11.5:1 pump gas

[Fullsizechevy9]

Is it possible? If so what do i do to turn a 12:1 piston into an 11.5:1? Or could i get away with buying say 5gal of 110 octane and mixing it with 5gal of 93 and using that with a 12:1 piston? I want to avoid 10.25:1 if i can so ill have a little more bottom end power.

[El Camexican]

Is it possible? If so what do i do to turn a 12:1 piston into an 11.5:1? Or could i get away with buying say 5gal of 110 octane and mixing it with 5gal of 93 and using that with a 12:1 piston? I want to avoid 10.25:1 if i can so ill have a little more bottom end power.

Avoid the guess work, get a blank dome piston, have it cut to suit your needs. O-ring the cylinder to run wire and shoot for 220psi. Max. .025” clearances in all areas should get you where you need to be. I would also put a smaller exhaust valve in it and switch over to fiber reeds and a 2mm smaller carb. If you turn the bottom of your cylinder down you can enhance the port timing and advance cam timing all with one easy mod. You’ll also want to run a slightly cooler plug as well, try something that has an 11 or 12 on it, the letter don’t matter once you eclipse the 200psi barrier.

You can also get rid of all your valve lash as it robs power to have them closed for all that extra time and of course it goes without saying that Denco makes the best pipes for your application. Also get a 3/8” wire cable pull start rope and have your starter housing rope hole professionally bored out to suit and don’t forget to run 90% 114 VP fuel with 10% fingernail polish remover (acetone) and some sort of zddp enriched oil with lots of esters in it. I promise your bottom end might be better than stock and you won’t have to worry about running a 10.25:1 piston in that beast.

[yaegerb]

Is it possible? If so what do i do to turn a 12:1 piston into an 11.5:1? Or could i get away with buying say 5gal of 110 octane and mixing it with 5gal of 93 and using that with a 12:1 piston? I want to avoid 10.25:1 if i can so ill have a little more bottom end power.

What you talkin’ bout Willis?

[Fullsizechevy9]

I seen where mickey from 4 stroke tech was saying he takes a 12:1 piston and rounds the edges and makes it an 11:1 and runs it on pump gas. I am a machinist by trade he charges 200 for the piston, well i was hoping i could doit myself and save almost 100$. I want to be above 10.25:1 and still run pump gas or at least be able to buy race gas and mix it 50/50 with 93 octane. From what i gathered i will have a better low end above 10.25:1 if i could mix 50/50 110 or 120 with 93 octane and still be close to 12:1 that would be great.

[Fullsizechevy9]

I have a 200s was thinking about getting a 2 stroke by time i mod this motor and barely reach 20hp i could probably buy a 250 2 stroke with around 40hp stock

[Fullsizechevy9]

Was looking at used 250s on ebay for around $1000 i have also seen cr250 and crf450 for around $2500 the whole bike i may mod this motor some then start looking for a nice cr250 for a bike to trike conversion

[Fullsizechevy9]

Is it a 200S ........or it could be a 200E ....series........or perhaps a 200ESSSS ....and you can convert it to a 2 stroke..........and den you can stroke it to work on 87 octane power piss..........and den buy a 259R stock not ported ........and den.......you can tie your mother down...........why ?

My mother committed suicide

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[Fullsizechevy9]

What a buzz kill ......

I had to

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[Fullsizechevy9]

What a buzz kill ......

On the other hand a 250 2 stroke in a s frame would be a fun project i dont do any mx mainly a bunch of long stretches so any suspension i put on it would work prettu good i have a friend with a rm250 i could probably get cheap would take some frame mods dif motor mounts make it a double down tube instead of single would have to be able to fit the radiators in front the tank though or just make the bike a trike the frame is pretty beat up though i had to weld a bunch of spots that cracked for him and gusset a few spots got it as straight as i could

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[yaegerb]

Is it possible? If so what do i do to turn a 12:1 piston into an 11.5:1?

You can recut the head to lower the compression

Or could i get away with buying say 5gal of 110 octane and mixing it with 5gal of 93 and using that with a 12:1 piston?

No. You need to run straight race gas for a high compression piston

I want to avoid 10.25:1 if i can so ill have a little more bottom end power..

Then buy a 12:1 and run VP 110

[Fullsizechevy9]

You can recut the head to lower the compression




No. You need to run straight race gas for a high compression piston

Then buy a 12:1 and run VP 110

If i get the compression around 11:1 would i be safe with pump gas like mickey is saying?

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[Fullsizechevy9]

If i get the compression around 11:1 would i be safe with pump gas like mickey is saying?

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He sells a 11:1 pump gas kit everybody seems to have a dif opinion on it you know so just trying to get everybodys opinion and find a happy medium

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[El Camexican]

You can recut the head to lower the compression




No. You need to run straight race gas for a high compression piston

Then buy a 12:1 and run VP 110

Yep, yep, yep. Toss that 10.25 in and shave your head .020” to .030”, slot your cam gears to get the timing 2 degrees advanced of stock and you’ll have a strong runner that eats pump gas.

[Fullsizechevy9]

Yep, yep, yep. Toss that 10.25 in and shave your head .020” to .030”, slot your cam gears to get the timing 2 degrees advanced of stock and you’ll have a strong runner that eats pump gas.

10 4 thanks that sounds easier than messing with the piston i can mill the head at work on the bridgeport. Could i just slot my stock cam? And then use a timing light to advance it?

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[Fullsizechevy9]

10 4 thanks that sounds easier than messing with the piston i can mill the head at work on the bridgeport. Could i just slot my stock cam? And then use a timing light to advance it?

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Thinking of a .395 megacycles cam

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