fouled plug
Road Captain
Joined: Oct 2010
Posts: 566
Likes: 3
From: rural ontario
It's time to buy a manual and learn how to do the top end.
You will enjoy it....
could be rings, guides, head gasket, head is loose. there are different tests you could do with a compression tester or pressure test the chamber.
I'd be curious to see if you have different compression between the two cylinders. if it is a large difference then call it a day and start pulling it apart. If the difference is slight then you can start the re-build when you have time available.
If your compression is below 100psi it's time to think about starting, below 90psi - time to start...it will fall fast from this point
You will enjoy it....
could be rings, guides, head gasket, head is loose. there are different tests you could do with a compression tester or pressure test the chamber.
I'd be curious to see if you have different compression between the two cylinders. if it is a large difference then call it a day and start pulling it apart. If the difference is slight then you can start the re-build when you have time available.
If your compression is below 100psi it's time to think about starting, below 90psi - time to start...it will fall fast from this point
How much fouling? A black, gooey spot on one side would be normal and indicate some oil coming down thru the valve guide. Black and oily, black and fuel, and black and sooty are other "choices", which? Does it affect starting and/or performance? or is it more of a visual concern?
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6th Gear
Joined: Jan 2009
Posts: 13
Likes: 0
I do have a shop manual and have for the 23 years I have owned this bike. Just wanted the opinions of others(and I do appreciate them).Last time I road it I was hauling butt up a mountain pass when it acted up. Pulled plugs on the spot,rear was a beautiful tannish brown,front was damned near dripping oil.When i got it home I tore the top end down.Both bores visibly good.No noticeable scuffing on piston skirts.No broken rings.A little carbon on rear crown,a lot on front .Front combustion chamber was on the oily side.For a couple of weeks leading up to this I had to adjust carb more than usual to keep it running right.I am guessing valve guide,but don't know if it would happen that fast.Oh yea going up that pass front quit firing all together
Last edited by rlcgun; Jan 22, 2011 at 04:19 AM.
I am neither a mechanic nor an expert with many years of experience; just "knowledgeable" based on the extensive work i have done on my own IronHeads and what i have learned from these forums over the past seven years. But it seems to me that the only path for oil to the plug is thru the guide, especially given the good condition of the other components.
You could post this question over here where there are guys with more knowledge and experience ...
Ironhead Sportster Motorcycle Talk (1957-1985)
You could post this question over here where there are guys with more knowledge and experience ...
Ironhead Sportster Motorcycle Talk (1957-1985)
Road Captain
Joined: Oct 2010
Posts: 566
Likes: 3
From: rural ontario
Do a compression check on the motor to see if the cylinders are close in value.
Do a compression check on the problem cyinder....dry first then add a bit of oil and recheck. If the value increases with the oil you have a ring problem.
Ride with a friend and have them watch your exhaust. if you are smoking with acceleration then rings again; typically, if it's a guide the engine will puff smoke when you let off the throttle.
IMO: once it starts smoking and fouling plugs it is time to do the work. You might as well do both juggs because the gaskets, rings, springs, valves and guides have the same miles on them. Do the job once, do it well, and ride without worry for many more years.
Do a compression check on the problem cyinder....dry first then add a bit of oil and recheck. If the value increases with the oil you have a ring problem.
Ride with a friend and have them watch your exhaust. if you are smoking with acceleration then rings again; typically, if it's a guide the engine will puff smoke when you let off the throttle.
IMO: once it starts smoking and fouling plugs it is time to do the work. You might as well do both juggs because the gaskets, rings, springs, valves and guides have the same miles on them. Do the job once, do it well, and ride without worry for many more years.
Road Captain
Joined: Oct 2010
Posts: 566
Likes: 3
From: rural ontario
one other thing: the rings wear. You are not looking for broken rings. You want to measure the wear in the rings...the size of the 'gap' where the ends meet indicates the wear. The limits are in your manual...I don't have mine handy.
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Tourer
Joined: Sep 2007
Posts: 400
Likes: 1
From: se ohio
i tore mine down last fall, to do guides,valves some port work, while i had the heads off i went ahead and pulled the cylinders, found the front cylinder had a broken top rig, fell out in 3 pcs, didnt smoke a bit!
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