MV agusta Checca 99 Sport 1964 Problems - MVAgusta.net
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post #1 of 18 (permalink) Old 11-05-2015, 03:50 AM Thread Starter
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MV agusta Checca 99 Sport 1964 Problems

Hi all,

i havea Checca 99 from 1964 bought and managed to register it. unfortunately i have problems running it properly. i already had it in the workshop, where the guy changed the carburetor needle and float, cleaned the carburetor, new fule lines, new spark plug but still it is not working properly.

when i got it from there first it worked fine but after the second start there the engine went out in idle after a few seconds. it was possible however to ride the bike. the problem seems to be that in ideleing the revs is falling down until the engine goes out.

this morning i tried again to start it. i managed it 2 times to get it started but it went out after a few secs . after that i was able to get it to start again, even not with pushing the bike forward.

i guess the spark plug is covered in fuel now?

i know there are 2 screws on the carburetor. one is for idle one is for mixture. no idea how to set these up.

any idea whats wrong?

Cheers,

Robert
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post #2 of 18 (permalink) Old 11-05-2015, 05:09 AM Thread Starter
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not sure if it makes sense to just try another carburetor? unfortunately i absolutely cannot find thedellorto UA 16b, which is built in, anywhere on ebay etc.

according to the ma´nual the other model, the GT has the ME 16 BS which seems easy to find:

http://www.ebay.it/itm/CARBURATORE-D...item3f56713609

can i just swap them?
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post #3 of 18 (permalink) Old 11-05-2015, 05:53 AM
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Not sure on swapping, but if Venturi is same diameter and basic jetting is same size, then should work.

The screw that directly touches the throttle valve is idle speed. In raises speed, out lowers.
The screw that is to front or back of slide center is fuel/air mix. Closer to air intake side is an air screw. Closer to engine side is normally fuel screw.
Air screw out leans mixture. Fuel screw out riches mixture. Normally either of these will be around 1-1/2 to 2-1/2 screws out from lightly seated.

A worn slide in the throttle will cause idle problems.....common on old Amal carbs.

So will tight intake valves when problem is worse with engine hot.

Air leaking at intake manifold is another possibility.

Lots of variables, but if the engine runs well, and just idles poorly, may be a simple repair.

I used to be fast....now I just dream about it.
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post #4 of 18 (permalink) Old 11-05-2015, 05:57 AM Thread Starter
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we are talking about this carburetor:

http://www.mvagusta.net/forum/attach...9&d=1418307980

there are 2 screws whith what adjustmentes should i start?
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post #5 of 18 (permalink) Old 11-05-2015, 06:05 AM
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Near vertical screw in center is speed. Turn in to lift slide (raise speed). The horizontal one toward mouth is an air screw. In richens fuel mix, out leans it.

I used to be fast....now I just dream about it.
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post #6 of 18 (permalink) Old 11-05-2015, 07:00 AM Thread Starter
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ahhm still not makes it clear, sorry
can you check if this this corcect?

"LEFT SCREW ON THE PICURE is speed. Turn in to lift slide (raise speed). RIGHT SCREW ON THE PICTURE is an air screw. In richens fuel mix, out leans it."
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post #7 of 18 (permalink) Old 11-05-2015, 07:36 AM
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Left screw (central to body of carb and angled upward) is speed. Turn in to raise, out to lower.
Right screw (going straight into carb body horizontally) is mixture. It is an "Air Screw", so turning out allows more air and leans fuel/air mix. Turning in reduces air and richens fuel/air mix.

I hope that helps.

I used to be fast....now I just dream about it.
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post #8 of 18 (permalink) Old 11-05-2015, 08:44 AM Thread Starter
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got iit thanks. with what position should i start at best?
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post #9 of 18 (permalink) Old 11-05-2015, 11:43 AM
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Quote:
Originally Posted by tenchu2x View Post
got iit thanks. with what position should i start at best?
I would suggest 1-1/2 turns out from lightly seated as a good starting point for the air screw.

But I suspect your poor idle is related to something other than that setting (minor overall affect). Examine slide and bore for wear (looseness) and jet needle/needle jet or wear....also check for air leaks and high fuel level???

And it may be weak ignition at low rpms...aging electrics that were never particularly strong even when new. Will the ignition jump an 8mm gap when you kick the engine over?

I used to be fast....now I just dream about it.
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post #10 of 18 (permalink) Old 11-06-2015, 03:03 AM Thread Starter
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now nothing works anymore, it does not start... no nmatter how hard i try. taking it back to the workshop, he has to sort it out i guess
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