Piston Skirt ????Good or not so good??

[OVERKILL 19]

Finally sent my jugs to Tom to get ported. Just wondering if these piston skirts look normal to all you 2 stroke guys out there. Pulled lots of motors apart, but this is my first 2 stroke "Virgin". Cylinders looked good no scrapes or gouges.

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[glengine]

How many miles are on the motor since it had a new set of pistons? Lots of the doo pistons wear like that.. but my thought is that if it has a fair number of miles on it then it might not hurt to just put a set of new pistons in as it is already apart. just my thought.

 

[OVERKILL 19]

Some were between 800 and 1100 miles, can't remember.

 

[snotterite]

The way you ride is a determining factor.....but I agree with gg your in there now...R and R them. Turboed or not we swap out at 1500 to 2000...but thats just us....did you happen to do a compression test before the tear down.....or was it not running?

 

[glengine]

then they should be fine.. It's just the coating that is on the pistons that causes the different colours or shinny spots.. I myself usually like to change out pistons around the 2000 mark or so.. If i put more than that on in a season then i will just change then during the off-season.. the way i look at it is it's preventative maintanance.. But as long as there aren't any scrapes or roughness on the pistons you should be just fine to use them, just put a new base gasket in and you should be good to go..

 

[OVERKILL 19]

Hey Glen do you guy's usally change out all the gaskets as well. The base for sure but my O ring ones look great. The BRP manual says change them all but I was thinking they just want to sell more parts. I was going to change anyway, just to be safe, but I was curious.

If I was going to change Pistons, I was considering a drop in kit. What do you recomend?

 

[OVERKILL 19]

The way you ride is a determining factor.....but I agree with gg your in there now...R and R them. Turboed or not we swap out at 1500 to 2000...but thats just us....did you happen to do a compression test before the tear down.....or was it not running?

She ran great, compression was 125 on both sides or very close to it. What pistons do you run?

 

[Summitric]

I would replace the o-rings.... For the security of the cheap price of a new seal set, verses an already heated, stressed o-ring set, i would replace them no questions asked! The piston skirts look okay, and that is the factory nikasil coating on the pistons and the way they wear..... I don't see any scuff marks, but then again, since you already have them apart, throw new jugs in with rings, for the added reliability i'm sure you would want..........

 

[Scotty]

I would replace the o-rings.... For the security of the cheap price of a new seal set, verses an already heated, stressed o-ring set, i would replace them no questions asked! The piston skirts look okay, and that is the factory nikasil coating on the pistons and the way they wear..... I don't see any scuff marks, but then again, since you already have them apart, throw new jugs in with rings, for the added reliability i'm sure you would want..........

I thought that the Nikasil was only applied to the cylinder wall?? I may be wrong? Not likely Summitric.. I think you mean "throw in new Pistons" in stead of Jugs?? I agree.. new rings for sure, as he has the thing apart. Pistons?... yah probably seeing that it is a doo. :d

Overkill 19... the tops of those piston look pretty black, maybe running a bit on the rich side.

All the burnt looking "bronze" ?? makes me think that maybe you have run it a bit Hot?? Maybe just the photography??

 

[Summitric]

"throw in new pistons" in stead of jugs??

Overkill 19... The tops of those piston look pretty black, maybe running a bit on the rich side.

All the burnt looking "bronze" ?? Make me think that maybe you have run it a bit hot?? Maybe just the photography??

yup, i meant throw in new coffee cans and rings... Sorry. The tops of the pistons are black with no "wash" area, meaning its running a little rich.... Not running hot, because a rich mixture is cooler explosion.... Engine temp looks good.... If anything, it may have idled a little too long at one point in time, or another, but no damage occured-- WOULD LIKE TO HAVE SEEN THE SPARK PLUGS WITH MY MAGNIFIER.

 

[OVERKILL 19]

I think the piston tops might be black as it has not run for at least a month. I ran it farly cold into the shop and shut it down as I did'nt want to wait for every thing to cool before ripping apart. She was white smoken pretty good.

 

[Modman]

I think the piston tops might be black as it has not run for at least a month. I ran it farly cold into the shop and shut it down as I did'nt want to wait for every thing to cool before ripping apart. She was white smoken pretty good.

