2 stroke not starting

[tigertim20]

have a slight issue.
Bik just had new top end, and has been run three or four times since the rebuild - each time only for about 5-10 minutes.
The other day I put an hour meter on it, and fired it up, no problems.

Next day, I wanted to take it out. I fired it up without an issue, and let it warm up, it was warming up fine for about 5 minutes or so, and as i was walking towards it to get on it, it died and wouldnt start.

I have tried removing the spark plug and kicking it over in case it was flooded,
checked the plug (which was new with the rebuild) and it is clean
spark is a strong blue spark
pulled carbs apart and cleaned and rechecked float height

still wont start

tried whipping the plug out and throwing some fuel down the hole and plug back in and kicking it over, - no go

just pushed it to the top of a big hill and tried to bump start it coming down, to no avail.
The best I managed coming down the hill was it would fire once every 10 or 12 revolutions.

what am i missing here?

1991 CR 125

[meteor]

If it's just died after starting and running ok, have you looked at fuel (old/dirty), fuel tap, fuel line over oiled filter maybe...

[tigertim20]

If it's just died after starting and running ok, have you looked at fuel (old/dirty), fuel tap, fuel line over oiled filter maybe...

have checked fuel, its only been in the tank a week, maybe two

[nzspokes]

If it's just died after starting and running ok, have you looked at fuel (old/dirty), fuel tap, fuel line over oiled filter maybe...

With putting fuel down the plug it would have fired for a sec if that was it.

Compression feels the same?

[tigertim20]

With putting fuel down the plug it would have fired for a sec if that was it.

Compression feels the same?

yes feels the same

[F5 Dave]

Oh good grief, change the friggin plug.

They can spark on the outside of the engine but not run when in.

MX bikes don't like to idle & likely it is jetted rich & just fouled the plug.

[FJRider]

Can the timing be altered ... ??? Sounds like a timing issue.

Does it have points ... advanced/retarded ???

[Fast Eddie]

if its def getting good air and good fuel. in the right amounts, and its compressing it - then id guess check the spark again, its easier for the plug to make a good spark outside of the cylinder with no compression/air and fuel going on..

maybe check some resistances of lead, the ign coil.. anything ign related?

bummer man - no starts are a fuckn pain - one of those things your just going to have to go through things one by one.

[F5 Dave]

Can the timing be altered ... ??? Sounds like a timing bissue.

Does it have points ... advanced/retarded ???
And clearly with all due respect you have no clue. No & No.

[ac3_snow]

I spent ages last sunday messing with alsorts of things trying to get my two stroke to run, in the end the spark plug gap was too big.

[tigertim20]

Oh good grief, change the friggin plug.

They can spark on the outside of the engine but not run when in.

MX bikes don't like to idle & likely it is jetted rich & just fouled the plug.

would this really be necessary on a plug that has had at most 20 minutes of running time from new, and is still clean?
I will try get another plug tomorrow to try on it, I just want to check that its not something simple and silly Ive missed that takes a few minutes, rather than spend coin on it.

I read that sometime hour meters can cause issues with spark, so I have disconnected that, and still no go.
I will much around with it and double check everything else is as it should be before I spend money on plugs

[Mom]

New plug required. Check the gap too.

[bogan]

Have you run the top end in properly? (is that what the three or four startings were)

Fouling plugs is generally symptomatic of another simple issue (like shitty tight pine forest trails :nono:), but you gotta put a new plug in to find the simple issue!

[Mungatoke Mad]

what am i missing here?

A 4 STROKE :rolleyes:

[tigertim20]

Have you run the top end in properly? (is that what the three or four startings were)

Fouling plugs is generally symptomatic of another simple issue (like shitty tight pine forest trails :nono:), but you gotta put a new plug in to find the simple issue!

yeah, thats what the startings were.
I asked because the shops are closed so I cant go buy a new plug right now, what I CAN do right now though, is tinker, so thought it was worth asking if id overlooked anything else I could fix, seems the general consensus is no, it will just be the plug, so now I have to sit, wait, and twiddle my thumbs until tomorrow after work!

[GrayWolf]

Was the bike standing a long time before the rebuild?
is it a high miliage rebuild on a bike that was 'in use'?
If standing for a long time maybe the crank seals became dry? Or if an in use higher miliage one.. then possibly the top end rebuild has put extra 'pressure' inside the crank cases and caused a blow by on the seals? Either would end up with fuel/air getting 'through' but extremely lean mixture..

[bogan]

yeah, thats what the startings were.
I asked because the shops are closed so I cant go buy a new plug right now, what I CAN do right now though, is tinker, so thought it was worth asking if id overlooked anything else I could fix, seems the general consensus is no, it will just be the plug, so now I have to sit, wait, and twiddle my thumbs until tomorrow after work!

I've had some good experience with cleaning up fouled plugs, bit of turps/petrol/acetone and a brass wire brush, then some fine sandpaper on the ground strap and electrode. Might have just been excess oil form the rebuild fouling the plug, get it running and rev the tits off it!

