Vento Phantom R4I '06 Startup Problems
 

Hey everyone! I'm new here. Sorry for the hefty post. I just wanna be as detailed as I can be. I bought this scooter (150cc Vento Phantom R4I) off a random dude on Craigslist. Didn't know much about scooters or anything automotive before I bought it so of course, I ran into a multitude of problems and now I'm at the point where it will not start and I cannot figure out the cause.

So the scooter only ran for a few days before breaking down. We dove in and found the scooter was running off a car battery. The carb was bad and the air filter was oily and dirty. So we bought a brand new carb and air filter. We also ended up replacing the clutch pulley as the old one practically fell apart when we took it off. Fuel filter was dirty and old looking so that was replaced as well. Upon putting things back together, one of the main bolts that secures the exhaust to the engine broke off so it was quite loud when I was running it.

I rode it again for a couple days before it broke down in the middle of nowhere. Couldn't figure out the problem so I let it sit for a few days. During that time, I switched out the 3 way valve (The air/fuel line one), changed the oil, cleaned the oil filter and changed the spark plug. Still didn't start up. When trying to start it up, it would seem as if it was losing power/slowly dying (Off a car battery, keep in mind). So I went to buy a normal sized scooter battery and boom, started up right away. I drove it around for a bit and all seemed ok. The following morning, I went to start it up and it had the same losing power/slowly dying problem. I thought maybe the battery I bought was too small. So I bought another battery a bit bigger, installed it, tried to start it up and it doesn't even turn over. Confusing. So I put the original battery back in (The car battery) and it started up fine. Confused about the whole thing, but happy it was running again.

Drove it for a few more days before it broke down again. Turned out the CVT belt got completely shredded to pieces (I think the person who put it on didn't make it tight enough somehow cause it was loose looking to me). I took it to a shop where I watch the guy do the work so I know he didn't mess with anything else. He replaced the belt as well as the variator. After that, it rode the best it's ever ran. Hitting 55+ and everything seemed smooth aside from the loud exhaust. I took a nap at a friend's and went to drive it home only to experience acceleration problems now. It would bog frequently around 25-30 mph and wouldn't really let me go any faster. Tried messing with the air/fuel mixture on the carb but didn't have any luck. Eventually, the scooter stopped turning over all together.

So it hasn't been running for a couple weeks now. During this time, I've replaced the CDI, the fuel and air lines, the spark plug cable and discovered there was an oil leak cause I drained my oil and I didn't have much in there...I was thinking I might've damaged the engine if I was running it on low oil. There were times when I would try to start it up and there would be a coughing, grunting-like sound. Dunno if that sounds familiar.

Thoughts? Thank you in advance for any help. My next step was to replace the starter but after reading about the symptoms of a bad starter, I doubt that's the issue.

Have you adjusted the valves? Poor starting, is the number one symptom of valves in need of attention.

Sounds like you may have a charging problem. Do you have a multimeter to check your charging system's output. Can be purchased at Harbor Freight for less than $10.

Better get that broken stud in the head fixed, a leak there will cause more problems with the exhaust valve.

Thanks for the reply! I went to check the valves (which were fine) and when doing so, the camshaft basically fell apart. Broken bearings and what not. So I ordered a new camshaft and went to install it, but it still won't start. Guessing it's a deeper issue. A friend says I might've messed up the timing? Not too informed on that. I'll do some research. However, when I put on the cylinder and top head, I undid the camshaft chain. I managed to get it back on, but I wasn't sure if I might've messed something else up during that whole process.

When starting the scooter, it just sounds like it's very...light? As if something isn't doing its job in the motor. Everything's spinning (Camshaft with chain, CVT belt, variator and fan) and I definitely got spark, compression, gas and air still but no luck. I'll likely be tearing it down tonight to see if I can get more clues as to what's wrong.

Ok, so I lied. The valves weren't ok lol. I also found out that I DID mess up the timing when putting on the camshaft. So I read up and watched how to do all that (TDC and using the feeler gauges) and it started up! Oh man, it's a great feeling to get something started that hasn't been running in weeks.

So it starts, but it won't stay on. It becomes harder to start after it gets warm too. I thought maybe the carb jets were clogged (Despite the carb being fairly new) so I checked them, changed the pilot jet (The small one, right?) just to be safe cause the main jet was fine and no luck. Kinda stumped again which makes me feel bleh...having done all this work and still not driving yet is getting to me but i'm trying to stay positive. Only thing I can think of is the rubber piece under the top of the carb has a slight tear on its side. Would that be important to replace? Hoping someone has an idea with all this info here :(

Harder to start when warm = tight valves. Adjust them again to .004" intake, .005" exhaust when engine is DEAD COLD.

A ripped diaphragm is game over. Get another diaphragm or carb.

Yeah Blueboy5000, I bought a new carb and it fixed my bogging issue. I ended up buy a whole new head cause the old one was worn and the valves were getting stuck and my scooter was working great for a while

Damn, this thread makes me cringe. It's like everything that can go wrong, went wrong.

Lmao man, tell me about it. My fault for just buying a random scoot from a local tho. Helped me learn a lot about scooters in the end so can't be that mad

Jueo! Hanbntbw6 sakej 7sne,sskz!!! (damn keyboard) :hehe: