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2006 FXDX, 88", Andrews 21, Thrashin 2-1, TRU-Track Stabilizer, PCV Auto-Tune, Heavy Duty Clutch,
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Discussion Starter #1
Hello,

I am looking for some diagnostic assistance on the condition of my top end. I have pulled the cylinders and I am in the process of planning the winter build. I am not super familiar with assessing engine health via piston appearance so I am curious if there is anyone out there who can analyze my piston and top end and possibly teach me a few things about the condition of my engine. I enjoy learning from the wealth of knowledge that this site contains.

A little back story - Bike has 27,000 miles I installed Andrews 21 cams last year and noticed a high rate of oil consumption about 500 miles later. (almost a quart every 250 miles, the rear end is covered in black soot from exhaust). I had 2 occasions when the oil pressure light came on mid-ride, I had to pull over and grab a quart of oil at the gas station to get home. I have finally pulled the top end apart and noticed carbon build up on the top of pistons. I am also not sure if the wear on the piston skirts is normal. I plan on rebuilding and installing a big bore kit, with the oil pressure light coming on briefly, does any one think a bottom end rebuild is warranted? Also, any ideas as to what would cause carbon build up on top of piston and cylinder heads? I performed a leak down test but everything passed. The oil must be burning some how though, I believe it could be rings or valve seals, thoughts? Thank you in advance
 

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2006 FXDX, 88", Andrews 21, Thrashin 2-1, TRU-Track Stabilizer, PCV Auto-Tune, Heavy Duty Clutch,
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3 Posts
Discussion Starter #3
Bad valve seals.
I'm surprised it started, spark plugs must've been crusted with burnt oil and carbon buildup.
The fouling was pretty horrific towards the end, plenty of misfiring. For my own educational purposes, what makes you land on valve seals? I thought that I may have accidently side loaded a valve while re-installing rocker arms after cam replacement. But I spoke with an indy about having heads re built and then ported. The salesman laughed at me and told me that valve seals rarely go bad and he doubts that's what the failure was, I was pretty surprised to receive that response.
 

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My Jeep is having the similar problem , last year I had the engine rebuilt ,it burns oil and leaves a cloud of smoke , oil pumped up to the head has to drain back down to the oil pan, some of the oil in the head finds a easier way out , it goes out a valve seal , then it hits the piston and the piston compresses it on the up stroke and burns it in combustion , but some of the oil pushed up by the piston forced the oil past the spark plug threads , if it was bad rings , it wouldn't have the compression to force the oil up and out a spark plug.
 

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I had many apart that looked much worse than these pics show.
'06 FXDX 88" TC, 1st year for the 6spd gearbox. Lugging in 6th gear to much ? Pouring to much fuel into the cylinders at to low a RPM. Excess fuel is washing oil off of the cylinder walls. Andrews cam is adding extra fuel too.
Notice the piston tops and where the carbon buildup is, also notice the clean patch around the outside of the piston top.
Also notice the clean head squish band.
I'm assuming the pistons and heads haven't been cleaned prior to this thread pics.
 
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Registered
2006 FXDX, 88", Andrews 21, Thrashin 2-1, TRU-Track Stabilizer, PCV Auto-Tune, Heavy Duty Clutch,
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3 Posts
Discussion Starter #7
I had many apart that looked much worse than these pics show.
'06 FXDX 88" TC, 1st year for the 6spd gearbox. Lugging in 6th gear to much ? Pouring to much fuel into the cylinders at to low a RPM. Excess fuel is washing oil off of the cylinder walls. Andrews cam is adding extra fuel too.
Notice the piston tops and where the carbon buildup is, also notice the clean patch around the outside of the piston top.
Also notice the clean head squish band.
I'm assuming the pistons and heads haven't been cleaned prior to this thread pics.
you are correct, heads are how it was taken off the bike. I will admit that I like to lug the engine and ride in the lower RPM range when cruising. Taking this into account, is there anything I can add to the upcoming build to help combat this? Would a better cam for my type of riding be of more assistance? A different tune or AFR?
 

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I would just decarbon everything, install all new rings gaskets and seals, B-B hone the cylinders and reassemble.
If there's a tuner installed you can contact the tuner mfg for a mapp that more closely matches your setup. Check for the mfg website. Looks to be running to the rich side to me.
Also stay out of 6th gear until you're at about 60 - 65 mph.
 

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Hi i have a 883 xl that had a similar problem, and it had incorrect jets in the cardy and the incorrect spark plugs.
I check the manual for all correct setting and after I did this every thing started to get good with no black smock.
So if you check your manual for your bike and see if the is different to the manual.
Clean your piston with a wirer brush to remove the carbon.
Cheers, niemo

9159, member: 266325"
Hello,

I am looking for some diagnostic assistance on the condition of my top end. I have pulled the cylinders and I am in the process of planning the winter build. I am not super familiar with assessing engine health via piston appearance so I am curious if there is anyone out there who can analyze my piston and top end and possibly teach me a few things about the condition of my engine. I enjoy learning from the wealth of knowledge that this site contains.

A little back story - Bike has 27,000 miles I installed Andrews 21 cams last year and noticed a high rate of oil consumption about 500 miles later. (almost a quart every 250 miles, the rear end is covered in black soot from exhaust). I had 2 occasions when the oil pressure light came on mid-ride, I had to pull over and grab a quart of oil at the gas station to get home. I have finally pulled the top end apart and noticed carbon build up on the top of pistons. I am also not sure if the wear on the piston skirts is normal. I plan on rebuilding and installing a big bore kit, with the oil pressure light coming on briefly, does any one think a bottom end rebuild is warranted? Also, any ideas as to what would cause carbon build up on top of piston and cylinder heads? I performed a leak down test but everything passed. The oil must be burning some how though, I believe it could be rings or valve seals, thoughts? Thank you in advance
[/QUOTE]
 

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Definitely don't lug the engine, it's really bad for it even if you could prevent the buildup you're seeing. You also have no power to get away when lugging, reducing your reaction time to a hazardous situation by necessitating a down-shift before you can power out.

If your 6th gear is overdrive, as Schmidty said, stay out of it unless you're doing a minimum 60-65. I have an overdrive 6 speed trans on my bike, which has a relatively heavily worked 80" Evo (pulls peak 85 ft lbs at 3700), and I never go into 6th gear (.86:1 ratio) unless I'm doing 75+ mph on the interstate (which drops me from running around 2850 rpms to about 2500, not entirely sure, my tach is jumpy between 2200 and 2800 rpms).

Definitely when you get it cleaned up and fixed, look into having it properly tuned. You said you've been running an Andrews 21 cam, admittedly I don't know much at all about TC's, I don't know how that compares to the stock cam for the bike, but it's considered a bolt-on upgrade right? Regardless, with this cam swap, did you already have stage 1 upgrades (higher flowing air intake and pipes) in place? If not, would be a good idea to get the most out of the cam upgrade. Also, did you not re-tune the bike after the cam upgrade?
 
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