tappet adjustment g2 engine

Ian 14 G2 · Post by **Ian 14 G2** » Sun Apr 04, 2010 3:08 pm

Having set the engine to TDC and adjusting the valve settings by the book and double checking everything over again I still have a tapping sound from my rocker box, any suggestions ?

1608 · Post by **1608** » Sun Apr 04, 2010 3:48 pm

Rocker shaft ? either running dry or excessive play.

wilko · Post by **wilko** » Mon Apr 05, 2010 3:16 am

I have found if hairpin springs are fitted the wrong way around they can hit the top of the rockerbox.

wilko · Post by **wilko** » Mon Apr 05, 2010 3:18 am

Sorry, i was referring to heavyweights!

chris kelly · Post by **chris kelly** » Tue Apr 06, 2010 2:41 pm

On my bike when I had it my lightweight was 'noisy ' from that area.
Even when my engine was completely overhauled new, with this and that, and the work done properly, it was still 'tappety'.

Actually I can remember reading somewhere in a manual that the lightweights are like this.
Chris.

T · Post by T » Tue Apr 06, 2010 11:03 pm

hi Ian , with the tappets set ok , tapping could be side play in the rocker bushes or maybe the ball ends on the pushrods/rockerarms/cups are worn , they will make it rattle a bit . - and yes , they do sound a bit 'busy'

Ian5913 · Post by **Ian5913** » Wed Apr 07, 2010 9:50 pm

Ian

You didn't state if this was after general maintenance or after a first time rebuild. If the oil is flowing they are not normally to bad. Do you have another machine in the area you can compare it with?

The key is to follow the book process (as you state), TDC on full compression on a warm engine. Leave no up / down movement but the rod should spin easily. Check for oil flow in the two visible places.

Ian

SPRIDDLER · Post by **SPRIDDLER** » Wed Apr 07, 2010 10:22 pm

Whilst we're on the subject; something I've pondered for years...

The pushrods are aluminium (o.k probably an alloy) which has a coefficient of expansion of about 12.3 and the cylinder barrel is steel (Mild steel C of Ex 7.3 and Austenitic steel 304 is 9.6.... take your pick).
The barrel is steel. So when the engine heats up why doesn't the greater C of Ex of the ali pushrod hold the valves off their seats as the 'aluminium' pushrods have a greater C of Ex than steel ?
Could it be that the pushrods never get very hot??
Yes, the 'Nil' gap should be set with the engine "warm" but 'warm' isn't going to cause much expansion is it?
Anyway I have aways set my valve gaps with the engine cold and I haven't had a single valve problem in 4 years and 30K miles
I need to know

1608 · Post by **1608** » Thu Apr 08, 2010 12:10 am

Thats 7,500 miles per year,You are keen.
Are you allowing for the alloy head mass ?

SPRIDDLER · Post by **SPRIDDLER** » Thu Apr 08, 2010 10:39 am

Yes, it is a lot of miles John. (It's 4 1/2 years in fact). The 350 is my daily hack - Tesco, club runs, foreign camping trips etc. It's only about 150 miles a week and I usually do about 100 miles at the weekends all year round, although it was off the road for three weeks this winter during the snow and ice.
In all those miles I have only been recovered three times: Two rear wheel punctures - both at night, and once when the spark plug blew out of the head. Curiously, all within 3 miles of home.
It's not pretty: The wheel rims are 'Waxoyled'. the mudguards plated with pop-riveted patches over the splits, the clutch lever is still held on with cable ties after I fell off her on a train in the Simplon Tunnel returning from the IJR in Italy and the seat is patched and frayed.
Rust abounds. She drips.
I did have to completely rebuild the engine soon after I bought it 'Fully reconditioned mechanically', but tyres are the main expense. The front brake mod previously mentioned on here is a bonus.
My MOT man (a classic bike enthusiast) takes it out for a 20 minute run at each MOT.
It owes me not a penny.