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Hi, for 50cc cross races I’m working on a 50cc Malossi RV with 19mm carb.
First thinking was to use a tuned standard Vespa 50cc cylinder in the RV carters.
As the cylinder sleeve diameter of a standard cylinder is smaller than the RV cylinder seat I was thinking to close that gap between sleeve and carter with a tube.
But with doing that I would need to bring the ports into the tube also. :con
Then I met a guy who is driving the RV carters with a 50cc Athena in cross races. This engine is running like crazy without a tube around the sleeve. Just plugged on the carters as it has anyway no long lifetime under the hard cross conditions.
So I decided to switch from a tuned standard Vespa cylinder to a 50cc Athena.
The engine is finished already and fixed in a modified Bravo but first start trials didn’t work.
I can see an ignition spark on the spark plug, so I assume that the reason can be the carb what does not have a choke so far.nice engine, very clean :).
In your perso you mention that the dudes 50 cc Athena on RV engine runs like crazy, what exactly do you mean? Could you describe it more specific?
Hope the engine will start soon, i am very curious what it will do.
aggressive and quick reaction on throttle movement, very high rev’s with wheely power.
Yes, like to drive this engine too, but still looking for the reason why it don’t like to start.
Having no choke on the carb, can that be reason? Or should it also start without choke?
As said, there is spark on the spark plug, but the spark plug is not getting wet from fuel. 😕
Any additional proposal what I should take care with the 19mm carb?I always have to start my RV with choke connected.
You don’t have a choke somewhere in your huge collection 😉 ?
http://www.jmpbonderdelen.nl/chokeset-kabelbediening-phbg-origineel.html
http://www.jmpbonderdelen.nl/handchokebediening-phbg.htmlHave you tried putting some fuel in the engineblock through the spark hole?
A choke would be usefull but ofcourse not necesary if the jet is the right size and the air etc are all set to run.
If you have another carb maybe you could try one with choke or even if you have 13mm inlet it would be usefull to try with that?Hans, I bought the carb 2nd hand and didn’t take care about this minor stuff :lol
Lennaert, I tried to spray start pilot into the air intake side of the carb, but not a mini start reaction on the engine.
Don’t have a second 19er carb for the RV, but trying a 13er could be an idea.I would say try the 13mm carb if still no use with the choke button then there would be a leak somewhere or the membrame isnt in best shape.
Lennaert :
Have you tried putting some fuel in the engineblock through the spark hole?
A choke would be usefull but ofcourse not necesary if the jet is the right size and the air etc are all set to run.
If you have another carb maybe you could try one with choke or even if you have 13mm inlet it would be usefull to try with that?Most RV i have tried won’t start without the choke connected. And if you don’t put in the choke part (brown tin) with the spring the choke will be open and it will give your engine a ‘veryyyy’ rich mixture.
I thought those carbs were unuseful without the choke-art connected, as this carb has a dedicated choke-circuit?
That also was my thinking, that the mixture for start function is different without shoke and that this can be the reason.
the only time that my rv starts without a choke is a 46.5 brev. but the jet was a little oversized.
now iam running a dr evo, and it starst after 5 seconds pushing , it works better with choke but my hand choke is broken.
(evo is also running very rich)what jet are you running now?
if a have to guess, 82/89 needle @mid
the loss of displacement on lower rpm causes it to lean out, thats my opinionsucces , very pretty engine
p.s. finger in carb and push , handchoke 😉
De budget beun tjoener: geen geld is te duur of het werkt nog niet
Link naar Mijn collectie / Projecten.thanks guys, it was the choke. 😀
First try and it was running with choke. The carb has a 76er main jet, just like I bought it.
Now fine adjustmen of jets is needed.I think that you won’t be able to finetune the right way, unless you have fitted the chokesystem.
Even if you had the system fitted in, the short clips make me think that it’s running quite lean?choke system is ordered. 😀
first drive with Multivar 8,4gr and 90mm Vario, Malossi TooBad, still 76er main jet, waiting for chokesystem 😉
Runs not bad as it is
also JuniorPiet had a smooth drive :lol
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