2-Stroke 800cc and crappy gas.

[Magnumb]

Wondering if anyone has figured out how to cure detonation problems when forced to buy gas containing %15 ethonal or stagnate premium gas?

My Ski-Doo 800r trips the knock sensor code and retards the timing on certain types of gas. It also seems to happen more often when my gas tank is less than half full.

Things I originally thought to be causing this:

Lean fuel mixture- Not thinking this is the case. Sled gets 11.8 MPG and this is typical for an 800PTEK.

Cracked Carb Boots or Y-Pipe- Checked both and no issues

Irdium Spark Plugs- Changed to regular and still having issues.

Compression too high- Both are reading 140.

Sensitive Knock Sensor- OHMs read within spec.

Some other noise tripping the sensor- I was told some aftermarket pipes can send out a freq. that the knock sensor can pickup. My can is stock and I see nothing else that could cause a high freg. sound.


Fuel pressure too low- Havn't ruled this out. It goes along with this happening more often when my fuel level is low but It also seems to happen more often when gas is bought from gas stations were you know people aren;t buying premium gas.

 

[G]

Pol had trouble a few years ago with their knock sensors on their 800's . They also read correct ohms but were defective some other way. Doubt if it is low fuel pressure. If the high pressure rail gets starved I believe it shuts the motor down completely.

 

[79_srx]

Had my 08 800r re flash and boom engine went 11mi later because bad gas, engine #2 went next year end of feb.. bad gas engine #3 went this year...bad gas

 

[snowfreak56]

I am not a big fan of it but you can run octane booster,some works some dont.You should not be putting E15 in it to begin with.And where are you buying E15 ? The nock sensor probably is not your issue,it is just doing its job.What year 800 P Tec ? I have a feeling you have a lean condition. What do the plugs look like ?

 

[anonomoose]

Had my 08 800r re flash and boom engine went 11mi later because bad gas, engine #2 went next year end of feb.. bad gas engine #3 went this year...bad gas

The odds of this being caused THIS many times because of "bad gas" is about the same as an earth killing asteroid whacking you in the head.

What you are far more likely to have is a lean burn issue where replacing top ends won't fix. Meanwhile, find a new gas station.

 

[anonomoose]

Wondering if anyone has figured out how to cure detonation problems when forced to buy gas containing %15 ethonal or stagnate premium gas?

My Ski-Doo 800r trips the knock sensor code and retards the timing on certain types of gas. It also seems to happen more often when my gas tank is less than half full.

...

Fuel pressure too low- Havn't ruled this out. It goes along with this happening more often when my fuel level is low but It also seems to happen more often when gas is bought from gas stations were you know people aren;t buying premium gas.

That engine was designed to run on 10% ethanol blended gasoline....IF it is stock. Look for a lean burn issue and end your troubles. You also could have a bad knock sensor.

But more likely you have some air getting sucked in from some place it isn't supposed to.

 

[rp7x]

retard it

do you have to much advance on your timming ?

 

[79_srx]

1st time at 5200mi #2 at 8600Mi #3at13000mi 1st time had 34% water in gas in up#2 was due to lean out with 89mid grade from a pump that was miss marked#3 was bad me ran last years gas with clean carbs

The odds of this being caused THIS many times because of "bad gas" is about the same as an earth killing asteroid whacking you in the head.

What you are far more likely to have is a lean burn issue where replacing top ends won't fix. Meanwhile, find a new gas station.

 

[likinit2]

I gave up, good gas is so hard to find so I set them up to run on regular. On my 03 Polaris 800's I went with the slp twin pipe heads. (Low compression) Runs cooler I was able to jet down also and get better mileage. Doesn't have the peak hp, loose a little grunt but it runs better all the time. With a clutching and gearing change, they are still pretty respectable. Just rebuilt an 06 800 doo and went with more base gasket. We will see how that works out....

 

[towtruck]

just want to throw something out there -
if you think you might have bad gas and are worried about your motor and you are in the middle of nowhere- would it make sense to add some 2 stroke oil directly in your tank -say 128 to one- would be one oz of oil per gallon of gas- or maybe a little more oil
any thoughts?

 

[thebreeze]

Run a gallon or two of 100ll or 110 race in each tank if you truly believe you are having issues with pump gas being under its rated octane.

 

[Magnumb]

I think I'm onto somthing.
Is oil mix related to fuel consumption?
If I were to lean out my oil mix would I get more fuel into the combustion camber? I'm currently running between 30:1 & 32:1 and could go to 40:1 or 45:1.

 

[snake]

1st=any alcohol=leaner burn. 2nd= adding oil to fuel=leaner burn. just an fyi. if I were having this issue,I would somehow get one known good fillup of noneth fuel and run to see if it still acts up,if yes,then you have something else going on.

 

[snake]

also=you can buy a very simple alcohol tester to see exactly how much alcohol is in fuel. we have found that the info on pumps are not always truthful!!the tester we use in the shop is actually for briggs and stratton,but I'm sure someone makes it for them

 

[(TK) Mustard Bucket]

also=you can buy a very simple alcohol tester to see exactly how much alcohol is in fuel. we have found that the info on pumps are not always truthful!!the tester we use in the shop is actually for briggs and stratton,but I'm sure someone makes it for them

If a gas station sold you gas that was over the amount that they claim you should be able to make them pay for any damages caused by the bad gas. IMO

 

[(TK) Mustard Bucket]

Had my 08 800r re flash and boom engine went 11mi later because bad gas, engine #2 went next year end of feb.. bad gas engine #3 went this year...bad gas

Where did you buy all this bad gas? You dont have to say names but what towns.

 

[79_srx]

1st time a bar in northern wi( not saying name tank above ground tho) #2 was in chatom mi (closed now)What in saying before the re flash it would go into limp mode all the time after the re-flash it would run like sH!P or take the top end out

Where did you buy all this bad gas? You dont have to say names but what towns.