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Talked to RHC today...

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I got to talk to Ron today and discussed future plans for my 02 450. This spring I'm planning on sending him my 02 head and have him work his magic with new valves and porting. He told me I should be in the ballpark of (I think) 54hp with my 12.5:1 piston.

I'm stoked, I can't wait.

BTW...sorry you felt like poo-poo today Ron. You did not sound good at all. Hope you feel better.

GT

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Man, ya gotta go with a 13.5:1, his 187 cam and a top end pipe from MRD, or a dual MRD setup. If you send your carb too, with all of the above and good fuel, you could easily twist the needle past 60 HP at the tire. Something like that is almost impossible to beat up Olds :applause:

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Hey Shawn,

I can appriciate your enthusiasm but after building a 400ex quad to the hilt and needing race gas, heavy duty headstuds, special gaskets, P/P, cam etc... I've decided that my new quad with the 450 motor I don't NEED to do all the stuff to be real fast. It's already appx 14hp faster STOCK than the built 426ex. With the new 12.5 piston and some porting I've already gained close to 20 hp over my old quad. That is HUGE.

I don't want this quad to be the never ending upgrade that my old quad was. Once I started THAT one I had to do everything else down the line for realiability reasons. That motor was a dinosaur compared to the water cooled 450's. I plan on running plain ol' 91 after the work is done....just like I am now.

Thanks,

GT

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I don't believe you will need race gas just from using a 13.5:1 piston, not sure about in the addition to all the other mods.

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Pro Med is right. You can run 91 in it and be fine. I was just saying that you could get to 60 if you jetted it nice and lean on good fuel, there's more power there than you might think. Id say the most common mistake guys make is running them too rich.

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well, I ride the sand dunes so almost immediately you lose HP right outta the gate. Sand robs ALOT of HP, so for me, every little bit helps.

GT

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I have the the same thing Shawn said to do with porting. The power is nice. Having the extra power is nice when you are trying to pass people that don't want to be pased. If you can get the tire to hold the ground you will be good. And hold on tight. As for the fuel I had no problomes with 91 with 13.5 piston. :applause:

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Using a 13.5 piston and 91 octane gas, No pinging even at high loads such as sand washes? Maybe the 02' have a less aggressive ignition curve?

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You definetly need to run race gas with a 13.5:1 compression piston. I have a friend who runs that piston in his 450R and right now hes mixing to race gasses for his quad, C-12 and MXR01. He runs the C-12 for the higher octane but has to run the mxr01 for the higher oxygen level. This is not something that he just made up either. The person who worked on his quad was Paul Turner, a friend of his and one of the most well known mechanic in the quad industry. Right now he is the mechanic for Pat Brown and the factory yamaha race team. I dont know how you guys get away with 91 octane but i would rather run race gas and trust the judgement of a proffesional mechanic.

Oh yeah, Shawn MC, does MRD really make a dual exhaust system for the 450???

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If you use a cam with late enough closing on the intake you can run pump fuel with 13.5-1 compresion my rhc 187 cam and 13.5-1 works fine on 92 octane pump i usally dont recomend it for long tracks or sand but i have had customers do it. mxro1 is usally to much octane for a 13.5-1 compresion unless the engine is running alot of ignition timing .mr 9 makes more power 89 octane .im not a profesional mechanic just a profesional engine builder and desighner.we made 61 hp on a legal yamaha 450 over 3 years ago we asked McCarty if he had any tips for us to make more power and he said we should be giving them the tips may be Paul should try some more cam and MR9

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If you use a cam with late enough closing on the intake you can run pump fuel with 13.5-1 compresion my rhc 187 cam and 13.5-1 works fine on 92 octane pump i usally dont recomend it for long tracks or sand but i have had customers do it. mxro1 is usally to much octane for a 13.5-1 compresion unless the engine is running alot of ignition timing .mr 9 makes more power 89 octane .im not a profesional mechanic just a profesional engine builder and desighner.we made 61 hp on a legal yamaha 450 over 3 years ago we asked McCarty if he had any tips for us to make more power and he said we should be giving them the tips may be Paul should try some more cam and MR9

Right on Baby ---

the cam has everthing in the world to do with the traped cylinder pressure.

and i can not believe the 2 stroke gange still uses the wrong type of race fuel in these 4 strokes :applause:

i can not tell you how many 13.5 motors i have out there ( i even have some 14.1 motors that all run great on pump ).

the old Turner and the 2 stroke gang have alot to learn about these new F1 four stroke motors !!

even some of the P.Turner 2 stroke set up's are week ----his pipes really need to be revamped ------you can take the old 250r with a just a 292 ( actually Ron --that was your design in the begining that everbody copied and made into a 310 and so on )

and make a correct pipe for it and just kill any P.Turner 310 up any of the hills in the dunes :applause:

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hey im just sayin what i heard and thats actually good news because i just got a 450 and i cant afford the race gas. was that 60 hp yamaha running on pump?

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hey im just sayin what i heard and thats actually good news because i just got a 450 and i cant afford the race gas. was that 60 hp yamaha running on pump?

the one 450 that i built last year that had Ron's head on it , and had Ron's bored 41mm fcr carb --with Ron's 187 cam made 61.4 hp on 89 oct MR9 fuel,

and it made 58 on 91 pump fuel :applause:

the fuel makes one hell of a difference ------but in alot of cases it is not needed ---

these combustion chambers are very good and with the correct cam you can run pump in most cases -------not all cases ----but most if you need to .

the race fuel is better ---the burn is better and cleaner ------but not a must have for the most part :applause:

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