I actually calibrated mine, ran 5 gallons of gas thru her, measured the exact amount of injection all (used the Polaris Blue stuff) , it worked out to about 60/1. After that, no more premix, and with a gutted out muffler it ran nice and strong, no smoke. It was a love hate relationship, I had to fix everything on it, it seemed, once I got it right, it was a real blast to drive, quick, nice ride and handled great. Got top dollar for it and bought my AC 400 and put $200 in my pocket.

If the pump wheel mark is set on the pump casting mark,then it's 50/1 ratio. You can adjust these if they're off by loosening the adjuster lock nut and turning the adjuster in or out. This carb is set a tad richer than stock. Look close and you can see the faint mark on the pump casting. The wheel mark is past it.

I have measured the bore and I feel my measurements are rather accurate.

I used the 6 cylinder head studs as a reference to take 3 radial measurements approximately 60° apart at 3 different heights throughout the bore. Here are the measurements:

~1/2 Down From Top:

1. 3.271
2. 3.271
3. 3.271

~In the Middle:

1. 3.271
2. 3.271
3. 3.271

~1/2 Up From Bottom:

1. 3.270
2. 3.270
3. 3.269

I believe this means the bore is just a bit outside the service limits and will require a re-bore. Can you please confirm if my understanding is correct?

Always go to the first over size piston that will clean the bore up.No way I'd stick a stock size piston back in.

Just to clarify, is that because of the actual bore measurements above or some other reason?

Sorry, but I just re-read the service manual. I had misread it before. The factory bore is 3.270", and the service limit is 0.006".

If you assume the bore gauge was slightly off, and the 3.269" is actually 3.270", then the highest reading is still 3.272", which is under 3.276". I'm not trying to argue, I'm just trying to understand why you said what you said...

If you wanted just to ball hone the cylinder to remove the glaze and try a stock piston and rings,fine,but a lot of mechanics wouldn't recommend it and neither would I.Plus service limit at .006 most pistons would sound like marbles in a tin can,but I had em brought in with .008 clearance and rattling but somehow still running and hadn't broken a skirt. Many that came in were not that lucky. Choice is up to you as to what you want to do,so don't shoot the messenger...

I think I understand what you're saying now - you feel the slightly larger than stock bore could cause the piston to be too loose.

For future reference (and for others that may read this), what do YOU consider to be the service limit? (At which point would you say re-boring is necessary?)

.005 imo is max on this machine and shows the same for many other two stroke brands. Look at this video and especially towards the end when he's using the "poor mans" method of measuring clearance with feeler gauges.

Ah, I think that I have been misunderstanding the meaning of the term "service limit" in the manual?

I read that to mean that the MAXIMUM BORE SIZE was up to 0.006" over the listed bore size, and thus a 3.276" bore size is acceptable. If that was correct, then the 3.271 I measured would have been well within that range.

However, I now believe that this is not the case, and that the 0.006" (or 0.005" as you say) is actually the MAXIMUM CLEARANCE. When taken that way, and given the built-in 0.0025" clearance on Wiseco pistons, I can see why you say it needs a re-bore. (It comes to between 0.0035" and 0.0045" before honing.)

Please confirm if my new understanding is correct.

Picture is worth a thousand words as they say.. Yes this is maximum clearance between the bottom of the piston skirt and cylinder. Only that I set up the finish bore and hone on Wiseco somewhat smaller to have more life from them. Cast pistons .0015-.002 normally like the manuals suggests. Forged Wiseco pistons .0025-.003 max piston to cylinder final clearance.Key on this is any easy break in period for the first few minutes until it's at operating temp then kill it and let it cool down.Then when cooled down take it for a ride and vary the throttle. The old water craft was a different story since they were sucking in cold lake water and heated somewhat through the exhaust before entering the cylinders. .005 clearance on these or chance a cold seizure if you didn't allow the engine to warm up.Plenty of idiots on these pwcs did that enough. I was a happy camper in 2003 when Polaris dropped the pwc line.