- Joined
- Apr 27, 2010
- Messages
- 90
![Netherlands Country flag](https://www.accessnorton.com/images/flags/shiny/32/Netherlands.png)
Hi All.
I´ve taken my MK3 engine apart, the main reason is that it vibrates. There´s more vibrations in the handlebars then on my Triumph T140. I´ve had the bike for about 10 years and it has always bin like this. It had 2 Amal when I got it, then a single Mikuni and now a SU. It had Boyer ignition until early this year, when I fitted a Pazon. All new isolastic´s and a Norvil headsteady. Everything set at is should be and double checked, but it still vibrates. I´ve found 2 things that can cause this. The isolastic´s. When I check the front iso on the right, there´s more play on top then at the bottom. When checking the the rear at the left it´s the opposite. When we fitted the Norvil Headsteady, we had to modify it to make it fit, the whole thing was moved to the left. So the whole engine isn´t vertical in the engine. This can be one reason for the vibrations. The second reason is probably the conrods. There´s 2 different rods!!! The weight difference is 7gram. Is this enough to cause vibrations?
I have asked in another topic (interstate-freshening-t15810.html) about camshaft wear and Jim (comnoz) have recommenden me that I should use oil with ZDDP. I don´t doubt that Jim is right and I will be using better oil in the future. I must admit that I haven´t payed much attention to what kinde of oil I´ve bin using, as long as it was 20W50 or singlegrade from a well known brand. But is the kinde of oil really my only problem? I´ve changed the camshaft twice, in the 10 years I´ve had the bike! When the first was gone, we thought it was just a “Soft” cam from the factory as the story goes. A new standard cam was fitted. That one was replaced with a Magacycle 560-NR. Both fitted with new or resurfaced followers and cam lube. I´ve fitted an oilpressure gauge and yes I know what many people think of that on a Commando. When the engine is cold the pressure goes up to 80psi, but it drops to 20psi when it gets up to temperature and running at 3500-4000rpm. When running stationary it´s just above 0psi. All the commando owners that I have come across who have an oilpressure gauge have lower pressure when cold and higher pressure when hot. My dad´s 750 have 60psi when cold and about 40 when hot. Remember, this is in the northen part of Europe where the temperatures rearly gets much above28-30 degree C. I´ve fitted a new oilpump and had the old one checked, it didn´t make a difference and the old one turned out to be good. I´ve fitted new rockerarms spindles and they do turn the right way around. I´ve also fitted another cylinder head, that also didn´t make a difference. The new head had nothing to do with the oil pressure, but was cracked. When I got the engine apart, I found that the oilpressure release valve were stucked in closed position. This probably explains the high oil pressure when cold, but not the low pressure when hot. The crankshaft was reground and fitted with new bearings, it´s still fit for use. I´ve changed the oil sealing washer (06-6190) on the oilpump whenever I´ve had the primery cover of. I´ve checked the Plunger in the timingscover (06-6199) and it moves freely and seems okay.
Here´s a Photo of the two old cams, the upper one is the first, the lower is the second standard. It´s both the left inlet.
Here´s Photo of the right inlet.
Here´s Photo of the Megacycle cam.
Before I throw a lot of Money in to the engine once Again, I´d like to check everything. So any ideas are most welcome.
Thanks.
Dan Christoffersen
I´ve taken my MK3 engine apart, the main reason is that it vibrates. There´s more vibrations in the handlebars then on my Triumph T140. I´ve had the bike for about 10 years and it has always bin like this. It had 2 Amal when I got it, then a single Mikuni and now a SU. It had Boyer ignition until early this year, when I fitted a Pazon. All new isolastic´s and a Norvil headsteady. Everything set at is should be and double checked, but it still vibrates. I´ve found 2 things that can cause this. The isolastic´s. When I check the front iso on the right, there´s more play on top then at the bottom. When checking the the rear at the left it´s the opposite. When we fitted the Norvil Headsteady, we had to modify it to make it fit, the whole thing was moved to the left. So the whole engine isn´t vertical in the engine. This can be one reason for the vibrations. The second reason is probably the conrods. There´s 2 different rods!!! The weight difference is 7gram. Is this enough to cause vibrations?
I have asked in another topic (interstate-freshening-t15810.html) about camshaft wear and Jim (comnoz) have recommenden me that I should use oil with ZDDP. I don´t doubt that Jim is right and I will be using better oil in the future. I must admit that I haven´t payed much attention to what kinde of oil I´ve bin using, as long as it was 20W50 or singlegrade from a well known brand. But is the kinde of oil really my only problem? I´ve changed the camshaft twice, in the 10 years I´ve had the bike! When the first was gone, we thought it was just a “Soft” cam from the factory as the story goes. A new standard cam was fitted. That one was replaced with a Magacycle 560-NR. Both fitted with new or resurfaced followers and cam lube. I´ve fitted an oilpressure gauge and yes I know what many people think of that on a Commando. When the engine is cold the pressure goes up to 80psi, but it drops to 20psi when it gets up to temperature and running at 3500-4000rpm. When running stationary it´s just above 0psi. All the commando owners that I have come across who have an oilpressure gauge have lower pressure when cold and higher pressure when hot. My dad´s 750 have 60psi when cold and about 40 when hot. Remember, this is in the northen part of Europe where the temperatures rearly gets much above28-30 degree C. I´ve fitted a new oilpump and had the old one checked, it didn´t make a difference and the old one turned out to be good. I´ve fitted new rockerarms spindles and they do turn the right way around. I´ve also fitted another cylinder head, that also didn´t make a difference. The new head had nothing to do with the oil pressure, but was cracked. When I got the engine apart, I found that the oilpressure release valve were stucked in closed position. This probably explains the high oil pressure when cold, but not the low pressure when hot. The crankshaft was reground and fitted with new bearings, it´s still fit for use. I´ve changed the oil sealing washer (06-6190) on the oilpump whenever I´ve had the primery cover of. I´ve checked the Plunger in the timingscover (06-6199) and it moves freely and seems okay.
Here´s a Photo of the two old cams, the upper one is the first, the lower is the second standard. It´s both the left inlet.
Here´s Photo of the right inlet.
Here´s Photo of the Megacycle cam.
Before I throw a lot of Money in to the engine once Again, I´d like to check everything. So any ideas are most welcome.
Thanks.
Dan Christoffersen