Can a kx250 2002 two stroke barrel be rebored or should the sleeve be replaced .

Greetings, I read your question and I think Reliable-Store can help you in this. Here's the site link.
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it could be your button i know this bike very well
does not matter if it is the xs 1 or the xs2 the same set up applies
there are a few components you need to test first
starter button
starter solenoid
wiring
main fuse

i will also tell you some major mods i did to one
when i was dragging the xs650 at super twins
which included a rebore to a 1056cc and having 7 gears
and a turbo

to eliminate the button
with the battery still connected
get a spanner or a screwdriver and not doing it to long
arc out the two polls on your starter solenoid
if you do not know what that looks like follow the main red wire
that goes from your battery
the first stopping point will be the starter solenoid
one poll clamps the main wire from the battery
second poll clamps the main wire to your starter motor
arc out the two polls with a spanner or a screwdriver
to test the motor
if your motor turns the engine then it is not your starter
the problem lies in either your

starter solenoid, (this is a sealed unit replace unit with a new one)
the wiring, (test main wire from your ignition to your switch
also test wire from your switch to your starter solenoid also clean all your wiring connectors)
your starter button, (strip and clean)
main fuse, (replace with a new one)

if the motor does not turn
then you will need to remove the starter motor
before you take the starter motor apart
test it with a multimeter
set on omes test each wire on the body of the starter motor starter
to check if the windings inside are earthing out on the body
if there is a reading on the multi meter
then your windings are earthing out
if there are no reading it may just need a clean up and new brushes fitted
and reassemble your ride

TRIED AND TESTED ENGINE MODS

if you play or really want to play there are a few major mods you can do that have been tried and tested

REBORE TO 1056CC GRASSTRACK MODS
parts needed
slab billet alloy 13in x 8in x 1.5in (for stroker kit)
or a pre brought stroker kit from halco tuning or wisco
get 2 mercedes benz 2.3 pistons ( for rebore)
2 barrel liners
find a good engineer and rebore your barrels and fit new sleeves
fitted with your 2.3 pistons

by fitting the stroker kit you will lose the standard top engine mount
or have more made as you by now should know a good engineer

EXTRA GEARS
remove kick starter reduction gears
find a good engineer and have 2 more gears made up
and fit

TURBO FITTING
tried and tested turbo fitting
a mk 1 land rover turbo is small
and can be fitted under the carburettors
with a heat shield fitted between the carbs and the turbo

these are all mods i have done to the xs650
i built and raced i got to 180 mph over the 1/4 mile strip
with a xs650 hardtail chop that looked like a standard engine

have fun

yes , resleeving is required for overstock size pistons.
sometimes you can bore the sleeve 1 - 2 time before resleeving is required.
when you go to order your pistons, the product description will tell you if resleeving is required.
Hope this helps you out.
Best Regards
Big Al

carbon on sparkplugs are caused by oil in the combustion chamber.

here are some things to do:
1. replace the sparkplug
2. replace your head gasket
3. check if your ignition timing is correct (timing in the distributor, camshaft, and crankshaft)

if these does not solve your problem, try this:
1. have your cylinder head checked for leaks/cracks
2. replace your piston rings

lastly, if all of these dont work, this is the solution (but quite pricey)
1. have your head rebored. reboring the cylinder head means making your combustion chamber wider so cracks/leaks on the wall will be removed.
2. after rebore.. you have 2 options: resleeve or replace piston rings. Resleeve means inserting sleeves in the bored chamber to replace the removed part. replacing pistong rings is also an alternative since your old one will not fit anymore ot the rebored head.

replace piston and rings and gudgeon pin and bearing , check condition of con rod for wear also ! check bore for wear and if it can be rebored ! ?? it will fail and cause more damage !!!

It seems you have worn rings and/or barrel and piston. You will have to get the barrel off the engine to ispect. Unbolt the carb and exhaust from the engine. Unbolt the 4 nuts on top of the head. Remove the head and barrel from the engine. Inspect the piston for scoring and wear. Remove the piston by removing the circlip next to the gudgeon pin. Do not drop the clip into the engine.(stuff some clean rags in the engine under the piston. The gudgeon pin can now be pushed out of the piston and the piston removed.Have the barrel and piston measured for wear.
If you're on a tight budget you can replace rings only but this is a penny wise pound foolish solution. You'll have the same problem in 2 months time.
It is best to rebore the barrel and fit an oversize piston and new rings. The barrel can also be resleeved but this is a more costly option and should only be exersized if you cannot obtain an oversize piston.

That means there's no compression at all... Check the engine block. Piston might need replacement and block rebored or re-sleeved.

Hi,
Most late modle MX & enduro (from about 1990 on plus some even earlier)
have what is called an electrofusion bore.
This is a very thin plating on the alloy cylinder. They use this so as to allow heat to dissipate quicker & can run tighter piston cylinder tolerances for improved performance.
To answer your questions,
No, they can't be re-bored(like the older style steel sleeved bore bikes could)
Yes, they can be honed but it requires a special type of hone(finger type bottle brush style hone).
Pistons are available increasing in size by much smaller incriments than the old style & are usually marked A,B,C,D(as the coating is much thinner than steel sleeve).
If it is scored very badly & you can see alluminum spots/scores anywhere on the cylinder surface there are several ways to deal with this.
Here in Australia there is a company(electrocill) that can re-cote the cylinder which is much cheaper(plus thicker & stronger) than replacing the barrel
If you have a cylinder re-coated It has to have all studs, seals & power valve assemblys removed.
You would also need to supply(or have them supply) a new piston in order for them to set the correct clearance.
Also here in Australia you can have most of the common models fitted with a sleeve & this gives you the abillity to rebore in the future.
In the U.S this company is known as Wisco(serco in Aust.)
It is worthy of noting that the piston rings are not interchangable between an electrofusion & steel type cylinder.(so if you opt for a re-sleeveing any spare rings from your spares kit ar of no use).
If you need a lead on how & if these services are available in your country(if your not in Australia) I suggest taking a look in the classified section of your local dirt bike magazine.
The trick is to undertake regular srevicing of your air filter(this is A MUST),oiling it properly with propper foam filter oil, useing a top quality 2stroke oil(motul,syn-lube for eg)
& regularly inspect & replace rings/piston as needed to get the best life from electrofusion or steel type bores
Hope this explains it all for you
Regards Andrew Porrelli

buddy its not an easy job to do as if the barrel has been damaged that much it will have to rebored to an over size piston or a new sleeve installed or if its just a little scratch you can get some glass paper and run it around the barrel not stying in 1 place at the same time do this until smooth also you can take it to a shop and get them to rehone it for you or rebore it also when you put the new one in oil the rings and make sure the arrow is pointing towards the exhaust valve