Rebuild Costs - 4T vs 2T

James

James

Staff member
CDA:
but my 125 buddies would replace the crank every 6 months.
Click to expand...
So do 2T go through bottoms faster?
Curtis74:
I like how you used MXTime.com for your link on seat cutting. They did mine and my brothers and we both have been really happy with there work.:ride:
Click to expand...
So you know Dave, cool guy, he helped me get my bike set up right. :ride: He's about an hour from me, but I still just ship it to him. (cheaper) :smirk: But, I do however drive my suspension up to Wiesner, I don't feel like paying for shipping. :lol:
KTMRack:
What do you think your average speed is?
Click to expand...
:thumb:

Bryce it's kind of hard to gauge hours from miles. Was your average speed 20 or 60 mph?

20 mph - 25 hrs
60 mph - 8 hrs

As you can see it a crap shoot, plus what about the times you let it sit and idle? My advice would be to just get a hour meter, they're only $30-40.
 
Bryce R

Bryce R

James:
So do 2T go through bottoms faster?

So you know Dave, cool guy, he helped me get my bike set up right. :ride: He's about an hour from me, but I still just ship it to him. (cheaper) :smirk: But, I do however drive my suspension up to Wiesner, I don't feel like paying for shipping. :lol:

:thumb:

Bryce it's kind of hard to gauge hours from miles. Was your average speed 20 or 60 mph?

20 mph - 25 hrs
60 mph - 8 hrs

As you can see it a crap shoot, plus what about the times you let it sit and idle? My advice would be to just get a hour meter, they're only $30-40.
Click to expand...

Yeah I see your point. I would guess my average speed was probably closer to 20mph with the stuff we are riding. I know I need an hour meter bad. You would think Yamaha would just build it in to the Odometer. :rolleyes: $30 and $40 add up. Its on the list along with about 50 other things. I have been just changing oil according to how hard I thought I was on the oil.


CDA

Are the bikes your talking 2t or 4t that you were racing?
 
snowflake

snowflake

I rebuilt my wr250f minus new valves work a few years back for 1k even
new crank/rod
new piston/rings
new clutch
timing chain
lapped the valves
it has been 4 years, nothing but oil changes and filter cleanings
 
Mihylo33

Mihylo33

This is an interesting thread with lots of input... I ride hard MX on an 06 RM250.
I rebuild my topend about every 50hrs. my cost is in the $120 area for the Wiseco piston, wristpin bearing and OEM Gaskets. I have done the topend for as low as $99... but thats a rare find. I also do this 2x a year sometimes.
My last topend was almost $280 because I had the cylinder replated by Powerseal.

Now when I do a total rebuild I always buy a
new Hotrod crank $200
piston kit $110

OEM gasket kit $40-$80 (I shop around and buy the cheapest.)
and a set of $40 Koyo/oem crank bearings, if they send the KBC bearings with the Hotrod kit(they usually dont)

I throw out all the aftermarket stuff that doesnt say Koyo or Suzuki on it. Not worth the hassle.

So for 350-400 bucks I have a totally new motor. I can add the tranny bearings and make it an even $500 and the motor is totally new...
Now I did my last new crank in June 2008, I did install new crank bearings in 2010 because I had a crankseal go bad and I didn't want to take a chance on a hot bearing.


Now I have friends that rebuild there entire bikes for about 12-1500 in parts plus motor work etc etc.... I've seen cranks go bad after 70hrs as well...
I think it all depends on how hard you ride the bike and to what extremes you take your maintenance..
 
Chokey

Chokey

I'm not going to turn this into a "2 vs 4" debate, there are enough of those on TT, and my opinion is easy to find over there if you want to look.

But with that said, something that seems to get left out of these "4 vs 2" threads is how the machine is used. I have a KX250, and until recently also had a YZ250F. I typically re-build the top-end of the KX at about 40-45 hours, and the piston will be right at the limits and close to being out of spec. The current price for a complete top-end kit for my bike is around $175.

Now for my 250F, keep in mind, I ride almost exclusively motocross, and I rode the snot out of that bike trying to run similar lap times to what I run on the KX. I used that engine for everything it had, the entire time I was riding the track. At about 85 hours, the top-end was completely shot. Rings and piston were worn out, valve springs were out of spec, timing chain was shot, etc...it was probably past time. I paid over $700 just in parts for the rebuild, plus $150 to machine the valve seats.

So even though the 250F did go almost twice as many hours, it cost four times as much to rebuild.

Another factor that doesn't get considered in these topics is engine size. When a lot of people talk about how long four-strokes last, they are often talking about 450Fs. 450s do indeed last much longer, but it's not because they are made better, or because they are a four-stroke, it's because they make so much power that most people simply can't push them very close to their limits. Just like a 500T, which also lasts forever, because nobody can push them to the limits.

