Improving gas mileage...update

[Venturous Randy]

Like several on here lately, I replaced my diaphragms and even though the bike ran stronger under wide open throttle, my low rpm torque seemed to go down some and my gas mileage seemed to drop a little also. I was getting around 38 to 41 with the old diaphragms and the next two fillups after the new diaphragms were about 37-38 and that was 1-up.

Yesterday I replaced the .123 thick washer on the needle with three #4 washers that came to about .093 and made a 250 mile ride today, 2-up. Before at about 140-150 miles, the red light was blinking on fuel. Today at 150 miles I still had two bars left. I should have filled up at that point, but I then did a twelve mile pull up the mountain from Morganton, NC to the Blue Ridge Parkway and stopped and filled it up. At the top of the mountain I had 162 miles on it and had just dropped to one bar. When I filled up and put all I could get in it, it only took 3.6 gallons, so that works out to 45 miles per gallon. And, not only did my MPG's go up over ten percent, but now I feel I have the low rpm torque back.

So, if you have not considered making the change on the needle valve adjustment, I am strongly suggesting that you do it. It only took me a few minutes to do it, but I don't run the lower fairings anymore and all I had to take off is my bikini side panels. Even taking all the lower fairings off, it is not a big deal and well worth the effort.

RandyA

[skydoc_17]

Hey Randy,

Thanks for taking the time to let us know the results of your needle shim mod. Many times someone will talk of doing a mod on their bikes and you never hear the results.

I have been doing a lot of Carb. Diaphragm replacements lately and I tell everyone that if you want to see an improvement in your gas milage, do the needle shim mod at the same time. Some get it, some don't. I would love to take a ride with you sometime, I bet that bike of yours is a real screamer!

Thanks again,

Earl

[Condor]

Ya know, call me stupid...or what ever, but I'm having trouble getting a mental picture of what's going on with this washer mod, and why it increases MPG. As Randy stated he replaced the thick plastic washer which measured .123", with a stack of 3 ea. #4 washers that measured .93" thick. Now here's where I get into trouble. If the needle is shortened by the lower washer height, then wouldn't the jet be opening up quicker and increasing fuel delivery??? And wouldn't this cause mpg to decrease?? I'm befuzzled....

[BigBoyinMS]

What it does is drop the needle lower which is slightly leaning out the main. It stays on the fat part of the needle longer.

[Venturous Randy]

Ya know, call me stupid...or what ever, but I'm having trouble getting a mental picture of what's going on with this washer mod, and why it increases MPG. As Randy stated he replaced the thick plastic washer which measured .123", with a stack of 3 ea. #4 washers that measured .93" thick. Now here's where I get into trouble. If the needle is shortened by the lower washer height, then wouldn't the jet be opening up quicker and increasing fuel delivery??? And wouldn't this cause mpg to decrease?? I'm befuzzled....

 

Condor, your thinking backwards again. By putting in a thinner washer, you are extending the needle out more with it sticking into the jet more. The washer goes under the clip and spring.

I bought three bags of washers at Lowe's for $.80 cents each and I bet I paid for them yesterday with the savings in ga$. Plus, the bike ran better for me.

RandyA

[Condor]

Condor, your thinking backwards again. By putting in a thinner washer, you are extending the needle out more with it sticking into the jet more. The washer goes under the clip and spring.

I bought three bags of washers at Lowe's for $.80 cents each and I bet I paid for them yesterday with the savings in ga$. Plus, the bike ran better for me.

RandyA

 

Yeah the light bulb just turned on.... The washer's on the inside of the plastic slide. Doh!!! It's been a while since I've 'screwed' around with a diaphragm.... You younger guys need to keep watch over us OF's....Thanks!!!

[Yammer Dan]

Glad I didn't jump in that one. Sometimes it pays to wait. Espically when you are thinking like Jack.

[Venturous Randy]

Glad I didn't jump in that one. Sometimes it pays to wait. Espically when you are thinking like Jack.

 

Dan, you thinking backwards too?

