For you 250 guys...top end question

Jeffro426 · Jul 28, 2004

Now mind you, im coming from a YZ 426 that i rode hard for 2 years, did a top end and everything spec'd out to near new tolerances....with that said, how long do you guys go between top ends on newer 250 2 strokes?? The Honda dealership(looking at an 04 or 05 CR 250) gave me some rediculous number like every 30-40 hours or something like that...if thats the case ill be doing a top end every other month!!! Now im sure hes just blowing a little smoke cuz after all...hes the dealership and hes only there to make money and get me to buy as many parts as possible. So how often do you guys go on a top end...does your premix ratio seem to have any effect on wear?? I usually have ran most 2 strokes at 40:1 in the past and never had a problem, but some have told me 32:1 will stretch out the time between new piston and rings.

zookieman · Jul 28, 2004

I ride alot (almost every weekend 8 months out of the year at least 40 mi. at a shot) and I figure every 1-1.5 yrs. I need to do a top-end. I run my premix @ 32:1 BelRay H1R. Besides a top-end is only $70-$120 that's piston, wristpin, circlips, topend bearing, and gaskets. They are even more simple than a 4-stroke.

shnalln · Jul 28, 2004

Last year I rode 2-3 times a week for about 3 hrs an outing (which equates to probably 1-1.5 hrs maybe since I'm trying to catch my breath most of the time) for apprx 5 months out of the year. Run 32:1 Yamalube, changed my piston when it was too cold to ride, and the rings where right at the service limit (oddly enough).
So what's that, about 50-60 hours on the piston? I'm slow too, so that 30-40 hrs for a fast rider is probably about right...I think the service manual actually says 20 hrs. It takes me a long time to get that many hours of "continuous" ride time, but I'm too outa shape to race, so...

pro2k · Jul 28, 2004

I have a 2003 CR250 and the maintenance schedule that came with the bike indicates that a new top end should be installed every 7.5 hours. Having said that, I've ridden the bike just about every weekend for the least year and half and the bike is still running like new. I suppose it all depends on how you ride the thing. If you race the bike every weekend then you will probably need to rebuild it quite frequently. If you are a recreational rider then you could get away with 2 years (like me). My buddy has a 125 and he is going on his 3rd top end in the same time period. He is a rec. rider and occasionally races. 125's are always screaming at high rpm's.

James · Jul 28, 2004

I end up changing the top end every 30-40 gallons of gas which roughly translates into 40 hours or so. I occasionally pull off the exhaust pipe and intake and look at the blowby on the piston to see if it is time. I can also tell it is time when it takes an extra kick or more to start it cold. It will run well past this point but you are losing compression and power when the blowby gets excessive.

pro2k · Jul 28, 2004

When my bike was new it ran rich but there was barely any spooge on the silencer. Now, 1 1/2 years later, spooge runs down the length of the silencer and drips on the swing arm. I have leaned the jetting quite a bit since it was new. Is all this spooge an indication that a rebuild is about due?? (or is it an indication that it is excessively rich?)

James · Jul 28, 2004

Your silencer is probably full of oil.

bedell99 · Jul 28, 2004

I ride also 3 times a week, but that only really equates to about to an 1 to 1 1/2 hours of real moto time on the bike per session. Thats roughly 3 to 4 1/2 hours a week and i change my top end twice a year and it looks pretty good when i take it out. I figure I put about 50-60 hours on a top end between intervals, which is a lot of riding. It also depends on how you ride. The top pro's(RC, Travis, Bubba) will go thru a top end in 2 hours of riding/racing, while a novice trail rider can go 2 years and still be good. Top Ends are direct function to how hard you twist the throttle and for how long, so 40 hours a true hard riding doesn't seem that far off.
Erik

pro2k · Jul 28, 2004

James, the silencer is pretty new. An FMF Titanium II

pace · Jul 28, 2004

Mostly I judge it by the seat of my pants. With the 250, it seems like it needs replacing about once a season for me. I ride 6 months out of the year, around 2 hours of actual running time per week. So I'd say I'm replacing it somewhere around 50 - 60 hours like Bedell. I have approx 40 hours on this topend and I can definitely feel a lack of snap compared to when it was fresh. But I ran about 10 gallons through it at the sand dunes recently and that took a noticeable toll on the motor.

My YZ144 had a Wiseco piston and that thing would come out after two seasons looking as good as the day it went in.

-Pace

WillyM · Jul 28, 2004

compression

Yes use a car compression tester.
should be around 150 lbs but not under 120.

A 2 stroke top end is EASY.
make sure to buy a base gasket head gasket ,and an exhaust gasket.

pace · Jul 28, 2004

WillyM said:
Yes use a car compression tester.
should be around 150 lbs but not under 120.

..if you're at or near sea-level. High altitude motors will show lower comp readings.

-Pace

shnalln · Jul 28, 2004

Seems like I read somewhere that it's good to change the piston after it has lost 20% the compression it had when the piston was fresh. Can't remember where I read that though, Eric Gorrs sight maybe? ...Probably, that's where I do most of my reading...

Jeffro426 · Jul 28, 2004

Some good responces here...now let me ask this...have you had to do anything to the cylinder, or just toss in a new piston, rings and gaskets??

shnalln · Jul 28, 2004

There is an extreamly long discussion regarding this in the first thread of this forum named "Cylinder Prep Before Installation".
I just clean mine up like it says "HERE".
But I'm a rookie, what do I know? ... :)

For you 250 guys...top end question

Jeffro426

zookieman

shnalln

pro2k

James

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bedell99

pro2k

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pace

shnalln

Jeffro426

shnalln

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