Pressure Testing a Minarelli Horizontal 2-Stroke Scooter Engine

Scooterinvasion.net. This video shows how to properly perform a pressure test on a 2-stroke engine. This method will work on most 2-stroke engines. Stay tuned to scooterinvasion.net for more scooter tuning and repair information!

Category:

Autos & Vehicles

Tags:

• pressure
• test
• 2-stroke
• stroke
• two
• 2t
• leakdown
• tester
• Minarelli
• Horizontal

[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).

[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.

[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.

[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

[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!

[poweressen]

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

[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.

[PhazeTwoOfficial]

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

[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.