| Kawi2strokes.com Forum http://www.kawi2strokes.com/forum/ |
|
| gurgling midrange on my yz465 http://www.kawi2strokes.com/forum/viewtopic.php?f=21&t=3155 |
Page 1 of 1 |
| Author: | 2stroke [ Tue Apr 24, 2012 6:17 pm ] |
| Post subject: | gurgling midrange on my yz465 |
Jetting and tuning is never cut and dry and the YZ465 is difficult to get right.... With the needle in the middle position, it pulled off ok but ran poorly all the way up and never cleared out. Dropping the needle one notch = pulled off well, midrange gurgled, and the top came on like a bat out of hell (Thats how I wound up racing my first race on it a couple weeks back) Dropping the needle two notches, (clip at the top most position on the needle) made the midrange BEAUTIFUL, but the top disapeared. I am running a 370 main, 50 pilot and a 3.5 slide that I ground out just a bit, probably not quite a 4 as it sets. (Was aiming for the Marty Moates formula there) but in any case, the bike is very fast and powerful, it almost doesnt even matter about the midrange being dirty, but Id like to take advantage of the bike's ability to chug third gear around a slow turn and Id rather it was cleaner... Im thinking of going with a different slide...maybe a 2.5...anybody have any suggestions? |
|
| Author: | Ja-Moo [ Tue Apr 24, 2012 6:24 pm ] |
| Post subject: | Re: gurgling midrange on my yz465 |
It must be something else, your needle position has nothing to do with WFO throttle (it's no the main jet from 3/4 to full throttle) You might try going up one or 2 sized on the main. |
|
| Author: | mraxl [ Tue Apr 24, 2012 7:52 pm ] |
| Post subject: | Re: gurgling midrange on my yz465 |
|
|
|
| Author: | scrambler73 [ Tue Apr 24, 2012 9:16 pm ] |
| Post subject: | Re: gurgling midrange on my yz465 |
Dale, that chart is misleading in that it claims the pilot plays no role after 1/2 throttle.. when in fact, the pilot jet is still feeding fuel during the ENTIRE range of throttle/slide position. When installing UFO's in VM round slide carbs, you end up dropping the pilot (at least) in half... And it is then recommended to up your main jet size to compensate for the large amount of "pilot" you've taken out of the over all mixture so you do not suffer a lean condition at wide open throttle. |
|
| Author: | mraxl [ Wed Apr 25, 2012 6:15 am ] |
| Post subject: | Re: gurgling midrange on my yz465 |
The chart shows maximum effectiveness of jetting items at a specific throttle position not constant fuel source. I put it up as the suggestion was offered about changing slide cutaway to cure a WOT ill..... not a likely fix. You are quite right about pilot fuel flow... that is the reason why the pilot/airscrew should be sorted first as the setting affects all other circuits. But still, it tends to be ignored by most. 
|
|
| Author: | Walms [ Wed Apr 25, 2012 8:32 am ] |
| Post subject: | Re: gurgling midrange on my yz465 |
2stroke wrote: Dropping the needle two notches, (clip at the top most position on the needle) made the midrange BEAUTIFUL, but the top disapeared. The simple solution is to jet up the main at this point... |
|
| Author: | Scully [ Fri Apr 27, 2012 8:01 pm ] |
| Post subject: | Re: gurgling midrange on my yz465 |
What premix ratio are you running ? Yamaha recommended 16:1, I tried it and my bike ran much better throughout the rev range...and quit seizing too...trying to remember what main jet I was running and think it was around a 380. Oh and check to make sure needle jet and jet needle aren't worn out from vibrations...I had to change both... |
|
| Author: | Merlin [ Sun May 13, 2012 8:16 am ] |
| Post subject: | Re: gurgling midrange on my yz465 |
Air correction jet is missing or too large. |
|
| Author: | 2stroke [ Sun May 13, 2012 11:48 pm ] |
| Post subject: | Re: gurgling midrange on my yz465 |
Two ways to go on it as I see.... with the needle all the way down, (good midrange) I could up the main jet to richen up the top with the needle one click down, (good top) I could grind out the slide to lean out the mid. Yeah I know the bit about WFO and the main, but maybe Im not talking about pegged....I mean I dont know if I EVER had the thing absolutely open.... lets just say in the range I was riding it, the front wheel lofted ALOT more with the one click down position. Bigger main would be the easiest thats what Im gonna try in a couple weeks when the next race comes around! I will figure it out. Busy with too much other crap to get to it yet though! As for premix, Im at 32:1 with a good quality modern oil, thats plenty for me. |
|
| Page 1 of 1 | All times are UTC - 5 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|