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XS Cams In a XJ
Putting a set of 78-79 cams in an 82 XJ will net a 2.5-3 hp gain just like they do in the 80-81 models. Be very careful when buying used cams and pay particular attention to the bearing journals making sure they are correct in size and are not scoured/scratched. You also need to measure the cam lobes for wear because in high milage motors the lobes will show signs of wear and the amount of wear will depend on how hot the motor got and what type of oil was used and how often it was changed.
The ignition timing in a stock XJ is 5 degrees @ 1100 rpm and 36 degrees @ 5500 rpm. Ideally it should be 10 degrees @ 1000-1500 rpm and be fully advanced @ 4500 rpm with 40-42 degrees and you don't want any more than 40-42 degrees @ WOT because too much timing will hurt the top end.
When you plug the YICS on the XJ you will need to change the main jet, pilot air jet and the pilot jet in the carburetors because with the YICS deactivated the carbs will be too rich. The stock jetting for an XJ is,
main jet #112.5
main air jet #140
pilot jet #47.5
pilot air jet #170.
These are Mikuni numbers and do not correspond with DJ numbers.
Blaine Hoops had a post on carburetors that everyone with an XS should read, it's very informative and there is very little I can add to it other than my own experience with the DJ stuff.
Before leaving this subject mention should be made that the air box on the XJ is more restrictive than the others and no K&N replacement filter is available for it but other members have made one that work.
Putting a set of 78-79 cams in an 82 XJ will net a 2.5-3 hp gain just like they do in the 80-81 models. Be very careful when buying used cams and pay particular attention to the bearing journals making sure they are correct in size and are not scoured/scratched. You also need to measure the cam lobes for wear because in high milage motors the lobes will show signs of wear and the amount of wear will depend on how hot the motor got and what type of oil was used and how often it was changed.
The ignition timing in a stock XJ is 5 degrees @ 1100 rpm and 36 degrees @ 5500 rpm. Ideally it should be 10 degrees @ 1000-1500 rpm and be fully advanced @ 4500 rpm with 40-42 degrees and you don't want any more than 40-42 degrees @ WOT because too much timing will hurt the top end.
When you plug the YICS on the XJ you will need to change the main jet, pilot air jet and the pilot jet in the carburetors because with the YICS deactivated the carbs will be too rich. The stock jetting for an XJ is,
main jet #112.5
main air jet #140
pilot jet #47.5
pilot air jet #170.
These are Mikuni numbers and do not correspond with DJ numbers.
Blaine Hoops had a post on carburetors that everyone with an XS should read, it's very informative and there is very little I can add to it other than my own experience with the DJ stuff.
Before leaving this subject mention should be made that the air box on the XJ is more restrictive than the others and no K&N replacement filter is available for it but other members have made one that work.
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