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-   -   Won't start, has spark - driving me nuts (https://www.horizonsunlimited.com/hubb/yamaha-tech/wont-start-has-spark-driving-41826)

Caminando 1 Apr 2009 09:26

Quote:

Originally Posted by BlackDogZulu (Post 235893)
Hehe, I developed asbestos fingers through having to do that nearly every day on an old Jawa two-stroke I used to own. Throwing them in the air like a juggler is good for reducing skin contact :) Or wear gloves ...

It's amazing how skilful you get as a juggler!:Dhot hot hot!

Threewheelbonnie 1 Apr 2009 10:27

Grease it up.
 
The plug spanner that is. Takes maybe 30 seconds- 1 minute before the grease goes soft and stops gripping, enough time to line it up and start turning.

Andy

BlackDogZulu 1 Apr 2009 11:05

... and ***start the thread off by hand***. Both heads on the Jawa had to be helicoiled before I learned this.

:(

Threewheelbonnie 1 Apr 2009 13:47

Are you the 9-foot tall, three meter pry bar owning body builder I bought my last BMW twin off ? Ever worked for Ural? :rofl:

The BM is the only piece of machinery I've ever had where I had to use an impact gun on M5 cap heads. The number of adapters to go from 1/2" impact drive to tiny hex would have had the health and safety bloke at work turning in his (shallow) grave. Oddly the corroded fasteners came out in one piece, unusual for the toffee/cream cheese based materials most bike manufacturers use.

Ural of course avoid the standard bodgers torque settings (Tight/V tight/B Tight/BF tight/RBF tight/STRBF tight) and instead used the two stage zero to Vodka fuelled gorilla method.

I was taught a very simple method for gas tight fittings: hand turn until it stops then as far as your wrist will go without letting go.

Andy

AlexD 2 Apr 2009 20:15

News, but not fixed yet...
 
As a variation of one of the suggestions here I dribbled some petrol into the open spark plug hole, put the plug back in and hit the button - it fired instantly but only ran for a second or so. So there is definitely spark at the right time, just no fuel.

Before I go back and complain that my carbs were set up wrongly, can someone confirm I put them on right! I have connected the 'big' inlet pipes, two in and two out of the carb and the clamp things are nice and tight, I can't slide them around or along.

I have connected the fuel pipe up to a barb near the float bowl. Fuel runs out of the float bowl when I open the drain screw. There are a couple of narrow pipes that sort of hang around which I'm hoping are breather pipes. That's it, I didn't connect anything else on the carb to anything else on the bike. Is that right?

Roamer 2 Apr 2009 20:29

Comparing
 
Alex,

I should get mine back from the garage tomorrow with the oil leaks fixed so i can run it over tomorrow night if it's urgent or on Saturday morning.

Euan

aukeboss 2 Apr 2009 21:34

altitude compensation ...
 
Quote:

Originally Posted by AlexD (Post 236183)
As a variation of one of the suggestions here I dribbled some petrol into the open spark plug hole, put the plug back in and hit the button - it fired instantly but only ran for a second or so. So there is definitely spark at the right time, just no fuel.

Before I go back and complain that my carbs were set up wrongly, can someone confirm I put them on right! I have connected the 'big' inlet pipes, two in and two out of the carb and the clamp things are nice and tight, I can't slide them around or along.

I have connected the fuel pipe up to a barb near the float bowl. Fuel runs out of the float bowl when I open the drain screw. There are a couple of narrow pipes that sort of hang around which I'm hoping are breather pipes. That's it, I didn't connect anything else on the carb to anything else on the bike. Is that right?

Probably not - if it's a real 3AJ it has altitude correction - a cilindrical device on the left side of the main frame beam. From there 2 hoses go to the carbs. If these hoses are not connected, and you are at sea level, the mixture will be very weak. The carburettor has the following hose connections:
1. Fuel in. On the left carb, outside, pointing backwards.
2. Altitude correction. On the left carb, outside, pointing forward. Copper pipe without edge. Connect to one of the 2 connections on the compensation device, or close.
3. Altitude correction. On the right carb, between the 2 carbs. Copper pipe, pointing upwards at an angle, without edge. Connectio: see 2.
4, 5. Aeration of float bowl etc. Two hose connections, both pointing backwards. Officially to be equipped with a hose dangling around behind the engine and ending nowhere. For now, not worries.

Good luck!
Auke

AlexD 2 Apr 2009 22:48

Euan,

I'm away this weekend, hoped to go on the bike:-( I'll have a crack at following Auke's instructions, if I get stuck I'll ask you over to compare our pipes:-)

Auke,

Sounds good, I'll check that out as soon as I can. Thanks very much.

Dave O 4 Apr 2009 17:55

Are the carb rubbers, to the head, in good order? If they are de-laminating around the metal, they will suck in air. I had this problen when I first got my 3aj.

Dave O 4 Apr 2009 17:56

Oh yeah - check your vacuum hose as well.

AlexD 7 Apr 2009 12:59

Still not there:-
 
Auke,

Mine does not have the pipes you are talking about on the sides of the carbs but it does have a cylindrical thing on the "beam" at the front of the carb. This is unconnected to anything, is this right?

Cheers.

AlexD 7 Apr 2009 13:01

Still not there:-(
 
Auke,

My carb does not have the pipes on the side of the carbs but it does have a cylindrical thing on the "beam" at the front of the carb. This is not connected to anything, should it be?

Cheers.

aukeboss 7 Apr 2009 13:09

??
 
That would mean somebody changed the carburettor for another one. If you do not have the altitude connections on the carb, no need to connect the compensating device. You could leave it out.

Then it is back to carburation; squirt fuel into the air filter and try to start, as an earlier post mentioned, if the bike then starts the problem is in the carburattor.

Auke

Babybadger 7 Apr 2009 13:29

Blow out all the airlines, then make sure you drain the petrol through so it runs out of the bottom, there is a small screw on the left hand side of the carb (at the bottom of photo in red, mine has a lever attached to the screw to make it easier to drain the float bowl), unscrew this gently (don't chew up the head) until the fuel runs through. try that and start the bike without the fuel taps on, if it starts ok, then turn on the left tap and see what happens. Good luck

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