TR4/4A Lost motion lever - what is it for - TR4

[Adrio]

on the carb linkage for the SU set on a TR4A is something called the "lost motion lever" (Moss part # 372-840. This part seems to put an intentional slop in the thropttle linkage but makes driving a pain as the first part of the pedal travel does nothing.

Does anyone know what it is there for. And more importantly does the pact that I filled this slop by putting a bushing in there have anything to do with the backfire that I am not able to get rid of.

 

[AltaKnight]

You got it.
The lost motion slop is intentional.
It's merely there for safety so that the carbs close fully when you take your foot off the gas.
Of course when you have a bunch of wear combined with the intentional slop it gets real sloppy and most of us do something to adjust some of this out.
No, I can't see this having anything to do with your backfiring problem.
Good luck.

 

[Adrio]

Thanks for the reply. I feel better about having put those bushings in.

In case anyone is wondering the bushing were available at the local bearing supply house for a buck a piec and fit on the pin perfectly and took all the slop out of the trottle linkage. If anyone needs spacifics just let me know and I will look up the size in my log book.