Realistic top end hours

[ononewheel]

I am about to get a rm125 o1 model, that I would love to ride 3-4 times a week for 1-2 hours.

i am a student so I can't afford renewing the top end like every 20 hours.

In your experience riding a bike this amount per week how long does the top end usually last.

A year would be perfect, as the new season for me starts in feb, and I would love to get in loads of practice before and after then.

Thanks

 

[2-Strokes 4-ever]

I rode/raced a 125 in the woods for years. I found that for my type of riding, the factory's specs. of "top end every 20 hrs." was overkill. However, doing top ends SO OFTEN was what led me to go 250. Based on my experience, with a 32:1 ratio, and a clean air filter... I would go 30 hrs. and do ring...then piston after another 30. This was about the life expectancy for my often low rpm riding. Check out the clutch plates regularly too.

 

[i_955]

If your buying a used bike buy a base, head and reed gasket set and a “manual for sure"... Take all the measurements in the top-end section of the manual.

You might have to replace the piston & rings immediately, then it completely depends on how meticulous you are on your air filters, how soon you have to do it again.

Half way through a year, buy another gasket set, crack it open and measure/inspect for damage, and at that point clean your air filter again hehehe...

 

[Senior KX Rider]

Depends a lot on how you ride it. If you are screaming it wide open most the time..........15 or 20 hours would be about right. I run the top ends on my 125s 30 or 40 hours.

 

[Spine_Thrust]

I have over a 100 hours on my 250. I'm not really sure how many but have never replaced the rings or piston and I did a compression test the other day and got 250 PSI with no leakage. Get a late model Yamaha YZ250 if you can, they are unbelievable.

I don't know how much it started with but I know it hasn't lost much. :)

 

[WillyM]

If you run good synthetic oil ,and never let your air filter stay dirty you can get 60 hours out of them.
I have one kx125 that I had about 70 hours on a piston and it still looked new, I rotated my airfilter with a spare clean one every other ride ,or 3 times a week, and I used Amsoil.
The thing you have to start to worry about is cracking the skirt on the piston, this is why I changed it.

 

[ononewheel]

I am getting the bike of a freinds dad who never really ride it fast and well maintaned it.

I want to ride a few times a week, but 60 hours for a piston!! I could probably do that in 10 weeks.

Better still how many minutes to a full tank, I expect to do through three tanks a week (three rides) a week when I first get it.

I did want a 250 2 stroke but can not race these here, as im intending to get a lift from my freind to the 125cc races.

CR500.... one day, one day....

 

[Rcannon]

I would not buy a 125 mx bike unless I planned to replace a lot of pistons. Sure, sometimes a person gets lucky and has one last 40 hours. Heck some even claim to get 100 hours.

I am working on a 2003 KX 125 that had @ 15 hours on it. The stock piston is now in many, many small pieces. The lower end is probably ok. I was able to blow and flush out all of the aluminum chunks.

The head is chewed up. This will be about 35 bucks to fix. The cylinder is bad. It will need a new plate job. Since it needs work, I suspect a 144 kit will be in order. I imagine this to cost 400-500 if I do the labor (free). There is also the option of a new oem cylinder..200-300 and piston...100.00.

The older Honda XR's were fun. They last forever with a minimum of maintenance. There is a guy that posts here, Cort, who has embarrased many 125 and 250 riders on his XR 250......myself included.

After spending this kind of money, the bike will need a rebuild again. It is a vicious cycle. A 250 YZ, KX, RM or CR would be much cheaper to maintain in the long run.

Consider the info and dont get discouraged. Finish school, get your degree, and own as many 125's as you want. With a decent degree, you'll have the money.

If your planning to race, you'll see more and more money dissappear. You have to have good tires to do well. Tires dont last very long. Gas and oil are a concern as well. Racing also tends to use up a part or two because of crashes.

 

[robwbright]

In May I bought a 2002 RM 125 with a fresh top end. I rode an average of 2 times a week - 3 hours each. I raced a total of about 10 classes at the local tracks.

