My atv has been sitting for about 3 years now without being ran hard. I emptied the gas tank, took the carburator out and cleaned it and the jets and checked out everything. When the choke is on it runs until I go alittle bit past half choke. Then it dies, I messed with the throttle stop needle to try to correct the fuel/air but does nothing. What do yall think about me putting high octane fuel in to burn out everything? Any messages would be appreciated

 

What gas are you running? That Suzuki engine has high compression and should be running 91 octane to begin with. Anything less and you are risking sending your valves out of adjustment.

 

That's messed up, my kawasaki dealer that i bought it from told me to run 87 because higher octane fuel will burn the o rings or something. It has always ran fine. But thanks for that info, I will for sure run higher octane fuel

 

<div class="FTQUOTE"><begin quote>Originally posted by: BonafideSpd3

That's messed up, my kawasaki dealer that i bought it from told me to run 87 because higher octane fuel will burn the o rings or something. It has always ran fine. But thanks for that info, I will for sure run higher octane fuel</end quote></div>

Well then the dealer is a moron....... higher octane will not hurt anything...

Here is the deal with manufacturers telling you to run 87, and I was told this directly by a Suzuki engineer.....

For each machine that any manufacturer makes that requires "high" octane fuel, they need to pay an extra tax to the government. The machine is considered a closed-course circuit machine, and it requires a special tax. So it forces Suzuki or Honda etc... to limit the number of high octane engines.

So what they started doing, was telling the customer to run 87 octane and then check your valves every 6mos. They do this because running slightly less octane than you need will cause valve run-out. What is happening is a slight pre-ignition that will over a few months eventually send your valves out of whack.

This is a win-win situation for the manufacturers, because not only do they avoid the tax, but they get you into the dealership for adjustments more often where they know you will spend additional dollars.

The z400 stock has over 11:1 compression, which any engine builder will tell you should have at least 91 octane. Sure you could get away with 87 and the machine will seemingly run fine, but it will not run optimal to its design.

There is a local engine shop here and on the wall the engine guy has an octane-to-compression poster. And I remember anything above 10:1 compression required 90 octane or greater. And as the compression went down, so did the required octane. Once you get around 9:1 you can safely run 87 octane. Which is why most cars take 87, because most automobile compressions are in the 8 range.....

ATVs in general have higher compression, so the truth is a lot more of them should be running 89-91 octane then actually are. I applaud Yamaha, because they seem to be the only one that is not afraid to pay the tax, and often their machines are marked as such...... as example is my Wife's Raptor 350 says to run 91 octane.... yet her compression is quite a bit less than my z400. So obviously Suzuki went cheap and didn't pay for that 91 sticker....... I have noticed that Suzuki and Honda are especially guilty of this but they are not alone.

Pretty much everyone I know with a z400 runs 91 octane or better so don't worry. on occasion I even run 93 if I cannot get to Sunoco...... higher octane won't hurt anything. I've even on occasion used it in my Rancher, my lawnmower or anything else that runs on gas..... of course if you don't need the octane you are wasting it so running it in a lawnmower is a waste of money.

 

why pay more for something you dont know is real.... how do you know ur gas station is giving you a higher octane?

 

<div class="FTQUOTE"><begin quote>Originally posted by: backtrailboy2332

why pay more for something you dont know is real.... how do you know ur gas station is giving you a higher octane?</end quote></div>

If they aren't they are breaking some serious laws and will incur some very hefty fines. If you are uncertain buy some and have it tested.

 

Well I put some 93 octane and it runs good when the choke is on but once I get it towards idle... It dies, and I can start it up from normal idle. Every once in awhile the the motor will do a clunk noise It only did it 2 times in 5 min. Any Idea what the problem is? I miss riding this machine. Sucks I haven't had time to ride it

 

By "clunk" do you mean misfire? I would make sure the spark plug is new and the air filter is clear......

 

Yes, like the motor will shake on the clunk noise. That could be the problem is the spark plug, I'm such an idiot for not even thinking about that. The K&N air filter is still really clean. Hopefully I can get time today to check the spark plug, Thanks again for your replies