2002 kdx 200-just pulled down top end for first time this afternoon and heres what I found-kips system a little gummed up but still operating smoothly, combustion chamber on head had a little carbon build up, took care of that-top of piston had approx. 1/32 inch af carbon build up all over top(can clean)- piston skirt on intake and exhaust side have visable vertical grooves and can lightly feel these while rubbing finger nail across them. what causes this? cylinder has same light visable scratches but cannot feel them with fingernail. anything to be worried about here or is this just normal? all specs on cylinder, piston, rings check out to be okay and am ready to put this thing back together but just wanted to ask about scratches. think i need a new piston? thanks
top end questions
- Thread starter minidog
- Start date
jaguar
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Mine is like that too. I just clean it up with sandpaper and keep going.
I think mine did it from riding it hard without letting it warm up enough.
Black carbon buildup on the pipston is from a too rich mixture from the carb. Try one size smaller main jet and then look at the piston after a few rides.
I think mine did it from riding it hard without letting it warm up enough.
Black carbon buildup on the pipston is from a too rich mixture from the carb. Try one size smaller main jet and then look at the piston after a few rides.
minidog and others,
First to minidog, it sounds like all you need to do is clean up everything and put a slight crosshatch with 400 wet&dry paper (like jaguar suggested). Install new rings (with new top-end gaskets) and your ready to go.
Now to other's, I have to laugh when I hear people complaining about carbon build up.....
Yes! your engine burns gas and Yes! it's pre-mix. Duh..., do you think that there will be a by product....?
Yes! it's carbon!
What most people don't realize is that any internal combustion needs to be serviced..... In this day and age with EPA and fuel management computerized engines in our cars that will run for 60K with no service, we automatically think that the two stroke engine is the same...., NOT!
From day one a service or tune in the old days on a two stroke was pulling the head and de-carbonize the head and piston, setting the timing, changing the oil, lubing/adjusting the cables and adjusting/lubing the chain.
Then the electronic ignitions came about, but all of the other service needed to be done......, But lots of people started putting off regular service because the bike would start and run (no more points wear)
They still needed service though, the carbon still built up and the cables still needed to be lubed and the oil still needed to be changed.
Now we have the water cooled engine which is expensive to de-carbon on a regular bases and has trick suspension that needs to be tended to. But you have to do it to make it last!
Still every one thinks it should be like the new car that only needs service every 60K. NOT!!!!!!!!
Treat you bike as a very sophisticated and high tech piece of equipment, because it is.
Lastly, if it does not have some carbon build up..., your not riding it!
Oh yea, break fluid should be changed yearly...., just part of matainance. Or you can wait till something goes wrong.
Thank you for your time reading this :)
First to minidog, it sounds like all you need to do is clean up everything and put a slight crosshatch with 400 wet&dry paper (like jaguar suggested). Install new rings (with new top-end gaskets) and your ready to go.
Now to other's, I have to laugh when I hear people complaining about carbon build up.....
Yes! your engine burns gas and Yes! it's pre-mix. Duh..., do you think that there will be a by product....?
Yes! it's carbon!
What most people don't realize is that any internal combustion needs to be serviced..... In this day and age with EPA and fuel management computerized engines in our cars that will run for 60K with no service, we automatically think that the two stroke engine is the same...., NOT!
From day one a service or tune in the old days on a two stroke was pulling the head and de-carbonize the head and piston, setting the timing, changing the oil, lubing/adjusting the cables and adjusting/lubing the chain.
Then the electronic ignitions came about, but all of the other service needed to be done......, But lots of people started putting off regular service because the bike would start and run (no more points wear)
They still needed service though, the carbon still built up and the cables still needed to be lubed and the oil still needed to be changed.
Now we have the water cooled engine which is expensive to de-carbon on a regular bases and has trick suspension that needs to be tended to. But you have to do it to make it last!
Still every one thinks it should be like the new car that only needs service every 60K. NOT!!!!!!!!
Treat you bike as a very sophisticated and high tech piece of equipment, because it is.
Lastly, if it does not have some carbon build up..., your not riding it!
Oh yea, break fluid should be changed yearly...., just part of matainance. Or you can wait till something goes wrong.
Thank you for your time reading this :)
- Thread starter
-
- #5
will clean up piston dome and sand piston skirt and cylinder walls with fine grit (#320) emery cloth and put everything back together-have new gasket set ready for it-where is best place to buy gasket set, I paid 40 bucks for mine and I think this is really high just for gaskets-also cleaned kips system with carb cleaner-did a real good job-I know from this post to use oven cleaner but had none available at time-thanks for replies
kdxfreeeek
Member
- Sep 18, 2003
- 38
- 0
kdx topend
hi i got my bike back that i built from a frame. from a guy that finished top end well he had a new sleeve instaled from la sleeve well the head was leaking. so i took apart to finish what i had origanly started and finish it my self he didnt even use a torqe wrench on head so i had to heli coil one bolt on the cylinder looks real good. solved that problem.
my queston is IS IT NORMAL FOR A NEW CYLYNDER TO WHERE MORE ON THE FRONT AND REAR OF THE CYLINDER MORE THAN THE SIDES ITS BRAND NEW.
any help would be helpful
hi i got my bike back that i built from a frame. from a guy that finished top end well he had a new sleeve instaled from la sleeve well the head was leaking. so i took apart to finish what i had origanly started and finish it my self he didnt even use a torqe wrench on head so i had to heli coil one bolt on the cylinder looks real good. solved that problem.
my queston is IS IT NORMAL FOR A NEW CYLYNDER TO WHERE MORE ON THE FRONT AND REAR OF THE CYLINDER MORE THAN THE SIDES ITS BRAND NEW.
any help would be helpful
Last edited:
89kdx200rdr
~SPONSOR~
- Apr 19, 2003
- 488
- 0
my queston is IS IT NORMAL FOR A NEW CYLYNDER TO WHERE MORE ON THE FRONT AND REAR OF THE CYLINDER MORE THAN THE SIDES ITS BRAND NEW.
i think its normal on any cylinder new or old. think it has something to do with the fore and aft angular movement of the rod or maybe its the offset between the crank journal centerline and the piston pin centerline. too many brewskies. someone will chime in, fear not.
i think its normal on any cylinder new or old. think it has something to do with the fore and aft angular movement of the rod or maybe its the offset between the crank journal centerline and the piston pin centerline. too many brewskies. someone will chime in, fear not.
89kdx200rdr
~SPONSOR~
- Apr 19, 2003
- 488
- 0
minidog are the edges of your intake and exhaust ports rough? if so, smooth them out