dmc2028372 Posted December 4, 2018 Report Share Posted December 4, 2018 Morning all. Recently bought a little used 18 factory evo 300 that when revved under load the engine almost ‘pings’ as if it’s running a little lean. Has anyone else had this issue? Is it carb adjustment/setup needed or is this just the way they are? Thanks Quote Link to comment Share on other sites More sharing options...
heffergm Posted December 4, 2018 Report Share Posted December 4, 2018 What is 'almost' pinging? If it knocks, turn the airscrew in a half turn, adjust the idle to compensate, and see how it goes. Quote Link to comment Share on other sites More sharing options...
section swept Posted December 4, 2018 Report Share Posted December 4, 2018 (edited) Pinking is actually detonation and is a really bad thing as it can cause piston damage. If pinging is your interpretation then it needs to be sorted. Poor fuel can cause detonation, ignition timing also. Altitude will also have an effect so if you are riding up a mountain so to speak the higher you go the more chances of ‘pinking’. The detonation makes the piston rattle against the cylinder walls and the sudden explosion creates a shockwave across the piston crown, too many and goodbye piston. An air leak in the intake can also weaken the mixture and cause this. Combustion is a rapid burning and not as a lot of people describe ‘an explosion’! Edited December 4, 2018 by section swept Quote Link to comment Share on other sites More sharing options...
heffergm Posted December 4, 2018 Report Share Posted December 4, 2018 You missed my point. He said 'almost'. Which leaves me confused as to the situation. Quote Link to comment Share on other sites More sharing options...
dmc2028372 Posted December 4, 2018 Author Report Share Posted December 4, 2018 32 minutes ago, heffergm said: You missed my point. He said 'almost'. Which leaves me confused as to the situation. Just to clarify gents, the bike is as sweet as a nut on low revs, but when revved under load it does make a pinking/faint knocking noise. I’m fairly sure it must be carb issues!!! Quote Link to comment Share on other sites More sharing options...
heffergm Posted December 4, 2018 Report Share Posted December 4, 2018 Air screw. Quote Link to comment Share on other sites More sharing options...
sprinter 27 Posted December 5, 2018 Report Share Posted December 5, 2018 “Reved under load “ will be your main jet curcit, not an air screw adjustment . I’d be thinking if it’s new to you and now the bike in colder weather it could be a main jet size lean , or raise the needle a notch to begin with if it’s part throttle 1 1 Quote Link to comment Share on other sites More sharing options...
section swept Posted December 5, 2018 Report Share Posted December 5, 2018 12 hours ago, heffergm said: You missed my point. He said 'almost'. Which leaves me confused as to the situation. I didn't miss your very valid point, but wanted to describe a potential causal effect. 12 hours ago, dmc2028372 said: Just to clarify gents, the bike is as sweet as a nut on low revs, but when revved under load it does make a pinking/faint knocking noise. I’m fairly sure it must be carb issues!!! Almost ‘pinging’ must indicate that the owner has heard a noise, otherwise why would he mention it? By describing what might be the causal effect can better help in any diagnosis....one mans pinging could be another mans ticking sound....all very difficult when diagnosing at a distance, or dog nosing as it is referred to in some trade circles. Quote Link to comment Share on other sites More sharing options...
section swept Posted December 5, 2018 Report Share Posted December 5, 2018 12 hours ago, dmc2028372 said: Just to clarify gents, the bike is as sweet as a nut on low revs, but when revved under load it does make a pinking/faint knocking noise. I’m fairly sure it must be carb issues!!! As sprinter27 suggests this could be your answer, note down every adjustment so that you can go back exactly if needed. Quote Link to comment Share on other sites More sharing options...
heffergm Posted December 5, 2018 Report Share Posted December 5, 2018 You guys are a trip. Quote Link to comment Share on other sites More sharing options...
mightychub Posted January 8, 2019 Report Share Posted January 8, 2019 I had the same issue on my new 2017 Factory 300 I rang John Lampkin and he told me it is normal and it's the way they set them. He said if I try and adjust the pinging out I will upset bike completely. I have never touched it and always make sure I use top notch fuel and the right amount of oil I always put a few ml less in and the bike does it's job pulls like a bus and is very smooth in sections. I hope this helps Quote Link to comment Share on other sites More sharing options...
lineaway Posted January 8, 2019 Report Share Posted January 8, 2019 Sprinter 27 advice makes a lot of sense with the cold weather. You could also raise the needle (Which is dropping the clip) That is the easiest and cheapest route, besides it changes the jetting all in the right direction. If you have the time I would do a quick carb clean just to verify the jets are clear and nothing is building up in the bowl. Make sure to note the jet sizes. You could easily go up one pilot jet size without rocking the boat too much. Good luck. Quote Link to comment Share on other sites More sharing options...
dan williams Posted January 8, 2019 Report Share Posted January 8, 2019 When you say revved out under load are you talking about a short burst or high speed road/fireroad/trail riding? The Keihin fitted to Betas is unable to supply sufficient fuel to keep the 300s float bowl supplied at full blat. Since most trials bikes aren’t ridden that way, prolonged full throttle, it usually doesn’t show up but put in a full throttle blast down the road and a 300 will start burbling and coughing from fuel starvation. Shocked the hell out of me the first time it happened. Thought I blew it up! All my large Betas with Keihins have done this. If it’s just short bursts then a disassemble and clean of the carb is a good idea. There is another possibility and that is you’re just not used to the power delivery of a trials bike which has instant power off the bottom, a healthy mid range and an early sign off. 1 Quote Link to comment Share on other sites More sharing options...
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