whats the proper octane fuel to run in my 1600 99? and why?

1600 and 1700 don't need anything higher than 87 octane.

87 if it's stock....... the compression is what determines the octane. A stock engine is around 8.5 to 1 if memory serves.........

They are 8.3 comp and with the motor cool etc 87 octane is enough in general like stated here & yami rec's it too.

But I have personally had mult issues with pump fuel over the past few yrs in the classic muscle cars i work on esp when it comes to quality control of octane lvl not to mention the ethenoled fuel starting to go bad in as little as 35-40 days in some cases depending on storrage environment/situation.

So with that in mind i run 1 step up/89 octane fuel for the time/s i may not in fact be getting the 89 octane fuel i am paying for so if that 89 fuel i paid for turns out to be only97 fule it still has enough octane to hopefully not detonate. But if you start out with 87 oct fuel and have that not be what its supposed to be and now your at who know's for example 84/85/86 octane that could detonate and detonation over time can cause real damage. If bad enough detonation can crack/break rings & even forged pistons trashing the motor esp when under hard load and or when @ WOT when on it hard. I have personally seen detonation blow up a perfectly good running hi perf 469 Pontiac a friend of mine had 1st hand because he forgot to add the kemco real lead booster when fillng up & broke /cracked 3 forged pistons when he was on it hard on a hot summer day,wasn't pretty.

Was running 93 oct thenoled pump fuel with 10.5 compression which isnt going to cut it in most cases,he was mixing the real lead Kemco booster to inc/boost 93 fuel to 98-100 octane whic he forgot to do that 1 time and got burned big time.

Also keep in mind the rec of 87 octane fuel is for a new motor thats not carboned up at all and isnt in an excessive heat sitution. As we all know these lrg v-twin air colled motors (esp the hotter running rear cyl) can get carboned/gumed up even with proper jetting increasing compression a bit (which can increase the octane requirment a smidge when that happens) not to mention if the bike sees extreem hot temps like in AZ / CA /Texas/Mexico,etc where hot motors can use little higher octane fuel too.

So i feel with all that in mind its well worth it for me paying 3-4 cents more a gallon for 89 fuel vs 87 fuel to ensure it SHOULD usually if i am luck have enough octane to not detonate for whatever the reason.

scott

I have completed my tour of duty as a Petroleum Transfer Engineer, And I can say that it all comes from the same spout (In your area) It is what they say it is, Reg Fuel with no ethanol is still available, (Typically Farm towns carry it) (odd huh, they are ones that make it, yet they want fuel without it in their equipment) They filter the heck out of it, and with the new EPA regs and everyone in compliance, (Going down to 10K gallon ground tanks) Gas now is used so fast I seriously doubt anyone is pumping gas that has been in the ground more than 5 days, anyone, My experience is that a station who ordered 8500 gallons was ordering the same 3 days later and had room for more in the tank when we dropped the new fuel.

I seriously have no idea how anyone is getting old fuel now a days.

87 with 10% ethanol is by far most popular fuel sold now a days. I can't see how it will lose Octane rating in even 10 days.

A typical Fuel delivery was 6K gallons 87, 2K gallons 91 and then in 4 days go back with just 87. So, the 91 sits much longer. I never measured the tank on a 91 I wasn't delivering into, so i had no idea what they sold, it just wasn't much I know that.

Fuel up at a busy gas station to make sure your fuel is fresh and run the cheapest shit they got. Once every oil change, run a tank of ultimate premium and give it a bit of a cleanout and the most important thing, run at least a tank of fuel through your bike each week.
The worst thing you can do to a motorcycle carbeurator is let it sit!!!

These old carbureted engines do more than sound like an old tractor, they also seem to have the same ability to run on just about any combustible liquid.

As an aside, I had also purchased a set of 10.25-1 pistons, valve springs etc.. to put in my 1999/98cuin/RS after the wreck last year, but was advised against it, because I wanted a long haul bike that would burn whatever gas I found on the back highways and I was told many, many things on a COMPUTER forum about octane and such, so I decided not to install them during the tear down.
Then later I met Jade (from here on the clinic) who has a hopped up 98cuin Star with 10.25's,etc.. and his will run like a scalded dog on the same crappy gas I use in mine ... really pissed me off about idiots that spout off that have no experience to base their OPINIONS on.
His bike does exactly what I had wanted mine to do when I decided to drop the cash for the performance parts, without the need for premium that I was warned about by riders on a forum that CLAIMED to know ...
Next time you get advice from a computer forum, check the mileage on the guys bike and how worn out his tools are, instead of the number of posts he's made.

