'01 CR 125 Engines Mods??

[monkeyonahill]

Hey guys, i just need some input (sorry if some of these questions sound stupid, im kind of new to modding the internals), my piston detenated just this last weekend, piston is screwed and the cylinder wall has a few scratchs + scor marks on it so im thinking about boring it out, i guess ehre are my questions:
1. How much would i have to bore the cylinder for a 56mm piston (.080 over)

2. Are there any advantages to long rod kits?

3. Should i get cc domes on the cyl. head?

4. What other mods would i benefit from? (im goin to be riding mainly tracks + some dunes)

thanks in advance!

 

[endofsilence808]

that bike cant bore very much do to the exhaust port thickness. eric gorr tried many things for that back when it was newer and I also rode one, sorry to say its just slow. if you want my specs let me know. i wouldnt waste money on major engine mods on a 125 for dune riding cause they aint made for it. keep it stock and you wont have engine probs like a mod would. but thats me. you wont gain much power with all the money you would spend on it.

 

[monkeyonahill]

im not going to be duning very much anymore, after what it did to my engine... haha, plus the 125 just doesn't have the power for super soft sand that we have. I'd love to hear the specs of ur cr, so if i bore it out to 144 i'll have problems with the exhaust port? =\

im going to be riding like 98% dirt after i redo my engine, and maybe some racing, basically i just want it to stand a chance against those 250f's. right now w/ pipes, filter, and other bolt-ons i got almost no chance. i dont want to risk ruining it again, that sand can hurt 'em bad if u get sand through your carb... no fun..

 

[endofsilence808]

my best setup for that bike, and i rode it in open b class against big bores and did well, was. cant remember the smaller needle in 3 spot. dosent matter what jets cause we are at different altitudes, but boyenson pro reeds , pc pipe and reg silencer. and that was it. nothing else mattered. i thought the reed spacer was ok but i was getting low end bogs and removed it. dont waste your money. i never had one prob with that bike and i ride mega sand all the time. air filters are your friend keep them clean and youre ok. i use maxima fft oil on the filter. i also rebuild every 4 to 5 races on 125s. unless you like total rebuilds do it this way. also jet a bit on the rich side for sand.

 

[CRazy250]

you will have little to no increase by going 80 over,and you shouldent because thats boring the cylinder to its limits and if you get a scratch u cant rehone it u must buy a new cylinder......just my 1 dollar of advicee

 

[monkeyonahill]

you will have little to no increase by going 80 over,and you shouldent because thats boring the cylinder to its limits and if you get a scratch u cant rehone it u must buy a new cylinder......just my 1 dollar of advicee

yeah i know about scratching it, instead of being stupid im going to be checking every 15-20 hrs of riding, running 94+ octane, and running a little bit richer. and i did the math for the dispalcement, with the 80 over piston and boring i should be around 134-135 cc's. Displacement = .7854 x Bore(squared) x Stroke, that's for cubic inches so i had to do some converting. and i didn't mess up, i've done it several times :nener: lol