2013 EC250R - 130hrs

[Jakobi]

Last couple rides I noticed the poor little bike getting softer off the bottom and through the mid. The kick starter felt to be rolling through a bit too easy, and often would take a 2nd or 3rd kick to fire up. Todays ride she was flaming out a bit when pulling up as well.

Compression gauge showed 15% loss from last piston.

Pulled down after the ride. Piston wash looked slightly rich in comparison to some of my others (which had been abused with lean jetting runs). Surprisingly not a whole lot of blow by noted, however quite a bit of polishing and wear on the skirts (both rear and front). Top ring gap measured .8mm. Lower ring .65mm.

All done in 65hrs ride time. Not sure what people are doing to get 300hrs out of their slugs.

 

[barossi73]

hear no evil,see no evil,cross fingers there wont be any evil!
its hard to feel compression through the e start button!(i dont have one,cant say i miss it,esp as everyone seems to have trouble with it!)
Do you rebuild at "x" hrs religiously or as jug wears reduce the interval between topends?
Ive done 1 top end at 60odd on the 200 and everything was very good,wished id run it out to 80 at least.(belray h1r til topend,great protection,but excess spooge unless wot,now on castrol tts,a little spooge,will be interesting to see the entrails next rebuild)
But with accumulated wear i was thinking it might be a good idea to shorten the interval a little each time?Esp on the smaller cc.What are others doing?

 

[Jacob 'Berg]

hear no evil,see no evil,cross fingers there wont be any evil!
its hard to feel compression through the e start button!(i dont have one,cant say i miss it,esp as everyone seems to have trouble with it!)
Do you rebuild at "x" hrs religiously or as jug wears reduce the interval between topends?
Ive done 1 top end at 60odd on the 200 and everything was very good,wished id run it out to 80 at least.(belray h1r til topend,great protection,but excess spooge unless wot,now on castrol tts,a little spooge,will be interesting to see the entrails next rebuild)
But with accumulated wear i was thinking it might be a good idea to shorten the interval a little each time?Esp on the smaller cc.What are others doing?

Shorter interval on ring replacement may help to get more life out of the piston. As one of my buddies says... 'piston is just a ring holder'. Some will say that you may as well swap pistons while the jug is off, but if it is looking good maybe just do the rings?

 

[Jakobi]

I had considered doing just the rings, but realistically most of the effort lies in cleaning the bike up enough to get to the piston. Pulling parts off is easy! Making sure there is no dirt around to go where it shouldn't takes a bit more time and effort.

I figure for the effort its easier to just do the whole slug. Many times you do start to see wear on the skirts, as well as the ring end opening up. The rings do wear the ringlands to a certain extent, and the wear on the skirts allows the piston to rock in the barrel more than it would otherwise which likely increases were on the nikasil. For all those reasons I simply replace the piston - it's not that much money for the time and effort you spend doing the job (inc cost of gaskets, cleaning products, etc).

I have found the stock vertex pistons start to get noisy around 70hrs. Happened on both my bikes. On the newer one, I did the first piston at 65hrs and everything looked pretty good wear wise. I have some pictures somewhere and could check my notes on wear tolerances, but do recall thinking they weren't too bad.. but I could hear the piston rattle a bit on decel.

I was going to stretch this interval out but the bike was really feeling quite down on power. Very notable drop in bottom and mid. The comp reading confirmed my thoughts. The wear pattern and ring end tells the story.

On my other engine I put 110hrs on a slug and rings, and the ring end gap was bigger, but I don't recall the power dropping off like it has this time.

It may also be a case that I am riding the bike in more challenging terrain, at larger throttle inputs and simply wearing things out in shorter time frames.

 

[Neil E.]

I'm at 140 hrs on my current piston (don't know what brand it is). There is a bit of piston slap and it feels like the power is down some, however the compression tester still reads 200 PSI the same as it did when the piston was new. I'll run it for another season and see how it goes.

 

[barossi73]

im really not that inclined to only do rings either,as you've done all the cleaning and dismantling anyway as above.its a bit like doing an oil change and not the filter i think(4t).i figure if you keep the slop to a minimum the jug must last longer,stay truer,and prolong its life(along with always having a fresh engine).then again if you can get 300 hrs on 1 slug you've saved enough $ to buy a new barrel!
new rings on a high hour piston are surely not going to seal as efficiently,and will probably wear faster and potentially give trouble IMO(far from expert,but plenty exp from chainsaws to tractors)
A new surface mated to a worn/pitted/polished surface never works as well and always wears faster(think new pads on worn discs,rapid wear)
anyone put a new diff head in a worn diff-usually makes them whine more!
would you replace a tapered wheel bearing inner race and leave the worn shell?
the exception would be the guys that are dead serious and do rings every 25 and pistons at 50 when the piston at 25hrs has very minimal wear
Jakobi you mention the stock vertex getting noisy around 70,i think you mentioned in another post that youve also used wossner,how did they compare?
BTW Im more than happy for you to keep abusing pistons with lean runs if it helps others with jetting/rebuild issues including myself!Your knowledge is a goldmine(high praise for an aussie,coming from a kiwi,keep up the good work!)

 

[Jakobi]

I've been able to pick up the 64mm Wossners for good prices (cheaper than Vertex). They don't make the same sounds, but that's not to say they aren't rattling around after some wear. It may be a case the cast ones resonate more.

