197? 7.5 hp flat spot

[joe_morgan]

Hi all, I have a 1970's (not sure) blue band 7.5hp. Serial number 2175212. It starts very well, runs well at WOT but has a flat spot from about 1/4 to 1/2 throttle. Also idles a little roughly until warm. Can anyone make a suggestion as to where to start looking to sort the flat spot out. Cheers.<br />Joe

 

[mellowyellow]

Re: 197? 7.5 hp flat spot

define flat spot.... boggs down?

 

[joe_morgan]

Re: 197? 7.5 hp flat spot

Flat Spot, idles OK. Flat spot - sucking air noise, maybe even a splutter, never stalls, engine still runs under load but bumps around, comes good just after 1/2 throttle. Seems to rev to about 4000. Maybe less (edited)<br /><br />Cheers

 

[joe_morgan]

Re: 197? 7.5 hp flat spot

Found a tube hanging off the carb last night not sure what its for but its on the left hand side (facing the front of the engine) and there are two of them. Maybe vacuum or fuel line. There is a bit of oil in the shroud. I'd say its fuel that has evaporated away. Hope that'll make a difference.<br />Joe