What gas mileage do you get ?

[greg_in_london]

Fuel capacity is 19-20 litres, that's 3 1/2 UK gallons or 4.3 US gallons. [Edit:correction, see below, that's 4.4 gallons, or 5.3 US gallons]

 

A while ago we had a long holiday across to the Czech republic. We were keeping the speed steady (didn't want a breakdown a long way from home) and were travelling at 55-60mph on the autobahns and 50-ish on other roads. We had plenty of time to check out the mpg without any significant acceleration, just kicking back, listening to the stereo, comparing miles to what the speedo said and checking out the scenery.

2100 miles in 20 days.

 

I had the bleed valve set to bypass so the radiator hardly got warm (was jammed when I first investigated it) and hoped that the mpg would get better when I replaced it and running temperature increased, but it didn't make a difference.

[BJB]

Uh Greg...I think you have a problem!

 

"Fuel capacity is 19-20 litres, that's 3 1/2 UK gallons or 4.3 US gallons."

 

20L coverts to 4.4 Imp Gal or 5.3 US gallons. Hope you just had a typo?

[Gearhead]

"I get about 30mpg (UK) with a sidecar, pulling a trailer, on a run; but I only used to get about 33-35mpg solo.

I've checked the float height, balanced the carbs, changed the plugs (currently iridium) and put on an easy flowing air filter."

 

 

Well, with a sidecar and a trailer I wouldn't consider your mileage to be out of line. That's a bunch of extra weight and drag. Also, I don't think we get better mileage because of our "aero" fairings, I think it hurts mileage because of the huge frontal area.

 

I ride a stock 87 VR. I've done all the tune-up - details following.

 

My best - 42 US, riding mountain 2-lane with skinny daughter on back, mellow speeds.

 

My worst - 25 US, blasting desert interstate at 107 deg F and 85-90 mph, wife on back of bike. I was disappointed to say the least.

 

My experience and others certainly points to speed as a huge factor. Why so sensitive? My Camry mileage drops from maybe 32 US at low speeds to 26 US at 85-90 mph. Why does the Venture drop so much more? Also, seems to me I get better mileage when weather is cool, sorry to be contrary :-)

 

I bought mine with 45K miles and considerable deferred maintenance. It was getting about 32 US in my normal daily cycle. I found vacuum advance not functioning due to corrosion in connector right under battery. That liberated a whopping 2 or 3 mpg. I've tuned carb pilots (only fuel pilots, by the way, no air screw), checked fuel levels (OK), replaced shot slides, checked plug wire resistors, air filter clean, changed all fluids, checked compression (OK), adjusted valves and I can't even remember what else. I've really done all the basics. I have NOT removed and disassembled the carbs, but I have no evidence that they are bad inside as the bike runs like a bat.

 

I've messed with the airbox a little. This bike may not be sensitive to exhaust tuning, but it IS sensitive to the airbox. Try to idle it and then give it throttle with airbox lid removed and you'll see what I mean. It won't take throttle. (4) 1/2" holes in airbox lid is considered to be OK and potentially beneficial to running and maybe mileage. I've done this, then taped them over, then opened again, not sure I seen any difference. Nothing major anyway.

 

One more data point. I also have an 87 Yammy Virago 1100. Stats:

 

VENTURE.................VIRAGO

800 lbs....................550 lbs

Full huge fairing.......mid-size shield

Huge luggage...........mid-size bags and soft trunk

1300cc....................1100cc

4-cyl........................2-cyl

~100hp...................~60 hp

38 mpg US avg........40 mpg US avg

25-42 US.................32-44 US

 

Notice the Virago isn't much better on gas than the Venture, except in the worst case. I've been in the same discussions on Virago forums, and the gamut of mileage reported is like 30 - 55 US. What these two bikes do have in common is low gearing. Most cruisers have much taller gearing than the Virago and get a little better mpg (mid-size cruisers, anyway). Most dressers have taller gearing than the VR. I've heard the 1800 Wings get around 40-42. They have a bunch of power, but also have EFI.

 

Go figure.

 

Jeremy

[greg_in_london]

Yeah BJBoomer - it was a typo - or at least a moment of misplacing some fingers when I was counting:bighug:.......

