Forum

[JTL]

Hi all... every advice I have read on setting tappets says: set them cold with no clearence. This has worked the way it should for me for almost allways. This hot summer made an occational difference. On a ride I lost compression with the sign of a seized piston. After pulling the top apart both cylinder and piston showed no sign of this. So I suspect the pushrods to have expanded just enough to have had the valves stay open not being able to close fully... Has anybody else had this experience? ... I have now set the tappets with just a little slack for an eventual expanding. It makes a little bit more noice. With the Samrat rockers it ends up with a rather distinct noice. Is this a tappet setting practice of other members of our forum? regards Jacob

[JTL]

sorry... forgot to mention my bike is a 2003 iron barrel 500 cc Bullet with some minor performance mods... Jacob

[jaffa90]

I don`t believe what I`m reading, tappet/valve clearances are set with engine cold. You must have a gap.

[Leon Novello]

Set them with no clearance when cold. If you set them with a gap
there is the chance that they won`t open enough to let the inlet and exhaust gases flow freely. There must be something else causing the problem

[Beezabryan]

If you dig far enough into old & ancient stuff you will find the same all except one book (that I can't bothered to look for) that gives 2 thou clearance on the Bullets ancestors,

[JTL]

Hi Jaffa and Leon... If I understand you two correct we have two different opinions. Jaffa says have a (very small) clearence between pushrod and rockers; Leon says no clearence. My experience until the mentioned incident is to have no clearence (cold engine) and the bike runs good. Now I'm trying with a very small clearence (cold engine) and the bike runs good. The very small amount of inlet opening time and the very small amount of restriction in exhaust must be of very little effect, since I can't really feel the difference, but I know theory/math might be of another opinion... Looking forward to hear more about what other members have experienced... Jacob

[simon]

Nil loose is the setting. That means the pushrods should spin freely but there should be no perceptible up and down movement. The reason for the nil setting is that the expansion of the barrel and the pushrods is basically identical so that a loose/clearance setting will stay loose no matter what the temperature (that is the theory at any rate).
I've fitted the Aluminium barrel and I thought this would make a difference. I can't stand noisy tappets though so I will have to check the spin of the pushrods on the hot motor this coming summer.

[Leon Novello]

We are talking about a 2003 iron barrel Bullet which I presume is the same as my 2000 Bullet for which the workshop manual says must be adjusted with the engine cold and pushrods can just be rotated with finger and thumb, no up and down movement.
Altough the Indian Bullet wizard, Gurunandan says,`adjust them with the engine HOT`
Certainly, nobody is saying leave a gap. These things are noisy enough even with earplugs.

[JTL]

I can't imagine setting tappet clearence with a hot engine: burned fingers and no real control over the amount of expansion. So, tappets are set with a cold engine (buisness as usual). The degree of expansion must vary with an iron barrel or an aluminum barrel (theoretically). I ride with stock pushrods (aluminum rods and iron adjusters). Somehow they must expand in a different pattern than the iron barrel (theoretically). Until now I have never experienced any problems with a no clearence setting, so if my loss of compression is not because of a little too long pushrods, what could be the cause then? ..Leon, you said it had to be something else. Could it be the valve stems or valve guides causing the valves to stick? The cylinder head is the tuned head form our host. If it is what would make that happen? It was one of those very hot summer days. Could air temperature/humidity lean out the air/fuel mixture so much it would cause excessive heat build up in the head? Jacob

[Riggers]

Mine's a 2000 iron barrel 500. I've always set them with the engine cold, and free to spin (but no clearance), and never had a problem. I can't see that a 2 thou clearance would lead to a push rod jumping out but I'd stay with the recommended settings (IMHO).