Hitchcocks Forum

My old iron 500 has rattled, clattered and made painful metallic sounds for the three years I've had it. When feeling the tappet pushrod clearences, it always felt there was no up and down movement and the rods were freely spinning. I have always put the clatter down to the way it was and ridden it anyway but I now have a quiet engine for the first time ever! I simply felt the pushrods a bit more thoroughly and discovered a tiny almost undetectable bit of up and down play of the exhaust rod. Since removing the play the engine now rustles rather than clatters along, almost (I said almost!)like a jap single. The adjustment was tiny and overlooked for years but has made a huge difference.

Glad you wrote that; I'm inspired to look at mine when there's a chance for the same reason. Regards, Chris

Hi chris, glad to hear the bike is running sweet.

Talking about pushrod adjustment,i read somewhere it was recommended to adjust with the engine hot..
reason being the alloy cases expand more than the steel and the gap increases, becoming noisey.

I can go with that in theory but wonder when cold wouldn't the valve be a bit tight?? Inviting burning and compression loss until warmed up... Does anyone else adjust this way? Just wondered.. gwilly

I adjust mine so that I can only just turn them with great difficulty; any tighter, and there is great strain on all the components in the drive train to the valves. Anyhow, have you noticed that after a long ride the engine sounds like it is going to fall to pieces? This is particularly
apparent on the ride home. It is the same syndrome in a car, it starts off very quietly, and after an hour or so one can hear every squeak and rattle; and even running over a matchstick feels like a log on the road. On arrival at your destination, you find that the music is turned up a lot louder than when you started out. A lot of this seems to be all in the mind; or, is it in our ears?

From experience adjusting when hot means no compression when cold and burnt fingers!

I agree Frank.
Another common cause of a noisy engine is the head steady - this must be tight.
I also get a lot of resonance when the tank is getting on for empty - it amplifies the tappet noise. I keep meaning to try dampening it somehow.
Anyone tried?

Hi CHRIS----------- can you describe those "metallic sounds" a bit more accurately ??..... Are they coming from a specific area or is it a general, all-over sound ??.........A lot of play can be attributed to wear in the actual rocker box assy. itself--- especially excessive end-float of the arm within the block.. Do you have those SAMRAT mods. fitted ??.. Have a look at the fit of the Samrat arm into the top of the push-rod........................opening up the internal oilways is always helpful....

---------- Dammit, forgot to say}--- Does anyone know what the tappet settings are for other OHV singles?..eg}--- BSA, ARIEL, NORTON ------------ might be of some help to compare ??

I had noisy tappets that were cured with our hosts rods and Samrat rockers with drilled out oil feed holes and alloy spring caps . Push rods at TDC were just spinable with the thumb when the engine is cold .

Pete, I found putting a couple of rubber washers, one on either side of the front tank mounting bolt, deadens the resonance very well. Protects the paintwork too when tightening the bolt. Those sold as being for hot water bottles are the perfect diameter and thickness for the job!