 

Gearhead:

Every now and then I think about how much weight I can be pulling and think 'Hey, it's not so bad' - but there really was not much difference in mpg when I put the sidecar on ~ 4-5 mpg maximum ~ and from experience a trailer does not affect mpg very much when you're on the flat and away from town traffic. (In stop/start traffic or through the hills, yes, but not as much as you'd expect)

 

If no-one else had said that they get much better mpg I would just put up with it, but if it is possible to get better mileage I'd like to know how. I'm going to fiddle with the vacuum advance/retard tomorrow - if it only makes 1-2 mpg difference that's still a help, but more would be better.....

 

Remember one of the first posts said that on average riders were getting 40-47 mpg US (45-55mpg UK) and that's an awful lot more than I ever managed. Let's hope I can find that Holy Grail.

[Gearhead]

Greg, I hope you find it! I could not. I would say, from what I've read here over the last 2 years, that the average is more like 38-40. Mabe they've made miles longer since that survey! :-)

 

Jeremy

[bobcat]

Most bikes but especially my 86 VRs mileage is determined by speed..Of course things like head winds and climbing hills are major factors but overall speed is the main factor..I usually get about 40 mpg as long as I keep the speed to 65mph or less and take off gently from stops..I live in Nevada which has a lot of open roads so I find myself going 80-90 quite frequently..then my mileage slips to 33-35 mpg..

[greg_in_london]

Hmmm, Bobcat - not quite sure what you're getting at here - when you're travelling at 80-90 mph you're getting significantly more to the gallon that some of us get at 50-55mph. It doesn't support the idea that it's dependant on riding style - tou're sure you're not just showing off ?? Either way you're saying that 40 to the US gallon (50mpg UK) is attainable - what do I have to do to get it ?

 

Back to the plot:

 

I pulled off the carburettors today to get at the vacuum advance/retard. I couldn't check for holding a vacuum other than by sucking on it and checking the vacuum against my lip, but it seemed okay. I did try checking it could hold pressure by pumping 10-12psi (manual says okay to at least 600mm Hg, so won't damage it) and it only lost pressure at the speed that the pump does anyway whne I put my finger over the end. So far as I can check it's airtight, then.

 

I checked the output voltage and it was about 2V. I've leant out/given away/had stolen my better multimeters and I've not much faith in the accuracy of the one I was using, but it should be close enough. I pressurised the unit to 10-12 psi, but the output voltage rose only to 3V, rather than 4.9v that the manual says. By just sucking on the tube I was able to drop the voltage to 1v.

When people have said they'd had problems it has been down to a dodgy connection or complete failure. Does this sound like a failing unit or is it within normal functioning range ? Are the exact voltages critical ? I could delay rebuilding it until I grab hold of a better meter, but if it's not critical could just put it back together - after all there won't be positive pressure much of the time, will there ?

[Guest Bigin]

Another thought, is your gasoline the same as ours? Does it have the same output when burned as it does here?

 

I know that there are many blends out there and am told the corn based methanol types do not have the same power output, and mileage is less when used.

 

Dont know about your area though.

[Gearhead]

If you have access to a mighty-vac hand pump, you can check that it holds vacuum, although your tests sound pretty much OK. You can easily see if it is working its magic like this. Get the bike running again. (Although while the carbs are off you might want to pull the bowls, slides and coasting enrichment diaphragms and check things out.) Disconnect the vac hose to the advance unit and plug the intake stub nipple. Adjust the idle up to about 2000 rpm, because the vac advance does not funtion below that. Now suck on the end of the hose, and the engine rpm should increase. Release the vacuum and it should come back down.

 

It will never have pressure on it, always vacuum.

 

Jeremy

[greg_in_london]

Thanks Gearhead, I've checked the float levels and will adjust them tomorrow (food beckons now) - before I checked them last time the level was too high, now it's a little too low.

 

I do find these carbs confusing - I really don't quite understand the coasting enrichment valve and so leave it alone. Whether it can be a cause of extra fuel consumption I don't know.

From checking the manual, it looks as if the mixture is defined by the air jet and the jet block and the pilot screw determines how much of the mixture is drawn in, rather than setting the mixture - unless the purge holes let lots of air in - or maybe I'm just confusing myself.

 

I'll try sucking on the pipe at 2000 rpm - I wouldn't have thought of it because I'd have expected there to be plenty of vacuum already (more than me sucking, anyway) - after I put it back together tomorrow.

[GigaWhiskey]

Most of you might think I carry a crack pipe after this post but maybe, when looking at lower mpg numbers, I would think that it could be related to something else other than the carbs (Not just the carbs by themselves).

 

Here is my thought. Yammy made what, 10/11 years of this bike. What would make you think that Yammy put these engines together exactly the same. I think it could be possible that the internal engine timings might be off a few degrees, either way, to make the difference that many of you are seeing.

 

The reason I had this thought back when I was a youngin, I had a '76 Honda SuperSport 400-4 with very low miles. I downshifted too many gears accidentally and blew a hole int he piston about the size of a dime. I changed the piston and timed it exactly to the specs provided by the manual I was using. After it was back together and running, there was a very noticeable increase in power. THis to me makes me think the manufacturer may have been a bit off on the internal timeing of this motor when it was initially built and mounted in this bike.

 

So, who knows, maybe I got something here, maybe I don't.

 

Pipe is empty now.

[Gearhead]

Well, GW, we all know there are lemons out there, your theory could be correct. Kinda sucks if you're one of those with low mileage.

 

At idle rpms the engine doesn't pull too much vacuum at each carb. The key is you put vac on the line, then let it out, and see if the rpm responds accordingly.

 

I'm not sure that the coasting enrichers can hurt the mileage. I think bad diaphragms there would just cause a very small vacuum leak. What they do it this: on the overrrun (letting off the throttle to utilize engine braking), engines tend to go lean and thus misfire. This is not really a problem, just causes popping in the pipes, but it increases emissions. The coasting enricher counteracts this by enriching the mixture a little under hi-vacuum conditions. Here's how. The pilot (idle) circuit meters a mixture of fuel and air thru a pilot fuel jet and two pilot air jets. Under hi-vacuum, the coasting enricher pulls against a spring and closes off one of the pilot air jets, reducing the air supply and thus enriching the mixture.

 

Jeremy

[Venturous Randy]

Laura and I took a 150 mile ride Sunday after filling up. I put 10 more on way to work and back and filled up and got 44.5. That is a little better than usual, but only about 20 miles of ride was 65 mph. The rest was 40 to 55 mph.

RandyA

[friesman]

Ive an 85 VR with 38000 kms on it that Ive had on the road for about 3 weeks now. So far I am averaging about 28-30 kms after putting on about 800kms. I am thinking the biggest reason for my poor mileage is the weather Ive been riding in is usually 2 celisius to 8 celsius so ive needed some choke on quite a lot of the time. Today I was out and about for about 150 kms with the temp about 16 celsius and i was able to back the choke way off for the first time since owning the bike.

 

Brian

[BJB]

Friesman1,

I live in Swift, just 150 miles down the road, and have been riding for a week or two already. I never have to have my choke on to ride. I just barely put it on to start it and that's it. I am getting 38-40 MPG (imperial) so far. Hope it will improve some in warmer weather.

[bobcat]

Hmmm, Bobcat - not quite sure what you're getting at here - when you're travelling at 80-90 mph you're getting significantly more to the gallon that some of us get at 50-55mph. It doesn't support the idea that it's dependant on riding style - tou're sure you're not just showing off ?? Either way you're saying that 40 to the US gallon (50mpg UK) is attainable - what do I have to do to get it ?

 

********************************************************************

 

Maybe my bikes a freak but thats what my mileage has been....I haven't done anything special except run Mystery oil and Sea Foam through the gas every now and then..I change plugs once a year and do a carb sync after I change plugs..I did change the diaphrams a few years ago just to get it out of the way before they went bad....Dunno what else to say about mileage..

 

Almost forgot....I did reroute the crankcase vent hose..Instead of it going into the airbox I rerouted it to the outside where the battery hose vents....I never liked the idea of a vent hose venting into the carbs.. shh, don't tell anybody

[hipshot]

Ive an 85 VR with 38000 kms on it that Ive had on the road for about 3 weeks now. So far I am averaging about 28-30 kms after putting on about 800kms. I am thinking the biggest reason for my poor mileage is the weather Ive been riding in is usually 2 celisius to 8 celsius so ive needed some choke on quite a lot of the time. Today I was out and about for about 150 kms with the temp about 16 celsius and i was able to back the choke way off for the first time since owning the bike.

 

Brian

 

brian.

could you translate all of that info,into AMERICAN???????

i don't do celcius, at all!:confused24:

lol

just jt

[Gearhead]

"So far I am averaging about 28-30 kms after putting on about 800kms. I am thinking the biggest reason for my poor mileage is the weather Ive been riding in is usually 2 celisius to 8 celsius so ive needed some choke on quite a lot of the time. Today I was out and about for about 150 kms with the temp about 16 celsius and i was able to back the choke way off for the first time since owning the bike."