RandyA

[Maritimer]

That sounds like a great mod to do but the problem is that I am not mechanicly inclined at all. How hard is that for a non-mechanic to do?

 

Pictures if required would help or at least a very detailed how to would be appreciated.

[Venturous Randy]

That sounds like a great mod to do but the problem is that I am not mechanicly inclined at all. How hard is that for a non-mechanic to do?

 

Pictures if required would help or at least a very detailed how to would be appreciated.

 

Can you put your shoes on by yourself? If you can, you got it made.

RandyA

[MasterGuns]

Like several on here lately, I replaced my diaphragms and even though the bike ran stronger under wide open throttle, my low rpm torque seemed to go down some and my gas mileage seemed to drop a little also. I was getting around 38 to 41 with the old diaphragms and the next two fillups after the new diaphragms were about 37-38 and that was 1-up.

Yesterday I replaced the .123 thick washer on the needle with three #4 washers that came to about .093 and made a 250 mile ride today, 2-up. Before at about 140-150 miles, the red light was blinking on fuel. Today at 150 miles I still had two bars left. I should have filled up at that point, but I then did a twelve mile pull up the mountain from Morganton, NC to the Blue Ridge Parkway and stopped and filled it up. At the top of the mountain I had 162 miles on it and had just dropped to one bar. When I filled up and put all I could get in it, it only took 3.6 gallons, so that works out to 45 miles per gallon. And, not only did my MPG's go up over ten percent, but now I feel I have the low rpm torque back.

So, if you have not considered making the change on the needle valve adjustment, I am strongly suggesting that you do it. It only took me a few minutes to do it, but I don't run the lower fairings anymore and all I had to take off is my bikini side panels. Even taking all the lower fairings off, it is not a big deal and well worth the effort.

RandyA

 

Randy, Did you check your plugs before this washer mod and compare them with how they are burning after the washer mod? I am just curious. I want to perform the same mod on my 86 and would like a little more details if possible. On mine, I am getting somewhere around 37 or so mpg and the plugs look a little rich so the sooner I get off my butt and do this thing the better.

[Venturous Randy]

Randy, Did you check your plugs before this washer mod and compare them with how they are burning after the washer mod? I am just curious. I want to perform the same mod on my 86 and would like a little more details if possible. On mine, I am getting somewhere around 37 or so mpg and the plugs look a little rich so the sooner I get off my butt and do this thing the better.

 

No, I did not. I put new plugs in it only a couple of weeks ago and the old ones looked a bit sooty. I will give these some miles and see how they look. I bet you that you can bump up to at least 43 and the bike run better. Mine does require a little choke now that it was not require earlier since the weather is warmer.

I tried first with only two washers and the bike did not like that at all.

RandyA

[Maritimer]

Can you put your shoes on by yourself? If you can, you got it made.

RandyA

 

LOL good. That makes me feel more confident that I can do such a mod.

[Rocket]

LOL good. That makes me feel more confident that I can do such a mod.

Did you pick up a 1st gen to play with, or are you going to try this with your 2nd gen????

[skydoc_17]

For anyone that is interested, If you go to page 2 of the thread below, you will see pics of the needle for the main jet, the original nylon shim and the replacement S.S. washers used in place of the nylon shim.

 

http://www.venturerider.org/forum/showthread.php?t=35110&page=2

 

If anyone has any questions, Feel free to contact me. This has been a very effective mod for increasing the gas milage on the First Gen. VR's

 

If anyone lives close to South Central Pennsylvania,and is mechanically challanged, I do the Carb. Diaphragm Replacement and Needle Shim Mod here in "my little shop by the creek" for a bargain price.

Earl

[Venturous Randy]

LOL good. That makes me feel more confident that I can do such a mod.

 

It also helps if you liked playing with a Jack-in-the-Box as a kid.

RandyA

[Yammer Dan]

It also helps if you liked playing with a Jack-in-the-Box as a kid.

RandyA

 

 

Jill in the box lot more fun!!