Unlike a lot of the "mine is better" arguments you see on TT, I feel that you just can't directly compare these engines, it's apples to oranges. Either type can last a long time if ridden at less than 10/10ths, and either type can wear out very quickly under the loving throttle hand of a "I can ride a 450 like a 125" rider. But in the end, a four-stroke does in fact have more parts to replace, so of course it's going to cost more to rebuild and repair.
 
suzuki_dude

suzuki_dude

Chokey:
I'm not going to turn this into a "2 vs 4" debate, there are enough of those on TT, and my opinion is easy to find over there if you want to look.

But with that said, something that seems to get left out of these "4 vs 2" threads is how the machine is used. I have a KX250, and until recently also had a YZ250F. I typically re-build the top-end of the KX at about 40-45 hours, and the piston will be right at the limits and close to being out of spec. The current price for a complete top-end kit for my bike is around $175.

Now for my 250F, keep in mind, I ride almost exclusively motocross, and I rode the snot out of that bike trying to run similar lap times to what I run on the KX. I used that engine for everything it had, the entire time I was riding the track. At about 85 hours, the top-end was completely shot. Rings and piston were worn out, valve springs were out of spec, timing chain was shot, etc...it was probably past time. I paid over $700 just in parts for the rebuild, plus $150 to machine the valve seats.

So even though the 250F did go almost twice as many hours, it cost four times as much to rebuild.

Another factor that doesn't get considered in these topics is engine size. When a lot of people talk about how long four-strokes last, they are often talking about 450Fs. 450s do indeed last much longer, but it's not because they are made better, or because they are a four-stroke, it's because they make so much power that most people simply can't push them very close to their limits. Just like a 500T, which also lasts forever, because nobody can push them to the limits.

Unlike a lot of the "mine is better" arguments you see on TT, I feel that you just can't directly compare these engines, it's apples to oranges. Either type can last a long time if ridden at less than 10/10ths, and either type can wear out very quickly under the loving throttle hand of a "I can ride a 450 like a 125" rider. But in the end, a four-stroke does in fact have more parts to replace, so of course it's going to cost more to rebuild and repair.
Click to expand...

i like the way you put that, roost for you :thumb:
 
1

14D

Just food for thought-

On a woods 2t like mine that's tuned very mild from stock, People can go 100+ hours on a top end... and From what I've read and seen, MX 4t's at least newer ones are supposed to have a top end every 50 hours or less.. at least that's from the manufacturer. I can get a Wiseco top end kit for 145 off ebay(http://www.ebay.com/itm/Wiseco-Top-...es&hash=item5ad0355cd6&vxp=mtr#ht_1883wt_1139) That includes the wristpin bearing and gasket kit. Even with the manual(50 bucks:foul:) it's still less than 200 bucks for a top end.
 
James

James

Staff member
140rider:
Just food for thought-

On a woods 2t like mine that's tuned very mild from stock, People can go 100+ hours on a top end... and From what I've read and seen, MX 4t's at least newer ones are supposed to have a top end every 50 hours or less.. at least that's from the manufacturer..
Click to expand...
It's all subjective to how you ride. Was talking to the dad of a kid that raced 125's and he said that they'd replace top ends every 8-10 hours. Next time I see him I'll ask what his maintenance schedule is now that they're racing 250f's.

Oh and I know a guy that's gone over a 100 hours on his 4 stroke piston (riding/racing motocross). I personally would never push the envelope that far, but hey it's doable.
 
Mihylo33

Mihylo33

140rider:
Just food for thought-

On a woods 2t like mine that's tuned very mild from stock, People can go 100+ hours on a top end... and From what I've read and seen, MX 4t's at least newer ones are supposed to have a top end every 50 hours or less.. at least that's from the manufacturer. I can get a Wiseco top end kit for 145 off ebay(http://www.ebay.com/itm/Wiseco-Top-...es&hash=item5ad0355cd6&vxp=mtr#ht_1883wt_1139) That includes the wristpin bearing and gasket kit. Even with the manual(50 bucks:foul:) it's still less than 200 bucks for a top end.
Click to expand...
James:
It's all subjective to how you ride. Was talking to the dad of a kid that raced 125's and he said that they'd replace top ends every 8-10 hours. Next time I see him I'll ask what his maintenance schedule is now that they're racing 250f's.

Oh and I know a guy that's gone over a 100 hours on his 4 stroke piston (riding/racing motocross). I personally would never push the envelope that far, but hey it's doable.
Click to expand...


the top ends are still cheaper for the 2502T $125 complete... and I get 40-50 hrs out of a top end on my Mxer 2T.

8-10 hrs is the norm for oem replacement especially on a 125.

The cost difference is in the other parts you need for rebuilds or if its catastrophic failure.... Catastrophic failure for my bike is right around the $600 mark and thats a new top end and a new bottom end and repaired cylinder. Add $40 for a head if needed.
 
Top