The 125 is fun, but my wr 09' has had every problem and is generally stuck with a black cloud of unreliable over it. It's been a very expensive ownership. My 4t experience has been way,way cheaper so far. So the small bore 2t thing i'm kinda over it and ready for a bullet proof ride I have yet to choose or figure out. keeping it stock would of helped a lot. So I take some blame for it. When it runs, its a sweet bike. We just take long breaks for rebuilds in our relationship. and that hurts.
Not sure it is that much more inexpensive to own a 2 stroke. You pay as you go with pistons and 2 stoke oil. Say you rebuild a 125 1-2 times a year, say $400. Then the oil say another $200 for a year. So $600 a year, you can do a 4stroke head every 1.5 years at that rate. and overall less work. No getting 2 stroke oil and mixing it or doing pistons / powervalve in that time. If you have a big failure withe a 4st it can be costly but a big failure on a 2 stroke is not cheap ether. Unless you loose a rod or something you can get many seasons on a 4stroke. K
Technically, a 250F needs top end service at the same rate or sooner than a 125, since they both have about the same stroke and run similar RPM ranges. A 250F tends to run hotter, also. A 450F should need top end service about 3X as often as a 250 two stroke, since it has a much shorter stroke and operates in a higher RPM and temperature range. Fortunately, most 450's aren't ran in their peak operating range, so you can probable go longer. But, pistons tend to be more expensive, too.
The best bang for the buck I have found so far is a 4t... You put an hour meter and when it reaches 90hrs you sell it and start over with a new one.
Huh? I have a TXC250 and WR125. the WR is on it's 3rd piston to keep it fresh and 100% power. The TXC is hardly broke in / valves have not moved. The wr has more miles but not a ton. Most say the motor does not even loosen up till about 600 miles where the WR125 is close to needing a piston at that point. Jakes WR250 yami has like 10K on it and has had 1 piston I believe. 250F's go a LOT further on a top end in my experience.
Clearly I am doing it wrong. This is the third hour meter, lost a couple and ran the first 2 years before putting one on... And the bike was used when I got it. Later,
I agree, my 144 is on it's second top end since march and one cylinder re-plate also (28hrs). The TC has reached 35 hrs with nothing but oil changes.
Boy i must be doing something wrong as i have gone 1 full year of desert racing well over 1000 hard miles on a 125 Then i replaced the piston and rings .The next time i went 6 months and only change the ring used the gaskets over .My 2006 CR 125 went 4 full years with only piston and ring changes THEN after 4 years i took it to George at Uptite he changed some bearings and rod along with a new piston and ring .STILL on the stock bore,all the gears and even the clutch basket are original .That bike is still racing . I have only owned and raced 4 strokes since 1975 ,but then i rode a Husky 2 stroke in 2006 and have never wanted a 4 stroke again
1000 miles sounds about right. My 04 TE450 had 3000 miles and was still very much in the compression range. Lots of 4st's will go 3-5K before needing rings. Jake hour meter is at 220, we typically do about 18-22 mph average so his bike has over 4400 of whats showing, he got it used and went through several meters before that. I think he guesses about 6K on it. Runs strong, does not smoke. he races it in the A class and pounds the crap out of it off road. I love 2st and 4st about evenly. Not common I know. I have not found ether to be obviously more / less $$ to own. The 2strokes are typically EZer to work on but seem to need it more. Pistons, muffler repacking, pipes needing fixed all the time, 2st oil to buy and mix, plugs, etc. My TXC has needed nearly nothing (one $14 temp sensor), my WR has been apart ,many times for power valves (factory issue), piston, 144 (which was my choice), pipes, muffler, carb etc. My ATK 490 would run forever without even changing the oil with the huge under-stressed Rotax mill
But, what are the recomended intervals? Higher than the two stroke, aren't they? Why? Because the reasons I stated above. The only reason people run 4 strokes longer is because they are more labor intensive to tear down and they end up costing more. A proper four stroke top end job ends up taking the average Joe days to complete. They do the two strokes because it's cheaper and easier. You can ring a WR125 in about 30min., easy. It's really not because it needs it any worse than the 250F, it probable needed it less. And thanks for your support ajax.
The 2st will loose compression WAY before the 4 stroke. My buddies WR250 becomes nearly unridable at about 1500-1800 miles because of lack of compression / power. A 4st will go 3-5K and still maintain compression. A big part of it is the 2st has a swiss cheese cylinder for the rings to bounce off the port edges and wear fast. the 4st has and nice smooth hole to deal with and constant ring pressure. I'm not trying to argue with you or disprove just interjecting my feelings / findings. It's all good.
+1 performance has a price. that goes for bikes, cars, truck. the more we try to squeez out of a power plant the more we are stressing things. id love to get a hold of a factory 144 kit to see how much if any long it lasts then my eg cylinder.
