VF500 fuel mileage

Something just occurred to me: you live in Ca. Don't you guys have crummy gas out there? That would explain a lot. I run nothing except non-ethanol premium gas. I can't say for sure that there is a direct correlation, but I've heard comments made to that effect.

 

Ethanol will ruin fuel economy.....Jamies right.

We need to post the Type of fuel we are using and whether or not it has ethanol.

EDIT: with the Cold temps and my carbs still in need of a tune I'm getting a consistent 40MPG :-(

That's using 91 Octane without Ethanol. 42 tooth rear sprocket....spirited riding....never sees redline.

 

I have remarked that I use Premium

I use the cheapest premium I can find. That's usually ARCO (BP)at the station second nearest to me. There is no ethanol in the gasoline, at least there is no sign saying that ethanol has been added to the blend. I have a 44 tooth rear sprocket. I don't know what I have for a front sprocket but I assume it is the standard sprocket. I live in the valley between mountain ranges. I have to go look for twisty roads if I want a thrill. My bike is not made for fast cornering ('84 Vf 500C, aka "Magna V30"). Its a cruiser type bike that you drive with your back and head up.

But here is the kicker. It turns out the gearing for the Magna is different from the Interceptor. In looking up the standard sprocket tooth counts (44/15) for both the Interceptor and the Magna I noticed that my Haynes manual gives different gear ratios to the
Magna vs Interceptor.

First gear (is the same 3.308 vs 3.308
Second gear 2.167 vs 2.353
Third gear 1.667 vs 1.850
4th gear 1.375 vs 1.545
5th gear 1.154 vs 1.154
final reduction ratio 2.933 vs 2.057

It's a little confusing in that Clymer does not give the 6th gear ratio per se. Clymer quotes a "Final reduction ratio". The Clymer final reduction for the Magna is given as 2.933, which coincidentally is the same ratio as the rear to front sprockets (44/15) . How the Interceptor ends up with 2.057 is anybodies guess? :crazy:

It appears that the Interceptor has a 'close ratio gear' set up between the first 4 gears, then it jumps to the same ratio for 5th and how the final gear ration ends up so different I can't tell you unless I sit down and calculate it all out. Maybe Jamie would have an advantage in having a gearbox open or the gears available to him. I'm blind regarding how Clymer has come up with these ratios and numbers. But if he is right there is a lot of differences between the final ratios and I would think it means that the Magna is supposed to have the highway mileage advantage. But I can't say for sure unless I put some time into looking at the actual gears and how they go together.

As for the sprocket selection my bike appears to have the stock set up 44 tooth rear and 15 tooth front.

Slowbird, you have a '-2' rear sprocket. that should make your bike get better mileage? Your inner sprocket need only revolve 2.8 times for you to have your rear wheel turn once. My inner sprocket needs to turn 2.933 times to get the rear tire around once. The assumption being that your engine is going 2.8/2.933 or 95.5% as fast rev-wise as my bike at the same final speed. How well this translates to better mileage I don't claim to know.

DKC

 

It's true that the Magna and Interceptor use different internal ratios on the gearbox. The problem is that the rest of the info in the Clymer manual is all wrong (not surprising). Pretty much just rip that page out of the Clymer and throw it away. Right after that throw the rest of the Clymer away and get a Honda manual.

 

Technically the 86 came with a 43 rear sprocket while the 84 and 85 came with a 44.

This entire season I've been running a 44 and just very recently dropped to a 42. I notice no fuel economy gain since the weather is slightly colder and I'm most likely wearing an extra 5lbs in clothing. :tongue:

 

5 lbs of clothing?

Hey, the reason I quoted the Clymer manual was because it appeared to have an error. I was looking for someone to varify that the Clymer was in error and then publish the correct gear ratios. I know the Clymer has errors but I subscribe to the school that figures even a Clymer Manual is better than no manual at all. I have 6 Vf manuals and one inline 4 manual. 2 of the Vf manuals are factory manuals (Saber/Magna 750 and a VFR 750) and the rest are Clymers. I got all of them for free or in the purchase of a used Honda cycle. The Clymer manuals are about 95% correct. Where they have errors is in details like the screw up over the "final overall" ration and the fact that they don't publish all 6 gear ratios. Clymer does not have the money to spend on getting a specialist for each kind of cycle he makes up a manual for.