 

I ride thru the Tucson winter, where it is not unusual for me to start out in near-freezing temps in the morning. Choke is only on for maybe two minutes. Start with choke, back out, drive part way down dirt road, turn choke off.

 

 

"Almost forgot....I did reroute the crankcase vent hose..Instead of it going into the airbox I rerouted it to the outside where the battery hose vents....I never liked the idea of a vent hose venting into the carbs.."

 

Did you put any kind of filter in line in that hose? I would.

 

Jeremy

[bobcat]

Did you put any kind of filter in line in that hose? I would.

 

Jeremy

 

Nope...no filter..If you're thinking its a dangerous situation by releasing oil in front of the rear tire, its never been an issue and I've had it that way for years..... At first I thought the same thing but no oil has ever appeared on the rear tire..One probably gets more oil on their tires while cruising through a Walmart parking lot..

[Gearhead]

I was actually thinking of dust in the crankcase.

 

Jeremy

[greg_in_london]

Hi Gigawhiskey

 

That's the sort of thing I've wondered about. I have seen big improvements on a bike after reinstalling a camchain, but that was more likely due to a previous owner than the factory. (Not an XVZ) If there were something that could have been wrongly installed, surely someone would have noticed by now, though. I know that they're a tough engine and simply don't need to be pulled apart , but surely someone would have had tocheck the valve timing or how some gears go together - if there are two ways two parts could mate together there would be a technical note somewhere saying 'WARNING' - don't mess this up.

The other, related, possibility is that Yamaha could have been sourcing some of its parts from two places, or using different parts in different markets, or have tried one design and switched to another, but used up the stock of old parts. Could it be that some engines have slightly different cam profiles than others, with different valve timings and/or durations ? [Are V-max cams the same ?]

Surely Yamaha could have come clean on this by now (albeit unofficially) if something like this happened - or maybe it's so long ago they've all forgotten/retired. Maybe I've just added a new conspiracy theory - oops.

 

Hipshot - the whole world uses Celsius - just remember '0' is freezing and after that it gets better. 20'C is room temp. 100'C and the kettle's boiling.

 

Gearhead - thanks for explaining that - I hadn't realised that it was a pilot air jet that was blocked and thought it pumped extra fuel in. My commuter is an XTZ660 which also has that valve. Before I changed the carb on that I was getting low 30s mpg (UK), afterwards 57mpg, but popping on the over-run. I might switch the valve over from the old carbs if it won't push the mpg down again.

 

Bobcat - I know what you mean about the air breather - I have an XJ750 that was breathing badly that I swear sucked up oil, but whether it's better to have one probably depends where you are. Some people say a slight vacuum in the cases is a tuning bonus, others that it helps drive out moisture. Parts suppliers recommend a filter if it vents to the air. I don't think it's a big thing though. I might try it after I've used all my other ideas, but won't hold my breath on it making a diference !

I'd happily try new diaphragms, but they're not exactly cheap and mine seem okay. If anyone wants to lend some new ones for an experiment though ...

Nope ?? Oh well never mind.

 

RandyA - well 44mpg is over 50mpg (UK) If that's in traffic or on litle twisty roads then that's quite acceptable. If it was on the freeway - 40mph - wouldn't you have been run of the road by trucks ?

 

Plan for today - reset carb floats and reinstall. I might try and check those plenum chambers if I can think of a way of doing it. I don't think blowing pressure in would be a good idea would it ? *pop*

[starriders777]

I get 40 to 42mpg on my 99 rsv

[GigaWhiskey]

I am usually around 40mpg. Just like in the chart.

[bobcat]

That one is easy to answer.....The inlet on the airbox cover is outside the filter..If that is still an issue you can alway tape the opening shut..

 

BTW: I just got back from your neck of the woods..went to a couple of spring training games..beautiful weather, nice riding country.

[Gearhead]

"My commuter is an XTZ660 which also has that valve. Before I changed the carb on that I was getting low 30s mpg (UK), afterwards 57mpg, but popping on the over-run. I might switch the valve over from the old carbs if it won't push the mpg down again."

What was wrong with the old carb that made mileage that bad?

 

 

"I'd happily try new diaphragms, but they're not exactly cheap and mine seem okay. If anyone wants to lend some new ones for an experiment "

 

If the diaphragms are bad you can see the holes. Hold them up to the light and look for little pinholes. Mine were much worse than this, no special light required!

 

Jeremy