Improving gas mileage...

[CrazyHorse]

 

Interestingly, I've read from at least two others here that their summer mileage is BETTER than winter mileage. I've never noticed this kind of seasonal difference before on my cars or bikes. So the wind resistance thing, which is somewhat unique to this bike with its full-fairing, makes sense to me. I could be all wrong though!

 

Jeremy

 

Yes in northern states that actually have winter you definetley loose a few miles per gallon in the winter.

[rhncue]

My spacers also measured right at about .100". However, there is also a little protrusion that sticks off the bottom of them which holds them up another .020, making the actual effective thickness .120". I wonder if yours are the same? If so, that would mean you dropped them from .120 to .052, a change of .068".

 

I dropped mine from .120 to about .070. I did it in a couple steps; I didn't notice much difference at .090, but from .090 to .070 was 3 mpg average. I wonder if another .015 or .020 would do mine like it did yours??

 

Jeremy

 

That little tit sticking down from the plastic spacer is supposed to fit into a hole in the slide. If when installed this little tit is not placed into that hole it will put the needle in a bind and at an angle. If it is installed correctly the spacer will only be around a .100 and the needle will be free to wiggle a little bit and align itself with the nozzle.

 

Dick

[Gearhead]

On mine there were two protrusions. There is one that is taller and fits into a hole as you say. Opposite that one (180 degrees around) is a larger but shorter one that actually sits on the slide and holds the spacer up by another .020". I took measurements of the actual needle prutrusion from the slide to confirm this.

 

Jeremy

[Venturous Randy]

On mine there were two protrusions. There is one that is taller and fits into a hole as you say. Opposite that one (180 degrees around) is a larger but shorter one that actually sits on the slide and holds the spacer up by another .020". I took measurements of the actual needle prutrusion from the slide to confirm this.

 

Jeremy

 

My carbs are like this, they have the locating pin and a raised area opposite the pin.

I have two sets of 83 carbs and none of the needles have the adjustment slots. As noted above, the spacer is about .123 including the raised area. I picked up a set of #4 washers(not 4mm washers) at Lowes and when I checked the thickness, it was about .033 each. But, if you stacked them with the burr side going in the same direction, three stacked up to about .090. I first tried two washers and the bike did not like that and it would have been a change of about .063. It did not want to idle at all and the off idle response was bad. Two washers was a change of about .033 and so far I am happy with the way the bike is running. It may even picked up a little more bottom torque that I lost with the new diaphragms. I am going to leave it like this and see if it helps.

RandyA

[rhncue]

On mine there were two protrusions. There is one that is taller and fits into a hole as you say. Opposite that one (180 degrees around) is a larger but shorter one that actually sits on the slide and holds the spacer up by another .020". I took measurements of the actual needle prutrusion from the slide to confirm this.

 

Jeremy

 

Sorry, my bad. I just took one apart again and now see what you described. I never noticed that before.

 

Dick

[rhncue]

My

carbs

are like this, they have the locating pin and a raised area opposite the pin.

I have two sets of 83

carbs

and none of the needles have the adjustment slots. As noted above, the spacer is about .123 including the raised area. I picked up a set of #4 washers(not 4mm washers) at

Lowes

and when I checked the thickness, it was about .033 each. But, if you stacked them with the burr side going in the same direction, three stacked up to about .090. I first tried two washers and the bike did not like that and it would have been a change of about .063. It did not want to idle at all and the off idle response was bad. Two washers was a change of about .033 and so far I am happy with the way the bike is running. It may even picked up a little more bottom torque that I lost with the new diaphragms. I am going to leave it like this and see if it helps.

RandyA

 

I also have two sets of carbs for an 83 and mine, like yours, have only one place for the "C" clip.

 

Dick

[Gearhead]

I first tried two washers and the bike did not like that and it would have been a change of about .063. It did not want to idle at all and the off idle response was bad.

 

Well that's weird, since the idle is controlled by the pilot circuit. I wonder why it killed your idle?

 

Jeremy

[Venturous Randy]

Well that's weird, since the idle is controlled by the pilot circuit. I wonder why it killed your idle?

 

Jeremy

 

Actually Jeremy, I wondered the same thing, but as you can see from my update post, I am real happy with the change I made.

RandyA

[MasterGuns]

After running with the three #4 washer mod for about 10 days, tonight I finally pulled a plug and it appeared to be burning way lean. So, if I was to add a 4th washer, I would darn near be back to where I started. Rather, I reinstalled the OEM plastic spacers, reassembled everything, threw my Carbtune on for a quick sync. I will take her on a good long ride tomorrow to check things out further but I am sure she is now fine. I am going to check my mileage and see how much it has dropped, if any.

[Venturous Randy]

It was rare that I got 40mpg. After the three washer change, The last three tanks have been 45, 48 and 45mpg. The 48 was 1-up and running from 40 to 55, thru the mountains last weekend. I put new plugs in about 1,000 miles ago and have not looked to see what they look like. The bike is running strong, it is running smooth and I have not noticed the fuel smell when it is idleing, like I did before.