Sorry slowbird, but I found the crack about having 5 more lbs of clothing on a bit hillarious, particularly because I am lugging around 265 lbs, (at least 75 lbs of blubber added onto my big shouldered and thick boned frame) and nobody is counting that as the reason I don't get 55 mpg. I saw from the pic of Matt in his new riding attire that he is anything but fat. So how do you explain my Magna cruiser getting 49 mpg at 80 mph while crashing through a 35 mph headwind carrying my 75 lbs of excess weight?

I do think there could be a valid issue in the change in fuel blends from winter to summer, especially in the frozen north. I don't know enough detail to say with any definition that you will get poorer mileage in the winter as a result of the additives they put in the fuel, but I would not be surprised by it.

But back to the manual issue. I'd appreciate getting a digitized copy of a Honda Vf500 F and C model factory manual over the web. I tried to copy the manuals off the VFRW site with no luck. Maybe, whoever you are, you could send it to my address as an adobe file that my telephone based internet machine could take in and store in my memory as an adobe file.
At the same time you could send one to '1983bob', who appears to not have a manual for working on his dad's 84 Vf 500 interceptor.

Thanks
DKC

 

That was before, lets see how she does now that you have the bugs out, Tink?
I was up late last night and I stumbled across a 1984 'CYCLE' magazine article on the "New Honda 500cc V4's". This was the introduction article on the Vf 500 c and f by CYCLE magazine. It had a comparison of the two cycles and a lot of technical stuff about the differences between the Vf 400 and the Vf 500's. It had photos of the transmission, the gear selector assembly, the pistons, the two bikes facing on opposite pages with and without tanks and plastics. The Vf500f got the nod for being a great bike. The Magna 500 was give significant praise for its performance. And both bikes were given gas mileage checks. You won't believe it. The avg gas mileage for the VF500f was 44+ mpg in combination driving. Meanwhile, the avg gas mileage for the VF500c was 45+ mpg in combination driving.

Before I laugh at the crowd demanding 55 to 60 mpg out of a good VF500 I want to clear something up. I found a problem in my fuel system that results in my probably underestimating my mpg. If I fill my tank to the vapor separator I get gasoline leaking for the first 3 to 5 miles I drive the bike. So I am loosing fuel when I fill to the brim in order to check my mileage at each fill up. I will avoid this in the future and try to find the leaks source and plug the leak asap.

So, Jamie and that crew out there claiming 55 to 60 mpg are all wet. I was doing good getting 50mpg on the round trip drive to Long Beach. And here is another great bit of information that the CYCLE article brought to my attention. The Interceptor has a close ration gear box and a lower top gear final speed than the Magna. The calculated top speed in 6th at redline (12600 rpm on the interceptor (ignition cuts out)) on the Interceptor is @130 mph. At 60 mph the interceptor is turning over at @ 5600 rpm. The calculated top speed in OD (sixth) at redline (11,800 rpm on the Magna (ignition cuts out)) on the Magna is @140 mph. The Magna will go to 102 mph in 4 th gear. The Interceptor will redline in 4th around 90 mph. At 60 mph the Magna is turning over at 4900 rpm.

Final irony, the Interceptor is slightly (a few lbs) heavier dry than the Magna.

Tinkerin has gotten his 85 interceptor back together with larger main jets installed. His interceptor had the smallest main jets installed. If you will remember, he got nearly 52 mpg while driving 180 miles at around 60 mph on the twisty roads in northern CO. So what will he get driving with mains that are over 10% larger than what he had in there? And what might I get (besides a burnt valve or piston top destroyed) if I were to switch to 95 main's ?

And finally, what will happen to Matt and the struggles he is having with his
'86 interceptor. At last thread he was ready to throw in the towel and switch to larger/84-5 Keitin VD 57-59's. And what of his benighted VD 32's? I hope he retains them and does not go through the hell of swapping over to the larger carbs. It's just asking for more trouble.

