Ducati Monster Motorcycle Forum banner

61 - 72 of 72 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #64
I managed to get the pulleys swapped, but I'm still trying to figure out a way to get the nut torqued down all the way. I was able to jam the pulley with an old belt and get it up to 40 nm so I've still got another 30 nm to go. I might need to grab one of those tools to hold the crank and get a buddy to help.

I tested compression with the new head and got 115-120 psi which is heaps better than before but not as good as the horizontal cylinder which gets 135 psi. Will the vertical cylinder psi go up after the engine runs a bit? If it doesn't, is this a reasonable difference in psi to run or should I look into lapping the valves?
 

·
Registered
Joined
·
320 Posts
A quick check and lapping of the valves is always a good thing whenever you've got it apart anyway. Perhaps the head as well just to see where it stands. Lap the valves and run it and it should bump up a little bit. Keep in mind that you ended up with a "C" oversize. The biggest they go. So your compression will always be lower than standard size bore. Even if everything is perfect.

Yeah, torquing that thing is a pain without something to firmly hold the pulley. Plus I forget what the spec is, but it seems crazy high. At least you don't have to worry about checking the cam timing afterwards like you would with the other style.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #66
I got the pulley torqued and the engine back in the frame with the help of a few people. Is the rear motor mount that runs through the frame supposed to have a nut on the end? It threads into the frame but is that all it needs? Also, I put the front sprocket back on and it has play along the shaft. I know it's normal for it to have some play front and back, but I don't know if the other kind of play is normal. Other than that, I have to get the carbs cleaned and sort out where all the emission and fuel lines go since some were cut/missing and then I can finally start it and hope it sounds fine.
 

·
Registered
Joined
·
320 Posts
I think you've got it right with the motor mount bolts. If your countershaft is cut for the sprocket to run with the flat side out, those tend to have alignment problems. Usually just chews up the retainer clip faster than normal. Once you get it up and running it would be worth looking into. Hopefully just a new sprocket and retainer. Then see if you need to do a little shimming.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #68
I got the bike to run today and it sounds great. I revved it a bit and didn't hear any knocking or other unusual sounds. It only runs on around half choke, but I was planning on rebuilding and cleaning the carbs with an ultrasonic cleaner after hearing it run anyways. I have oil pressure and no leaks, but the thing shoots out white smoke from one side of the exhaust. Both cylinders run to both sides of the exhaust so I'm not sure why only one is smoking. I'd imagine it is just burning stuff off so I'm going to try and run it some more tomorrow and see if it stops.

Here's a video of it running. You can see it smoking at the end after I kill it by turning the choke off.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #70
So I ran a compression test on the vertical cylinder and it was 100 psi. Spec is a minimum of 115 psi. When I tested it on the bench I got 120 which made me think everything was good, but I suspect that the oil in the cylinder from assembly boosted the compression. I believe my rings may be bad despite supposedly being from a running bike. I guess technically my bike is a running bike too. I used the two top rings from the used piston and the oil ring from my piston because the oil ring from the used piston was broken. I tested the gap on the rings I used and it was fine. Maybe this is why it was smoking when running too. Engine has to come out again, but can it be done without draining the oil? I'd imagine it can be as long as I work around the oil filter.
 

·
Registered
Joined
·
320 Posts
Well the smoking problem could definitely be related to the fact that you put the std. size oil ring on the oversized piston. The drop in compression wouldn't necessarily be caused by that though. Before diving into a complete redo I would try a little troubleshooting first. Changing out the oil ring at the very least would be wise anyway, however it would be good to get to the root of the problem first. So you don't find yourself in the same place after all that work. Did you add a touch of oil to the cylinder and try it again? And did you prop the carbs wide open with the fuel disconnected for the test?
 

·
Registered
Joined
·
26 Posts
Discussion Starter #72
Are the rings different for the A, B, and C pistons? I only see one part number for a piston ring set. I didn't prop the carbs wide open during the compression test, I forgot about that. Hopefully, that's the problem. I need to charge the battery before I can try again.
 
61 - 72 of 72 Posts
Top