Piston/cylinder alternatives

[06roadglide]

Back in the fall I had an issue with oil coming out of head breathers on a long freeway run.
Upon tear down the rear cylinder is in pretty bad shape and no doubt it's what was causing the blow by.
It's a 4.135 bore 117. Already .010" over.
My options are to bore these to .020" or if needed .030". They are axtells that I got back in 2009 when there seems to be a lot of issues with them.
Or.... Buy new cylinders
My issue is. I want to install a set of 20 degree domed Pistons this time which would be easy if I stayed with axtells cylinders but since I've had 2 issues already with this set I'm not sure I want to try a third time.
If I still went with the 20 degree Pistons from axtell how should I go about getting cylinders?

S&S 117 cylinders are shorter than the axtells so the compression height wouldn't be right.

Are there other options out there for the Pistons that will match the cylinder height?
Trying to keep the cost as reasonable as possible so I really don't want to order custom Pistons.

Possible buy a set of S&S cylinders that are 5.013 tall and have them cut down? 

Then there's the issue of, will the spigot fit my existing case bore?  I don't want to go that far into tear down.

How about having MTC line a set of stock cylinders?  Is that cost affective to buying new?

[Don D]

 Been down this road many times. S&S has cylinders shorter for the 117. Or they will make them to a length I specify. If your pistons are not roached they can be reused by honeing the new cylinders.

[djl]

MTC will machine the cylinders to fit your case bore and set up the bore undersize so you can bore/hone to fit your existing pistons. If changing pistons, check the weight of the piston/pin/ring pack against your existing set.  If there is more than a 10% difference you could experience some undesirable crank harmonics later.

[06roadglide]

I think the my axtell cylinders are 4.917" + .020" for the base gasket. 

Cutting the height would be an easy option but what about the spigot dia. ?

[06roadglide]

MTC will machine the cylinders to fit your case bore and set up the bore undersize so you can bore/hone to fit your existing pistons. If changing pistons, check the weight of the piston/pin/ring pack against your existing set.  If there is more than a 10% difference you could experience some undesirable crank harmonics later.

The weight of the .020" OS axtell 20 degree domed pistons are 1144 grams. pistons, pins, rings and clips.
I'm not sure what weight my old pistons are.

[mtrhead269]

Thought stock pistons clips pins rings were 525 each

[djl]

I think the my axtell cylinders are 4.917" + .020" for the base gasket.  Cutting the height would be an easy option but what about the spigot dia. ?

Axtell case bore for the 4.125" cylinders I was running is 4.310"-4.315" X 1.625" then step bore from 1.625" deep and 4.160" diameter X .250" deep.  This information was provided to MTC for the machining of the sleeved cylinders.  As for the diameter, I ran some H-D 4.060" cylinders on those same cases with a smaller spigot diameter by .050"; .025" all the way round.  Used base gasket for the cases with no issues.  I ran MTC pistons in that setup but they were about 15% lighter than the JE pistons that came with the Axtell kit and I did experience a nasty harmonic between 2800-3000 rpms going up and down.  That's when I went to the MTC cylinders and was able to use the 4.135" JE pistons from the Axtell re-bore when the original cylinders went tits up.  The JE's were scuffed a bit but checked out dimensionally so I use them; no issues after 5K miles.

If the original pistons are JE, they will have a PN and you can get the weight from Axtell.  My 4.135" JE piston (flat top/PN 801-845B) assembly weighed 656g each.  I would be checking for sure.

[06roadglide]

I think the my axtell cylinders are 4.917" + .020" for the base gasket.  Cutting the height would be an easy option but what about the spigot dia. ?

Axtell case bore for the 4.125" cylinders I was running is 4.310"-4.315" X 1.625" then step bore from 1.625" deep and 4.160" diameter X .250" deep.  This information was provided to MTC for the machining of the sleeved cylinders.  As for the diameter, I ran some H-D 4.060" cylinders on those same cases with a smaller spigot diameter by .050"; .025" all the way round.  Used base gasket for the cases with no issues.  I ran MTC pistons in that setup but they were about 15% lighter than the JE pistons that came with the Axtell kit and I did experience a nasty harmonic between 2800-3000 rpms going up and down.  That's when I went to the MTC cylinders and was able to use the 4.135" JE pistons from the Axtell re-bore when the original cylinders went tits up.  The JE's were scuffed a bit but checked out dimensionally so I use them; no issues after 5K miles.

If the original pistons are JE, they will have a PN and you can get the weight from Axtell.  My 4.135" JE piston (flat top/PN 801-845B) assembly weighed 656g each.  I would be checking for sure.

Thanks for that info on dimensions.
Your 4.135 axtell Pistons are the same ones I've been running. That weight difference is huge compared to the 20 degree domed set.

[06roadglide]

Crap! Went back and reread message from axtell about the weight of the domed set. That was 1144 grams for BOTH Pistons.