Possible that the piston tops are completely black due to over oiling? (common factory setup is slightly rich on the oil IMO). I have seen this on other motors. If it is fuel rich, then you should see washed spots at the transfer ports and exhaust port (the richer it is, the bigger the washed areas). Wash will not change quickly (i.e. running for a few minutes), takes a few hours of running to notice a difference unless there is a drastic change in the motor. Otherwise plugs are the best bet for monitoring engine changes.
Here is a piston diagnosis guide.


Sorry, the pics weren't up when I looked at this thread so I'm only guessing as to what the tops look like.

 

[Summitric]

possible that the piston tops are completely black due to over oiling? (common factory setup is slightly rich on the oil imo). I have seen this on other motors. If it is fuel rich, then you should see washed spots at the transfer ports and exhaust port (the richer it is, the bigger the washed areas). Wash will not change quickly (i.e. Running for a few minutes), takes a few hours of running to notice a difference unless there is a drastic change in the motor. Otherwise plugs are the best bet for monitoring engine changes.
Here is a piston diagnosis guide.


sorry, the pics weren't up when i looked at this thread so i'm only guessing as to what the tops look like.

yup, i agree... Best way is to inspect the spark plugs.

 

[OVERKILL 19]

So while we wait on jugs to be ported, I thought we would get the V force reeds put in my brother's XP........sweet mother of all that is holely. My respect goes out to all that wrench on these sleds daily. Not much room to do anything. What is your quickest way to do this we pulled the seat and move the gas tank back.

 

[glengine]

So while we wait on jugs to be ported, I thought we would get the V force reeds put in my brother's XP........sweet mother of all that is holely. My respect goes out to all that wrench on these sleds daily. Not much room to do anything. What is your quickest way to do this we pulled the seat and move the gas tank back.

You dont have to pull tank.. Just pull airbox, unhook gas line from fuel pump, drain antifreeze so you can unhook hose from carbs to head. Take the top bolt out of the fuel pump so you can move it to one side to get the one carb boot bolt, also remove secondary clutch and loosen the bolts that hold the bracket that secondary clutch mounts in so that it can move a little bit, but dont take nuts right off.. as there is a slight chance that bolt could come out and then you'd have to pull track out to get them back in.. Then i use a 1/4" rachet and socket to get bolts out.. Hope it helps.

 

[OVERKILL 19]

You dont have to pull tank.. Just pull airbox, unhook gas line from fuel pump, drain antifreeze so you can unhook hose from carbs to head. Take the top bolt out of the fuel pump so you can move it to one side to get the one carb boot bolt, also remove secondary clutch and loosen the bolts that hold the bracket that secondary clutch mounts in so that it can move a little bit, but dont take nuts right off.. as there is a slight chance that bolt could come out and then you'd have to pull track out to get them back in.. Then i use a 1/4" rachet and socket to get bolts out.. Hope it helps.

Thanks alot Glengine, we shut it down around mid night and that was the one bolt we had left "behind the secondary bracket". Alot of work for one dumb little bolt. I was hoping we did not have to pull the secondary out but oh well whats 20 more bolts. Great tip on the bracket bolts with leaveing the nuts on. I would have probably pulled them all the way off ! Thanks again

P.S next time I'm in McBride I own ya a beer.... or 2 or 3 for your help.Thanks again

 

[glengine]

No problem.. Glad i could help you out..

 

[Deano670]

You dont have to pull tank.. Just pull airbox, unhook gas line from fuel pump, drain antifreeze so you can unhook hose from carbs to head. Take the top bolt out of the fuel pump so you can move it to one side to get the one carb boot bolt, also remove secondary clutch and loosen the bolts that hold the bracket that secondary clutch mounts in so that it can move a little bit, but dont take nuts right off.. as there is a slight chance that bolt could come out and then you'd have to pull track out to get them back in.. Then i use a 1/4" rachet and socket to get bolts out.. Hope it helps.

Yeah what this dude says.LOL Oh and just my opinion here, replace those pistons as it is apart, replace your base gasket as they dont always like to seal twice and well its just my experience with head orings but they do like to swell when you take the head off and reomve them from the cylinders so id replace those to, they are cheap insurance.

 

[OVERKILL 19]

And the conerversal ??? What pistons should a guy through in? Stock, aftermarket or some form of drop in kit?

 

[POWDERCHOWDER]

Throw in rk-tek they work very well,they are also duel ring. talk to ken at mountain magic.