Dickwad Posted March 25, 2012 Share Posted March 25, 2012 Iv increased the main jet size by x 2.5 set the needle to the bottom setting and put another 20 thou washer under the needle, and its still back firing and missing when I open her right up, she's ok up to say half throttle, do I need to go bigger still with the main jets, oh and the plugs are a very light tan, Im getting pissed off with it now, this is the second time the carbs have been out, I'm tempted to put the original jets back in and the stock pipes back on, but these big bore slash cuts do sound good, what to do??? Link to comment Share on other sites More sharing options...
Noise Posted March 26, 2012 Share Posted March 26, 2012 Sadly it sounds like you need bigger jets again, i know how you feel man i had my Carbs out 4 times till i got her running good and now i need to take them out again as i just checked my plugs and she is running a bit rich. Sadly changing pipes have a knock on effect to the carbs and its all trial and error with setting them back up again. Keep your chin up......its all worth it in the end. Link to comment Share on other sites More sharing options...
Dickwad Posted April 3, 2012 Author Share Posted April 3, 2012 Finally got it running properly, I had to go up to 127.5 and 130 main jets, plus lift the needles to their highest position and add another 20 thou spacer, but it runs really well now and has excellent torque, pulls like a train from zero to full throttle, no missing or back firing, and sounds great, thanks to all who gave advice, especially "noise" Link to comment Share on other sites More sharing options...
Noise Posted April 3, 2012 Share Posted April 3, 2012 Not a problem mate any time! i know what its like its a pain in the chocolate star fish till you get it spot on! ride it for say three four days, (long rides) then say at the week end take the plugs out and check what colour they are, if black then your too rich, if its going white then its weak but seeing now you have bigger jets you may find that they will bee a bit black as you have more fuel going in Now go out and enjoy the bladdey thing!! Link to comment Share on other sites More sharing options...
paperback Posted April 6, 2012 Share Posted April 6, 2012 I have had the same problems on my 650 and have just had much larger Jets put in. Mine would be fine until opening the throttle fully then would hold and then clear. Took it back to my local Yamaha dealer who had it for a couple of days. It still has the very very slightest of delays barely noticeable - but is safe and much faster. This all happened after changing the pipes to slash cuts. If I had known then what problems it would cause - would I have kept to the standard hair dryers - still not. The bike is so much better now! Link to comment Share on other sites More sharing options...
Dickwad Posted April 6, 2012 Author Share Posted April 6, 2012 hi paperback, it sounds like the needles need adjusting, I have found out the hard way that you can't enlarge the main jets without raising the needles, this allows the richer mixture to enter the carbs quicker, this may be what is causing the delay. Have a look at the reply from noise above, where he recommends checking the plugs, might be worth trying that. I know what a pain it is , but its worth it, to have a bike that sounds throaty, and not like a under powered canal barge. Link to comment Share on other sites More sharing options...
paperback Posted April 12, 2012 Share Posted April 12, 2012 Thanks mate- yes cant undertand why main dealer reset the needles, back to normal- will have to sort Link to comment Share on other sites More sharing options...
Recommended Posts