Help needed: Hard starting, and wont idle

[t3mp0r4ry nzr]

Hi all! Wise head/s needed for a lil problem of mine! Since I brought to a while ago now, my 1996 CR125 has been a pig to start and it cant idle. Also, it will quickly foul a plug if you are napping.

Ive been getting around all this so far by: a) a starting ritual of ritual of dragging the bike around in top gear (twice!), before giving her 1 kick and it'll buzz into life like a raped chain saw (b) on down hill sections with no throttle applied, killing the engine to avoid a fouled plug.

Obviously not a good way to deal with the problem!

Bike has a FMF gold series pipe. air filter is clean and oiled of course. Running 30:1 TTS with 95RON.

Got the carb to bits. I was suspecting a blocked pilot jet, but was clean and clear, as with the main jet. Pilot is a 52 (standard is 55). Main is 170 (standard is 172?). Choke/idle speed knob is screwed right in. Hence it cant idle. If I screw it out, the throttle gets very boggy ie.rich. The choke needle looks undamgaed to my needle virgin eyes. Air screw is 2.5 turns out. BR9ES plug.

Starting: it wont kick start if left for a day. need to turn the motor over with fuel tap on to get to start, or drain carby and change plug. (which one is easiest!?)

Would love to get this sorted!

Any advice appreciated (except selling the bike!, it is great otherwise)!

[eelracing]

What about the carbs float needle,maybe it is worn and hence flooding the carb.I ask coz a mates bike used to flood so bad (due to worn petrol tap)that we had to push it around in gear with the exhaust pipe off and spark plug out to clear out the crankcase of petrol.Vmx bikes can be a bitch like that.

[tommorth]

how long since the rings were done?

[t3mp0r4ry nzr]

how long since the rings were done?

dunno to be honest. it goes well and doesnt smoke excessively. could it be a factor?

forgot to mention, have done plug chop tests and the insulators a nice coffee colour

[oldskool]

Heres my 2 cents worth. Check for an erratic CDI unit or condensor. Check for air leak due to slight crack in inlet manifold. Oh yeah and grounding kill switch.

[courts]

30:1 a bit rich aint it , lean it out to 40:1. your needle prob needs checkin , some of the 2 dinger boys should be able to fill the gaps,good luck .

[oldskool]

30:1 a bit rich aint it , lean it out to 40:1. your needle prob needs checkin , some of the 2 dinger boys should be able to fill the gaps,good luck .
? There's actually more fuel in 40:1 than 30:1, but that's prob what you meant anyway. But the plug colour is sweet and once it goes it goes like a cut cat. If there is a good fuel/air mix, the spark timing is spot on and the plug aint fouling it should still start on oily fuel regardless.

[t3mp0r4ry nzr]

Heres my 2 cents worth. Check for an erratic CDI unit or condensor. Check for air leak due to slight crack in inlet manifold. Oh yeah and grounding kill switch.

I only have a problem starting when cold. When hot, it starts first kick. Does this change your opinion?

[oldskool]

I only have a problem starting when cold. When hot, it starts first kick. Does this change your opinion?
Yeah it sounds like you're gonna have to do a real thorough step by step.
From checking the sparkplug cap down to a leaky crankseal. So you've checked the compression and the fuel/air mixture. You've checked the carby floatbowl. You've checked the spark timing. CDI and condensor. hmmmm Sounds like you need to sell me the bike for a few hundy so I can put a 250 thumper init :devil2:

[tommorth]

mate had a dt200 that had stuffed rings was an utter bitch to start from cold it spent a few lonely nites out in the orchard because it wouldnt go once it was going went great we used to ride up the road to a swiming hole it would still do 140 two up was easy to start when hot
eventually he replaced the piston and rings problem went away it idled fine thou so maybe not the problem

when you say choke idle speed nob screwed it do you mean the air screw or the screw that the slide comes down to ?

you can check your inlet for leaks by spraying engine start on it if the revs go up it leaks same test works for flywheel side crank seal probably a bit difficult with a bike that wont idle though

also what state are your reeds in ?

[t3mp0r4ry nzr]

quick update:
spark looks weak and fuel float level is out a bit. will adjust fuel float level, see what kinda difference it makes, then tackle spark issue.

