200x avgas???

[trikeAZ]

so iv got an 84 200x, stock except the 350x front end, i was told 100ll avgas is good to run because it runs cooler and lubs the valves, shold i run it straight or mix it?? really need so advice befor i buy some. found a place at the local airport that said hed sell it to me for my bike, its $6 and that seems cheaper than race fule plus it has some lead in it. iv got a 62b carb witch is right for the 84 but its running a 110 main inseed of the 108 the book calls for, i also have the needle at the middle clip position, and the pilot screw is about 2 1/2 out. any advice or suggestions would really help

[tvpierce]

The higher octane is only a benefit if you experience pre-ignition (pinging) -- which I would not expect on a stock 29 year old engine originally spec-ed for 9.8:1 compression. One of my former bikes -- a Kawasaki Concours, which has basically an de-tuned 80's era Ninja motor -- had a 10.2 compression ratio and still spec-ed 87 octane fuel. So in terms of octane, even premium pump gas is overkill for your 200X.

[tri again]

Mine seems to really like non ethanol gas.
A buck more per gallon but they run cooler.

My tractor was throwing heatwaves off the muffler about 8-10 inches tall with E85 pump crap.

I came back to the barn only to discover i had no more cheap gas so I had to use
alc free and the heat waves were less than 2 inches tall.

Av gas has certainly has some pretty cool bragging rights however.

[trikeAZ]

from what iv figure 9:1 calls for a min of 89 and a max of 96, and the 200x is stock at 9.6:1 , if i do a mix at 2 gal av and 3 91 it should be about 94.6 octane, the lead in av gas is 300 milligrams per gal, thats more than back in the day at a mix of 50/50 av/91 itll be 95.5 octane and 150 milligrams of lead per gal, now idk how much lead was in fuel back in the day but at the 2-av:3-91 i figure should be a good mix because it cuts the lead percentage by a little over half. itll run cooler and the valves and rings will love the lead, atleast this is what iv found in my research in the mater

The higher octane is only a benefit if you experience pre-ignition (pinging) -- which I would not expect on a stock 29 year old engine originally spec-ed for 9.8:1 compression. One of my former bikes -- a Kawasaki Concours, which has basically an de-tuned 80's era Ninja motor -- had a 10.2 compression ratio and still spec-ed 87 octane fuel. So in terms of octane, even premium pump gas is overkill for your 200X.

[Ghostv2]

from what iv figure 9:1 calls for a min of 89 and a max of 96, and the 200x is stock at 9.6:1 , if i do a mix at 2 gal av and 3 91 it should be about 94.6 octane, the lead in av gas is 300 milligrams per gal, thats more than back in the day at a mix of 50/50 av/91 itll be 95.5 octane and 150 milligrams of lead per gal, now idk how much lead was in fuel back in the day but at the 2-av:3-91 i figure should be a good mix because it cuts the lead percentage by a little over half. itll run cooler and the valves and rings will love the lead, atleast this is what iv found in my research in the mater

Well now that just surpassed my high school education with all those technical terms.

[trikeAZ]

haha it took me about 4 hours to truly start figuring it out because it had me confused, this chart tho really helps when figuring out octane ratings when mixing 100 oct& 91 oct

Well now that just surpassed my high school education with all those technical terms.

[tvpierce]

from what iv figure 9:1 calls for a min of 89 and a max of 96, and the 200x is stock at 9.6:1 , if i do a mix at 2 gal av and 3 91 it should be about 94.6 octane, the lead in av gas is 300 milligrams per gal, thats more than back in the day at a mix of 50/50 av/91 itll be 95.5 octane and 150 milligrams of lead per gal, now idk how much lead was in fuel back in the day but at the 2-av:3-91 i figure should be a good mix because it cuts the lead percentage by a little over half. itll run cooler and the valves and rings will love the lead, atleast this is what iv found in my research in the mater

I think your math is right, but then you have to convert your final figures from RON (Research Octane Number) to PON (Pump Octane Number) -- PON is the number that's on the pumps in North America. A good rule of thumb is that PON will be 4-5 points lower than RON. For your engine, Honda called for a minimum PON of 86, so 87 should be fine. While all engines are different, my guess is that you'd have to be in the 11:1 range before requiring 91 PON.

