| Author | Message | ||
     Xenox |
I installed a 180 in place of the 175 I had put in last year. I actually had to readjust the idle mixture to get best idle @ 1 3/4 turns out .Does this sound right? How will I know if the 180 is too much? The bike is running great and pulls very well through the first four, fairly effortlessly ,fifth is not as enthusiastic, it seems I need to wind out 4th to get 5th going strong. The bike is an 04 with a k&n , bent intake, 48 slow jet , racing plug and corner cut stock muffler. Thanks. (Message edited by Xenox on April 04, 2012) | ||
| Gearheaderiko |
It all sounds way too rich for a Blast with a stock exhaust and cams. Adjusting the idle mixture is possible, yes. A better idea would have been to shim the needle to richen up the mid range and keep the same jet for the top end. Bikes are usually only lean in the idle/slow jet circuit, which is what the EPA checks. Main jetting is usually adequate. By running a super rich idle/slow jet all you're doing is compensating for not having an accelerator pump. Jumps off the line, but you're killing mpg and washing away your cylinders at a steady rpm. {Richer jetting can also compensate for low compression} There's more to tuning carbs than just changing jets and there's more than one way to get to a final tune. I ran a 180 main and although the dyno showed it made more power, it slowed its time to redline and I lost some of the crispness in the exhaust note (indicating a cleaner fast burn). The 180 was great for pulling stumps, but bad for accelerating out of a corner! (and I do have cams, exhaust, ignition and air cleaner to support richer jetting). Thats my opinion, your results may vary! | ||
| Xenox |
Thanks for the detailed and informative response. Oops I knew I was forgetting something, I did raise the needle. 050 . I guess this makes it all that much richer and should go back to the 175? (Message edited by Xenox on April 05, 2012) | ||
| Ezblast |
170. | ||
| Xenox |
Thanks Ez and Erik I just switched that in along with the 45 , runs well and much better fuel economy. Spot on advice. One final thought...... Would I be pushing things to install the 42 for additional mpg? Does the raised needle help out if I do install the 42? If it runs good with no flat spots it should be ok? | ||
| Gearheaderiko |
You can go to a 44. I wouldnt bother with a 42, but since you're getting good at this, try the 42, then shim the needle. Shimming the needle will help out a little with the 42. But all I see being gained with a 42 is hard starting  You can now pass on your experience with others when questions arise Thats how Badweb works.  | ||
| Gearheaderiko |
...and if it runs good with no flat spots, thats what you want. You dont have to put in 2 shims. You can just add 1, or 3, or 4, etc. But you're finding out they are all connected and you can achieve better results by trying a slightly different approach (like shimming instead of increasing jet size). EZ's a fine example of years spent fine tuning his CV carb, making it better and better. There's always little improvements that can be made, but it takes real dedication and patience. | ||
| Xenox |
Thanks for the valuable insight, otherwise no telling how much fuel I could have wasted! I'll try not to be such a stranger, thanks again. |
