03 kx25 impossible to kick start

[EncyclopediaRonnie]

hey guys got myself an 03 kx250 has aparently had a full rebuild top and bottom end its got an ankle snaping 170psi comp so i dare say its been built but its near a nightmare to kick, cold its a ******* of a thing warm not so bad, it will clutch straight away but,

imediatly i suspected reeds and as such replaced them with boyosen dual stage carbon reeds, no difference made if anything a touch worse,

its got an fmf gnarly pipe and shorty silencer runs on 32:1 which im thinking of droping to 30:1 runs b8es plugs or if they dont have the b8 i get the br8es,

the jettings not perfect im in the process of trying to tweak that but i havnt been out much to do so,

im thinking either

a) plug gap
b) magneto air gap or base timing wrong
c) maybe jetting wrong but why clutch and not cick?

where would you start looking

 

[arnego2]

170psi on a newly rebuild top end isn't too good IMO. So far my numbers are around 220Psi freshly rebuild Cold and @ WOT.

Does it run? Something not very clear to me when reading through your thread.
Not running comes down to several points.
Spark, Carb, Reeds, worn crank seals also contribute to hard starting.

 

[EncyclopediaRonnie]

runs good, comps good,

as said reeds are brand new, carbs clean

just a prick to kick start, you can clutch start it easy as just not quick it

 

[arnego2]

As I said your comp numbers are quite low for a new top-end. I think its a worn out Topend. Have a peak view into the cylinder by taking off the expansion chamber (pipe). If you see a lot of blow-by you know it old and you should measure the cylinder. Some people go as far to just throw in a new piston into a worn out jug to sell a running bike. Not saying that yours is one of those though :)

Normally the piston clearance is between 0.05mm to 0.1mm in Japanese 2 stroke engines. Everything larger than would cause a drop in the "normal" compression.

 

[EncyclopediaRonnie]

mate ive built plenty bike engines in the past im telling ya now the top end is not the reason i wouldnt have asked up on here if it was a dead top end, factory specs say a rebuild should have 170-190 odd and at around 130 odd its rebuild time, 220 psi in a 2 stroke is a really high comp ratio,

ohh and for what its worth ive had a look at this top end, its not worn at all..........


does anybody have any ideas on spark, ignition etc , other than my top ends worn ffs

 

[arnego2]

Try a new spark if you haven't done that already. Manual should give you some OHM values to check you electrical components. When going through electrics clean all connection points, open them up and spray some electric cleaner into them and reconnect. '03> the bike is ten years old, dust could well be crawling into those.

 

[Bonehead]

how old is your gas? Sounds like bad gas to me

 

[RM_guy]

I had bad gas once. The bike started fine but no one wanted to ride behind me.

 

[EncyclopediaRonnie]

fuels fresh,

arnego2 im not sure how to test that stuff im guessig with a multimeter but ive never actually done it hey, what do i need to do,

 

[arnego2]

Your manual should tell you the values, you need a multimeter to check those.
Not too difficult using one. I had a cdi problem once and my multimeter was easier to manage than I thought.

I found that cleaning all contact points already helps starting.

 

[EncyclopediaRonnie]

might look into the cleaning, atm im waiting for a carb kit so i can pull it down go over it top to bottom check all wiring ignition, timing rebuild the carb check reeds again etc etc and see where that gets me, i wa able to have a quick read through the manual i got and i know my plug gaps to big