Replaced the ring in late September. Piston was fine. There was a tiny bit of blow-by on the side of the piston under the ring. Could have been a worn ring or perhaps the cylinder is slightly worn - although it was within .0004" of spec all the way around - so I suspect it was the ring.

My father in law races a CR125 shifter cart. He has raced 3 out of 4 weekends from spring to present, including recently at mid-Ohio. Of course, shifter cart runs at 10,000+ rpm start to finish. He doesn't change a thing all year and rebuilds each winter ("the motor runs better when it's broke in"). After a proper jetting he just keeps an eye on the plug and compression. If they don't change significantly, there's probably not a problem. Note: He's been racing go carts for 40 years, modifieds for 30 (builds his own motors), makes his living as a transmision mechanic.

Rob

 

[robwbright]

By the way, are you SURE you want a CR 500? LOL. My friend (6'2", 235 lbs) recently bought a 98 CR 500 - he hadn't ridden in awhile and thought the extra weight he had put on would make him too heavy for a 250. After three rides and a nasty crash he sold it. He was a reasonably good rider and could not get used to the sheer amount of power. The wreck was caused by coming up slightly short on a VERY small double, having left hand come off bar and right hand twisting the throttle. He and the bike ended up in a small 2 foot deep pond. LOL.

 

[BigSwole]

By the way, are you SURE you want a CR 500? LOL. My friend (6'2", 235 lbs) recently bought a 98 CR 500 - he hadn't ridden in awhile and thought the extra weight he had put on would make him too heavy for a 250. After three rides and a nasty crash he sold it. He was a reasonably good rider and could not get used to the sheer amount of power. The wreck was caused by coming up slightly short on a VERY small double, having left hand come off bar and right hand twisting the throttle. He and the bike ended up in a small 2 foot deep pond. LOL.

He came up short, that's not the 500's fault. Little more twist is all he needed. Buy a 500, I would like to see more people out there like me riding them. The 5honey is a dieing breed. Get one while you can.

 

[ononewheel]

I have had a 250 before and loved the power. But Ireally want to race.

I've wanted to race since I was about 16, I am 19 now!!

I want a 125 as that is all I can race, and I think I would learn a lot more on a 125 then migrate to a 250 for playing when I can jump etc.

I would like to learn to corner as fast as I can on a 125 then start to ring the nuts off a YZ250 etc.


Yeah a CR500 is my dream bike, fully MX'd up, with a set of supermoto setup i.e wheels, brakes etc.

I ****ing hate 4 strokes!!

Soo does any one here ride in Surrey England then?

 

[2-Strokes 4-ever]

I relate to your enjoyment of riding a 125...me too! Based on the amount of riding you plan on throughout the month... sounds to me like setting about one evening a month for top-end maintainance is mandatory. Once you have it down, a couple hours is all that's needed. Ring and base gasket on month...($30?) and piston kit the next month...($90?) I also did a top-end bearing every other piston. This was pretty much my routine...worked for me...we play, we gotta pay.

 

[robwbright]

Notice I used LOL in my post about the 500. I was half joking. The impression I was getting from "ononewheel" was that he was not terribly experienced . . . Perhaps that was a wrong impression. Nevertheless, my point about the 500 is that even a small mistake can have dire consequences. The "double" I was talking about was more like a whoop - about 1 and a half feet tall. On my 125 I'm sure I wouldn't have gone down and I doubt my brother woud have on his 250 either. Regardless, I personally thought he was crazy to sell the 500, but I understood after his injuries . . .

 

[BigSwole]

I know you were joking. I did not mean no harm by it. I never messed around with a 125 before but I would think you would be faster on the 125 VS 250. I've seen guys just leave them wide open all the way around the track.

 

[#1YZ125RACER]

i have a yz 125 have had it about a year,i ride every weekend atleast 1 day 5-8 hours
its time for a new top end now,i ride trails mostly 2nd and 3rd gear at higher rpms...
i know i have put atleast 75-100 hours on my current top end but its slowing down
try smokey mountain offroad its a mail order company you can get a weisco piston and ring set for under $60 should save you some cast
125 two strokes kick @$$ dont give up on them!!!!

