| Author | Message | ||
     Chagertyxb |
I recently tore down the top end of my motor because my rear head gasket was starting to leak oil (bike has 30,000 on it), and decided to fix it, rather than wait for it to blow out completely. After getting the motor torn down, i noticed alot of carbon build up on top of the pistons, and a little pitting on them. I decided to replace them as well. Upon further inspection of the cylinder walls, i noticed some minor pitting in the rear cylinder. I have been told by some that I didn't need to replace them, and that it shouldn't affect it. I've also been told that I need to replace them. Any ideas or advice on replacing them would be GREATLY appreciated. Thanks in advance! | ||
| Chagertyxb |
Heres a picture of the cylinder wall.  | ||
| Chagertyxb |
I ran a piece of paper over the area, and it didn't snag the paper at all.... | ||
| Noone1569 |
It's just slight pitting, but I wonder if we would lose compression. Anyone have a good ideal what caused that? | ||
| Greg_e |
You should have the cylinder honed so that the new rings seat properly, might get rid of those small imperfections too. And replace your valve stem seals, that may be where the old that produces the carbon is coming from. (Message edited by Greg_E on August 13, 2011) | ||
| Iamarchangel |
Looks like a casting flaw. Can't see how it can affect compression. Might even aid lubrication. If it hasn't blown apart yet, it likely isn't going to. Hone it, do the paper test, and use your finger tip as well to check the firing area. Make sure there are no sharp edges to focus the heat. | ||
| Chagertyxb |
I did the paper test, and ran my fingertip over it. I felt no resistance w/the paper, and no sharp edges. Is it absolutely neccesary to hone the cylinder walls when putting in new pistons and rings?? | ||
| Etennuly |
You will have to at least use a "glaze breaker hone". If you put new rings in like it is you will likely burn oil and have less compression because they need to break in together. | ||
| Iamarchangel |
Few things are "absolutely necessary". Honing is darn close. Shouldn't be too expensive and doesn't have to be done at a HD shop either, if that is a concern. Most sub it out anyway. Look for a local race shop. They might want to see the piston and rings which isn't a bad idea. You've got some concerns that we're guessing at from pictures and comments. | ||
| Pammy |
Before you order pistons, take the cylinder to a qualified shop and have them measured for true. That pitting shouldn't be there. If you put it back together like that you aren't doing yourself a good service. | ||
| Chagertyxb |
Ok...cylinders measured and honed. When I put everything back together, is it ok to use synthetic oil for the break in period, or should I buy regular HD oil like the service manual says???? | ||
| Chagertyxb |
And the honing got rid of the imperfections in the cylinder | ||
| Kdogshirow |
I would not use synthetic oil to break in your new rings , use regular . Thats what the guys at Nallin Racing told me when I did a big bore kit a few years ago . Synth. is to slick . | ||
| Reepicheep |
I'd use non synthetic, but mainly because whatever I put in there I would run for about 300 miles, then drain and replace. Non synthetic is cheaper to throw away. | ||
| Pammy |
My vote is for non-synth as well. New rings? | ||
| Blake |
Use regular oil as you'll be changing it very shortly anyway. No problem using synth, but no advantage either with such a short change interval. >>> Synth. is too slic . That is an old myth, completely untrue. | ||
| Noone1569 |
Ok, so we got everything back together, cylinders honed, new rings and pistons installed, and rotated the engine back up. All torque specs were followed. Fired it up and are hearing this: http://www.youtube.com/watch?v=j1nGM89SJnU&feature =youtube_gdata_player A few people have told us this sound is normal for the pistons bedding themselves in and what not. What concerns us the most is the fact that it looks like gasket material spewing off of the primary side.. Any thoughts on this? (Message edited by noone1569 on August 22, 2011) | ||
| Reepicheep |
If the lifters were bled out, it sounds awful when it first comes back up. I don't think it actually lasts that long, but it feels like forever making such awful noises. | ||
| Spikey |
Sounds alot like a compression leak, or a really loose plug, did you check the heads for warpage? | ||
| Pammy |
Sounds like a gasket leak. Did you use new rings? (Message edited by pammy on August 23, 2011) | ||
| Chagertyxb |
All back together and running great. The noise turned out to be a leaking head gasket on the rear cylinder. I think when torqing the rear head bolts, one of them must have caught on the threads, or head and gave me a false reading. We got the head off and replaced the gasket, retorqued everything and it fired right up. Running strong as ever. I originally thought I needed to do 500 miles under 3k rpm, but was told by harley I only needed between 100-150 to let the rings seat properly. Any advice? Thanks for all the help everyone! It was greatly appreciated! Glad to have my bike back after almost 2 months of hard work. | ||
| Kalali |
"The noise turned out to be a leaking head gasket on the rear cylinder." Isn't that where you started!? Just kidding. Glad you got it all fixed up. Enjoy. |