With today's gasoline, I doubt the plugs will give as good a reading as they did years ago, unless you are running very rich.

RandyA

[Moparlvr4406]

I know this is true with diesel fuel but I think gas is the same year around.

 

I would guess getting better gass milage in cooler weather would have something to do with the air being more dense.

Actually in the midwest there is a difference

Ethanol content will run higher in the winter than summer to remove winter condensation and ...too much ethanol in the summer can cause vapor lock and a condition called "hotsoak"...hotsoak occurs on short hot shutoff periods when the alcohol boils in the fuel lines and basically pushes the gasoline out of it's way and causes long crank times and possibly a vaporlock no-start.

 

BTW...my 93 1300 gets 43-45 on good quality regular grade fuel

[Guest curtismiller]

I would suggest you measure your exhaust gas temp before and after this leaning.As a pilot I know too lean aint always good. curtis

[greg_in_london]

Well on Saturday I finally got aroung to pulling the carb slides to do both carb diaphragms and the spacers under the c-clip.

 

I know it is always better to do one job at a timeand check the differences, but doing two jobs at the same time alos means that they both get done.

 

The diaphragms went much more easily than I expected - so much so that I worried I was cutting a corner somewhere.

I used a flathead screwdriver to open the two plastic rings slightly to make it easier to work the diaphragm out, just pulling gently. I then stretched the inner lip of the new diaphragm over the two discs and worked the lip into the gap with a thumbnail.

I would have preferred to have used some lubrication, but the rubber grease was not to hand and none came with the kit. In any event, they went together easily. I used the ones from the group buy deal.

 

I measured the plastic spacer under the clip on the needle (no adjustment on my 83) as 2.5mm (120 thou) and the washers a neighbour provided were about 0.6mm. Three of those made 1.8mm (70 thou according to my calipers).

 

[if some early Ventures DID have adjustable needles, wheras others did not, this mightlend credence to the idea suggested in that long thread on economy I started last year - there could hve been significant difference in carburation on some bikes, which might not even have been model specific !]

 

First impressions were pretty good. Winding it open in first had a sound as if the bike was clearing its throat at about 5 thousand, but I didn't usually rev that hard in first, so wasn't sure if that was new. At all other rev/speed combinations it seemed very happy. I'm aware that any new change always seems to have a honeymoon effect, probably because I want it to work, so today I'm going to do a few miles to see if the mpg has improved.

[Venturous Randy]

I measured the plastic spacer under the clip on the needle (no adjustment on my 83) as 2.5mm (120 thou) and the washers a neighbour provided were about 0.6mm. Three of those made 1.8mm (70 thou according to my calipers).

 

[

 

From my 1st try, .070 would have been too little on my bike. I believe I ended up with about .093 to make my bike happy.

Thanks for the note and look forward to the update.

RandyA

[Gearhead]

With today's gasoline, I doubt the plugs will give as good a reading as they did years ago, unless you are running very rich.

 

That is my impression. I've read it in engine-tuning books. Plug reading was always an art, and nowadays it's lost some validity.

 

Jeremy

[saddlebum]

interesting I will have to try it for sure:think:

[greg_in_london]

Ok, well sorry I've been slow getting back. It took a little while to clock up any miles and then we were on holiday for three weeks and then back to work.

 

I kept track on mileage and fuel top-ups, but there is no consistency to types of use.

 

Overall, though, I was acutely aware I had not had time to balance the carbs. They felt as if they were misfiring under accelearation at highish revs, but on a gentle throttle did rev cleanly. It felt as if it were less torquey, but the clutch still slipped, so maybe it just ran into higher revs more easily. I'm not sure.

 

I've left fuel amounts in litres, so you can work it out in your funny sized gallons, but my estimated mpg figures are imperial.

 

Mileage

250 filled tank

355 14.75l 32mpg mixture of traffic and A-roads

448 13.6l 33mpg " " "

558 15.65l 32mpg A-roads and motorway

675 15.1 35mpg A-roads, choke left on by accident

787 16.5l 34mpg A-roads and motorway. Traffic jam (40mins) in Dublin.

868 11.7l 31mpg mixed Irish roads, some hills..

[During an Irish music festival the trip meter got reset, which is annoying as I was pulling a trailer for this part of the trip and I wanted to compare this mlieage particularly.]

086 12.6 31mpg Irish roads, mostly without trailer

181 16.0 27mpg Diverting through Wales, striking scenery, but wet and slow.

268 12.5 31mpg A-Roads and motorway

376 15.7 31mpg nearly all motorway, heavy rain

 

Probably not useful to others, as I have a sidecar, but it is still possibly a small improvement.

 

I just don't know when I'll be able to tweak the carbs. It does sound as if I have a small exhaust leak too, but in all the time away, it was never dry enough to want to crawl underneath to have a look notthat I would have been able to do anything, anyway.

[Ozlander]

your funny sized gallons

 

Hey, the King started the gallon thing. At least we are loyal to the King in that respect.

