hein weijers
XS650 Special (5E6) 1982
Hi Grizld1, Do you know what the inspection lash is for the 447 camshaft?
Regards, Hein
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cam lined up?
- Thread starter baldyforks
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Hi Grizld1, Do you know what the inspection lash is for the 447 camshaft?
Regards, Hein
Inspection lash is .012" for 447 cams as well; it's in the Appendix to the factory manual below the valve timing specs, but left unlabeled, just to make life interesting. IO=36* BTDC, IC=68*ABDC, EO=68*BBDC, EC=36*ATDC.
Might as well give an example of lobe center calculation here. The formula is this: (Opening in degrees + Closing in degrees + 180) / 2 - smaller valve event in degrees. For the 447 cam, the opening and closing numbers are symmetrical, so one calculation does it for both intake and exhaust lobes: (36+68+180)/2-36=106*. If you have a bit of a misgrind you tweak the valve events to put the lobe centers as close as possible to spec. or, if you're tuning for special purposes, to either side of it. The lobe centers are the reference points for determining whether valve timing is advanced or retarded.
Might as well give an example of lobe center calculation here. The formula is this: (Opening in degrees + Closing in degrees + 180) / 2 - smaller valve event in degrees. For the 447 cam, the opening and closing numbers are symmetrical, so one calculation does it for both intake and exhaust lobes: (36+68+180)/2-36=106*. If you have a bit of a misgrind you tweak the valve events to put the lobe centers as close as possible to spec. or, if you're tuning for special purposes, to either side of it. The lobe centers are the reference points for determining whether valve timing is advanced or retarded.
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hein weijers
XS650 Special (5E6) 1982
Hi Grizld1,
I measured the cam timing on my rephased 447 cam and found out that the LH (unchanged) exhaust cams have the lobe center on 101.5* and the RH (rephased) exhaust cams on 98*
I measured and remeasured a lot of times and at different openings of the valves. Depending on what the correct lobe centers for a 5V4 are, 105 or 106, the LH cams are 3.5 or 4.5* retarded and the right cams 7 or 8* retarded. For the LH cams it can be due to a worn chain, but the difference between RH and LH is clearly wrong! The (normally very capable) guy who did the rephasing admits his mistake and makes a new camshaft for me. But he also assures me that I will not feel the difference! What do you expect?
Kind regards, Hein
I measured the cam timing on my rephased 447 cam and found out that the LH (unchanged) exhaust cams have the lobe center on 101.5* and the RH (rephased) exhaust cams on 98*
I measured and remeasured a lot of times and at different openings of the valves. Depending on what the correct lobe centers for a 5V4 are, 105 or 106, the LH cams are 3.5 or 4.5* retarded and the right cams 7 or 8* retarded. For the LH cams it can be due to a worn chain, but the difference between RH and LH is clearly wrong! The (normally very capable) guy who did the rephasing admits his mistake and makes a new camshaft for me. But he also assures me that I will not feel the difference! What do you expect?Kind regards, Hein
Hein, when you time the camshaft, use the formula to find what opening/closing events will put the LC's where they need to be, and move the sprocket accordingly. Don't expect perfection; distribute grind error to get as close to spec as you can. It's normal to have to do that; play with the formula a bit. Right, the problem with your camshaft is the 3.5* error between cylinders. That's more than I'd want to see if I'd gone to the expense of a rephase, but expect some error in the alignment.