[trikeAZ]

11:1 calls for a min of 96 to 102 max in that chart i found so 91 wouldnt even cut it in that matter

I think your math is right, but then you have to convert your final figures from RON (Research Octane Number) to PON (Pump Octane Number) -- PON is the number that's on the pumps in North America. A good rule of thumb is that PON will be 4-5 points lower than RON. For your engine, Honda called for a minimum PON of 86, so 87 should be fine. While all engines are different, my guess is that you'd have to be in the 11:1 range before requiring 91 PON.

[trikeAZ]

and wile compression and octane go hand and hand, but you have to remember a lil higher octane can help you run cool, how ever if you go to high its a wast because its ment for higher compression to resist detonation, plus im cutting the 100LL wit 91UL to make a special blend of 94.6 PON because both 91UL and 100LL are the pump octane numbers lol

I think your math is right, but then you have to convert your final figures from RON (Research Octane Number) to PON (Pump Octane Number) -- PON is the number that's on the pumps in North America. A good rule of thumb is that PON will be 4-5 points lower than RON. For your engine, Honda called for a minimum PON of 86, so 87 should be fine. While all engines are different, my guess is that you'd have to be in the 11:1 range before requiring 91 PON.

[trikeAZ]

and just cuz i did more looking into it, PON is really Anti-Knock Index (AKI) and its written as (r+m)/2, lol this stuff just interest me lol, but its the number is the average of the
RON and the MON, Motor Octane Number (MON)& Research Octane Number (RON)

[rjs89ia]

For the amount of temperature change that might happen you probably won't see a difference, only in your wallet. If your looking for lead go down to autozone or oriellys and pick up some TEL additive and you'll be set. For something thats been running on pump gas for almost 30 years changing to a higher octane leaded fuel probably isn't going to give you much more benefit other than self satisfaction.

[barnett468]

Hello trikeAZ


Since you’ve done a bit of research on this and seem to like to read I thought I would give you some interesting articles regarding mixing different fuels etc you might not have seen yet.

The compression ratios you are referring to are called static or uncorrected compression numbers and actually are not the numbers the mfg’s use to determine the octane rating a particular engine will require. The numbers they use for this are the dynamic compression and cranking pressure numbers. In short the reason for this is because the dynamic and cranking numbers are the primary ones used to determine what octane an engine requires and those numbers change with the port timing in 2 strokes and the valve timing in 4 stroke engines.

Any static compression vs octane requirement charts that exist are more of an estimation of octane requirement for a particular static compression ratio not an exact one irregardless of who made it. .


GAS OCTANE TOLUENE XYLENE ETHANOL METHANOL OCTANE LEAD “SUBSTITUTES”

https://home.comcast.net/~ericdouthitt/pump_gas.htm


Av gas is not seasonally varied, however pump gas is. See link and article quote below

http://www.automotiveu.com/mixingleaded.htm

Another potential problem is that each time that you blend racing gasoline and street gasoline, you do not necessarily get the same end results. This is because street gasoline is “seasonally varied” six or seven times per year based on the temperatures that are anticipated in your particular area. Racing Gasoline remains the same throughout the year, but with the variable of the street gasoline, one can get some less than ideal mixtures that can contribute to vapor lock and/or make consistent tuning difficult.

A good racing gasoline is designed to burn efficiently between 5,000 and 9,000 RPM. A good street gasoline is designed to burn efficiently from idle to 3,000 RPM which is the highest speed most engines see during the EPA test for exhaust emissions. Mixing the street gasoline with the racing gasoline compromises the good high-speed burn characteristics of the racing gasoline thereby reducing the potential engine output. This also reduces the octane quality of the blend.

http://www.motortrend.com/roadtests/...l/viewall.html


COMPRESSION RATIOS EXPLANATION

http://www.sacoriver.net/~red/uccr.html

[trikeAZ]

i will read all of this for sure, befor i get in to it just yet tho what kind of fuel would you suggest, because i think the gas now days is crap, nd the stuff we have where i live seems to have probles, some of the stations have had to have tanks replaces because of water in the fuel and stuff like that, so i dont trust pumps anymore lol, and i want to get a lil lead in it for the rings and valves, and ppl have said why change the fuel its been running on for 29yrs, its not because of power but the fact that fuel has changed ALOT in 29 yrs, back then they had lead lol!!!

[KASEY]

your WAY over thinking this... gas the thing up and ride it,,,, its no way a high performance motor ,, it will run on half water and gas ,,,

[briano]

Just put some gas in it and ride it. I've witnessed an older Honda fourtrax 300 run on off road diesel and gas mixed, there was more diesel than gas and it ran fine other than some smoke.