98 RM 125 just wont start up

[Skullb]

I have looked to solve my problem on this forum but havent succeded so i'll explain first
i have a completley standard 98 RM 125 (first bike except a 90 KMX 200) and early december i changed the piston and ring because i'd owned the bike over 6 months and as it had never blown up i thought it was the time to do so, everything went ok like barrel was undamaged and put all new gaskets in and after i got it back together i noticed alot of compression (more than befroe anyway) and the bike ran nice while i was running it in.

On new years eve in the day i went to a small local quad track with a group of friends and the bike was running perfect, I was kind of racing my mates but not really punishing the bike like i had done before the piston change and for a period of half hour i could feel the bike slowly losing its power, not much but noticable. Then when i was on my way back to give the bike a break it just stopped and conked out in a nice muddy patch and the bike had zero compression, one of my mate thinking i just stalled came near me and showered me in mud like most of us do to each other for a laugh, I didnt look at the bike there i just pushed it to my house (only a mile away luckily) and locked it up so i could go out on the piss (new years eve remember).

I looked at the bike a few days later after cleaning it and seen the spark plug had unscrewed itself and was still stuck in the cable and all coated in a ball of mud, i cleaned up the area on the bike near the barrel and cleaned the spark plug then took the top of the barrel off and made sure it was all clean inside, knocked it back up and the bike kicked up within 15 seconds and i let it warm up a bit i then gave it a 30 minute break, i kicked it back up and it started first time. I then rode it to where i keep my bike locked up (half a mile away) and all went fine. I then started washing the bike with a pressure washer like i always do and got it all cleaned up, put it away for the night and the next day for some reason i cant start it back up :bang:

I had then searched these forums and set about firstly checking the barrel piston and al that area, all came up fine but bike still wont start.

Then the carb came out and i opened it up to find the slow jet had something blocking it and i sorted that problem but the bike still wont start.

The spark plug got replaced and like before the bike wouldnt start

I'm at the end now and my very little knowledge of bikes is not enough to sort it out. Any ideas or help anyone can give me?

 

[Mike R.]

Check

to make sure you are actually getting spark.
You can do this by either using a Plug Tester found on like Snap-On trucks or simply gorund the plug to the motor and kick it over.
I also would highly suggest getting a Factory Service Manual as it will tell you how to properly test the ignition CDI, Stator and such.
To rule out internal problems get a compression tester and check to see what your reading is.
You want in the ballbark of 150psi+ even though a bike will fire at around 100psi its a tell tale sign of needing a top end.
It doesnt sound like anything internal though and sounds more Ignition or Fuel related esp. since you said you have already found a partially clogged jet.
Best of luck firguring it out and hope all goes well :cool:

 

[sick 96 250]

I bet you got water down in the exhaust which went into the crank after you washed it. this will cause it not to fire up if a decent amount got in there. Search the forum for water in crank. Sounds like thats your problem since it originally was the plug coming lose and then it ran again then after you washed it it wouldn;t start. its a very common problem when washing bikes if you dont plug the exhaust and dont say away from the filter with the water. Good luck

 

[Skullb]

ok then i've got somewhere with the bike, the the spark plug i put in was the same as recommended in the clymer manual a R6918B-8 but a mate popped in with a dirty old spark plug from his 95 rm 250 a B9ES (something like that) i put it in and it kicked first time ????

Before that i did lay the bike on its sides to see of anything like water or what not was stuck somewhere, then kicked it for 15 minutes and i heard a faint bit of life (fired up for 5 secs then died) and that gave me a bit of hope

Nice one for the reply's i'll get on to what you advised but i've put the bike away for the night but hoping a "brand new" plug i'll buy in the morning will sort it out and then get my carb seen to in the week for the mixture to be sorted by someone who knows how

 

[nickyd]

that's a good one...I've got a 96 RM 250 that runs excellent - new top end, etc....man it screams..UNLESS you wash it...then no matter what you do - it will not start......put a new plug in and it fires first kick and runs great...until you wash it. so I don't wash it. hahaha