434 Ty250 Won't Start

[phunksean]

Hello,

 

Bought a ty250 as a running bike, saw video of it running ( i live far from where it came from), had it shipped and now i can't seem to get it running.

I have kicked and kicked till my foot is bruised, have had it burp and fart a bit, won't start. Tried a bit of fuel directly in the plug hole which got it turn over 3 times but not catch and go.

I've spoken with the seller he says he cleaned the carb as well as put new points and condenser on prior to the video. He said he had heard of the condenser packing it in on installation which doesn't make sense as he got it to run.

I'm out of ideas, anyone have any insight.

 

PS not sure how much difference this will make but the bike is from around sea level elevation and I reside at 3000' above sea level.

 

[goudrons]

First thing to check is the spark?

Remove the plug, rest it on one of the engine fins (with the plug cap attached) and crank it over while watching the plug.

It can be hard to see in strong daylight, but you should be able to tell if it sparks or not.

 

If it doesn't spark you need to check the rest of the ignition system, plug, plug cap, coil, points and condenser.

 

If it sparks, dry and clean the plug and refit.

Now repeated kicking over without it firing should, if fuel is getting through, soak the plug wet through with fuel.

If when you check it after repeated attempts to start and it's still dry, you need to check the carb.

 

Check fuel it actually running from the tank first, rust and muck can clog up the tap/filter inside the tank.

 

Also fuel goes stale very quickly and can cause a green sort of gum in the float bowl that clogs the carbs jets, so it's worth checking the jets are clear by unscrewing them and holding them up to the light, also check the fuel inlet valve isn't sticking, this is the little valve that works on the float arm and regulates fuel into the float bowl.

Edited May 16, 2016 by goudrons

[phunksean]

Cheers,

 

I have spark, and plug was wet after repeated attempts and drying of plug. Wasn't sure if fuel filter was working properly so I bypassed it, still no luck.

 

Fuel couldn't have been more than 3 weeks old in the tank, was almost bone dry when i got it and have added 1:50-1:45 fuel (2.5 L) on the weekend.

 I bought manual for it which arrives tomorrow, hopefully it will shed some light on the adjustment screws on the side of the carb.

 

thanks for your input.

 

[spen]

Try another spark plug, if it's soaked/weak/knackered it might be that the spark is visible outside the engine and appears alright but is getting snuffed out under compression.

[phunksean]

cheers will do that

 

 

[feetupfun]

Check for a sheared flywheel key. With this you will get spark but it won't run because the spark is not at the right time

[lineaway]

If it`s soaked, the crankcase could be flooded. Leave the fuel off, pull the plug out and try to clean out the cylinder by kicking a dozen times. This can be dangerous, so hold the kill button while doing this. Worst case would be to remove exhaust to clean out also. A wet plug will not fire. So keep the plug fresh and clean.

[goudrons]

So it's sparking and as it ran before, you'd presume it's timed right enough to run, so don't mess with the timing, yet, not until you've ruled out fueling problems.

 

As the plug is getting wet, it's fueling too, so it may be a case of it flooding up.

 

Check this:

 

 also check the fuel inlet valve isn't sticking, this is the little valve that works on the float arm and regulates fuel into the float bowl.

 

A sticking float bowl inlet valve the open position will allow the fuel to run right through the carb and into the engine.

They often stick a bit if the bike has been left a few weeks with fuel in the float bowl.

 

You often find fuel pouring out of the float bowl over flow tube, but by the time you notice it's too late and the crank is flooded up.

A sharp tap on the float bowl often frees the valve off, but it really wants cleaning and checking it operates as it should.

 

As mentioned above, turn the fuel off and remove the plug.

Lean the bike over as flat as you can get it on the left and work the kickstarter over and over.

If the crank is flooded it will spit out black oily fuel out of the plug hole.

[phunksean]

Right on thanks, was playing football last night but tonight I will try to get this sorted.

cheers for the input.

[phunksean]

have given up and sent to the local shop, thanks for the input everyone

[phunksean]

Hello again,

 

so it's been in the shop a long while now (that's another story) and while it is starting and running now it starts to miss after running for  5 or so minutes.  mechanic thinks its the ignition coil, i did some research and decided that it may be the source coil so I got a new one and replaced it, but still having the same issue, so trying to source a new ignition coil but the shops supplier says it will be Dec before they can get one.

 

anyone got a line on ignition coils for a 74 TY250, preferably in Canada as it is easier for me to get.

[guy53]

Where are you in Canada ?

Guy

[feetupfun]

MCS brand make replacement HT coils for TY250. It is a HT coil that suits lots of old Yamahas (and I even use one on my Sherpa T) You should be able to get one from a motorbike shop or from an ebay seller. I will find a link to one after work if you haven't got it sorted by then

[feetupfun]

http://www.ebay.com.au/itm/AFTERMARKET-IGNITION-COIL-YAMAHA-TY250-TY-250-74-78-NEW-/282088176043?hash=item41adc3f9ab:g:4XgAAOSw-KFXd8hp

[phunksean]

BAH!!! "New" coil arrived yesterday, shop just called to say it doesn't work, no spark what-so-ever. FFS, 

 

mechanic said he tested the original ignition coil and it was fine, but suggested replacing since the bike goes into slow (1/2 firing) idle after 5 min, what else could cause this symptom beyond electrical issues?