honda305 Home honda305 Auctions honda305 Gallery honda305 Forum

Auctions  Mailing List    Registry   Marketplace

honda305.com Forum

Login
□ Search
□ FAQ 
□ 
Vintage Honda Owners,
Restorers, Riders and
Admirers

Fuel Type

Fuel System: Gas (Petrol) tanks, Carburators
Post Reply

What type of fuel do you put in your bike?

Unleaded
74
45%
Unleaded Plus
15
9%
Super Unleaded
67
41%
AvGas 100LL
8
5%
 
Total votes: 164

cbxmountainman
honda305.com Member
Posts: 270
Joined: Sat Apr 22, 2006 10:20 am
Location: Green Mountain,NC

Gasoline in CB/CL77s etc

Post by cbxmountainman » Sun Oct 12, 2008 8:18 am

If I'm not mistaken, I have read where premium fuel burns slower/cooler than the lower octanes. I just run plain ol Regular in my CLs.

hooptytank
honda305.com Member
Posts: 17
Joined: Thu Aug 10, 2006 1:31 am

Re: Gasoline in CB/CL77s etc

Post by hooptytank » Mon Apr 20, 2009 12:11 am

cbxmountainman wrote:If I'm not mistaken, I have read where premium fuel burns slower/cooler than the lower octanes. I just run plain ol Regular in my CLs.
Correct.

Higher octane burns slower, keeping the fuel from exploding in the combustion chamber of higher compression engines, which is what happens when the engine pings or knocks.

So in a low compression engine you may actually loose power. Probably not enough to feel, but may be visible on a dyno.

Basically run the lowest octane that won't ping when the engine it tuned properly with the right timing, points gap, jets, etc

conbs
honda305.com Member
Posts: 989
Joined: Mon Mar 16, 2009 3:29 pm
Location: SW Idaho

Post by conbs » Mon Jun 29, 2009 11:54 am

While the issue in this thread is whether your bike will run alright on no-lead fuels, I recently found other issues that I don't know the answer to, but are probably important in the discussion about what should go into your gas tank.

The May '09 issue of Mustang Monthly has an article on new fuels in vintage vehicles. They claim that today's gas has ethanol and other additives designed to "clean up emissions and help sagging octane". Those additives are "especially hard on vintage mustangs with their rubber float needle valves, die-cast bodies, galvanized tanks and lines". They suggest annual replacement of rubber parts in the fuel system because ethanol accelerates deterioration of vintage fuel systems. The issue is deterioration of rubber leads to fuel leaks that can result in fire.

Also, because "ethanol tends to be hard on rubber and cork components, you can wind up with leaks and bits of rubber in the fuel system, which can cause a sticking float and plugged passages.

Also ethanol"tends to be hard on die-cast carburetor bodies" and "zinc and ethanol don't get along well" "Like brake fluid, ethanol likes to retain more water than gasoline."

Is this just a pitch so the vendors that pay for advertising in the magazine can sell more parts? I can't tell. They don't really say whether 10% ethanol is as bad as E85, but they do say flatly "E85, which is 85-percent ethanol and 15 percent gasoline, should never be used in a classic mustang."

Anybody heard about these claims? The fuels systems on Honda's are much simpler than on a Mustang, but if these are real issues, with the scarcity of many parts shouldn't we all be paying attention to them?

LOUD MOUSE
honda305.com Member
Posts: 7816
Joined: Mon Aug 15, 2005 8:23 am
Location: KERRVILLE, TEXAS

Re: Gasoline in CB/CL77s etc

Post by LOUD MOUSE » Mon Jun 29, 2009 4:19 pm

Were I to be able to read the exhaust temperature with regular gas/fuel or high octane which should I see the higher temperature at the same distance into the exhaust pipe?. (4 inches in particular) ................lm

hooptytank wrote:
cbxmountainman wrote:If I'm not mistaken, I have read where premium fuel burns slower/cooler than the lower octanes. I just run plain ol Regular in my CLs.
Correct.

