How to set ignition timing on 350 B Gt. -
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post #1 of 7 (permalink) Old 06-22-2015, 07:39 AM Thread Starter
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How to set ignition timing on 350 B Gt.

I have newly bought a 1972 MV 350 B GT (turismo) 6 V . Is there
someone that can explain in detail how to set correct ignition timing on
this bike. In the instruction manual very little is said about this. I think this is explained in the workshop manual, but where to find one?
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post #2 of 7 (permalink) Old 06-22-2015, 03:05 PM
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Are you familiar with the general process of ignition timing?
Do you have a degree wheel and a means to attach it to the crankshaft?
Do you have a piston stop, and do you know how to find TDC(top dead center) on the compression stroke?
Do you have a light or buzzer that you can use to indicate when the contact breaker(points) opens?
It's not hard to do if you have the equipment and some general knowledge.
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post #3 of 7 (permalink) Old 06-23-2015, 04:13 AM Thread Starter
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How to set ignition timing on mv 350 B GT

Thank you for your answere . I have done this before since I have
a classic car, but I am not so familar with bikes and I have never used
a degree wheel. As I understand you can by a degree wheel from a
motorshop and put it on the crankshaft. On this bike where is the
crankshaft? Is it on the axel where the dynamo sit? In the instruction
manual it says that the fixe advance is 15 + 19 degree . Is it correct that the degree wheel shall stay on zero degree when the engine is
on its TDC? Then turn the engine arround to the wheel are 15 to 19 degree before TDC. Then the little lamp attached should go out. The
ignition should then be correct.
Why I am engaged in correct timing is because of after driving the
bike I think the engineblock is extremely hot. You can not hold your
hand on it. Can wrong timing do the overheated engine?
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post #4 of 7 (permalink) Old 06-23-2015, 06:10 AM
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Well, this little machines engines are getting hot so that You can burn Your skin touching it.
There is oil floating in it which gets only cooled by tiny fins.
Other than that if it is running fine why do You want to change timing?
Why would the previous owner have changed timing?
Correct heat rated spark plugs, some lead additive in the fuel, enough oil and everything should be fine.
And as You see in the manual there is not much to check on the breaker.
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post #5 of 7 (permalink) Old 06-23-2015, 10:03 AM
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You should consider buying a pistol style infrared thermometer, they only cost $10-$15 on Ebay, and then you'll know what your engine temperature is. This Youtube video shows one:
Usually incorrect ignition timing makes an engine hard to start(too advanced), or it won't run up to higher RPMs(not enough advance)- if your engine seems to be running OK I wouldn't mess around with ignition timing yet- like Haupti advised.
If the engine is running too lean, it will run hotter. The heat range of the spark plug doesn't have much, if any, effect on engine temperature- just the temperature of the plug electrode. If the motorcycle sat for a long time before you bought it the carburetor could be slightly plugged up. If the fuel jets and passages aren't clean the fuel mixture will be lean- have you cleaned the carburetors?
In addition to lubrication, the oil carries heat away from the cylinder head- any restriction in the oil passages or a worn oil pump would raise the engine temperature. If you put the bike up on a center stand and spin the rear wheel with the transmission engaged you should see some oil being pumped into the head- might be worth a check.
And, I've never even seen a 350B, so I'm just offering generic advice- the first step should be to determine if the engine is really too hot.
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post #6 of 7 (permalink) Old 06-24-2015, 03:03 AM Thread Starter
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Thank you guys for all the iformation and help. Yesterday I was
driving with my bike and I meet some guys with Japanese bikes. I put
my hand on their engins and I must admit that they to was very hot. I have an old 2 stroke Jawa that I have compare the MV with. Maybe
therefore its big difference.

My MV is starting easily and the spark plugs is brownish, I think the engine is going normal. Since this is new bike for me I must admit
that I maybe has been to careful and on watch for thing to happen.
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post #7 of 7 (permalink) Old 06-30-2015, 04:09 PM
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Excepted the vacuum diaphragm, the work is the same for a bike

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