 

[bedell99]

Put an hour meter on your nike. They cost $30.00 at Sears.

Erik

 

[ononewheel]

I live in the UK so a UK dealers would be good.

SO I could get away with replacing the ring every 2 months and then the piston and ring another 2 months later yeah??

The thing i am not to sure about is...


Is this all that is needed to keep the engine fresh just constant piston changes and a little cylinder erm deglaze, score??? not to sure what it is called, you know the criss cross???

so I am looking at about £50 for every top end yeah??


Just can not wait to get this bad boy RM's with DEP pipe.

Do you think around a £1000- £1300 is a good price for a 01 bike??

 

[bully_23]

hi i am in the market for a new 125cc class bike and I dont know what will be cheaper in the long run 4 or 2stroke if i got a 4strk it wuld be an 03yzf and if ai got a 2strk prob ktm suzuki or a yammie can someone help me out please

 

[BMWPower]

The two-stroke will be cheaper to maintain.

 

[Daisycutter]

He came up short, that's not the 500's fault. Little more twist is all he needed. Buy a 500, I would like to see more people out there like me riding them. The 5honey is a dieing breed. Get one while you can.

I've never had a wreck I could blame on the extra CCs. FWIW, CR500 top-ends usualy go until the piston skirt cracks to the point that the piston fragments. For a once per week rider, you should change rings and examine the piston skirt every 6-months. Generally I preemptively replace the piston once a year.

Many 250cc guys get a couple years on a piston. The CR500 vibrates a lot, and has a lot of mass reciprocating. IMO, stuff breaks faster.

Also, FWIW, CR500s have only a few HP more than a CR250/CRF450. And the smaller bikes rev faster and much higher.

A CR500 is an old lazy man's bike.

 

[2-stroke diehard]

The older Honda XR's were fun. They last forever with a minimum of maintenance. There is a guy that posts here, Cort, who has embarrased many 125 and 250 riders on his XR 250......myself included.

Yes they were. A 4-stroke off roader used to have the advantage of being VERY reliable and low maintenance. Not so much any more, although they are MUCH much faster now.

 

[cr125drew]

I live in the UK so a UK dealers would be good.

SO I could get away with replacing the ring every 2 months and then the piston and ring another 2 months later yeah??

The thing i am not to sure about is...


Is this all that is needed to keep the engine fresh just constant piston changes and a little cylinder erm deglaze, score??? not to sure what it is called, you know the criss cross???

so I am looking at about £50 for every top end yeah??


Just can not wait to get this bad boy RM's with DEP pipe.

Do you think around a £1000- £1300 is a good price for a 01 bike??

don't go by months, years, etc. go by hours. i think an hour meter and a good compression tester would be a worth to get. for the area i live in (california), those prices would get an okay-decent bike.

 

[rm125dd]

I live in the UK so a UK dealers would be good.

SO I could get away with replacing the ring every 2 months and then the piston and ring another 2 months later yeah??

The thing i am not to sure about is...


Is this all that is needed to keep the engine fresh just constant piston changes and a little cylinder erm deglaze, score??? not to sure what it is called, you know the criss cross???

so I am looking at about £50 for every top end yeah??


Just can not wait to get this bad boy RM's with DEP pipe.

Do you think around a £1000- £1300 is a good price for a 01 bike??

I DONT KNOW WHAT THAT EQUALS TO IN USD BUT I AM PAYING 800 USD FOR AN 03 RM 125 AND THAT IS A CHEAP PRICE HERE

 

[Chili]

I DONT KNOW WHAT THAT EQUALS TO IN USD BUT I AM PAYING 800 USD FOR AN 03 RM 125 AND THAT IS A CHEAP PRICE HERE

This thread is closing in on four years old so I'm thinking he already decided if the price was worthwhile or not.