[greg_in_london]

The imperial gallon is based on the ale gallon, whereas the US gallon is based on the wine gallon. (Source: [ame]http://en.wikipedia.org/wiki/Gallon[/ame])

 

Must say something about the different national priorities....

[1joeranger]

I was gonna update everyone with a picture of my plugs after going 15,000 miles, 12K of which was hauling a trailer across most of the US and 1/2 of Canada this summer. After catching up on my reading here I see that plug reading isn't really viable anymore. So I will spare the picture. I will say that the plug looked fine. I cleaned and reinstalled her and I am still averaging 45mpg when not hauling the trailer or doing 85 into the wind while out west!

 

Thanks 5bikes!

[GaryZ]

This is a very interesting carb tuning instruction found on a Vmax site;

 

http://www.vmaxoutlaw.com/tech/cv_carb_tuning.htm

[SaltyDog]

I have a '83 standard that has about 70K miles and this last summer I wanted to check the mixture with my brothers Air/Fuel meter. I placed the sensor into each tail pipe after the bike was warmed up and took some initial readings. With no real suprise the bike was quite rich at idle and throughout the rpm range up to 5K RPMs. I haven't had any problems with the plugs fouling but I wanted to get the bike into a better air/fuel ratio range.

 

 

I considered using small washers to adjust the needle depth but I like the stock plastic centering washer. With alittle careful sanding on the top, I reduced the thickness of the stock plastic washer 1mm, from a measured 2.5mm (.100") to 1.5mm (.060"). I figured if this was too thin, I would just add shims on top of the plastic washer below the c-clip on the needle. On other CV carbs I have tuned (car and bike), the piston needle is biased or located in the needle jet bore. The Venture carb needle plastic washer also keeps the needle from spinning in the piston. I don't think it moves much during use but I like to keep the variables to a minimum.

 

 

After reducing the thickness of the plastic washers and reassembling the carburettors, I ran another test with the Air/Fuel meter. The mixture dropped close to perfect at idle and slightly rich during higher RPMs. I called it good and then ran the crap out of the bike the rest of the summer. The plugs look good and show no sign of overheating. The bike starts great when hot (I already upgraded the electrical starting system) and no problems when cold.

 

 

This is a great modification to attempt on these bikes and will show real world improvement. My gas mileage had been running in the 40-45 MPG range with all my 50-60 MPH runs through the hills and curves in Arkansas (not bad but I wanted to see if more was possible). After the change to the plastic washers, my mileage has moved up into the 45-50 MPG range. I ride pretty mildly when in the hills (too many deer and slow farm trucks) and my rides include alot of hills and curves. On my trips where I can get on a 4 lane highway, my mileage has stayed in the ~50 MPG range. I run the speed limit ~65-70 MPH and really like the power the bike has when needed to pass slow vehicles.

[CrazyHorse]

I have a '83 standard that has about 70K miles and this last summer I wanted to check the mixture with my brothers Air/Fuel meter. I placed the sensor into each tail pipe after the bike was warmed up and took some initial readings. With no real suprise the bike was quite rich at idle and throughout the rpm range up to 5K RPMs. I haven't had any problems with the plugs fouling but I wanted to get the bike into a better air/fuel ratio range.

 

 

 

I considered using small washers to adjust the needle depth but I like the stock plastic centering washer. With alittle careful sanding on the top, I reduced the thickness of the stock plastic washer 1mm, from a measured 2.5mm (.100") to 1.5mm (.060"). I figured if this was too thin, I would just add shims on top of the plastic washer below the c-clip on the needle. On other CV carbs I have tuned (car and bike), the piston needle is biased or located in the needle jet bore. The Venture carb needle plastic washer also keeps the needle from spinning in the piston. I don't think it moves much during use but I like to keep the variables to a minimum.

 

 

After reducing the thickness of the plastic washers and reassembling the carburettors, I ran another test with the Air/Fuel meter. The mixture dropped close to perfect at idle and slightly rich during higher RPMs. I called it good and then ran the crap out of the bike the rest of the summer. The plugs look good and show no sign of overheating. The bike starts great when hot (I already upgraded the electrical starting system) and no problems when cold.

 

 

This is a great modification to attempt on these bikes and will show real world improvement. My gas mileage had been running in the 40-45 MPG range with all my 50-60 MPH runs through the hills and curves in Arkansas (not bad but I wanted to see if more was possible). After the change to the plastic washers, my mileage has moved up into the 45-50 MPG range. I ride pretty mildly when in the hills (too many deer and slow farm trucks) and my rides include alot of hills and curves. On my trips where I can get on a 4 lane highway, my mileage has stayed in the ~50 MPG range. I run the speed limit ~65-70 MPH and really like the power the bike has when needed to pass slow vehicles.

 

Your bike shouldve had adjustable needles to begin with.

[SaltyDog]

Mine ('83) came with fixed needles and so did another set of carbs from a '83 donor bike. I don't believed Yamaha installed the adjustable needles on all the '83 bikes. I have heard the same story over and over that they should have these adjustable needles. I would be interested in knowing the serial numbers of a bike that DID come with them from the factory.