UK Monster Owners Club Forum - View Single Post - M600 poor idle and low speed

sram · 21-10-2017, 05:14 PM

Thanks for all of the suggestions and thoughts.

I've just come back in from the garage. About five hours in total today! I must be the world's slowest worker, although a good hour or two must have been spent lapping shims.
I believe I have a good overall 'feel' when it comes to mechanics and engineering (not claiming to be an expert in either, though!) and I know how important it is to lap these shimmy shims so that they remain square. As I was lapping I was taking multiple measurements around the shim to ensure that there were no high points.

I managed to get the closers that needed replacing to a nice and tight clearance, barely perceptible. I was sure to give the shims a spin and take repeated measurements to ensure there were no tight spots and that the cam turned over with no interference. One of them I just about managed to get a 0.03 blade in whereas the other one wouldn't even accept a 0.02, so I'm happy with that. The other two closers are not as close, but they are well within the 'checking' tolerance. All of the openers are now perfect, although they're the easy ones to do, so that's no surprise.

When I was trying to source collets and shims, I found an ebay seller that I sent a message off to. He didn't have the sizes I needed but we had a few messages back and forth and I mentioned to him that it was such a pain to hold down the arm, push down the closing shim and then remove the collets. He suggested pushing down the arm and then inserting a large screwdriver or similar from the opposite side. I tried this and found that putting an 8mm Allen key in held the arm down and allowed me to work on removing the collets and shim with both hands. I've never seen this mentioned in any of the guides but it has transformed the entire experience so it is well worth mentioning and I recommend trying this the next time you happen to be removing closer shims.
He also reminded me to use foam ear plugs to block the oil return holes so that collets didn't find their way down them, which would be disastrous. I owe this guy a beer for sure!

The light started to fade and I was really starting to suffer from the cold wind, so I called it a day after getting all of the valve covers back on. I'll pop the belts back on tomorrow, finish the reassembly and then hopefully go for a ride to see if it's helped with the low speed running and idle. I've got to nip over to my dad's to use the grinder and bench, as I bought new tensioner bolts to replace the current ones due to the Allen sockets being fairly rounded. I couldn't find the exact same length in the low profile head and so I went a few mm longer. Let's just hope the rain holds off tomorrow so I can sort these bolts and then get the whole damned thing back together again.

I'll be sending all of the larger closer shims back to EMS in order to benefit from their shim exchange service. I'll never need these larger sizes, but the next time I do this (or let someone else do it!) it will be very beneficial to have a few shims in the 5.9-6.2 size (the one 6.2 that I had was lapped down to 5.85, boy did that take some time).

Thanks again, will hopefully update with good news tomorrow :-)

21-10-2017, 05:14 PM	#17
sram Registered User Join Date: Aug 2015 Location: London Bike: M600 Posts: 72	Thanks for all of the suggestions and thoughts. I've just come back in from the garage. About five hours in total today! I must be the world's slowest worker, although a good hour or two must have been spent lapping shims. I believe I have a good overall 'feel' when it comes to mechanics and engineering (not claiming to be an expert in either, though!) and I know how important it is to lap these shimmy shims so that they remain square. As I was lapping I was taking multiple measurements around the shim to ensure that there were no high points. I managed to get the closers that needed replacing to a nice and tight clearance, barely perceptible. I was sure to give the shims a spin and take repeated measurements to ensure there were no tight spots and that the cam turned over with no interference. One of them I just about managed to get a 0.03 blade in whereas the other one wouldn't even accept a 0.02, so I'm happy with that. The other two closers are not as close, but they are well within the 'checking' tolerance. All of the openers are now perfect, although they're the easy ones to do, so that's no surprise. When I was trying to source collets and shims, I found an ebay seller that I sent a message off to. He didn't have the sizes I needed but we had a few messages back and forth and I mentioned to him that it was such a pain to hold down the arm, push down the closing shim and then remove the collets. He suggested pushing down the arm and then inserting a large screwdriver or similar from the opposite side. I tried this and found that putting an 8mm Allen key in held the arm down and allowed me to work on removing the collets and shim with both hands. I've never seen this mentioned in any of the guides but it has transformed the entire experience so it is well worth mentioning and I recommend trying this the next time you happen to be removing closer shims. He also reminded me to use foam ear plugs to block the oil return holes so that collets didn't find their way down them, which would be disastrous. I owe this guy a beer for sure! The light started to fade and I was really starting to suffer from the cold wind, so I called it a day after getting all of the valve covers back on. I'll pop the belts back on tomorrow, finish the reassembly and then hopefully go for a ride to see if it's helped with the low speed running and idle. I've got to nip over to my dad's to use the grinder and bench, as I bought new tensioner bolts to replace the current ones due to the Allen sockets being fairly rounded. I couldn't find the exact same length in the low profile head and so I went a few mm longer. Let's just hope the rain holds off tomorrow so I can sort these bolts and then get the whole damned thing back together again. I'll be sending all of the larger closer shims back to EMS in order to benefit from their shim exchange service. I'll never need these larger sizes, but the next time I do this (or let someone else do it!) it will be very beneficial to have a few shims in the 5.9-6.2 size (the one 6.2 that I had was lapped down to 5.85, boy did that take some time). Thanks again, will hopefully update with good news tomorrow :-)