ndickey Posted July 25, 2007 Share Posted July 25, 2007 so i'm adjusting the valves on my 78 xs400 and the right side comes out just fine. the left side, when i adjust to the correct gap at TDC, if i move it slightly off of TDC the gap widens to probably almost 1/8" (3mm) and the rocker arm kind of flops loosely. if i set it to it's widest point and gap it there, of course at TDC it leaves no gap at all. Also if i gap it at TDC and run it it knocks pretty badly. is this maybe a problem with the rocker arm needing adjusted? will it hurt anything to run it as is? this sounds like it could be more than i want to really get into, but the dealer here only seems to like to work on new bikes. thanks for the help Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 25, 2007 Moderator Share Posted July 25, 2007 so i'm adjusting the valves on my 78 xs400 and the right side comes out just fine. the left side, when i adjust to the correct gap at TDC, if i move it slightly off of TDC the gap widens to probably almost 1/8" (3mm) and the rocker arm kind of flops loosely. if i set it to it's widest point and gap it there, of course at TDC it leaves no gap at all. Also if i gap it at TDC and run it it knocks pretty badly. is this maybe a problem with the rocker arm needing adjusted? will it hurt anything to run it as is? this sounds like it could be more than i want to really get into, but the dealer here only seems to like to work on new bikes. thanks for the help are you using the timing marks on the rotor for tdc? it should read LT (left) RT (right) with BOTH valves closed (that's inlet and exhaust) on the same side and compression is felt with your thumb over the spark plug hole. Then adjustment is made on that side If its not that, I wonder if your cam chain is loose and not adjusted out enough and then the slack is taken up via the crank turning. I would take off the cam cover (use a manual for sequence) and then you can check cam chain, mechanical adjuster and the rubber blades that go in front and back of the cam chain tunnel. While your at it you can easily check the rockers and camshaft lobes for wear. Link to comment Share on other sites More sharing options...
ndickey Posted July 27, 2007 Author Share Posted July 27, 2007 are you using the timing marks on the rotor for tdc? it should read LT (left) RT (right) with BOTH valves closed (that's inlet and exhaust) on the same side and compression is felt with your thumb over the spark plug hole. Then adjustment is made on that side If its not that, I wonder if your cam chain is loose and not adjusted out enough and then the slack is taken up via the crank turning. I would take off the cam cover (use a manual for sequence) and then you can check cam chain, mechanical adjuster and the rubber blades that go in front and back of the cam chain tunnel. While your at it you can easily check the rockers and camshaft lobes for wear. yes, i've checked and rechecked the LT and RT marks several times, both valves closed, etc. I looked at my Clymer manual and it says that the cam chain is automatically adjusted and no adjustment is required. Is it something that can be checked and adjusted anyway? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 27, 2007 Moderator Share Posted July 27, 2007 yes, i've checked and rechecked the LT and RT marks several times, both valves closed, etc. I looked at my Clymer manual and it says that the cam chain is automatically adjusted and no adjustment is required. Is it something that can be checked and adjusted anyway? If the chain and/or chain guides wear the auto tensioner would be out as far as it goes thus its possible that the chain is loose. I would just take off the cam cover and have a look and check the timing marks align up with the LT/RT and you can see what's going on with the valvalves. Link to comment Share on other sites More sharing options...
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