Author Topic: Mk 4 noisy tappets ?  (Read 3226 times)

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Offline Evanc

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Mk 4 noisy tappets ?
« on: 15 Apr 2014 at 12:45 »
My Mk 4 seems a bit rattly at idle. When I first got it I adjusted the valve clearances and it  made little difference. I then pulled the timing case off to inspect the gears, in case the noise was coming from there. It all looked o.k. in there. I assumed the noise was normal. The bike had been unused for about 8 years and after a short time it started to idle badly and I removed  a head as the compression was low on that cylinder,  and had it reconditioned, including 1 new valve and the other valve was machined. I put the bike back together, noise still there and rode the bike for a few weeks, but the extra vacuum/ compression the bike had developed had caused the bike to blow a lot of smoke, so I removed both heads and barrels to replace the rings. The other head is being overhauled also. the bike would have done no more 150kms since the first head was overhauled, however I have noticed the tops of both valves were quite badly damaged where the tappet adjuster contacts them. The tappet adjusters have some mild damage also. Can anyone suggest what has caused the damage to the end of my valves? There seems to be plenty of oil in and around the rocker cover. I have been a mechanic for around 35 years so tappets are not a problem for me, but considering the excess noise at idle, is there too much clearance? I set them at .005" which is what I believe is the right clearance. Inspecting the rocker mechanism, one of the 4 seems a little notchy, the other three have normal play and move freely.  My thoughts are that any binding in the rockers may case push rod wear but should not cause wear on the ends of the valves. Do the 350's rattle a bit at idle? Any tricks to adjusting the tappets? Cam followers and push rods all look fine.
Any advice is  appreciated, Regards, Evan

Offline Evanc

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Re: Mk 4 noisy tappets ?
« Reply #1 on: 20 Apr 2014 at 08:23 »
I have just rebuilt my motor and have noticed the geometry of the tappets to the tops of the valves is wrong. it would seem the cam followers or cams have been machined which has caused the tappets to contact the edge of the valve rather than the middle. 

Offline eddie

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Re: Mk 4 noisy tappets ?
« Reply #2 on: 20 Apr 2014 at 11:14 »
          It is possible someone has at some time replaced the rockers with a set from either a generator engine or a T35 Mk1. These engines had a deeper combustion chamber - hence the valves are set at a greater angle - likewise the arms of the rockers. Except for the arms, the rocker assemblies are identical, so identification is not easy!


Offline C Clay

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Re: Mk 4 noisy tappets ?
« Reply #3 on: 22 Apr 2014 at 15:46 »
I recently rebuilt my T35, which by the way has a Mk1 frame with a Mk3 engine and gearbox. I was also surprised at how noisy the tappets are, I have them set at .005" as per the maintenance manual. They become less noisy with a few revs on.
Unfortunately as I have no previous experience with and no friends with T35s I am not sure if the  tappets are normally noisy at tick over and if I am worrying unduly.
So if there is anyone familiar with T35s who can give some advise or feedback I would be appreciative.

Offline kev

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Re: Mk 4 noisy tappets ?
« Reply #4 on: 23 Apr 2014 at 08:53 »

 had something like engine had wrong year cam followers...and the followers were not going all the way down to the heel of the cam...I adjusted and adjusted...trying to get the clicking out....but didn't find out what was what until one of the followers finally broke up from their regular beating...