[Smitty161]

Okay...so last night I did the needle shim mod. Used two #4 S.S. washers in place of the stock plastic one. Found out that I need to replace my diaphragms at some point...kind of krinkled but hole free. I first reset the idle mixture screws 2 1/2 turns out. Then I did the mod and reset idle to about 1000rpm. I then moved on to sync the carbs. All went well. This morning though on the way to work I now have a hesitation when throttling from 1000-2500rpm. At about 2500 it pins me when the gas catches up. I seem to be starving the motor a bit. May it be as simple as adding one more washer or should I play with the other adjustments. What do ya all think?

[MasterGuns]

If it were me, I think I would have no choice but to add another washer. I would be thinking it is running a bit on the lean side and that is what might be causing the hesitation. I think I would also have a looksee at the plugs as far as color. I am going to perform this mod this weekend but before I do, I am going to remove and replace the plugs. That way I will be able to compare a before and after of the most effective way of analysing lean versus rich conditions. I will, however, replace the plastic spacer with three washers. Good luck.

 

 

Okay...so last night I did the needle shim mod. Used two #4 S.S. washers in place of the stock plastic one. Found out that I need to replace my diaphragms at some point...kind of krinkled but hole free. I first reset the idle mixture screws 2 1/2 turns out. Then I did the mod and reset idle to about 1000rpm. I then moved on to sync the carbs. All went well. This morning though on the way to work I now have a hesitation when throttling from 1000-2500rpm. At about 2500 it pins me when the gas catches up. I seem to be starving the motor a bit. May it be as simple as adding one more washer or should I play with the other adjustments. What do ya all think?

[Smitty161]

Masterguns

Thanx...I believe I will add another washer...unless someone has another idea. I will let you know how it goes tomorrow with the third washer.

Jonathan

[Venturous Randy]

Masterguns

Thanx...I believe I will add another washer...unless someone has another idea. I will let you know how it goes tomorrow with the third washer.

Jonathan

 

As I noted, my bike did not want to run good on two washers. Three did fine and changed the needle location about .030, which made a difference.

RandyA

[Gearhead]

FWIW, Dynojet adjustable needles generally have the clip slots spaced at intervals of .040", and they supply a .020" washer for adjusting half-way in between. So, they give an adjustment resolution of .020". Hardware store standard washers are generally at least .031 (1/32") thick, often more. So I shopped around a couple Ace's with my caliper, looking at all the different types of washers that fit in the slide, to find different thicknesses for better adjustment resolution.

 

Jeremy

[Gearhead]

Hey Randy, what were your average speeds on your 45mpg run?

 

Does anyone else find that their mileage actually tends to be BETTER 2-up than single? I find that mileage is much more heavily affected by speed and throttle than by passenger-seat occupation, and my speeds tend to be lower with my bride on the back.

 

Jeremy

[Smitty161]

Okay, so last night I tore back into it and added the third washer. If I had thourghly read you Randy I could have saved myself some time. The third one was the ticket.

 

Need to ask...My low end is back but I still have a bit of a bobble starting out. New development for this bike. Has power but stumbles a bit. Could krinkled diaphgrams, hole free though, cause this. I will be replacing them just not right away.

 

3 #4 washers installed

Pilot screw 2.5 turns out

Idle set at about 1000rpm

Carbs sync'd

 

Jonathan

[Venturous Randy]

Okay, so last night I tore back into it and added the third washer. If I had thourghly read you Randy I could have saved myself some time. The third one was the ticket.

 

Need to ask...My low end is back but I still have a bit of a bobble starting out. New development for this bike. Has power but stumbles a bit. Could krinkled diaphgrams, hole free though, cause this. I will be replacing them just not right away.

 

3 #4 washers installed

Pilot screw 2.5 turns out

Idle set at about 1000rpm

Carbs sync'd

 

Jonathan

 

I doubt that the diaphragms as you described would cause the off idle hesitation. I would be tempted to stick the stock setup back in for a quick ride and see if it goes away. These bikes are slightly different and what may be optimum on one may not be on another.

Just out of curosity, have you synced your carbs lately?

RandyA