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aiuto per il mio nuovo for my new engine

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Ciao a tutti
Prima ditutto vi volevo ringrazziare per i consigli che mi avete dato ,a proposito degli o ring di viton e piston ring,per ora ho provato gli anelli o ring di viton nei miei 2 motori hit &mis engine durano molto di piu rispetto a quelli che usavo prima ( o ring rossi ) e sembra anche che il motore abbia un funzionamento piu fluido.
Veniamo al punto !!!
Ora sto costrueundo un motore a benzina 4 tempi.
Ho fatto alcune prove con cam diverse sia sull aspirazione che sullo scarico ,ma a parte qualche scoppio ( e scoppia molto forte ) non parte.
E anche con le stesse cam variando di poco i vari angoli non c è  una grande differenza lo scoppio e qualche giro è sempre lo stesso .
Può essere che sia perché è senza volano ? c è solo l attacco per l avviamento.
Il diametro del pistone e 30 mm e la corsa 36 mm rapporto di compressione circa 6 /1.
Puo essere il carburatore ?? ho usato un carburatore per motore d aereo radiocomandato e un carburatore da me costruito del tipo hit & mis ( un semplice venturi )
Hello to all
First of all I wanted to thank you for the advice you gave me, regarding the viton o rings and piston rings, for now I have tried the viton o rings in my 2 hit & mis engines they last much longer than the ones I used first (red o-rings) and it also appears that the engine runs smoother.
Let's get to the point !!!
I am now construeundo a 4 stroke petrol engine.
I did some tests with different cams on both the intake and exhaust, but apart from a few bursts (and bursts very loudly) it does not start.
And even with the same cams by slightly varying the various angles there is not a big difference in the burst and a few turns are always the same.
Could it be that it is without a shuttlecock? c is only the starting connection.
The diameter of the piston is 30 mm and the stroke is 36 mm, the compression ratio is approximately 6/1.
Could it be the carburetor ?? I used a radio-controlled aircraft engine carburetor and a carburetor I built of the hit & mis type (a simple venturi)
Grazie tante .

Without being there it's hard to say. Here is a simple check list of things to check. Hopefully if I forget something others will add to the list

Are the valves and rings sealing?

Is the cam timed properly? On a multi-cylinder engine a quick check is when the piston is at top dead center, the valves should be open about the same distance. Exhaust should be almost closed and the intake should be starting to open on cylinder #1. On a hit/miss with only an exhaust cam the valve should be almost or fully closed at TDC

Is the ignition timed properly. I actually use a timing light. You should fire between 4 and 36 degrees before the opposite TDC. By opposite I mean 360 degrees crank rotation from the cam timing check. Start about 4 to 6 degrees and slowly increase until you find what the engine likes. Also it can be difficult to get a spark plug to fire under compression. Check to see if the voltage isn't leaking out somewhere. Crank the engine with the lights out (but not total darkness) and look for arching from the top of the spark plug to the base of the plug. Check along the plug wire and also at the coil for arching. Fresh clean plug wouldn't hurt.

Is your fuel system good. You mentioned a purchased carb so you just need to find the proper adjustment. Be sure the fuel tank is mounted lower than the fuel line inlet going into the carb. If it's higher it can flood the engine. I mount my tanks about 1/2 inch lower than the inlet hose. Fresh gasoline/petrol. Gasoline has a lot of energy and is easy to ignite. Once running well and everything adjusted you can easily switch back to coleman/lamp/camp fuel. Give yourself the best chance. If you suspect flooding, pull the plug out and clean it. When trying to start the engine, start with the needle closed and slowly open it as you crank the engine to avoid flooding. Also if you have a clear fuel line check to be sure there is fuel getting to the carb and there are no air bubbles in the line. If fuel isn't flowing plug the inlet of the carb with your thumb (choke finger) and crank the engine and you should see the fuel move into the carb. if not open the needle on the carb a little and try it again.

Are you cranking the engine fast enough? When trying to start a fresh built you may need to crank the engine faster than normal until valves properly seat or to compensate for leaking compression and things being out of adjustment. Try using a drill motor at high speed instead of hand starting until things are dialed in.

Can't think of anything right now but this is where I would start.

In settimana dovrei riuscire a provare ancora !!
Non ho tanta esperienza anche se la passione per costruire e tanta .
E ho notato che alle volte e un piccolissimo particolare nella costruzione che fa funzionare o no il progetto che stai eseguendo . :stir:
In the week I should be able to try again !!
I don't have a lot of experience even if the passion to build is a lot.
And I have noticed that sometimes it is a very small detail in the construction that makes the project you are doing work or not. :stir:

Roger B:
Much the same as Steve:

Is the compression good (springy or bouncy)?

Check the operating sequence;

Inlet valve opens just before Top Dead Centre.

Inlet valve closes a little after Bottom Dead Centre.

Spark plug fires just before the next Top Dead Centre.

Exhaust valve opens a little before Bottom Dead Centre.

Exhaust valve closes just after Top dead Centre.

The inlet and exhaust valves should be slightly open together at the non firing Top Dead Centre.

Ciao a tutti
oggi finalmente sono riuscito a mettere in moto il motore per la prima volta :cartwheel:
Non va ancora bene come pare a me ma funziona, va in moto girando a mano il volano abbastanza bene.
vorrei pubblicare una foto e un filmato ma non so come si fa
Ora e montato su una base di legno di fortuna ,prossimamente costruiro anche il carrello per trasportarlo.
Sono contento !!
Hello to all
today I finally managed to start the engine for the first time: cartwheel:
It's still not as good as it seems to me but it works, it runs by hand turning the flywheel quite well.
I would like to publish a photo and a video but I don't know how to do it
Now it is mounted on a makeshift wooden base, soon I will also build the trolley to transport it.
I'm happy !!


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