I hesitated to post this because I have to publicly admit that I screwed up again. :-[ But there are important lessons learned that I feel compelled to pass on in the hope that others may avoid some of the pitfalls if they ever have the misfortune to have to go deep into the motor. I may be the only one, or at least one of the very few, that have had to pull and rebuild the motor twice. :'(
It all started one year ago with a valve adjustment gone bad as documented in my “Valve adjustment Nightmare” thread. The short version is that I managed to inadvertently get the cam chain installed off to the side of the guide which resulted in the CCT running directly on the chain. It ran great. . . . for about 50 miles. Then the cam chain jumped off and then the whole piston-valve love thing happened necessitating two new valves and a complete tare down, clean out chips, and rebuild. ???
All seemed good after the rebuild. The bike ran well, made no strange noise, but did use more oil than before. So I took it on a long trip starting in mid-July. Orlando – Portland OR – Orlando. About 7500 miles. I had 8000 miles on the re-build at that point and I assumed the high oil consumption was something I could live with by just adding about ½ a Qt a day. (600 mile days) However it got worse as the miles piled up and by the time I got back to Orlando it was using a Qt every 200 miles! I had to add at every gas stop and in the end had to stop even more often to add oil than for gas. The bike still ran OK and was even getting normal MPG. But it was clear the motor had to come out again for rebuild # 2.
Once I got the head off, the problem was immediately clear. There was a deep scratch in the right cylinder wall. You can see that here:
And once the piston was out the cause of the scratch was clear. The lower oil ring was missing about an inch of its normal circumference. You can see that here and also a broken part of the spacer:
Clearly I had managed to break off part of the ring during the last install. More on that later.
First lesson to pass on. Parts:
In the on-line parts finch, (any of them) the piston and rings are shown as Item 10 and Item 11. Each has a part number. I noticed that the part number had been superseded but failed to notice that both of the new numbers are the same! Apparently that new number gets you both the piston and the ring set. So if you order a ring set, you will get both a piston and a ring set. Same if you order a piston. I ordered two pistons and two ring sets and got 4 sets of piston and rings. So I will have to send some back. Also note that I used cheapcycleparts.com. They have been very good and their prices are the lowest I have found. The cylinder was $487 but was around $100 more at Bike bandit for example.
Second Lesson learned. It is a bear to get the pistons in to the cylinder without catching and/or breaking on of the oil rings! I have built a fair number of MC motors and never needed to use a ring compressor. I just feed the piston into the cylinder while compressing the rings with my fingers. That is exactly what the manual tells us to do and they even have a picture of a hand squeezing the rings. But the oil rings are very thin and fragile and because they are so thin, it is hard to notice if one jumps out of the groove and folds over. That is apparently what happened the first time. This time around I was looking for the problem and taking great care. I ended up doing it over and over because those darn little oil rings would jump out and I would have to start over again. Once you get one piston in the second piston is even harder because you have to avoid dislodging the first one. And the whole time you have to keep the cam chain and guide in side chamber. I managed to fold over another one but of course this time I was watching for it and had an extra set.
It is not always this easy to see but here is what it looks like when the ring snags bad;
And if you fail to notice and push the piston in, this is what happens to the ring:
All of us that have had the fun of compressing the CCT in order to install it know how much fun that is! I saw the nice video of someone using a socket and ratchet and it looked so easy. But it didn't work for me at all. Here is how I did it:
The rubber (inter tube) keeps the plunger from rotating and the plastic on the body side with a bit of oil allows me to rotate it as I close the vice. Works great!
The last item to pass on is that getting the motor back in the frame is an adventure in itself. There just isn’t enough space between the front wheel and the drive shaft to fit the motor in with it anywhere near horizontal. You have to get it under the frame flat and then as you lift, tilt the back end of the motor way up and then kind of inch it in. Not much fun by yourself. But I got it in after several hours of jacks, ropes, levers, and a lot of cuss words.
The good news is that I got it all back together Sunday afternoon and it seems to run like a new motor. (A lot of it is new!) I only have about 70 miles on it now (I am on work travel now – by airplane ) but there is no unusual noise, idiot lights, or other issues so I am hopeful it is all good this time. ::001::
John
It all started one year ago with a valve adjustment gone bad as documented in my “Valve adjustment Nightmare” thread. The short version is that I managed to inadvertently get the cam chain installed off to the side of the guide which resulted in the CCT running directly on the chain. It ran great. . . . for about 50 miles. Then the cam chain jumped off and then the whole piston-valve love thing happened necessitating two new valves and a complete tare down, clean out chips, and rebuild. ???
All seemed good after the rebuild. The bike ran well, made no strange noise, but did use more oil than before. So I took it on a long trip starting in mid-July. Orlando – Portland OR – Orlando. About 7500 miles. I had 8000 miles on the re-build at that point and I assumed the high oil consumption was something I could live with by just adding about ½ a Qt a day. (600 mile days) However it got worse as the miles piled up and by the time I got back to Orlando it was using a Qt every 200 miles! I had to add at every gas stop and in the end had to stop even more often to add oil than for gas. The bike still ran OK and was even getting normal MPG. But it was clear the motor had to come out again for rebuild # 2.
Once I got the head off, the problem was immediately clear. There was a deep scratch in the right cylinder wall. You can see that here:
And once the piston was out the cause of the scratch was clear. The lower oil ring was missing about an inch of its normal circumference. You can see that here and also a broken part of the spacer:
Clearly I had managed to break off part of the ring during the last install. More on that later.
First lesson to pass on. Parts:
In the on-line parts finch, (any of them) the piston and rings are shown as Item 10 and Item 11. Each has a part number. I noticed that the part number had been superseded but failed to notice that both of the new numbers are the same! Apparently that new number gets you both the piston and the ring set. So if you order a ring set, you will get both a piston and a ring set. Same if you order a piston. I ordered two pistons and two ring sets and got 4 sets of piston and rings. So I will have to send some back. Also note that I used cheapcycleparts.com. They have been very good and their prices are the lowest I have found. The cylinder was $487 but was around $100 more at Bike bandit for example.
Second Lesson learned. It is a bear to get the pistons in to the cylinder without catching and/or breaking on of the oil rings! I have built a fair number of MC motors and never needed to use a ring compressor. I just feed the piston into the cylinder while compressing the rings with my fingers. That is exactly what the manual tells us to do and they even have a picture of a hand squeezing the rings. But the oil rings are very thin and fragile and because they are so thin, it is hard to notice if one jumps out of the groove and folds over. That is apparently what happened the first time. This time around I was looking for the problem and taking great care. I ended up doing it over and over because those darn little oil rings would jump out and I would have to start over again. Once you get one piston in the second piston is even harder because you have to avoid dislodging the first one. And the whole time you have to keep the cam chain and guide in side chamber. I managed to fold over another one but of course this time I was watching for it and had an extra set.
It is not always this easy to see but here is what it looks like when the ring snags bad;
And if you fail to notice and push the piston in, this is what happens to the ring:
All of us that have had the fun of compressing the CCT in order to install it know how much fun that is! I saw the nice video of someone using a socket and ratchet and it looked so easy. But it didn't work for me at all. Here is how I did it:
The rubber (inter tube) keeps the plunger from rotating and the plastic on the body side with a bit of oil allows me to rotate it as I close the vice. Works great!
The last item to pass on is that getting the motor back in the frame is an adventure in itself. There just isn’t enough space between the front wheel and the drive shaft to fit the motor in with it anywhere near horizontal. You have to get it under the frame flat and then as you lift, tilt the back end of the motor way up and then kind of inch it in. Not much fun by yourself. But I got it in after several hours of jacks, ropes, levers, and a lot of cuss words.
The good news is that I got it all back together Sunday afternoon and it seems to run like a new motor. (A lot of it is new!) I only have about 70 miles on it now (I am on work travel now – by airplane
) but there is no unusual noise, idiot lights, or other issues so I am hopeful it is all good this time. ::001::John
