Forum

[Balf]

Hello all,
I just wondered if the 350 1991 indian bullet is designed to have spinning push-rods. The reason I ask is because on mine, the inlet push-rod spins whereas the exhaust one does not. They have been adjusted when the engine is warm and both display the same resistance to turning by hand. Perhaps the cam follower surface is not perfectly square to the cam?
Balf

[Beezabryan]

Mine are set with the engine stone cold so the push rods can just be turned with finger & thum. Othe methods are available and will be published here shortly

[mauri]

adjustment of the pushrods is only performed on a cold engine.

cold being at rest for at least 24h



when at working temperature a pushrod engine will have pushrod/valve noises, thats the nature of the beast.



if not enough play on the inlet valve the inside of the carb will be black

if not enough play on the outlet valve you'll run the risk of burning the valve eventually.

you basically have a continuos loss of compression.


in both cases the engine will be difficult to cold start, and have a wandering ticker over rpm while warming up.

with added coughing and spluttering galore.


and they should indeed just spin freely with no vertical play on a cold engine.

[Balf]

I didn't intend this to become an argument about adjusting push-rods which has been covered countless times here before. It was just the spinning I was interested in. Just as an aside:
http://www.nandanmotors.com/adj_pushrod.html

[papasmurf]

Balf I don't want to baffle you with science but pushrods should ALWAYS be set with the engine cold due to the coefficient of linear expansion.
The manufactures say set the tappets cold for that reason.
Setting them warm or hot will end in tears at some stage.

[Balf]

Unfortunately when the engine gets hot the aluminuim head gets hotter than the push rods and so the clearance increases as the engine gets to operating temperature. Cold no clearance - no noise, hot too much clearance and so noise. The balance is to get a little noise at running temperature so you know the valves are fully closing. Here in france I set the clearance differently in the summer (can be 40C) to the winter (can be -10C) I haven't had a burnt valve yet so it seems that Nandanmotors theory is o.k. The book says do it cold which means the valves don't open fully when hot but you'll never get a leaky valve due to small clearance of the push rods.
But what about the spinning?

[Revband]

Yes Balf I just checked your link re adjustment, only two polite words to cover that, total nonsense.

[papasmurf]

Balf basically please yourself if you wish to believe some crackpot instead of manufacturers with 100 years of experience feel free.

[Dennis C]

The pushrods ability to spin does not require the cam follower to be square to the cam it is independent and has a cup at each end and nothing other than a badly fitted or badly adjusted pushrod will prevent it turning, I have on a number of occasions found that a pushrod has been fitted with the edge of the cup misaligned with the ball on the rocker and has cut into it causing damage on every occasion the bike has been running ok, but for goodness sake before going into any further investigation try adjusting cold as Royal Enfield have always advised 60+ years, just to see what happens, it may answer your question.

[Mickey]

Hi Balf, if its any consolation my inlet push rod rotates when the engine is running too on my 350 (tappets usually adjusted cold-ish). The tappet noise on my 535 was really excessive when engine warm so, on advice of of a knowledgeable mechanic in India I have always adjusted when hot (well, enough to burn fingers). After 15 years of Bullet riding no problems yet as the engine still starts o.k. & is quickly up to running temp. before any real valve damage can occur. Mick