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View Full Version : 13.5 to 1 piston


dustinb
08-08-2006, 08:33 AM
is a 13.5 to 1 piston going to hurt the reliability of my motor at all?
Edawg112091
08-08-2006, 03:40 PM
HAHA i think alittle but thats just me!
Ride1Rob
08-09-2006, 06:55 PM
No it won't hurt your motors reliability. Your not boring the cylinder you're only going to a higher compression piston. It will on the other hand hurt your pocket alil more b/c depending on the setup you may have to run race gas :p
dustinb
08-09-2006, 08:56 PM
thats what i was looking for. Thanks
seamonster
08-10-2006, 02:18 PM
I run a 13:1 piston in my motor and it's strong......but the race gas does tend to get expensive......:)
pnut420
08-10-2006, 02:42 PM
Its not going to hurt it, but it will wear it faster. You telling me that higher compression doesnt put more pressure on the crank, valves etc...

Lower compression motors always last longer than high compression. And race gas does get expensive thats why Im still at stock compression, costs me enough to get to where I ride already.

Id run a 12.5 cp piston or somewhere around there, should be able to run half race gas and half pump.
Ride1Rob
08-10-2006, 05:13 PM
Originally posted by pnut420
You telling me that higher compression doesnt put more pressure on the crank, valves etc...

Lower compression motors always last longer than high compression. And race gas does get expensive thats why Im still at stock compression, costs me enough to get to where I ride already.

Id run a 12.5 cp piston or somewhere around there, should be able to run half race gas and half pump.

That's why you change to a stronger rod and crank as well. Why go inside to do half the job?
440racer66
08-10-2006, 05:21 PM
dude i have a 13 :1 in mine best thing ive done yet
seamonster
08-10-2006, 07:07 PM
Originally posted by Ride1Rob
That's why you change to a stronger rod and crank as well. Why go inside to do half the job?

he's right.....mine also has a Falicon crank and has been totally reworked.......best of luck
pnut420
08-10-2006, 08:37 PM
Originally posted by Ride1Rob
That's why you change to a stronger rod and crank as well. Why go inside to do half the job?

How many people actually get a stronger crank that have 13:1 on stoke bore, if you do the rod and crank yeah it will be great, but on a stock crank and rod it will wear it faster and their is a chance of breaking a rod, happened on my 426ex.
Ride1Rob
08-10-2006, 09:40 PM
Originally posted by pnut420
How many people actually get a stronger crank that have 13:1 on stoke bore, if you do the rod and crank yeah it will be great, but on a stock crank and rod it will wear it faster and their is a chance of breaking a rod, happened on my 426ex.

I don't know how many peeps get a stronger crank that have 13:1 on stock bore. Are there any graphs or polls to see? For every problem there's a solution... You stated the problem and we're giving solutions to that problem. DustinB, get the High comp piston and a stronger crank my man. Hell, I've seen stock cranks and rods crap out after a few months on stock pistons so what the hell right :rolleyes:
dustinb
08-10-2006, 09:51 PM
the thing is i am buying a bike that has a fully rebuilt motor the oil mod cam mod and the cp 13.5 to 1 piston in it. and im concerned about reliability of the motor for rec and racing it.
pnut420
08-10-2006, 10:36 PM
Originally posted by dustinb
the thing is i am buying a bike that has a fully rebuilt motor the oil mod cam mod and the cp 13.5 to 1 piston in it. and im concerned about reliability of the motor for rec and racing it.

Should be fine, but that still doesnt help to much they could have stuck with a stock crank and rod or done a wr crank or any other aftermarket crank and rod. Either way it should be fine 13.5 isnt to high on a yfz on stock bore.
pnut420
08-10-2006, 11:01 PM
Originally posted by Ride1Rob
I don't know how many peeps get a stronger crank that have 13:1 on stock bore. Are there any graphs or polls to see? For every problem there's a solution... You stated the problem and we're giving solutions to that problem. DustinB, get the High comp piston and a stronger crank my man. Hell, I've seen stock cranks and rods crap out after a few months on stock pistons so what the hell right :rolleyes:

I gotcha, sorry for any disagreements, I was pointing more toward a stock crank and rod, sounded like at first he wanted to slap a 13.5 into his yfz
Ride1Rob
08-11-2006, 06:26 AM
Originally posted by pnut420
I gotcha, sorry for any disagreements, I was pointing more toward a stock crank and rod, sounded like at first he wanted to slap a 13.5 into his yfz

That's cool PNut. We're all trying to help each other out ;)
2muchquad
09-14-2006, 11:00 PM
I run a 13.5 to 1 on a stock rod with 93 oct for 3 yrs now,never a problem.Thats one of the advantages of liquid cooling.;) Sure a higher compression piston does put more load on the bottom end but so does 11000 rpm;)
jones256
10-02-2006, 09:33 AM
13.5:1 ok....just whatever you do, dont go overbored... we built my buddy's 04' up to little over 14.5:1 and that thing would last about 2 races and blow the headgasket...we rebuilt it about 6 times and he bought a new 06' yfz....as much money as he was pouring into it to keep it running...he could afford a new payment.