Higher octane burns slower, keeping the fuel from exploding in the combustion chamber of higher compression engines, which is what happens when the engine pings or knocks.

So in a low compression engine you may actually loose power. Probably not enough to feel, but may be visible on a dyno.

Basically run the lowest octane that won't ping when the engine it tuned properly with the right timing, points gap, jets, etc

jwbert
honda305.com Member
Posts: 89
Joined: Wed Jan 05, 2005 5:47 pm
Location: McFarland, WI

Post by jwbert » Tue Jun 30, 2009 9:41 am

I try to run the fuel that does not contain any ethanol, which is usually the 91 octane where I fuel up.

sotxbill
honda305.com Member
Posts: 110
Joined: Wed Feb 04, 2009 9:34 pm

Re: Gasoline in CB/CL77s etc

Post by sotxbill » Sat Dec 05, 2009 8:32 pm

LOUD MOUSE wrote:Were I to be able to read the exhaust temperature with regular gas/fuel or high octane which should I see the higher temperature at the same distance into the exhaust pipe?. (4 inches in particular) ................lm

I would be surprised if you see any difference between high octane and low octane. If your engine is not pinging, either fuel should burn the same temperature and have the same power.

BUT if your compression is so high that it pings or knocks, then a higher level octane will fix it and burn correctly to give it more power. but once that level is reached, adding more octane will do nothing. no more power in higher octane fuel.. just more lead or other additives to keep it from pre igniting.

so I would be surprise to see any difference between the temps of high octane vrs regular if its not knocking. should be the same. Explosive forces are the same under this example, this engine, this compression level. higher octane might be a tiny bit less temp, but I would be surprised if you could measure it. The btu content would be the same and burn fast enough to completely burn through the cycle. All of the usable btus would be given up, even if it took a billionth of a second longer for high test to burn. The difference should not be significant.

Sound plausable????? anyone have some lab results?? or a myth buster episode?? thought I would throw in my best quess.
two cl77, three cb77, ca77, ca72, cb160, s65 and cb750

Help Stop Global Whinning

Its considered bad luck to be superstitious.

teazer
honda305.com Member
Posts: 798
Joined: Mon Feb 08, 2010 10:32 pm
Location: Midwest US

Post by teazer » Mon Mar 29, 2010 8:30 am

It's an old thread, but many questions were left unanswered.

100ll is designed to burn slowly in a slow running aircraft engine. The old myth about it being good for performance came back in the 50s when gas was about 80 octane and compressions were low. The car guys wanted more compression and that caused detonation, so if they were able to beg borrow or steal some av gas they could run a higher compression without meltdown.

So higher compression was the power generator. Av-Gas allowed them to use it.

We found on the dyno that 89 octane made marginally more power than VP C12 with a smoother power curve - that was on a full race CB160 turning 11,500 with raised compression.

Some race gas burn faster than others and a faster burning gas will have more burned before it leaves the exhaust port. Others are slower burning. Some have a low evaporation curve and some don't evaporate until at least 100 degrees higher.

All the gas is not used before it exits the port. Poor atomization and non effective squish mean that some of the larger fuel droplets are still burning as the gas goes down the pipe.

A hot running two stroke may well reduce it's EGT with a race gas, but it has to be the right gas. Sounds like LM got lucky that time.

Any more octane than a motor needs to avoid detonation is a complete waste of time and money and usually results in less power and a lighter wallet.

The only thing I really like about leaded race gas is that it tends to burn cleaner than unleaded and needs a cooler spark plug which is much easier to read at the race track. Unleaded tends to leave a sooty deposit and often needs a hotter running plug to keep clean.

Ethanol and methanol are hard on fuel systems, but we don't have rubber tipped float needles, or galvanized fuel lines, so that is less of an issue. Ethanol will leach the resin out a fiberglass tank though.

E85 is a whole different story though. It generally needs larger jets, more spark advance and can stand much higher compression. Alcohols generally need to be jetted differently than gasolines.

Post Reply
cron




 

CB-77 | CYP-77 | Road Test | Riding Log | Literature | Zen | Marketplace | VJ Survey | Links | Home