[tigertim20]

A 4 STROKE :rolleyes:
I have two of those in the shed as well, and they bring enough problems of their own!

Was the bike standing a long time before the rebuild?
is it a high miliage rebuild on a bike that was 'in use'?
If standing for a long time maybe the crank seals became dry? Or if an in use higher miliage one.. then possibly the top end rebuild has put extra 'pressure' inside the crank cases and caused a blow by on the seals? Either would end up with fuel/air getting 'through' but extremely lean mixture..

I dont really know to be honest, it came to me from a couple of young guys who I dont think were too kind to it (you can see my build thread for more info in that regard) so I dont really know.

In all likelyhood, its just the plug, which I will try and swap out tomorrow, and hopefully it fires up and problem solved.

If it ends up being much more complicated than that, Ill probably get fucked off and sell it as it is, my circumstances changed recently, and I can no longer afford to throw large chunks of cash at toys at the momment

[RideLife]

Still useing 91 octane?

[tigertim20]

Still useing 91 octane?

yes, should I not be?

[RideLife]

yes, 91 usually helps two strokes start easier in my experience. Just checking you hadn't just made an octane change.

[5150]

I had a similar issue with my old CR250. Same thing was happening. Every time I threw a new plug at it, it would start and run for a minute or two and die. Went through about 5 new plugs and still no luck. I pulled off and cleaned the expansion chamber which was dirty as hell. But what the main issue was, about a week or two prior I dropped the bike (slow crash in a wet grass) and broke the little perferated pipe inside the muffler (the one that the packing goes around) The packing moved and basically clogged up the muffler. The effect was similar to sticking the old potatoe in the pipe and bike could not breath out.

So to cut long story short, pull your expansion chamber off. Make sure it is in good and clean condish. Do the same with your muffler. Repack fresh if necessary and make sure there is nothing brocken or foreign inside. ;)

[Fast Eddie]

If it ends up being much more complicated than that, Ill probably get fucked off and sell it as it is.

holla at me when its sell time haha :D

u can clean up old plugs aye shouldn't need to buy a new one.. but a single plug is pretty cheap.

if it was going before the wiring in of an hour meter and not after, maybe something happened there.. although if its sparking n shit.. one of those gay things eh

good luck

[jasonu]

have a slight issue.
Bik just had new top end, and has been run three or four times since the rebuild - each time only for about 5-10 minutes.
The other day I put an hour meter on it, and fired it up, no problems.

Next day, I wanted to take it out. I fired it up without an issue, and let it warm up, it was warming up fine for about 5 minutes or so, and as i was walking towards it to get on it, it died and wouldnt start.

I have tried removing the spark plug and kicking it over in case it was flooded,
checked the plug (which was new with the rebuild) and it is clean
spark is a strong blue spark
pulled carbs apart and cleaned and rechecked float height

still wont start

tried whipping the plug out and throwing some fuel down the hole and plug back in and kicking it over, - no go

just pushed it to the top of a big hill and tried to bump start it coming down, to no avail.
The best I managed coming down the hill was it would fire once every 10 or 12 revolutions.

what am i missing here?

1991 CR 125

http://www.youtube.com/watch?v=G-tCIRJH9p0

[Parlane]

Is your battery all good?

Don't get me started on battery problems >: (

[F5 Dave]

And here's another Turkey (with all due respect hehe) Its a CR! if you don't know. . . , Sheesh!

[Kickaha]

Is your battery all good?

Don't get me started on battery problems >: (

CR doesn't have a battery, here's another vote for a new plug, it's always the first thing to change when a two stroke doesn't go properly, dunno what it is about them but cleaning just doesn't seem to work as well

[pete-blen]

did you get your fuel mixture right ?..fuel oil ratio
Has the oil started to separate & sitting on the bottom
of the tank?
Reed valves closeing..they do lose there memory and don't
fully close after time..

[jasonu]

If all else fails, check the calibration of the kerfuffler valve and the powerband spring. They must be within .037 degrees of eachother.

[5150]

They must be within .037 degrees of eachother.

Is that advanced or retarded .037?

[Katman]

Is that advanced or retarded .037?

This is Kiwibiker - definately retarded.

[tigertim20]

just got home from a long day at work. the wife was kind enough to use her lunch break to go get a new plug, I chucked it in, kicked it over and boom, started first kick as it should.
Guess its been way too long between smokers for me that I forgot just how easily those plugs shit themselves.

Ive been down the clening the plug route before, and I fond its easier to just by a new one for a few bucks. If I was gunna keep it long term, Id buy 5 of them and keep them in the toolbox, which is exactly what I did last time I had a 2 stroke.

Its probably a combination of two things, 1, it hasnt had a good run since being built, so not running at high rpm at all will increase the fouling of the plug, and secondly, the oil fuel mix in the tank might be a tad heavy on the oil side, so I will drain it and start over.