2013 kx250f with 113hrs no parts changed.

Manny555
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Manny555
Edited Date/Time 8/3/2015 10:04pm
So I got a 2013 kx250f and as you can see in the header....its got 113 hours and I have never changed the piston,rod, valves(not even adjusted) so im going to be tearing into and wondering. What the hell do I go with aslong as parts and what to change while im in there. I can feel that I have lost alot of power on my bottom end and its harder to get into another gear and higher speeds/rpms. So guys any advice helps thanks
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DTHA70
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DTHA70 7/13/2015 12:06pm
7/13/2015 12:06pm
ditto with above^^^

with that much time on a 250f, a bottom up rebuild would be cheap insurance before a catastrophic failure.

crank&bearings
piston
new cylinder
check valves/new valve seals
leakdown test head
deck head and cylinder
new trans bearings
new seals throughout engine
inspect clutch components(replace as necessary)
nage0139
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nage0139 7/13/2015 8:21pm
7/13/2015 8:21pm
DTHA70 wrote:
ditto with above^^^ with that much time on a 250f, a bottom up rebuild would be cheap insurance before a catastrophic failure. crank&bearings piston new cylinder...
ditto with above^^^

with that much time on a 250f, a bottom up rebuild would be cheap insurance before a catastrophic failure.

crank&bearings
piston
new cylinder
check valves/new valve seals
leakdown test head
deck head and cylinder
new trans bearings
new seals throughout engine
inspect clutch components(replace as necessary)
Total rebuild on a motor that abused, agreed. It's a ticking time bomb unless you check absolutely everything.
markit
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markit 7/14/2015 9:55am
7/14/2015 9:55am
I had a 03 that almost made 30 hrs.lol As above stick a new crank & bearings in there as well.

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Bressler11
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Bressler11 7/15/2015 9:14am
7/15/2015 9:14am
my my 2013 kx 250 blew at 53 hours make sure to put a forged piston in it the 2013 oem cast ones suck
Manny555
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Manny555 7/31/2015 12:55am
7/31/2015 12:55am
Bressler11 wrote:
my my 2013 kx 250 blew at 53 hours make sure to put a forged piston in it the 2013 oem cast ones suck
What brand of crank and piston should I run?
Phillip_Lamb
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Phillip_Lamb 7/31/2015 11:45am
7/31/2015 11:45am
With that many hours I would replace crank and piston. Typically pistons wear out faster on 250f but since your opening up everything might as well. and this will help insure for many more hours
Manny555
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Manny555 7/31/2015 2:53pm
7/31/2015 2:53pm
I found this on ebay and I know cp is good for car parts(I build car motors)

slipdog
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slipdog 8/1/2015 5:12am
8/1/2015 5:12am
Manny555 wrote:
I found this on ebay and I know cp is good for car parts(I build car motors)[img]https://p.vitalmx.com/photos/forums/2015/07/31/99463/s1200_Screenshot_2015_07_31_02_04_07.jpg[/img]
I found this on ebay and I know cp is good for car parts(I build car motors)

CP is top of the line, but that is a complete CP/Carrillo long rod kit. It's a custom kit with a longer than stock connecting rod and custom piston with an altered pin bore so goes together with stock gaskets and no spacer plates. Excellent performance upgrade, but you'll always have to use that custom piston in the future(or anyone you eventually sell the bike to).

Matt Fisher
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Matt Fisher 8/1/2015 8:50am
8/1/2015 8:50am
If you managed to get 113 hours on an untouched 250F motor without turning it into a pile of shrapnel, odds are very good you're not very hard on the motor because you're not very fast around a track. A 14.2:1 compression ratio will require race gas, and at the speeds you're likely going that would be a very unnecessary expense. I cannot think that money isn't an issue with you, as indicated by going 113 hours on an untouched motor (if you had significant discretionary income you likely wouldn't have chanced it). Put it back together with OEM quality components, they obviously served you very, very well. Maybe don't wait quite so long until your next rebuild, just to be on the safe side.

My comment isn't meant to be demeaning, btw. Heck, I could probably get over 100 hours out of a 250F, while my son would grenade one in less than half that time. It's a whole lot cheaper for me to ride than him....
Manny555
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Manny555 8/1/2015 9:10am
8/1/2015 9:10am
Matt Fisher wrote:
If you managed to get 113 hours on an untouched 250F motor without turning it into a pile of shrapnel, odds are very good you're not...
If you managed to get 113 hours on an untouched 250F motor without turning it into a pile of shrapnel, odds are very good you're not very hard on the motor because you're not very fast around a track. A 14.2:1 compression ratio will require race gas, and at the speeds you're likely going that would be a very unnecessary expense. I cannot think that money isn't an issue with you, as indicated by going 113 hours on an untouched motor (if you had significant discretionary income you likely wouldn't have chanced it). Put it back together with OEM quality components, they obviously served you very, very well. Maybe don't wait quite so long until your next rebuild, just to be on the safe side.

My comment isn't meant to be demeaning, btw. Heck, I could probably get over 100 hours out of a 250F, while my son would grenade one in less than half that time. It's a whole lot cheaper for me to ride than him....
Im actually a 250 school boy and stay mid to front of the pack in a race I got this bike from an auction and it haf 80 hrs on thr meter and no clue if the previous owner did anything to it. But thats true by no means am I fast rider I guess a smart good rider id sat
Paw Paw 271
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Paw Paw 271 8/2/2015 12:41pm
8/2/2015 12:41pm
Looking at a 500+ piston, but will not invest in a manual.......That's just wrong.

Paw Paw
EL Sammo
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EL Sammo 8/3/2015 10:04pm
8/3/2015 10:04pm
I'm just impressed it has made it this far! Above advice is spot on, get a workshop manual, you can probably download a PDF one for free if you look around a bit.

Read and understand the manual, and make a nice clean tidy work area before you start tearing the bike apart.

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