Same thing as; You can't go to school to become a mechanic any more than you can read a book to pick up girls, knowledge is only a start, experience is the authority.


So burn that cheap gas and laugh as you jingle your change at the guys WITH OTHER ENGINES THAT HAVE TO BURN PREMIUM and ride with pride on your oldtractorcycle Road Star.


Max

EDIT: I didn't exactly address the "Why?" ; The dual plug heads have alot to do with it, but there are other marvelous factors designed into at least the 98cuin carb engines that enable them to run on practically any gasoline.

Oh yeah, as far as 'High Mileage', I have a friend with a shop in Ok who had a Road Star with 300,000 miles brought in for 'refurbishing' he said when he tore it apart to look at it, all it really needed was new gaskets to put it back together .. !!!

Enjoy your ride.

Max

I used to think that running a higher octane would carbon up the engine but I've since proven myself wrong. The energy content of a gallon of the different octane fuels is the same. The only difference is the higher octane fuel's ability to prevent detonation which happens at the same time as ignition.

I've seen posts claiming higher fuel mileage with higher octane fuel and it has happened to me. I'm trying it (89 octane) long term to see if the higher mileage holds up. I'm only talking about 2 mpg or so.

The only reason I can figure for the higher fuel mileage is that there must have been slight detonation occuring that I couldn't hear. It's very hot in my area and under those conditions it's very possible detonation can occur even on a low compression engine. Very slight detonation may not hurt the engine but it is a power robber.

Scott B.

on my bike with the high compression pistons here in NC I havent had any issues it was 102 here yesterday, the only detonation I have had any experience with as of late is the hammer of a gun hitting the bullet

The fuel requirements for The Road Star are regular unleaded. I'v found there's no discernable benefit in mid or Hi-test fuels. With such a low compression ratio, it's wasted monies to buy Hi-test/Premium. Having said that, in the next closest town over in South Carolna, there's a Sunoco station that sells pure gas in the three grades without alchahol in it. I buy there as often as convienience will allow. I'v never experianced detonation with 'any' type of regular however. My riding habits are probably more sedate than the majority of Road Star owners, in that I 'cruise, accelerate rather slow, short shift alot. I ride like a Highway Patrol was behind me, ie. making as little pipe noise as possable as I have V&H Longshots w/ebay 8" baffles that I installed. There are ordinances in these parts alowing The Law to cite for (loud) anything from boom boxed cars to loud exhausts, thus I keep a low profile. I have taken 1 or 2 hundred mile trips where I conistantly cruised between 70-80 when it was prudent though, on the 'loud' handle, and under acceleration, I still fealt or heard no detonation. For everything that is stock, regular is sufficient. On the later bikes with electronics and FI. it's processed to an even finer degree to thwart detonation. Mine is an 02, somewhat akin to yours, with carburation, in stock form other than a little cosmetics.

I'll *edit* and add that a little 'SeaFoam' will also keep the carbon buildup at bay. I'm a believer in the stuff, and for those on the cheap, there's a home-brew on the web that exposes the ingredients and ratios of each part of the recipe with easily bought chemicals from either a hardware, Wally's or Lowe's. Do a search under 'Seafoam' and you'll run across it on the first or second page. So instead of $8 or $9, you can make it for $3 to $4 a quart.

MS1700 wrote:
I have completed my tour of duty as a Petroleum Transfer Engineer, And I can say that it all comes from the same spout (In your area) It is what they say it is, Reg Fuel with no ethanol is still available, (Typically Farm towns carry it) (odd huh, they are ones that make it, yet they want fuel without it in their equipment) They filter the heck out of it, and with the new EPA regs and everyone in compliance, (Going down to 10K gallon ground tanks) Gas now is used so fast I seriously doubt anyone is pumping gas that has been in the ground more than 5 days, anyone, My experience is that a station who ordered 8500 gallons was ordering the same 3 days later and had room for more in the tank when we dropped the new fuel.

I seriously have no idea how anyone is getting old fuel now a days.

87 with 10% ethanol is by far most popular fuel sold now a days. I can't see how it will lose Octane rating in even 10 days.

