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About a year or so ago I brought a Bultaco Pursang mk9, 1977 I believe. The bike under went a re build before I brought it and it does run great, the problem is it is a nightmare to start, the carb is a bing with no choke just a tickler on it , I have tried putting petrol down the plug hole to just priming the carb a bit but nothing works, when it does start it will just bust into life, the bike has a good spark and like I said when running it does go well. Any ideas what the starting problem is.

Thanks

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No the carb is complete just has this tickler that you push up and Down, I have seen pictures on the internet Of them On Bultacos. i have had bikes like this back in the day but they were never hard to start, I must have kicked that thing over 70 times to day before it started, by then I was to knackered to ride it.

4 minutes ago, sam triple said:

Seen some people cover the bell mouth and give it a few kicks before there’s had fired into life 

Not got anything like that on it unfortunately.

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Hold the tickler down until petroil drips out of the carb. Kick over twice with the ignition off to prime it.

Throttle 1/4 open.

Ignition on and kick smartly.

If that fails, then try a one grade hotter plug and a squirt of easystart into the carb mouth or air filter.

Carb or crankcase seals may be knackered - who knows if you didn't actually do the rebuild

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20 minutes ago, amateur said:

Hold the tickler down until petroil drips out of the carb. Kick over twice with the ignition off to prime it.

Throttle 1/4 open.

Ignition on and kick smartly.

If that fails, then try a one grade hotter plug and a squirt of easystart into the carb mouth or air filter.

Carb or crankcase seals may be knackered - who knows if you didn't actually do the rebuild

I will give that a go, another annoying thing with Bultaco is the kick start hits the foot peg when you kick down so you all ways feel your not getting a full kick.

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39 minutes ago, countryman said:

I will give that a go, another annoying thing with Bultaco is the kick start hits the foot peg when you kick down so you all ways feel your not getting a full kick.

Can you fit a folding footrest?

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1 hour ago, amateur said:

Hold the tickler down until petroil drips out of the carb. Kick over twice with the ignition off to prime it.

Throttle 1/4 open.

Ignition on and kick smartly.

If that fails, then try a one grade hotter plug and a squirt of easystart into the carb mouth or air filter.

Carb or crankcase seals may be knackered - who knows if you didn't actually do the rebuild

what he said     also clean the points with a fine sandpaper if that works     change the condenser as fowling the points up   also check ignition timing  app 3mm btdc 

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I had a bultaco sherpa in early 80s that was a right pig to start . Tried different grade plugs amongst everything else we could think of .... ended up shifting it on .... 

But in hindsight I wished I'd kept it 

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Giving a little more thought to this......

1. After you have been trying to start it, when you remove the sparkplug, is it wet with petroil or dry?

         If wet, leave the plug out and kick the bike over with a wide open throttle to clear the overfuelling from the cylinder and crankcase. Replace the plug with a clean, preferably hotter plug and try again.

          If dry, spray easystart down the plug hole, replace the plug and try again.

2. As written above, if you have a nice fat spark, recheck the ignition timing. If the spark is a bit weak, clean and gap the points and check the ignition timing.

3. If all the above fails, put a fuzzy photo on eBay. Advertise it as a "Desirable Classic barn find, not run for a while" and use the proceeds to buy a proper English fourstroke that you can spend thousands on and tear your hair out, but will sound much better.

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1 hour ago, amateur said:

Giving a little more thought to this......

1. After you have been trying to start it, when you remove the sparkplug, is it wet with petroil or dry?

         If wet, leave the plug out and kick the bike over with a wide open throttle to clear the overfuelling from the cylinder and crankcase. Replace the plug with a clean, preferably hotter plug and try again.

          If dry, spray easystart down the plug hole, replace the plug and try again.

2. As written above, if you have a nice fat spark, recheck the ignition timing. If the spark is a bit weak, clean and gap the points and check the ignition timing.

3. If all the above fails, put a fuzzy photo on eBay. Advertise it as a "Desirable Classic barn find, not run for a while" and use the proceeds to buy a proper English fourstroke that you can spend thousands on and tear your hair out, but will sound much better.

Tried what’s been suggested this morning except timing, the plug is wet when I take it out after trying to start, my left leg is now much muscular than my right. When I do get it started it runs great but I can not get it to tick over as well, adjustment of the carb just makes it run to fast and the throttle response goes, it just revs up and slowly dies down. I am close to booking it in to some off road bike shop and let them go over it, may be the carb is worn.

 

 

 

 

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Good luck with finding anyone who understands classic motocrossers and particularly Bing carburettors!

If the carburettor is original and the throttle slide has any play, consider it to be knackered.

Were it mine, I would be talking to Burlen and replacing the Bing with a new Amal. They can supply a correctly sized and jetted Amal at probably less cost than trying to sort out the Bing.

Back in the early 80s, I had a Rickman Zundapp and swapped out its knackered Bing for the Amal equivalent and it ran like a demented  clockwork mouse.

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Edited by amateur
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been around old engines a bit    push tickler until floods visible fuel      ignition  off kick over 2 or 3 times ignition on     no throttle   kick over first or second kick should start   only use the highest  octane fuel   check float in carb not sticking or contaminant holding it open  modern day fuel has ethaline blend which ******* up rubber hoses and seals makes everything sticky and chewing gum like your idle mixture is an air screw     tick over nicely wind in 1/8 turn      main running the needle can be adjusted up or down for the right mix plug color    a tan brown     black ritch   white lean   hope this works if not  pm your number and weal have a chat 

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23 hours ago, countryman said:

Tried what’s been suggested this morning except timing..........

That one is critical.

It is said that 90% of carburetion problems are ignition related. 😁

Edited by amateur
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1 hour ago, ditchman said:

once it is running and then you stop it.....is it still hard to start when it is warm/hot ?

Yes it is, I have someone coming next week who is a lot more knowledgeable than me so hopefully he will throw some light on the problem. 

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  • 2 weeks later...
On 24/10/2020 at 11:00, ditchman said:

then start with the timing ,...get that right....then the carb.....im sure you will get it right in the end.....let us know what the outcome is ...

Timing is out. After lock down I am going to get the timing and carb jets sorted.

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If you're planning to keep the bike, do yourself a favour and fit a Mikuni carb on it. I've got a Bultaco and a Husqvarna that both had Bing carbs on them, they now have Mikuni carbs fitted and are better for it. They usually start second or third kick even after standing for a few weeks.

Dave Renham is your man for any Bulty parts  https://www.inmotiontrials.com/product/mikuni-pursang-motocross-carb-complete/

 

Edited by sheene7
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On 09/11/2020 at 20:23, sheene7 said:

If you're planning to keep the bike, do yourself a favour and fit a Mikuni carb on it. I've got a Bultaco and a Husqvarna that both had Bing carbs on them, they now have Mikuni carbs fitted and are better for it. They usually start second or third kick even after standing for a few weeks.

Dave Renham is your man for any Bulty parts  https://www.inmotiontrials.com/product/mikuni-pursang-motocross-carb-complete/

 

Thanks I’ll keep that.

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