Cheers tommoth, low compression can be crossed out.

:)

[t3mp0r4ry nzr]

Yeah it sounds like you're gonna have to do a real thorough step by step.
From checking the sparkplug cap down to a leaky crankseal. So you've checked the compression and the fuel/air mixture. You've checked the carby floatbowl. You've checked the spark timing. CDI and condensor. hmmmm Sounds like you need to sell me the bike for a few hundy so I can put a 250 thumper init :devil2:

u cheeky bugger! shes worth more than a couple hundy my friend (when it gets running!). If anything it could be an excuse to put a 250 smoker in it! I take it you mean XR200 thumper or similar? do they go alright with that conversion? Im slowly trying to rebuild and improve it, with the aim of a bit of club mx next year.

Soo, adjusted the fuel float a couple of mm to bring it back to 16mm. bung it all back together after a clean and it started fairly easily, albeit without a header or airbox. Just need to oil up the new air filter and waiting on exhaust gaskets, then it can be tested.

Still, the spark was a yellow/white colour, not a "fat blue" the workshop manual describes. Will look into that next week, probabley the reason for poor idle lies with that. probabley down a bit of power due to it as well.

[barty5]

if you dont know when rings etc where done last i would have a look see not a big job

[tommorth]

did you spray paint your tires?
the stickers on the tank make it look quite good I always thought the 90s crs looked a bit odd like the shrouds were off another bike and didnt quite fit being pink often didnt help tidy looking bike any how

long live the two smoke!!!!!!!!!!!!!!!!!!!!!!!!

[vr4king]

Hmmm sounds like what my old 1992 cr used to do.............

Tracked it down to a bad coil
Replaced that still fouled
Did a piston/ring swap
Dropped the neddle down in the carb by raising the clip now on highest piont
Leaned out pilot not by much
Replaced wet crank side seal
Took all the electric shit out from other side and cleaned it up like new
Running 40:1 castrol TTS/95
Jetting now at 170/50 dunno where air screw is
Turn your "choke" nob hard down then back out 1/2 turn(got that tip off the cart guys)
Set the idle if you like by the adjuster on the cable just makes for a very responsive one(i dont set mine to idle i just deal with it)
BR8ES/BR8EG plug one step hotterf than manual calls for

Used to foul every 15mins or so havent put one in for months now and starts first kick with it choked

You try starting it unchocked when cold if its better sure sign its to rich down low(by low i mean pilot etc)

Plug chops now very good guide unless you chopping it in every rev range

These are pigs to tune but i got there eventually now very happy with goes like a rapped ape

Pm me if you wanna chat more on it

[oldskool]

u cheeky bugger! shes worth more than a couple hundy my friend (when it gets running!). If anything it could be an excuse to put a 250 smoker in it! I take it you mean XR200 thumper or similar? do they go alright with that conversion? Im slowly trying to rebuild and improve it, with the aim of a bit of club mx next year.

Soo, adjusted the fuel float a couple of mm to bring it back to 16mm. bung it all back together after a clean and it started fairly easily, albeit without a header or airbox. Just need to oil up the new air filter and waiting on exhaust gaskets, then it can be tested.

Still, the spark was a yellow/white colour, not a "fat blue" the workshop manual describes. Will look into that next week, probabley the reason for poor idle lies with that. probabley down a bit of power due to it as well.

You're right, there are a few hopup combos with the CR125/XR200 and a good one done here in NZ too but I'd wanna try with a XR250 donk simply because the 200 is equiv to a CR80 in regards to max horse power. And yes the CR125/XR200 do go well with the conversion because of the broader power range. (well, if you're a 4stoker, better than a standard XR200 anyway!)
Hey if your bike starts okay without the expansion chamber maybe it's all coked up and needs a cut and tuck?!?!

[t3mp0r4ry nzr]

if you dont know when rings etc where done last i would have a look see not a big job

yeah Im sure it is pretty straight forward. Would I be better removing the head or barrel and what would I be looking for?

[barty5]

yeah Im sure it is pretty straight forward. Would I be better removing the head or barrel and what would I be looking for?

I you dont know when they where done i wouldnt bother looking to far into it id just replace both then you know there good beats finding out miles from home as i did once ( half way up beach to bombing range loooong push back)