yam175ty Posted May 30, 2011 Report Share Posted May 30, 2011 Hi, My 2004 315R suffer of engine knocking from 1/8 to 1/4 throttle position or when I cutout rapidly the throttle. I tried to change the jetting and to use VP racing fuel with no results! Is that your bike has this problem too? Is anybody have a solution? Thanks! Quote Link to comment Share on other sites More sharing options...
copemech Posted May 30, 2011 Report Share Posted May 30, 2011 Hi, My 2004 315R suffer of engine knocking from 1/8 to 1/4 throttle position or when I cutout rapidly the throttle. I tried to change the jetting and to use VP racing fuel with no results! Is that your bike has this problem too? Is anybody have a solution? Thanks! This is a delorto PHBL carb bike, right? I'm no Mont expert, but I never got rid of that on the Sherco till I went to a #38 pilot jet. What jet do you have now? Others may have other idears, but? Quote Link to comment Share on other sites More sharing options...
yam175ty Posted May 31, 2011 Author Report Share Posted May 31, 2011 Yes it is a phbl bs carb with a #38 pilot. I could maybe try a #40. Thanks! Quote Link to comment Share on other sites More sharing options...
yam175ty Posted May 31, 2011 Author Report Share Posted May 31, 2011 Finally I'm going to install a Keihin PWK 28 to solve the problem. Someone alteady try this before? Thanks! Quote Link to comment Share on other sites More sharing options...
copemech Posted June 1, 2011 Report Share Posted June 1, 2011 Finally I'm going to install a Keihin PWK 28 to solve the problem. Someone alteady try this before? Thanks! Personally, I would try the #40 test first, as it is cheap. Also insure the transition circuit in the carb is not restricted. There are two small holes in the carb circuits, the main idle circuit in the engine side of the bore, and another just behind the slide which is the transition circuit in the range we are talking about. Both feed off the primary jet, yet only the first is metered by the fuel screw. If the second passage has blockage, or the jet is insufficient to support the transition, it will be lean and ping. In reverse, if the primary jet is too rich, it will blubber in the range, as the jet is the determiner, not the screw or needle. I would have never thought it, but going from the 36 to 38 fixed mine, so just goes to show. This crap drove me crazy untill I figured it out. Add, they all vary a bit. Yes I gotta run the fuel screw in just a bit at between 1.5 and 2 turns out, so in a more selective range on the day. A kiehin is a good carb ,but finiky as well and also more power accross the range typically. Quote Link to comment Share on other sites More sharing options...
yam175ty Posted June 1, 2011 Author Report Share Posted June 1, 2011 Thanks copemech, i'm going to try the #40 pilot first and cleaning these little fuel holes. Thanks Quote Link to comment Share on other sites More sharing options...
bikepilot Posted July 14, 2011 Report Share Posted July 14, 2011 Hopefully you've solved this by now, but if not... Mine knocked on overrun like that when I got it. I thought it was because I was using pump gas rather than race gas. However that wasn't it at all! Turned out the previous owner had fitted a B6ES spark plug while the bike should have a BR6ES. The lack of the resistor, it seems, was causing all sorts of issues (it also randomly acted like it loaded up and sounded terriable, but was ok if I shut down and re-started). Switched to the BR6ES and it hasn't knocked once since (all stock carb on an '01 Mont). Anyhow, before you try a different carb, make sure you've got the proper plug in there. Quote Link to comment Share on other sites More sharing options...
nelly1 Posted July 14, 2011 Report Share Posted July 14, 2011 Hopefully you've solved this by now, but if not... Mine knocked on overrun like that when I got it. I thought it was because I was using pump gas rather than race gas. However that wasn't it at all! Turned out the previous owner had fitted a B6ES spark plug while the bike should have a BR6ES. The lack of the resistor, it seems, was causing all sorts of issues (it also randomly acted like it loaded up and sounded terriable, but was ok if I shut down and re-started). Switched to the BR6ES and it hasn't knocked once since (all stock carb on an '01 Mont). Anyhow, before you try a different carb, make sure you've got the proper plug in there. i had the same with the b6es changed to an iridium plug and perfect i also cleaned out my exhaust and re packed the silencer dont know if that helped Quote Link to comment Share on other sites More sharing options...
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