lets talk octane!

High test? My baby looooves the cheap stuff. Doesn't run as good on the better stuff. No surprise considering what she's expecting...

 

Most regular I see is 87 octane.

 

Right. 87 PON (Pump Octane Number). If you look at the tag it says 91 Research Ocatane (RON) . PON is a tougher standard. 87 PON is roughly 92 RON.

 

You will notice on that decal that these bikes ARE built to run leaded fuel. If you don't add some lead substitute every once and a while your valves aren't getting the lubrication they need to last their full life. You are also wearing out your exhaust valve seats prematurley. I have almost 41K miles on my xj650j and have been runnin lead sub. since I got the bike at 25K mi.. It runns just as stong as the day I got it. I know that on the older heads from leaded days (v-8 chevys and fords) they needed the lead because they don't have hardened exhaust valve seats or hardened valve guides. If these xj's do than the nolead gas is ok.

 

Whats a good Lead additive to use then? Well oiled machines run better <---FACT
-Chris

 

I would check with your local auto parts store. They will have a lead substitute, you can't buy actual lead additive anymore. If you have a gas station that sells the 110 oct race gas that has lead in it also, but it costs $6 a gal. I try to use it every 3 to 4 tanks but its more like every 6 or 7 now.

 

if you arent using it constantly i wouldnt bother. also, the manufacturers knew that lead was being deleted for a LONG time, and the engines were designed accordingly.

no lead=no problem.

 

so your saying that the exhaust seats in our early 80's xj's are hardened?

 

i don't KNOW, but i would be SHOCKED if they weren't. we run mid 70's atv's on unleaded with no issues....late 70's American autos were unleaded prepared, why would our 80's bikes NOT be able to run unleaded?

 

If anyone is still "out there" allow me to complicate the situation. This topic is important to me because I live at 8,000 feet elevation, just bought a 1981 XJ750, and am spending hundreds of dollars getting the carbs rebuilt, resynched, etc. the whole nine yards. This yammy dealer has a great reputation for carb work, but also very slow.

So I want to get the fuel right.

At elevation, the octane is 83 or 85 (I forgot!). Soo, I guess my question is, will I HURT anything or foul anything with premium fuel here?

Thx.

 

no, you will not HURT anything.

 

Just askin', although I'm not SHOCKED by the answer :wink:

Thanks. BTW, my XJ has been in the shop TWO WEEKS getting the carbs fixed and new oil due to fuel in the oil, etc. Slow but good.

Anyone know the frequency of the hollow floats getting holes and filling with fuel? The yammy dealer said they couldn't buy original Yamaha floats anymore. While it saved me a ton of money, just wondering how likely hollow plastic floats would be to sink...

 

Stock Hitachi floats ain't hollow!

 

That's the best news I could ever get -- the "ain't hollow" part.

The Yamaha dealer wanted desperately to sell me new floats along with all the other carb parts. I reluctantly agreed since I wanted the first rebuild of them done correctly (in other words, not by me). But as I said he couldn't get OEM floats...thank goodness!

So, are these floats foam, or solid?

When I bought it two weeks ago, I knew and we agreed that the bike was running very poorly. Seller didn't know that lots of gas going into the crank case. He did know that it had set for quite a while, and his mechanic didn't fix it right despite a lot of $$.

BTW, I paid $700 for a 1981 XJ750 Seca with factory fairing, saddle bags, <15,000 miles, runs, new fork seals, never wrecked, good rubber, tried to get a good deal, but I love the bike!

With the support you guys offer each other, I am not afraid to tear into the bike this winter and do things myself. I just wanted the first major carb work to be done by "experts." I am willing to break things and take things apart as is my nature.

If it ever gets out of the shop I will share pics of this very nice bike with you all. Meanwhile you are great people and I am learning a lot by reading your words of wisdom! Thank you and I love this site.

 

"Solid ultra-dense foam"!

 

i have a question about octane - if you're bike is running just a hair inside of too lean - i.e. you know it's lean, but several hundred miles have not yet yielded catastrophic results, would running a higher octane fuel push you into a safer "cooler" zone or a more dangerous "hotter" zone - or would there be no difference at all?

 

As far as high ethonal ratings in the near future i have a theory. Yes one reason is known it is enviromentalists and what not.

But my thinking is as follows. We all know that ethonal decreases our fuel economy correct? Well look at it this way, While the Govment maybe stupid they are also kinda smart in a way. They KNOW it will decrease our fuel economy. While the average american prolly doesnt. Gas prices will remain the same. Therefore with our decreased fuel economy we will be buying more fuel then before and the Govment will be making more money off the taxes from the fuel while the gas and oil companies will still be making a killing.
I have come to find out that out nations govment and most municaple govments are out to get our money. They and lawyers have their hands in everyone elses pockets but their own.

Now on another not. I run high grade in my seca. Ive always ran high grade in all my quads and dirtbikes. Espeacialy My motoX bike i had it had a hicomp set up.

Just my 2 cents

 

I run the high octane stuff in this baby just cause I can. At $7 for 100 miles I really cant complain. Higher octane means less carbon deposit right? Coupled with a seafoam every like 4-5 tanks I'd like to think I'm cleanin her up nicely and keepin her insides clean