[djl]

Still about 13% lighter than the original pistons which is enough to give me cause for concern.  There was about 16% difference in weight between the 4.060 pistons I tried; lighter than the JEs. The bike ran good but I couldn't live with the vibration.  Was your crank balanced to the original JE pistons? If not, you should be comparing the 20* piston weight to the OEM piston weight. Can't help with that but do know that the OEM pins are heavy but I am guessing they are in the 1100g range.

[06roadglide]

Its an S&S 4.375 flywheel.  So I really should ask what S&S balances them to or for.

[2006FXDCI]

https://www.delkron-mfg.com/products/products.asp?pg=CylindersTwinCam
I was talking to Dan Baisleys son the other day about the balance factor of the new S&S cranks using JE 20* pistons . He said that there should be options available to get the balance correct

[turboprop]

S&S will balance them to whatever piston weight and factor that the customer requests. They are not one size fits all.

[gordonr]

There is another option, you can play with the pin weights by removing material or even switching up one of the pins to titanium.

[Matt C]

There is another option, you can play with the pin weights by removing material or even switching up one of the pins to titanium.

That might be too light. There are probably lightened steel pins out there somewhere as well.

[06roadglide]

I spoke with Axtell today about my cylinders and I'm going to send them to them for inspection. 
The scratches I'm less concerned about and think they'll hone out fine to the next size. They were scratched from top to bottom all the way around. Almost like it was extremely dirty at some point.  For that reason alone I'm going to look at other air filters.  The front wasn't so bad but it did have a very odd spot in the liner. It looked as if material was flaking off the liner about 2" below the deck right between the left front stud and oil return passage. That one concerns me. 

To the guys that see a lot of engine builds...
When you suspect an air filter letting in dirt and scratching the cylinders up badly, do you see it worse in the rear cylinder?  Any merit to that?  The hottest oil temp I've ever seen was about 235.
What does an over heated cylinder look like? Scratches? or do they discolor in spots? Using the best tools I have to measure with, the middle of the cylinder is right at 4.1355" front to rear and the pistons are 4.132".  But my measuring tools aren't the best so that's up to the machinist to decide.  The pistons are definitely scuffed but nothing catastrophic. Keep in mind, this engine was still running great and made 136/136 just a few thousand miles ago. I only tore it down to freshen up my heads and look into my oil blowing out head vents this past fall.

[06roadglide]

There is another option, you can play with the pin weights by removing material or even switching up one of the pins to titanium.

That might be too light. There are probably lightened steel pins out there somewhere as well.

I'll look into what my original piston weight was when we first did this build back in 09 with the standard size pistons from axtell.  That'll be the weight I target with the new set.

[gordonr]

There is another option, you can play with the pin weights by removing material or even switching up one of the pins to titanium.

That might be too light. There are probably lightened steel pins out there somewhere as well.

You can lighten the existing ones or like I have done in the past is to only have one Ti the other steel.

[Billy]

Is the cylinder & piston scoring heavier on the thrust surfaces?

[06roadglide]

Pistons are scratched up on thrust sides, not gouging, just scratched. Rear cylinder, scratched all the way around bore, thrust sides aren't any different from the sides.
I'm really thinking the air filter just wasn't catching the dirt.

[Billy]

Pistons are scratched up on thrust sides, not gouging, just scratched. Rear cylinder, scratched all the way around bore, thrust sides aren't any different from the sides.
I'm really thinking the air filter just wasn't catching the dirt.

Just concerned about the con rod bearings, if bad, oil pressure will wash the swarf out and centrifugal force will sling it up into the cyls, scoring the cyls and pistons heavily on the thrust surfaces.

[06roadglide]

I'll investigate that Billy.
I know when I was feeling the rods for play they felt good. It didn't have any abnormal sounds prior to tear down.

[kd]

With respect to the "scratching" you report, have you previously performed a decarbonising by water or sea-foam etc. through the intake? There was a thread here where the OP claimed a similar type of cylinder / piston scoring and carbon traces in the oil.

[06roadglide]

With respect to the "scratching" you report, have you previously performed a decarbonising by water or sea-foam etc. through the intake? There was a thread here where the OP claimed a similar type of cylinder / piston scoring and carbon traces in the oil.

I didn't do any decarbonizing.
Prior to tear down I thought I was looking for a bad head breather and since it had 50K miles on it id just go ahead and send my heads off to get freshened up.  I didn't suspect that the cylinders would be that scratched up since it ran so good still.  I vent my heads to ground and the carbon build up on the piston is just a bit on the heavy side of normal.
I don't know if I mentioned it already.  The "scratches" I refer to are light enough that you can't feel them with a finger nail. 
Before I sent them off I deglazed the walls with a ball hone for about 5-10 seconds and 90% of those scratches came out just from that.

[Billy]

I know when I was feeling the rods for play they felt good. It didn't have any abnormal sounds prior to tear down.

This is good.
You may want to open the oil filter and inspect at a minimum, if suspect, send an oil sample out for analysis.

I'm really thinking the air filter just wasn't catching the dirt.

What air filter? Why do you think it wasn't doing it's job?