel to stop the rear cylinder from becoming too rich. | ||
| Bombardier |
By the way do you still have the crankcase breathers routed into the airbox? | ||
| Id073897 |
If the rear cylinder goes outside that range of temperature you mentioned then the front cylider mixture should become leaner as the O2 sensor in the rear in conjunction with the cylinder head temp sensor will start to remove fuel to stop the rear cylinder from becoming too rich. Sorry, I don't get the point. With temperatures above the mentioned 240 degC the enrichment stays constant. I don't see any relation between temperature and O2 sensor readings. The front cylinder get's an enrichment regarding to engine temperature. If or if not the rear cylinder is running rich or lean has nothing to do with that. If you want to check if the front cylinder runs lean, then cbeck it using a wideband sensor. Ifs and thens won't bring you any further. Regards, Gunter | ||
| Bombardier |
Why is there a temperature sensor in the rear cylinder head? Is it not the link for the fuel map to adjust the amount of enrichment to the front cylinder? | ||
| Id073897 |
The temperature sensor is monitored mainly to calculate warmup enrichments. Compared to those tiny front cylinder add-ons these are really huge. Regards, Gunter | ||
| Jkhawaii |
looks just like my plugs at 10,000. the oil that gets sucked in to the intake manifold must go all to the rear cly |
