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High compression piston

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I got a 06 250R and its time to check every thing over in the top end and i was wondering if we should put stock piston in or if we put a high comp. piston. What kind if we do that? does any thing need to be done like change jetting or stuff like that, Different gaskets, or is it just a bolt on type thing? What about gas, will it run on pump gas or u need a higher octane. Race about every 3rd weekend on motocross track, lot of practice sessions, and do alot of trail riding. How do they wear compared to a stock one? Dont know much on this subject. thanks for the advice.

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I put a JE 13.5:1 piston in my 250X with CCC mods, HotCam stage 1, CHM exhaust. No jetting changes, no special gaskets, 91 octane pump gas works fine. Piston comes with rings, pin, and circlips. Very happy, feels like it produces more torque.

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you have to watch out with 13.5 pistons the rings wear out faster. Also I have no idea how all these guys in the U.S run those things on pump gas.

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Also I have no idea how all these guys in the U.S run those things on pump gas.

We do here in Canada to...... :thumbsup:

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some people say that after the high comp piston, they had less top end revs, their bikes did not rev out as far, because the springs arent stiff enoughf.

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you have to watch out with 13.5 pistons the rings wear out faster. Also I have no idea how all these guys in the U.S run those things on pump gas.

Maybe this has something to do with the Winter fuel mix available at the pumps:excuseme: The winter mix if not sold by the end of winter still goes to the pumps well into summer.

Maybe RHC can chime in on this

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yeah good luck running in deep sand on pump gas where I am. I have seen some spectacular failures on wiseco and je pistons on pump. If you run a quality race fuel like U4 or MR9 you wont have problems.

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yeah good luck running in deep sand on pump gas where I am. I have seen some spectacular failures on wiseco and je pistons on pump. If you run a quality race fuel like U4 or MR9 you wont have problems.

I dont understand what sand or riding conditions has to do with the type of fuel you choose to run:excuseme:

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yeah good luck running in deep sand on pump gas where I am. I have seen some spectacular failures on wiseco and je pistons on pump. If you run a quality race fuel like U4 or MR9 you wont have problems.

I have found great inconsistant quality with both fuels recomended.

Ask Team Suzuki about 06 Atlanta, BBMX last year.

Fuel right out of the can failed the fuel test.

No both teams have there own test equpment

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I dont understand what sand or riding conditions has to do with the type of fuel you choose to run:excuseme:

The load placed on the engine.

Much greeater load in sand or other similiar conditions. or a high end rider.

All will contribute to the engine killer detenation.

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The load placed on the engine.

Much greeater load in sand or other similiar conditions. or a high end rider.

All will contribute to the engine killer detenation.

i see

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yeah no doubt that there are inconsistencies from vp and other race fuel suppliers but generally it is in the area of oxygen content. You are right for sure sometimes you can get a can that does not jet in quite the same as normal. The variances In fuel never affect detonation issues that I have found or heard about. I will tell you what anything is possible some weird stuff can happen.

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Octane rating is a measure of the fuel's antiknock or detonation resistance.

MR9 is 87 octane.....lower that premium pump. I use it all the time....at high compression ratios for the power increase from the oxygen content. I could run pump premium with no problems in my 450 supermoto, on pavement mostly....HEAVY load.

I will agree under heavy load conditions with a fast rider you may need the assistance of a higher octane fuel, for your average rider pump is fine.

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Yeah your right. True that high octane prevents detonation but sometimes that number will mislead you. Additives in the fuel that the supplier mixes in that prevent detonation like MR9 can tolerate high compression ratios because they are made for performance applications not street cars. High rpms, and heat not so much as fuel economy and engine cleanliness. Look at your exhaust valves after using these race fuels and all the deposits on them. They are made with one thing in mind and its performance. Fuel like MR9 is great but the trade off is their corrosiveness and fuel boiling all these other factors. I believe you when you say that your 450 can tolerate pump fuel but you have to remember that 250's have a lot more stress on them. Im of the train of thought if your going to spend 8 grand on a bike and start modding it spend the money on the proper fuel choice. Save yourself the cost of rebuilding it after your piston cracked and your connecting rod went through the side of the cylinder wall (my poor bike I almost cried that day):thumbsup:

Just my thoughts every guy has their own opinion, try pump if it works well good on ya, if not holy moly I feel for you.

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Heres a small point of intrest as the rpm goes up and past where the peak torque ocurs the fuel octane requirements are reduced as cylinder pressure starts droping .A fast rider may be able to get away with using low octane fuel on a hard track.One of my riders ran out of race fuel this summer @ a local race and ran pump fuel for a entire moto winning the race.this was on one of my 42 hp suzukis with 14.5-1 compresion of course he told after he had done it i looked @ the piston after and just installed new rings for a couple of more races.

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