Glenn Stevenson Posted July 29, 2021 Share Posted July 29, 2021 HI, I picked up a Laser 100 with what appears to be a super tigre carb, ive been trying to get it to tickover but it just splutters to a stop on low throttle openings when the glow starter is removed. Tried umpteen settings of low and high needles but no joy. I remember someone saying that the carb has rubber seal that doesnt last long. Would the newer purple or black carbs work? Glenn Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 29, 2021 Share Posted July 29, 2021 Is the spray bar in the right way round? folk like to turn them round for some reason and yours looks like it could be in backwards. The other favourite is when the slow run needle misses its hole in the spray bar and just pokes out the side doing nothing. Also, what prop, plug, fuel, and top end rpm are you seeing? Its possible the engine itself needs some love. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted July 29, 2021 Share Posted July 29, 2021 Nice forward facing tank vent there ? and tank position? Quote Link to comment Share on other sites More sharing options...
Glenn Stevenson Posted July 29, 2021 Author Share Posted July 29, 2021 Prop is 14*6, OS 8 plug (new one), Revs well, flew it with high tickover and it performed very well. Just pulled the carb off and needle was outside the spray bar, try again when the neighbours have gone to bed! The spraybar slot is facing the inlet port so that looks ok. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 29, 2021 Share Posted July 29, 2021 Glenn, hope you get it sorted, I have a couple of very old Lasers with the Supertigre carb, they both throttle very well, I have never changed the rubber O ring. Quote Link to comment Share on other sites More sharing options...
Glenn Stevenson Posted July 29, 2021 Author Share Posted July 29, 2021 I would imagine that the needle being outside the spraybar would make a mess of the carburation. I.l report my findings when I try it again. Thanks All Glenn Quote Link to comment Share on other sites More sharing options...
Don Fry Posted July 29, 2021 Share Posted July 29, 2021 14 6 is a small prop for that motor. And a no 8 plug normally does a 2 stroke, OS F plug for that? Quote Link to comment Share on other sites More sharing options...
Glenn Stevenson Posted July 29, 2021 Author Share Posted July 29, 2021 Thanks Don, I dont know why I said OS 8, it really is a new OS F. 14*6 was all I had in the box! Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 30, 2021 Share Posted July 30, 2021 14 hours ago, Glenn Stevenson said: Prop is 14*6, OS 8 plug (new one), Revs well, flew it with high tickover and it performed very well. Just pulled the carb off and needle was outside the spray bar, try again when the neighbours have gone to bed! The spraybar slot is facing the inlet port so that looks ok. As already mentioned 14x6 is a bit small. 14x7 is the normal minimum i would recommend but its not a big deal in this instance. Again, the OS F plug is the way to go. A wonkey needle is likely to be your issue, its pretty common as its easy to do. The spray bar is always a pain as some (a minority) were manufactured 180 degrees opposed to the standard ones. Generally inlet nipples pointing backwards means its in the wrong way round. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted July 30, 2021 Share Posted July 30, 2021 It used to be said that twisting the needle assembly on an ST carb was what adjusted the mid-range response, It looks like the previous owner took this to the extreme. Quote Link to comment Share on other sites More sharing options...
Glenn Stevenson Posted July 30, 2021 Author Share Posted July 30, 2021 The spraybar has its opening facing directly towards the inlet valve, I cant imagine it would work very well facing the outside of the carb. It is very easy to miss the hole when the needle is removed and replaced, however it was inserted incorrectly when I bought the engine but did not examine it closely. Glenn Quote Link to comment Share on other sites More sharing options...
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