V-Force & Gas Mileage

[toddwunsch]

I am really trying to preserve gas mileage with the smallest expense to the real reason I bought this bike.  The great power.  I have the jetting tuned in and re-geared to 15/45.  I have a Ty-Davis KX-KIT on the way with a 3.7 gal tank, pipe and silencer.   I have a moose spacer and 14oz. flywheel weight on order and am considering the V-Force reed cage.  I read a post that basically explained that the V-Force allows twice as mauch fuel and air in resulting in more power.  Sounds logical.  Any idea what that will do to mpg.  Right now I'm  at 22 mpg and hoping to get a few more with the flywheel weight and spacer (allowing me to use a little more bottom-mid).  I need to get 90 miles out of this monster for some rides in Baja this winter.  Right now, with the Zip-Ty tank, I can get that and carry a little gas just for backup.  I really don't want to blow that by replacing the stock reed cage.  Any thoughts would be appreciated.

[mikesmith]

I didnt notice a change in gas mileage from running a v-force one way or another.Best things for gas milage I found were gearing,home made power now,correct jetting/air screw adj. (dont just set it once and forget it,jetting changes with weather conditions and altitude),raising float level a few mm higher than spec,and always running a clean air filter befor each ride.Ive gotten 60 miles or so on a stock tank.

[toddwunsch]

That's very helpful to summarize all of those points.  I have, and am getting better, with the jetting.  I was just thinking that after doing all of this work to improve the bottom end / mid range, that I might want to consider the V-Force to gain some power back.  I have a few questions.  1.) Float height.  Can you explain.  Are you allowing more fuel to be stored in the bowl by raising the float height or vice versa.  And how does it save on gas mileage.  My guess is that it prevents waste ?  Also, how do I get my hands on a Power Now device.  I've checked out a few recommended web sites and can't find anything for a KX-500.  Is there a Power Now for another bike that works on a 500.  Is it difficult too make your own ?  The pictures looked like it was a machined cone type of part.  Thanks again for your help.  Also, can you tell me a little about the Moose spacer ?  I have one on order based on advice that it helps the low end / mid range and may save on gas mileage.  It's a fairly inexpensive part (I think $25) but thought I would get some more feedback.

[mikesmith]

I changed the float level a little higher than stock (less fuel in bowel) because of my bikes "blubbering" over real rough terrain and it helped my gas milage from the stock setting.Im sure on the stock setting I was loosing fuel from the vent lines over the rougher trails,that was causeing the rough running of the bike.I made my own "power now" out of sheet aluminum (you could use stainless steel)its been a while ago that I made it so I dont remember what guage aluminum I used.It needs to be thick enough not to flex to much or not at all,cut it to fit inside the air box side of the carb horizontally,in the middle of the throat ,as close to the slide without it touching as possible(I used a cardboard templete)and Im guessing I left 10/15mm sticking out into the airbox.I made the first 1/3 of it wide enough to fit into some grooves I cut in the throat of the carb body and epoxyed it in place.I made this by looking at the picture from there web site for the 2-stroke power now,just forget about the cone part of it and look at the flat part.Make sure it DOESNT interfere with the slide,I hope this doesnt sound confusing because its not hard to do.I think it allowed me to lean out the main one size,helped my gas mileage some,and going out of a corner allowed me to pull a taller gear,better smooth throttle response.Its been awhile so Im just going by what I remeber,dont expect miracles but for something you can do for free and a little time it was worth it.Its all the little things you do that add up to improved power/milage.                                                                               I dont have the Moose spacer on my 500 (Im makeing my own)but my wife has one on her KX85 and it helped smooth out the "hit" and did help low/mid range,she doesnt ride enough for me to be sure if it helped gas milage(It did seem to a little),but its only $20.00 and from the post Ive read its worth it.Some of the mods Ive done a few at a time,so to be sure how much "bang for your buck" your getting do one at a time and log the results in a note pad.

[Sharc]

Good stuff Mike. How'd you slot the inside of the carb for the power now mod...??

[toddwunsch]

Thanks.  I just got my KX-KIT from UPS.  I'm a little bumbed.  There's a small quarter sized dent right in the fat part of the pipe.  Since my bike spends just as much time on the ground as it does on it's wheels, I'm wondering if it's worth it to send the pipe back.  I've already got a similar dent in my stock pipe after only 3 rides and about as many crashes.  I did notice that they purposely dented the pipe where the water hose goes so that should alleviate the problem I've heard in the past.  I am interested to know how you put the grooves into the carb throat and would like clarification on "not touching the sides".  Does that mean that only the 1/3 part of the aluminum that you epoxied to the carb is touching the carb ?

[mikesmith]

OK dont laugh,I used a 4" hack saw to cut a groove on each side of the carbs throat,it was a snug fit for the plate I made and epoxyed it in those grooves,its been in there over a year with no problems.Both sides of the plate fit snug against the carbs throat walls and into the grooves I cut.Tear the carb down afterwards and clean it out.I think you mean "dont touch the SLIDE",you want the plate close to the slide as you can without the possibility of it causing the slide to stick open.I work 10hr shifts,but if you can wait untill I have some free time Ill take pictures  and post them nekt week so you can get a better idea.

[Sharc]

Very cool. A photo'd be great. Nice old-school do it for free in your garage mod, like they USED to have in Dirt Bike magazine back in the day....Now they get $7,000 bikes, put $3, 500 in "needed" extras and call it good....


Sharc

[toddwunsch]

Thanks.  I'll save the $100 and wait for the pics.

[mikesmith]

Well I tried to get some decent pictures but my $29.00 camera isnt good for close ups and to get a clear picture its to far away to see the detail.Its raining all week,and to have a bright enough light to get a pictue makes it hard to see,(washes out the detail), so you can get an idea hopefully from these.Its .042 sheet aluminum,60mm wide at the mouth,46mm in length,1/16" clearance at the slide.The first picture shows how much hangs into the air box boot,the last picture shows the shape to fit around the slide looking down from the top of the carb(horse shoe shape).The center pictures I was trying to show how it fits in the grooves in the mouth of the carb.The new issue of Dirt Bike magazine has a picture of one installed on a KX125 you can look at,sorry for the poor pictue quality.