Honda XR125 Won't start all of a sudden

[beatts]

Hi

I rode my bike home at lunch time today, all was fine. However when I went to go back to work it wouldnt start.

I tried everything, choke in / out, bump starting etc but nowt, I was really late for work in the end and totally pissed off!!

after work I tried again, and its turning over ok, but won't fire up.

I took the plug out and cleaned it and checked the gap, all looks ok but still nothing. Ht lead looks ok.

Now the bloody batteries flat from too much trying.

yes it has petrol and no I didnt flood it. Well I may have eventually.

Normally it is a pretty good starter and like I said it got me home at lunchtime fine, but then 45 mins later sod all!!

any ideas, as I don't really live near a garage and don't have towing facilities.

[virus]

check that its firing properly, take the plug out and put it back in the plug cap, then hold it against the head and tun it over, should have a big blue spark.

If its sparking, then try putting your thumb over the spark plug hole (after taking plug out of the lead, HT voltage smarts a bit) and cranking it over, if you can feel a fair bit of pressure then its got compression, which leaves fueling.

check your carb/ fuel filter isnt full up of crud.

Cheers
John
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[beatts]

thanks Virus, is it easy to check the carb is full of crud??


what if no compression, does that mean dead engine??

Its been absoloutely fine till now.

[nightshaddow]

good advise from virus, you almost cirtainly will be ok with compresion you would almost cirtainly hear and tell something if your rings piston or barrel was at fault, though good to check any way, The carbs are pretty easy to check but also check your air filter i had a few problems with mine and would cause it not to start,

but as virus said check the plug first for spark if it sparks it may need changing anyway i have a hoda that would spark but not fire up i changed the plugs and away it went,
____________________
"WHAT DO YOU MEAN 100 MPH THATS IMPOSSIBLE Its chinese OFFICER."
Current rides CB 125 TDE(the next project) NS125RK ( now on the road ) CB125TDC (soon to be project 17) melody ( the nephews )

[virus]

If there was absolutely no compression, then something has gone wrong, in past experience it has been valves, but could be damaged piston/piston rings/ barrel.
If it was working fine and then stopped then compression would be the least likely on the list.

as nightshadow says, try a new plug, plugs can occasionally fire fine outside of an engine, but when inside, the spark has to deal with compression and on a dying plug it might not work.

Id check compression and spark first, as they are the easiest to do, then make sure your float bowl is filling up by opening the drain on the bottom of the carb, if petrol comes out then there was fuel in there.

if you suspect carb, then take the bowl off the bottom (usually 3/4 screws) and check it is clean, personally id take the carb off completely and clean all the jets out (pilot jet being the more likley to be the cause of the problem, as you dont use main jet to start)

as said before, try a new plug, for the sake of £3 its worth it just to rule it out.


Cheers
John
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[beatts]

superb, thanks fellas,

I'll go and try those things.


fingers crossed it's just a plug.


The bike has only done 1200 miles so i'm a bit concerned

[nightshaddow]

[beatts]

Hi

just got round to taking a look at the problem,

still un diagnosed whats wrong with it, I changed the plug - no difference,

Plenty of pressure from the cylinder (put my thumb over hole), and the plug (new and old) plugs are definately not sparking.

I haven't dismantled the carbs etc yet I was hoping there may be more simple checks before I looked at this.

could it be HT lead or ignition coil or something????

It was working one minute then not the next (well... within an hour)

[The Artist]

well if its not sparking then its part of the ignition system.

Check all ignition wiring
Check for any physical damage to coil, wires etc.
If you have got a manual, test coil(s) resistance etc.

Just check the ht lead is screwed in at both ends properly.

I don't know that particular bike but check those.

Do the lights work and other electrical things. if not then your ignition barrel or something else around there could be wrong.

[2006 _p1]

If your battery is flat from trying so much, try a new plug. The one you have in is probably been fuked by so much petrol. My bike had a spark out side the engine but when i put it in it wouldn't fire i kept on trying but no luck.

got a new plug and fired right up. Best to take plug out and let it dry out too.

[beatts]

yeah all the other electrics work fine, I will have a good look at the ignition system.

f.a.o of 2006_p1 - yes I already changed the plug - not sparking at all.

as allymoss pointed out it is probably part of the ignition system


thanks

[2006 _p1]

Oh so now its not sparking at all? Have you disconnected anything to have a look? Maybe some things gone back together wrong or your battery is flat again.

[beatts]

hi

just had a look at all the wiring and everything seems perfectly as it should.

the sparkplug is still not sparking and it seems that the other end of the HT lead is bonded onto a cylindrical component which I assume is the ignition coil.

is there any way this could have failed or a way to check it. I assume if I get 12v at the coil then the output should give a reading too?? The output being the HT lead I assume

???

[----]

Yes
Check the wires that go into the coil to see if they have voltage.
If they have,then it's probably the HT lead at fault.
If there is no voltage going into the coil,then it could be a number of things,most likely a bad connection somewhere.
____________________
DRZ-400sm

[The Artist]

everything CAN fail its just somethings are more likely than others.

On my old bike, some of the coils in the magneto part failed then the CDI unit failed. No idea why though!!

Check your fuse is the correct rating for next time.
Use a manual to find readings for coils etc. Mine was like this

"red and green wire = 180ohms"
"blue and white wire = 240ohms"

See if you can find a manual for your bike

[beatts]

me again!!

right, I have a green and yellow wire going into the coil, the yellow is connected via an inline crimpt type thing before it gets to the coil, this seems ok,

I put my leads and meter onto D.C Volts across these two wires and cranked the engine, but no reading at all.

Therefore what is it that supplies the coil??

There is no manual for this bike unfortunately, well there is but it is a Honda Workshop manual and they are like rocking horse shit apparently.

[UKKWF]

did you ever sort your problem?

[bikenut]

handle bar kill switch fitted to this bike??
____________________
nuts about bikes

[dade]

I have a manual for the Honda XR125 in PDF format along with the parts catalog covers 2003 to 2006, If anyone wants a copy I'll need some help finding somewhere dump it so you can download it.

Don't know if I'll get spanked by mods for attaching 48MB in PDFs

[Alpha-9]

6 years later if he's still trying to kick it over but he's got legs like tree trunks by now
____________________
Fzr-600 1999

[noonan94]

hello I have an xr 125 purchased as a field bike with no key so when I connect the wires the bike will start but when I separate the wires bike turns off how do I get the bone to stay running please

[Rogerborg]