I have a yz 250 yamaha layed it over now it won't start put new plug in has spark when you kick it

Murtaza Akberali Versi

• 767 Answers
• Posted on Feb 02, 2009

SOURCE: yz 250 wont kick start

Hi andersondts.

To get you right there i believe it should read as 'jump' start and not 'bump' start ...:-)
Well the problem could be with the battery, is it a maintenance free (dry) or is it a wet 0ne (uses sulphuric acid specific gravity 1250).
( 1) How old is the battery?
( 2) If its a wet one ,check the specific gravity of the acid in it, if its low thn charge it.You may hve to add or top up to its required level , if so thn use distilled water only !
( 3) If the battery is more thn 17months old ...replace it.
( 4) Its not bad to get the charging rate of your bike to make sure that it is working properly as required.

I hope this will help.
GOOD -LUCK.

Knight.

Paul W

• 404 Answers
• Posted on Feb 06, 2009

SOURCE: yz 250 wont kickstart

Hi!
You obviously look after your machine and very sensible when laying up, however as you are probably aware 2 strokes rely heavily on compression, A. to produce excellent combustion and B. to draw fuel into the chamber. So when you try kick starting you can't get enough revolutions to draw the correct amount of fuel into the cylinder, where as you push start you constantly turn over the engine increasing compression slightly and bingo it fires.
Can you remember how when kick starting it before this problem the feel on resistance when kicking over? has it now become a lot easier? if so you possibly have worn or broken compression piston rings.
A compression test will reveal this, I hope this sorts your query?
Press the Blue button please for my FREE effort,
Thank You!
Paul 'W' U.K.

SOURCE: hi i have a 1998 yamaha yz 250 that when you start

Are you loosing transmission gear oil? I seem to remember an older bike I had with a crank seal issue. Gummed up plug is usually only 2 things:
1) Carb too rich. Check jetting or sticky float needle valve that will dump fuel into the intake manifold.
2) Too much oil (check mixture ratio or crank seals that is mixing crankcase oil with the fuel mixture). Either of these two oil issues should produce a massive amount of tailpipe smoking and a noticable drop in power.

SOURCE: 1989 tw200 yamaha won't start

G'day egdbcs . Ok.now lets see.You say good spark,so i'm presuming you are doing the old sight test.Try bending the arm on a know good sparkplug about 5-6mm,earth the plug and kick'er in the guts(crank it over)Be very carefull , high voltage danger.If there's still a good spark it's safe to say that there will also be a good spark under pressure in the combustion chamber,speaking of which you should also do a compression test,anything over 100psi should be ok. as i'm not to sure of the extent of the re-build,hopefully the valves were lapped and checked for straight and true and valve seals replaced,if you notice oil on the tip of the spark plug you could have a leaking valve seal or oil seal .Try putting a small amount of fuel directly into the combustion chamber ,tighten up the spark plug ,install the plug cap and.......Yeah ..You guessed it ..."kicker in the guts".If all the abouve are correct and true it should fire up.If it runs for 5-10 seconds then stops you've got some sort of fuel starvation problem , could be dirt in the carb,blocked idle jet ,or air passage or even the needle could have come off it's clip,believe me with an old bike like yours anything could be worn and loose inside that carby.The only other thing to consider is the timing.There may be a good spark but is it happening at the right time inside the engine???. I'll leave it all in your capable hands EGDBCS.Hope this helps to solving your worries. Chow for now......Tilleydog..

SOURCE: 1992 yz 250 won't start

A couple of things.1.Check the fuel oil mixture is correct.It seems rich.2.Check that the carby is not running to rich.With new reed valves etc.it may need to be set back to the original manu. specs.With older parts it may have been retuned to make it run with the old parts.(carby jetting etc.)3 make sure the fuel oil mix is using a good quality oil.It does make a world of difference.I hope this is a start to get you going.