74 Comando wont turn over

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Daveinsguy

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Hello all. I have an 850 1974 that I recently bought. It was running way rich so I pulled the single Mikuni and discovered that the needle was fitted ABOVE the plate that holds it down. Ok great that has to be it, put it back together and it stated but was running too high RPM with the throttle closed, choke on. Turn choke off and it dies, no amount of throttle will keep it running. It was running before but rich, fouling plugs. Took carb back down, cleaned, blew out (this is an new carb) and it would not start. Got spark. Then it just locked up, would not kick, I pulled the primary cover and put a wrenck on the bolt on the stator, would not move so I turned it backwards it it wold move to a point then would not turn. Moved forward to the same point and it would go no further. Bike has 1100 miles on a complete rebuild. Any ideas?
 
Don't try turning the motor over any more
Remove the carburettor again and make sure every component in or on the carburettor is accounted for
What single carb kit is it?
IE does the inlet manifold bolt on with 2 bolts or 4?
If it's 4 check the two inside the inlet manifold are still there
 
Lots of things internal could keep it from turning with a wrench. Take the valve covers off and see if any of the valves have dropped into the combustion chamber. If that all looks good, that rebuilt motor probably needs to come apart because of an assembly error.

If you are really lucky, Baz is correct. Do what he said first. My scenario is a little negative. The high idle could have been because of an air leak due to those bolts baz mentioned coming loose until one or both got sucked into a combustion chamber. In the end you will still probably need to pull the head off.
 
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I really dislike reading of problems of this sort. They make me empathetic for the owners faced with a bad situation. Anyway Daveinsguy I hope you find it easily fixed with little or no real damage.
 
Pull the spark plugs and see if you can turn the engine over manually (wrench on stator bolt). JUST IN CASE: Keep face clear of spark plug hole to avoid fuel blowing out of the spark plug hole. ;)

It could, of course be a "swallowed" valve but it could by hydraulic lockup caused by carb float valve/float setting issue...
 
MexicoMike said:
Pull the spark plugs and see if you can turn the engine over manually (wrench on stator bolt). JUST IN CASE: Keep face clear of spark plug hole to avoid fuel blowing out of the spark plug hole. ;)

It could, of course be a "swallowed" valve but it could by hydraulic lockup caused by carb float valve/float setting issue...
Click to expand...
Get a torch and look inside before you try and turn it over.
 
Schwany said:
Lots of things internal could keep it from turning with a wrench. Take the valve covers off and see if any of the valves have dropped into the combustion chamber. If that all looks good, that rebuilt motor probably needs to come apart because of an assembly error.

If you are really lucky, Baz is correct. Do what he said first. My scenario is a little negative. The high idle could have been because of an air leak due to those bolts baz mentioned coming loose until one or both got sucked into a combustion chamber. In the end you will still probably need to pull the head off.
Click to expand...
Got a feeling you may be right with the high idle /bolts getting sucked in scenario
All depends what manifold he has, and who was last in there!!
 
cash said:
Get a torch and look inside before you try and turn it over.
Click to expand...
Daveinsguy. I'm sure he means a flashlight. Don't use a torch with a flame!!

Between the US and UK, we all speak English; however, some words have different meanings. =:-O

I posted the following in the Pub.
www.accessnorton.com

English versus English

Good day folks. Do you place a boot in the trunk or a trunk in the boot? I am posting this because the use of a "torch" where a "flashlight" is required could be dangerous. These discussions have been seen elsewhere, but I didn't find one on the forums here...
www.accessnorton.com www.accessnorton.com
Russ
 
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jbruney said:
I really dislike reading of problems of this sort. They make me empathetic for the owners faced with a bad situation. Anyway Daveinsguy I hope you find it easily fixed with little or no real damage.
Click to expand...
Too true and not sure if this is a positive or not , but if a bolt or nut from the suspect carb had dropped inside the engine ther ewould have been a heck of a clatter before the motor cutout
 
oldmikew said:
Too true and not sure if this is a positive or not , but if a bolt or nut from the suspect carb had dropped inside the engine there would have been a heck of a clatter before the motor cutout
Click to expand...

No, read his description again. The bike ran poorly, so he took the carbs apart. He found a displace throttle needle and fixed it. Then he put it back together and the bike ran, but wouldn't run without the choke so he took the carbs off again... After he reassembled the carbs the 2ND time the engine was now stuck... and had not run after the 2nd reassembly..

So it kind of makes sense that maybe something dropped into the head... If a valve lost it's keeper and the valve dropped into the head, it would have been totally coincidental that it happened after he took the carbs off the second time... because the bike ran two times prior to his beginning his carb disassembly work...

.
 
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Sounds like more than a misbehaving carb..... Valve could've been just been barely hanging in there and then a sudden drop. Speculation has started wars..... He'll do his research, and I'll not apply any more despair and possible gloom until he gives a report.
 
Long time ago, I went with my brother to pick up a MK II that had been repaired due to a broken cam. For grins, we took the valve covers off and there was an exhaust valve collet which wasn't installed correctly. They easily fixed it, but it would have dropped a valve. I liked the spark plug thread air fitting which held the valve closed with air so they could fix it.
 
Daveinsguy said:
Hello all. I have an 850 1974 that I recently bought. It was running way rich so I pulled the single Mikuni and discovered that the needle was fitted ABOVE the plate that holds it down. Ok great that has to be it, put it back together and it stated but was running too high RPM with the throttle closed, choke on. Turn choke off and it dies, no amount of throttle will keep it running. It was running before but rich, fouling plugs. Took carb back down, cleaned, blew out (this is an new carb) and it would not start. Got spark. Then it just locked up, would not kick, I pulled the primary cover and put a wrenck on the bolt on the stator, would not move so I turned it backwards it it wold move to a point then would not turn. Moved forward to the same point and it would go no further. Bike has 1100 miles on a complete rebuild. Any ideas?
Click to expand...

Did you have any luck with figuring this out after?
 
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