Stay tuned boys and girls.

 

sounds like the #90s had your mains by the throat.

Well, its sort of Matt's '86 Interceptor in reverse. We get to see the effect of richening the mix while at the same time twisting the throttle with more gusto. Keep us appraised of the plug color situation too. I Want to see pictures of those puppies after a tank or two if (knowing you) you don't have them out already.

What was the PO thinking when he went to the 90's. And this brings up another question/thought. Matt had his problems after he took his cycle to the dealer to have a jet kit installed. What were those jets they put in. And why didn't squirrelman checkout the jet kit situation when he had them apart? Did the fact that Matts cycle sports VD 32's result in a big screwup because the chump's who installed the jet kit used on for the larger model VD 57-59 carbs? We will probably never know. Too bad.

DKC

 

It sounds like you are questioning my honesty. That's cool, no biggie. Something you forgot to mention was that you (and others) were getting mid-30's and thought that was ok. Maybe we got mixed up around certain numbers (like 50), but my point was that if you are getting 35mpg then something is wrong. Thanks for establishing proof of that being true.

Laugh at me if you will, but I'll sleep well tonight knowing that I gave good advice.

Oh my, it's anything but "hell". It's as simple as replacing the 86 carbs with another set of 86 carbs. Seriously, just that easy. Back in the 80's it was the hot setup, everyone with a 500 was trying to find a set of 84-85 carbs because it was the easiest way to get a hp or two.

 

?????????????????????????

 

32mm vs 30mm

Why would there be an issue with a carburetor switch from an '86 set to an '84* or an '85 set? It's my understanding that the '84*/'85's larger 32mm bore (in comparison to the '86's 30mm bore) is the cat's pajamas for the VF500F.

*Honda Service Bulletin VF500#4, Aug '85 corrects driveability and hot start issues for the '84 model year.

 

This has been hashed out decades ago - the stock 84 jetting in 84 carbs works perfectly with the 86 engine.

 

I swapped an '86 engine in my '85 and there was no problem! Putting '85 carbs on an '86 motor only requires you to use the '85 boots.

Dont knock it till you try it!

 

their right this is the big power adder for the 86's i've been plaining on doing this swap for awhile now just didnt have the time, im sure its going to require some dyno time but its the end number im looking for.

 

Why did Honda go to the VD 31-32?

Perish the thought Jamie mi'boy. It's dem damn CYCLE magazine liars I 'm pissed at, tellin me dat da Vf doon only got 45 mpg. I 'll git dem back fer dat. I's neber gona read der lion cheatin' an mose consarniest magazine agin. Damn if do. Double damn darn it if I do. :biggrin:

We're all allowed a little 'eggsadyurashun' now an' den. Damn right we are. But "lieing"? Never.

Shuck's, I never doubted you a minute. In fact I'm in the middle of changing my '84 Vf500C over to a set of Keitin VD 32's ri' na'. An I did a load a wash, a sink full of dishes and cleaned the basement besides in the spare time I had between takin' the old VD 59's off and slidin' those sparklin' 32's in place.:thumbsup:

All in jest, Jamie. Like the song says, "don't take yourself so seriously". So your Vf500f gets 60 mpg. I'll be happy (more like relieved) to get low 50's on the highway. And I can tell you I'll never loose, like the song says, "a minit o' sleep, worryin' about the way things 'sposed to be' Big wheel keep on turnin', proud Mary keep on burnin', Rollin' Rollin' "

Rolling down the River

DKC

 

32 vs 30

Wouldn't the carburetor switch be an upgrade?

VF500F Carburetor Specs

'84
Model No. VD56A - 32mm Throttle Bore, 6.2mm Float, 102F/105R Main

'85
Model No. VD56D - 32mm Throttle Bore, 6.2mm Float, 90F/90R Main

'86
Model No. VD31AB - 30mm Throttle Bore, 7.3mm Float, 90F/90R Main