No real difference in performance. In theory the Vertex is a bit lighter and should rev a bit more freely.

 

[barossi73]

Interesting,i initially thought the bike felt/sounded slightly different after installing wossner but it was so negligible i wasnt sure if it was my imagination,i used a wossner on 1st topend but still have 20hrs or so til rebuild so will compare then.the recessed area in the piston(balancing,weight reduction,voodoo port?i havent a clue!)is a different shape than the vertex but i have no idea if it makes any difference as its below the rings?only theory i can think of is it may have a subtle effect on drawing crankcase mix into the skirt area?or the volume of the mix in the skirt area?
It doesnt particularly matter as both work well,but am curious.
Most probably its far simpler...they need a point of difference!

 

[Jakobi]

Interested to hear your thoughts once you pull the Wossner out.

 

[rubber Jonny]

I have no idea how people get so long from their piston \ rings. Mine was shot 1.4mm gap at about 90 hours. My mate who I ride with runs the same oil as me got 252 out of his and under 1mm gap.

 

[Jakobi]

I have no idea how people get so long from their piston \ rings. Mine was shot 1.4mm gap at about 90 hours. My mate who I ride with runs the same oil as me got 252 out of his and under 1mm gap.

Lots of variables from one rider to the next.. but without a doubt RPM has a large impact on wear.

Consider 90hrs at an average of 5000rpm, vs 90hrs at say 3000rpm. Equates to approx. 27million revolutions vs 16.2million. Fair difference in work. You can see why MX race maintenance intervals are so short, when the engines spend a fair amount of time revving hard.

Air filter maintenance, riding conditions, water ingress (bringing silk/dust through with it), etc also have a huge impact. Only really takes one instance for damage to occur.

While we're talking Rubber, did you ever get to the bottom of the over volting? I'm considering swapping the whole stator out from my 2010 to check if it makes any difference.

 

[3beejay3]

I have no idea how people get so long from their piston \ rings. Mine was shot 1.4mm gap at about 90 hours. My mate who I ride with runs the same oil as me got 252 out of his and under 1mm gap.

It has a lot to do with how and where they are ridden. Oil type may play a role as well.

A bike that is aggresively ridden on a lot of 2-track & on the pipe a lot is going to go thru pistons and rings a lot quicker than a smooth, lazy rider who cruises thru the singletrack, only on the pipe once in a while.

I'm going to comp test mine soon, it has 220+ hours on the original top end. I cruise thru the ST most of the time.
I have a new cast Smart Carb to go on it, so may freshen up the top end before doing so.

 

[Jakobi]

I ride single track more often than not, but that's not to say the throttle doesn't get turned.

 

[Capz85]

I put a wossner on at the start of the year on my sm 300, will be replacing it with another while it is apart for other mods, it looks to be in great condition, I'm sure it doesn't need replacing but for peace of mind I will, I do love these Pistons

 

[Capz85]

The left one is the wossner I put in which has 70hours on it the piston on the right is a vertex with unknown hours but was very noisey

 

[Neil E.]

Did you ever get to the bottom of the over volting? I'm considering swapping the whole stator out from my 2010 to check if it makes any difference.

I'd be surprised to see this making any difference, but it is a good test. Any time the flywheel is spinning significant revs, the actual AC voltage will be high. The voltage regulator is supposed to hold this at ~13 volts. I notice my DC voltage constantly varying from 13.0 to 15.4 volts.

 

[Jakobi]

I've tried 3 x regulators (inc one new, and one off my other bike that doesn't overvolt). Checked the earth more than once, but haven't ran a second grounding wire from the reg yet. All bounce way too high, even at moderate revs.

Got everything cleaned up and back together yesterday. Went back over the engine mounts and nipped a couple up a bit more which weren't loose, but weren't really as tight as I'd like. Powervalve cleaned, cylinder cleaned, all gasket surfaces, head, etc. More cleaning than anything else. B piston was a very nice fit too - right time to do that! Flushed the rads and rad lines.. Coolant was quite murky so I'll replace that too.

Engine is mostly buttoned back together, water pump and exh spigot to still go back on. Want to do a few more odd jobs before putting everything else back together. By hand you can feel compression is back up again! Not even broken in yet.

 

[rubber Jonny]

Never got the bottom of that problem, spent ages on it, extra earth didn't work I even earthed the bike to a metal bench to test it no change!

would be interested to know a solution if you find one though, good luck!

 

[Neil E.]

About the only thing I can suggest is to try a full wave rectifer/regulator. The idea being to run the lights on rectified DC voltage without using a ground. So the original AC stator output would remain grounded, but the new DC voltage would be isolated (floating).

The power side of the lighting would connect to the plus of the rectifier. The other side would connect to the minus of the rectifier. To do this none of the original lighting would be grounded, those wires would be removed from ground and now go to the rectifier minus.

The power side would have to route through whatever switches you require.

 

[motopsycho87]

Or, run more 2 stroke and a slightly richer mix. Had my piston in almost 2 years now riding a minimum of 4 hours a week. Had the top end apart recently to machine the bowl, piston and rings still in spec. I've not read anything that proves less oil works better than more. And the condition of my engine is just another point to prove otherwise .