taniknight
XS650 New Member
Hi everyone,
My name is Tani and I'm rather new to bike land. I have myself a '78 XS650 that was cafe'd out 2 owners ago and after MUCH time and messing around I have gotten to a point where she is running pretty strong but I'm having richness and carbon build up problems. While with me 3 different workshops have had their hands on it and god knows how many prior to that. Hence I decided to take matters into my own hands despite being time poor (who isn't). Since then I've made a lot of progress. More details on the bike:
Ignition: Pamco with E-advance, 5k caps, 82kV coil (I believe), BP7ES plugs, gaped 0.035, timing checked. Tested resistance of coil and measured good. Spark strong.
Charge: PMA by XSCharge (I think), small battery, kickstart only.
Carbs: BS38, 30 pilots, Z-2 needle jet, SO2 needle at slot 3, 125 main (yes, smaller than standard but I'm suspect about the possibility that a previous owner drilled the jets.... I've ordered replacements). They have been recently reconditioned by a professional and I've had them apart to clean them after tank gunk got back in them. I've since de-rusted and Red-Koted the tank and added inline paper filters. New "XS" brand oval pods filters fitted to replace ill fitting K&N pods. Tuned the mixture screws using dead cylinder method and then sync'd using a manometer.
Engine: Compression ~148psi each side, cam chain tension set (a ~1mm bounce of the pin), valve clearances 5 thou exhausts 3.5 intakes, fresh oil. Other than that I haven't been inside.
Exhaust: Aftermarket pipes with Comando style mufflers.
Ive attached photos of the spark plugs after a half hour ride at 70-100km/h along with a look at the combustion chamber.
The evidence of richness will hopefully be due to someone previously drilling out the jets and will be cured with new ones. I was expecting to find big jets when I opened the carbs as the exhaust and pods generally call for. Smaller than stock main makes me suspect something's up with them.
Now for the questions:
- As for the messy pistons, do I need to pull the head off and clean?
- What might have caused this given that the compression is good?
- Could the carbon build up be causing the plugs to foul rather than rich mixture?
- I have found that an oil leak from the head/jug joint is likely due to a poorly torqued head (I'll be re-torquing tomorrow); could this cause an oil leak into the cylinders but hold up to a compression test?
- Would an oil leak into the cylinders even cause them to look like they do?
- Where do I go from here?
Many, many thanks for your time.
Tani.
My name is Tani and I'm rather new to bike land. I have myself a '78 XS650 that was cafe'd out 2 owners ago and after MUCH time and messing around I have gotten to a point where she is running pretty strong but I'm having richness and carbon build up problems. While with me 3 different workshops have had their hands on it and god knows how many prior to that. Hence I decided to take matters into my own hands despite being time poor (who isn't). Since then I've made a lot of progress. More details on the bike:
Ignition: Pamco with E-advance, 5k caps, 82kV coil (I believe), BP7ES plugs, gaped 0.035, timing checked. Tested resistance of coil and measured good. Spark strong.
Charge: PMA by XSCharge (I think), small battery, kickstart only.
Carbs: BS38, 30 pilots, Z-2 needle jet, SO2 needle at slot 3, 125 main (yes, smaller than standard but I'm suspect about the possibility that a previous owner drilled the jets.... I've ordered replacements). They have been recently reconditioned by a professional and I've had them apart to clean them after tank gunk got back in them. I've since de-rusted and Red-Koted the tank and added inline paper filters. New "XS" brand oval pods filters fitted to replace ill fitting K&N pods. Tuned the mixture screws using dead cylinder method and then sync'd using a manometer.
Engine: Compression ~148psi each side, cam chain tension set (a ~1mm bounce of the pin), valve clearances 5 thou exhausts 3.5 intakes, fresh oil. Other than that I haven't been inside.
Exhaust: Aftermarket pipes with Comando style mufflers.
Ive attached photos of the spark plugs after a half hour ride at 70-100km/h along with a look at the combustion chamber.
The evidence of richness will hopefully be due to someone previously drilling out the jets and will be cured with new ones. I was expecting to find big jets when I opened the carbs as the exhaust and pods generally call for. Smaller than stock main makes me suspect something's up with them.
Now for the questions:
- As for the messy pistons, do I need to pull the head off and clean?
- What might have caused this given that the compression is good?
- Could the carbon build up be causing the plugs to foul rather than rich mixture?
- I have found that an oil leak from the head/jug joint is likely due to a poorly torqued head (I'll be re-torquing tomorrow); could this cause an oil leak into the cylinders but hold up to a compression test?
- Would an oil leak into the cylinders even cause them to look like they do?
- Where do I go from here?
Many, many thanks for your time.
Tani.