Post by richard on May 11, 2010 21:47:17 GMT -5
So today I decided to take a look at the cylinder that came off my XS1B to see if I could use them. The only way to know if the cylinders are usable is to hone them and check for wear afterward. I check for a ridge and scratches. If the flaws are small then I hone them until they are gone and check again. Then I place the pistons in the cylinders with out rings and check the clearance between them.
First let me say that before any of this was started I miced everything so I knew I wasn’t wasting my time. I have two sets of pistons. One old set that can from the bike and one new NOS set I wanted to use. I thought the new pistons might be too tight in the cylinders, if that were the case I would have to use the old pistons with new rings. Fortunately after honing the cylinders and measuring them one more time the new piston seemed to be the best fit.
In a perfect world the cylinder would have no ridge at the top but in this case there is some marking where the ridge was. My opinion is you should not be able to feel the ridge at all if you are going to re-ring a cylinder. If you can feel the ridge the piston with new rings could hit it and the rings could shatter. In this case after honing the cylinders I couldn’t feel or measure the ridge. I didn’t want to hone it out any more than I had to because it would create un-necessary slop between the piston and cylinder. Time will tell if I am right.
This part is hard to explain but I’ll make it short. The diameter of a cylinder can be different from top to bottom. You don’t want any more than the spec. calls for in this case I didn’t want more than a few thousands say.002-.003. There is a way to check that with a piston and used original ring, sliding the old ring up and down in the cylinder and measuring the ring gap. It’s not an exact science but it works after a fashion and has always worked for me. There is math involved or you can just eye ball it and decide if the run out is acceptable for yourself.
Once everything was honed and cleaned up I put both old and new pistons in the cylinder to see which fit the best. I decide to use the new pistons because they had the best fit in the cylinders
This is a short feeler gauge because I couldn’t hold the long one up and take a picture at the same time. I was worried the guage would rip the .002 if I let it go so I used the short one for the picture. Anyway you get the idea of how they can be use to measured the cylinder. Anyway With the old pistons I could slide a .004 thousands gauge between the piston and cylinder walls with the piston at top of the travel. It was kind of snug but to me it seemed like it would be better if there were less slop. Next I tried the new pistons and the .004 feeler gauge would just fit in the top of the piston but that was it. This is on both cylinders. The .003 thousands feeler gauge would fit on one cylinder and also on the other but in both cases it was very tight and at one point I thought it was stuck so in my mind I labeled them both at less than .003 thousands slop, which was close enough for me. I marked the pistons with a felt pen and the cylinders to keep track of which piston fit each cylinder best.
I just copied the felt markings on the top of the fin next to the cylinder.
Afterward I greased both cylinders and wrapped them up for storage until all the parts were together for reassembly.
Rust is a big deal on cleaned new parts especially valves and cylinder bores. I once have a head all for my Chevelle ready to go and I set it on the garage floor because I had to go to work. Within a week it was ruined because I was in a hurry and didn’t do anything to prevent it from rusting. I had to redo the entire head to remove the rust. So now I am paranoid about rust. I coat everything once it is cleaned up Grease or WD40 which ever seems best for the application.
[img src="http://i61.photobucket.com/albums/h70/rlgetrichman/CylindersGreesedSML.jpg![]()
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After I finished working on the cylinders I started looking at the valves and this is what I saw. These two pics are looking into the intakes. The exhaust ports look about the same. Black but nothing out of the ordinay.
This is number two
and this is number one.
Well that's it for now. I hope you enjoy this post.
First let me say that before any of this was started I miced everything so I knew I wasn’t wasting my time. I have two sets of pistons. One old set that can from the bike and one new NOS set I wanted to use. I thought the new pistons might be too tight in the cylinders, if that were the case I would have to use the old pistons with new rings. Fortunately after honing the cylinders and measuring them one more time the new piston seemed to be the best fit.
In a perfect world the cylinder would have no ridge at the top but in this case there is some marking where the ridge was. My opinion is you should not be able to feel the ridge at all if you are going to re-ring a cylinder. If you can feel the ridge the piston with new rings could hit it and the rings could shatter. In this case after honing the cylinders I couldn’t feel or measure the ridge. I didn’t want to hone it out any more than I had to because it would create un-necessary slop between the piston and cylinder. Time will tell if I am right.
This part is hard to explain but I’ll make it short. The diameter of a cylinder can be different from top to bottom. You don’t want any more than the spec. calls for in this case I didn’t want more than a few thousands say.002-.003. There is a way to check that with a piston and used original ring, sliding the old ring up and down in the cylinder and measuring the ring gap. It’s not an exact science but it works after a fashion and has always worked for me. There is math involved or you can just eye ball it and decide if the run out is acceptable for yourself.
Once everything was honed and cleaned up I put both old and new pistons in the cylinder to see which fit the best. I decide to use the new pistons because they had the best fit in the cylinders
This is a short feeler gauge because I couldn’t hold the long one up and take a picture at the same time. I was worried the guage would rip the .002 if I let it go so I used the short one for the picture. Anyway you get the idea of how they can be use to measured the cylinder. Anyway With the old pistons I could slide a .004 thousands gauge between the piston and cylinder walls with the piston at top of the travel. It was kind of snug but to me it seemed like it would be better if there were less slop. Next I tried the new pistons and the .004 feeler gauge would just fit in the top of the piston but that was it. This is on both cylinders. The .003 thousands feeler gauge would fit on one cylinder and also on the other but in both cases it was very tight and at one point I thought it was stuck so in my mind I labeled them both at less than .003 thousands slop, which was close enough for me. I marked the pistons with a felt pen and the cylinders to keep track of which piston fit each cylinder best.
I just copied the felt markings on the top of the fin next to the cylinder.
Afterward I greased both cylinders and wrapped them up for storage until all the parts were together for reassembly.
Rust is a big deal on cleaned new parts especially valves and cylinder bores. I once have a head all for my Chevelle ready to go and I set it on the garage floor because I had to go to work. Within a week it was ruined because I was in a hurry and didn’t do anything to prevent it from rusting. I had to redo the entire head to remove the rust. So now I am paranoid about rust. I coat everything once it is cleaned up Grease or WD40 which ever seems best for the application.
[img src="http://i61.photobucket.com/albums/h70/rlgetrichman/CylindersGreesedSML.jpg
After I finished working on the cylinders I started looking at the valves and this is what I saw. These two pics are looking into the intakes. The exhaust ports look about the same. Black but nothing out of the ordinay.
This is number two
and this is number one.
Well that's it for now. I hope you enjoy this post.