A typical Fuel delivery was 6K gallons 87, 2K gallons 91 and then in 4 days go back with just 87. So, the 91 sits much longer. I never measured the tank on a 91 I wasn't delivering into, so i had no idea what they sold, it just wasn't much I know that.

MS1700,you seem to be takin aim at what i posted buy you are kinda misunderstanding what i said and havent had some of epxeriences i have encountered 1st hand over the past almost 40 yrs working on cars/bikes when it comes to fuel going bad,esp todays crappy ethenole'd pump fuel.

So let me set the record straight & maybe better explain what i meant and where i was comming from when i stated what i did.

I never said fuel was ging bad in storrage tanks at fuel stations or fuel depots and never said octane was being reduced somehow at mfg /storrage facility etc.

What i said was its a known fact (that you may not be aware of yet) which i have experienced 1st hand mult times ove past few yrs is that fuel with enthenol in it can and does begin going bad in as little as 30-60days. I just hit that problem with my mothers Maxima sitting with a full tank of ethenol'd fuel for approx 40days or so when she was recovering from an operation. But luckily for me the fuel hadnt gone completely bad yet so seafoam fixed that issue .

Also,the Mairne/boating indusrty had done a lot of testing on fuels with ethenol comming up with that result of the fuel going bad very quickly because they were experiencing a lot of ethenol related bad fuel issues when boats are stored in humid environments even when boats were only sitting for short periods of time. That screwed up/corroded a lot of carbs/fuel systems untill thery figured out what was going on when the ehtneole'd fuels when they were 1st ontroduced to the public.

I had kept up with and studied a few of those thenol fuel tests/studies the marine indusrty did because classic cars see the same type extneded periods of non use at times and i am knee deep in that hobby working on other peopls classic cars & bikes a times too. So thats where i found the fuel testing stated/proved the fuel with ethenol can & does in fact go bad much faster then non ethenoled fuel of the past.

When ethenole'd fuel starts going bad i would think the octane lvl would have to be out to lunch/reduced some too.

As for the octane deal,i knew a couple of people that had worked in 2 local fuel storrage depots in the past that lcoal fuel trucks filled up at to srvc/fill local gas staions in my area. They told me that the fuel can in fact have quality issues at times esp when drawn from the lowerst portion of the fuel storrage tanks they are still allowed to still draw fuel from before having to stop pulling from that particualr storrage tank untill they recieve more fuel in that tank. Do i know in fact thats the case,no but these people taht worked at those fuel storrage depots had no reaso to BS me either with no gain at all to them telling that. Does it seem like something that could possibly happen yes & did it seem like something that could have caused issues i have encountetred 1st hand with fuel going bad in motors i was working on ,yes . So those 1st hand exp i had with bad fuel supported the info i had recieved from people that worked at thos fuel storrage facilities tat you could in fact get a bad load of fuel delivered to a station .

Approx 5 months ago another friend of mine with brand new Benz got such a bad load of fuel from a local staion that had its storrage tanks just refilled litterly 2-3 hrs prior to him filing up that his car just about quit running all together apporx 2-3 miles post filling up,cost $3,500 to get fixed .

And this was a station local to him that all his family uses to fill their cars up all the time for many yrs without ever having an issue.

Long story shrot was post investigation by oil/fuel mfg it was determined the fuel that was delivered to that start was in fact bad and had to be all sucked out of the fuel tank and fresh fuel refilled in the tank at that station.

I got litteraly 4+ gals of water in an 18 gal fillup a few yrs back back from a local station i often used. That too was determined to be a bad load of fuel that was just delivered prior to me filling up,what a pia that was . When i drianed the fuel i found 4+ gals of water in the 18 gal fillup in a classic 69 chevelle i was working on.

And thats just a few situations 1 person little old me has had so who knows how many problems like this there are throughout the entire country thru thru the yrs or how many stations are still arround that are little businesses that have not had the old fuel tanks changed out yet with issues allowing water/condensation into the tanks etc fouling up the fuel too.

The ethenol in the fuel is like a sponge for water which is a big issue with that type fuel.

These issues were where i was comming from when saying you never know what your getting at times and that there can in fact be quality issues at times with the fuel your recieving which i have had 1st hand problems/experienc with mult tomes over the yrs.

Scott