impulse

[Steve Hall]

sorry to ask a dull question but what exactly is meant by impulse hose what does it do or is it just another name for fuel pick up pipe ?

[ScotClayShooter]

When your little 2 stroke runs the crankcase changes from positive to negative pressure every cycle, The Impulse hose transfers this from the crankcase to the fuel pump diaphram on the carb.

This in turn makes the little pump work.

 

Many many 2 strokes dont have an impulse hose as its done direct through drillings in the carb manifolds.

[stuartc44]

The impulse pipe connects the crankcase to the carburettor. The changes in pressure in the crankcase, when the engine is turned over, cause a pulse in the pipe which acts upon the diaphragms in the carburettor to pump the petrol at the required rate.

 

 

I believe that is the basics of it. If not it won't be too long before I am corrected.

 

(You got there first!)

[spudulike]

Pretty good descriptions, the impulse line is not the fuel pickup line and the diaphragm mentioned is not the large one that meters the fuel but the pumping diaphragm where the fuel comes in to the carb!

[MattyF]

Hey spud were in herts are you I have a 357 I need looking at.

[spudulike]

Just North of Baldock - just sorted a 357 so I am familiar with them and what makes them fail.

PM me with what needs to be done - I have a bit of spare time at the moment whilst I wait for spares to come in.

[Steve Hall]

hello all thanks for explanation i have never come across impulse hose prehaps my kit is to old ? all makes logical sense now thanks again (hate not understanding )