Pressure Testing a Minarelli Horizontal 2-Stroke Scooter Engine

[4evermetalhead]

if you want to check for air leaks i strongly recommend VACUTEC which is a leading company on smoke machines based in america.

[womackke]

where did you get that black bulb pump from?

[barthoedemaker]

Well mostly it's the bearing gone ( crankshaft play ), and vacuum testing is easil done with the carburateur off, and put your hand in front of it then kickstart of use electric to feel how hard it sucks. And compression test is well you can feel that by just kickstarting. I have really now time for all those " tools " and this basic knowledge works out all the time, never had any problems. Another tip: NEVER install 6204 C4 in Minarelli, not even with race setups. C3 is fine for all.

[barthoedemaker]

I have my own scooter repair company @ w w w dot bartsscooterservice dot nl

[2610ksj]

Is this a CPI engine??

[areomyst]

@2610ksj This engine is basically just like the CPI - A Chinese Minarelli clone. All the parts interchange, though the cylinder and and crankshaft on the CPI is slightly different (12mm small end bearing on the crank on the CPI, and a smaller boost port tunnel).

[peer91]

Hey! I have a huge question. I disassembled my scooter the other day and I just want the motor. Its a 4 stroke motor. I have NO idea about motors. The question is: how do i get it to start? Do I need the battery to get it working? Or can I just use the kick and it will start after some time? I’ll send a link of my engine on mail if some one wants to see what I’m talking about. Engine name: 50CC 4 STROKE GY6 SCOOTER ENGINE 139QMB MOTOR AUTO CARB

[MrBerenguer67]

@peer91 hi,i have vespa et2 and i got problem wheen i drive the scooter the scooteer not develop the speed, before i drive around 40 to 45 and now i just dive 15 my battery is not good you thing is because the battery dead our not,or the carburretor is cleaner, can you help me please many tks my email is venancioberenguer@hotmail.co.u­k

[2610ksj]

@peer91 Yeah 4 stroke engines need the battery to start, as the CDI unit gets power directly from the battery.

[bwrodczek]

but this is not testing the pressure that the piston rings hold

[barthoedemaker]

I'm a professional certificated scooter mechanic, by experience I would never do this, the crankseals might blow out under pressure. You only need to check vacuum pressure. Bad piston rings, can decrease that, thus making the fuel mixture from the carb not be sucked up rightly. Vacuum testing is SAFE, overpressure testing can blow out seales.

[areomyst]

@barthoedemaker Leakdown pressure testing is a widely used & safe method. When your piston is on the downstroke, the air in the crankcase is being pressurized anyway - there is no harm in pressurizing the engine. Furthermore, you only use 6 PSI so that you do not blow out seals or anything of that nature. I am also a professional and certified Vespa/Piaggio scooter mechanic.

Pressure testing makes finding leaks very easy with soapy water as well. How easy is it to find leaks with vacuum?

[barthoedemaker]

@areomyst If there are leaks the engine will not run good anyhow, it's called experience. I only recommend vacuum testing.

[PhazeTwoOfficial]

@barthoedemaker and you're right about the Vacuum part, since it actually IS saver though.

[areomyst]

Thanks for your input barthoedemaker. I respect your methods and agree that vacuum testing can work. Most find pressure testing to be safe and effective. Many professional tuners working on 2-stroke ATV, dirt bike, go-carts, etc use this method and have for years. Simply put, it's safe, and it works. You are right though, if you overpressure the engine, you can blow your seals out. That's why we just use 6 PSI. If 6 PSI blows a seal out, then there's a problem with the seal.

[barthoedemaker]

@areomyst Yes, it's both OK. But I almost never use it anyhow. Last week I had a Kymco scooter engine, which had a faulty crankshaft due the previous owner, tried to " assemble " it with a hammer. The engine did only run OK when cold, but when warm it stalled, cause it stretched the crank seals when running. the crankshaft was ruined at first assembly.

[poweressen]

@barthoedemaker How so, i tought using a hammer was the best way to repair engines?

[goldfishcarlos]

@barthoedemaker Is it with the carb on or off? Some engines are tricky, sometimes i bet to myself they have enough compression/ vaccum and in the end it does not suffice. Bottom line i am determined to find tools to test those properly, save time and be more efficient. Could you please show me and other youtubers how you do it? Thanks!

[PhazeTwoOfficial]

@barthoedemaker ok, hi there, you're right at some parts BUT until you said the word overpressure. @ 6 PSI No seal will blow out, this is a super easy method. eventhough i think both ways are easy lol, but still 6PSI will not blow out any seal, since the engine itself creates presure inside itself, thats why i had some problems with my Sprinting engine, it blew out its seal cause of it generating almost 20Psi,

anyway Have a nice day, no offence, you are right at some things.

[barthoedemaker]

@PhazeTwoOfficial I'm sure your a good mechanic aswell, we just share different opinions. In the end we both get the work done. Have a nice day to..

[PhazeTwoOfficial]

@barthoedemaker thanks, yep i'am a pretty good mechanic, but, don't fall on your back now, im only 17 years old, eventhough i've been into these things from the age of 8 my dad is a known tuner here (The netherlands) not at all fields but mostly at the karting field, maybe thats why i know pretty much, cause i've been into tuning myself for like 4years now, tuned my own Derbi Senda (Am6 vertical) 50cc and it runs a well 120Km/h i think thats like 60mp/h but im not sure since im dutch.

[gkld2006]

thanks thas really good!

saludos desde españa

[Bartek506645026]

yes! yes! yes!!!

[trueOverrev]

great video josh

[areomyst]

Thanks! Wish I had time to put the rest of them together. :)

[areomyst]

Just realized that I said "paid prescription" website instead of "paid subscription". Ah well. :) 2-stroke tuning is an addiction anyway. Prescription works. Gotta get our fix eh?