CR125 won't kick start but will push start?

[mad_max]

my Honda CR125 wont start by kick start. Whether its hot or cold but after a bit of a push it will start and run mint. Then when i stop it again, the same thing. wont kickstart and have to push again. This is not that good on a trail ride obviously so I need to fix it. Checked compression, thats not great but not the problem. New spark plug. checked reeds, theyre like new, cant be them.

Any ideas?

[Katman]

One of the first signs of low compression is difficulty starting with the kick starter.

Try fitting a new set of rings at least.

[unstuck]

One of the first signs of low compression is difficulty starting with the kick starter.

Try fitting a new set of rings at least.

What he said.:yes:

[barty5]

ill third that you said comp was good so what was it ?

[CRF119]

Yea what is the compression, I could be wrong here but should be about 180psi??

What plug are you running?

[mad_max]

I measured about 90-100psi but have recently been told i had to have the throttle wide open which i wasnt aware of so will try borrow a tester and test again soon. I am unsure how much difference it will make but it does make a lower reading than with throttle open. I am running a BR9ES (i think) just the same plug as the bike had when I got it and what I could find was right online.

[barty5]

I measured about 90-100psi but have recently been told i had to have the throttle wide open which i wasnt aware of so will try borrow a tester and test again soon. I am unsure how much difference it will make but it does make a lower reading than with throttle open. I am running a BR9ES (i think) just the same plug as the bike had when I got it and what I could find was right online.

anything much less than round 120 and youll be having probs the cr250s we just built both had round 190psi

[CRF119]

Depending how many times you kicked it will depend on the increase in PSI from closed to open. I think you will be lucky to see a 10-20spi gain so i guess its time to order a top end kit for it. I will test my mates CR125 tomorrow and let you no what it is but pretty sure urs needs a rebuild.

Just hope its not crank seals :(

[CHOPPA]

If its that low on comp it is way overdue for a top end! A couple of hundy and an hour out of your day would save a lot of hassle

[morg_nz]

br8eg is the plug you want - it is hotter than the br9 and the eg is the race version of the plug compared to the es - you will really appreciate it

[mad_max]

Oh yea, so might the B8eg at least make it run? maybe a contributing factor why it wont fire easily maybe? I had a 89 YZ125 way back and I could kick it over with my hand, it ran like shit but still ran and started. I am going to rebuild it, I just wanting to know why it wont run because im sure it would suddenly not start, I thought it would just take longer to start. It doesn't feel like it has that little compression for it not to start.

I was only riding for about 2 or 3 hours on a new plug when it stopped so maybe it killed the plug because it was the wrong plug

Cheers

[cheese]

Na you've just got shit compression. New piston and rings and it will going mental again.

[CRF119]

Yea a 8 series plug will sort any fouling problems you might have especialy when you are learning but id recomend replacing that with a nine series cooler plug if you start to really abuse it.

2 Stroke plugs just die no warning other then a slight bog then its over.

[mad_max]

So a 9 plug when I rebuild it you reckon? (just wanting to order a few good ones) Because as soon as it gets run in it will be getting abused :yes: Ive got a mate that runs a 8 in his CR250 and I ran one in my old YZ125, ktm 200exc and rm125. The only 9 Ive ever really come across was in a tf125

[scott411]

So a 9 plug when I rebuild it you reckon? (just wanting to order a few good ones) Because as soon as it gets run in it will be getting abused :yes: Ive got a mate that runs a 8 in his CR250 and I ran one in my old YZ125, ktm 200exc and rm125. The only 9 Ive ever really come across was in a tf125

nearly every 125 runs a 9 heat range plug, as well as KDX200's,

Most 250 2t's run 8's, which is one hotter heat range,

some of the 85's come with 10.5's, as well

[ktm84mxc]

As for the right plug rock down to your local bike shop & ask to see the NGK booklet with there plug fitment guide it will list the suitable plugs for your bike.
If it was my bike I'd chuck a piston & rings in it , and get the conrod play measured while itz apart.
Also wen waz the muffler repacked as this can cause a flat feeling with the power delivery, you can also de-coke the expansion chamber. A lot of little things add up to make a larger problem.

[mad_max]

I put a new plug in it out of another bike, started 1st kick, ran well, was only running for 30 seconds (not exaggerating) up the drive, hit the kill switch, went to start again and nothing. Put plug back in bike it came from and nothing there either. So it buggering plugs in a matter of seconds. Must be something more wrong that just needing a rebuild. It didn't stop itself, ran mint. that's the one thing that's most depressing, it runs mint and doesn't stop unless I stop it

I don't want to go spending a heap to rebuild something that doesn't go properly anyway so wanna get this sorted

Got told it could be magneto??? Any thoughts on that?

[CRF119]

What oil ratio are you running? Also use 98 gas

[cheese]

I had a bike that was like that, it was a leaking crank seal fouling the shit out of the plugs. Spray your like with CRC and hit it with a wire brush and see if it goes again. But seriously, put a new piston in it.

[mad_max]

Hi, I just started to take apart, took sub frame, tank, plastics etc off. Then I took the expansion chamber off, filled with antifreeze. I dont have clue how it would get there but Im pretty sure its not good. took the head off and its all in the cylinder. I am not very experienced with motors so dont know what it is but I know one of you will know straight away. Hopefully something not too expensive :crybaby:

Thanks for any help

[noobi]

Coolant can only get into the cylinder through the head or base gaskets, and judging by "full of antifreeze", the gaskets are well past their use by date. Replace the top end, including gaskets and o rings.

[mad_max]

Yip, just found that the head gasket was actually the wrong gasket. I think it was off a different year or something but definitely was wrong. Cylinder and everything else looks good so will rebuild and hope like hell it was just the gasket

[barty5]

Hi, I just started to take apart, took sub frame, tank, plastics etc off. Then I took the expansion chamber off, filled with antifreeze. I dont have clue how it would get there but Im pretty sure its not good. took the head off and its all in the cylinder. I am not very experienced with motors so dont know what it is but I know one of you will know straight away. Hopefully something not too expensive :crybaby:

Thanks for any help

blown head gasket hence hard to start cause your plug is wet while your push starting it is turning over fast enough to clear the water/coolant and then starts. hopefully the head is not damaged from the heat as it must have been low on water given it was using it.

[mad_max]

Yea, it was low on water and I put some more in it assuming it had leaked somewhere when I was riding because the pipes aren't the best, when it started with a new plug it seem to disappear with no visible leakages, turns out it had made itself at home in the bottom and and expansion chamber.

[CRF119]

Some 2001 CR125 bikes require 2 x head gas kits or they keep blowing them. My mate blew 2 before he found this out.

He started his one day and coated the house in black oil and water :lol: