Minarelli V1 Engine noise

I have a 1978 Gadabout with a 49cc Minarelli V1 engine. I had an oil leak fixed and the carb cleaned and after getting it back I took it for a long ride and it started having a loud knock (Clunking, Clanking noise). I took it back to my mechanic and at first he thought it was the rod bearing and said he'd pull the top end. He said the cylinder and piston don't "look" bad, so now i'm stuck with a decision. Do i spend the money and replace the cylinder, hoping it fixes the noise? Do i drive it around sounding like shit until it breaks down on me and then figure it out? Any other suggestions what this might be?

Summer is almost over!

thanks,

kevin

972.839.3331

joiner.kevin@gmail.com

Re: Minarelli V1 Engine noise

ill bet your clutch drum came loose, if it goes away when you gas it then thats what it is

Re: Minarelli V1 Engine noise

Darrell Gabbard /

too tight of a chain seems to vibrate a rediculous noise through the engine also. start buying parts to do engine rebuild over the winter.

Re: Minarelli V1 Engine noise

just got the moped back from the mechanic. he still doesn't know what the problem is. here's a video of the noise. can y'all think of anything else?

Re: Minarelli V1 Engine noise

It's obvious... You have popcorn kernels in there and your bike is hot enough that it pops them. Just take the top end apart and get em out!

Re: Minarelli V1 Engine noise

now that you mention it... my ped had been setting at the "moped mechanic's" shop for three months and brought it back to me yesterday. he pulled the top end 3 times to check the rod because he thought that was the issue.

I had it out and a neighbor came by and suggested that the spark plug was the wrong type (he had the same noise with his camaro). I realized the mechanic had changed my spark plug and spark plug cable without telling me. so i put in the previous type of plug and it still had the noise. drained the fuel, then refueled, still had the noise.

The noise was coming from the magneto so i pulled it, unscrewed the coils and wiped down all the dust that had accumulated on the magnet and put everything back together. Now the knock is gone.

Not entirely sure what the problem was but i'm assuming when he put in a different plug it threw something off in the magneto making it knock on the coils? If anyone can explain this I'd appreciate it.

Re: Minarelli V1 Engine noise

yes i changed the plug and your plug cap was broke and replaced it for no charge. sorry for the wait

Re: Minarelli V1 Engine noise

Do you have the bushing or needle bearing in your conrod that the wrist pin sits in?

Re: Minarelli V1 Engine noise

The mechanic checked the cylinder and rod 3 times and that wasn't the problem. the noise was coming from the magneto wheel and the coils. On the inside of the magneto I could see scratches from where it was catching.

Re: Minarelli V1 Engine noise

not a good mechanic if he didn't notice that

Re: Minarelli V1 Engine noise

Replacing the cylinder wouldn't fix that noise

Re: Minarelli V1 Engine noise

i don't know what the deal was this time, but he has helped me out with my ped in the past when i was at a total loss.

Re: Minarelli V1 Engine noise

if its the bosch flywheel, they are just pressed into the tapper piece, at some point they will come loose from each other, allowing the flywheel some slop to slap coils and make noise.

you probably didn't have the flywheel on tight enough, or a coil bolt was loose and allowing it to scrape.... if you didnt use a piston stop / rope trick, then your flywheel is loose...

Re: Minarelli V1 Engine noise

Hatters hate

Re: Minarelli V1 Engine noise

If your flywheel is loose I would check your woodruff key too. If could be shearing due to a loose magneto.

Re: Minarelli V1 Engine noise

Flywheel is loose for sure. If you rev it up and the noise goes away then its your flywheel. The magnetic forces at idle can allow the flywheel not to spin with the crank, when it finally overcomes the force it "catches up" and slams against the woodruff key.

Re: Minarelli V1 Engine noise

Is it bosch or cev?

Re: Minarelli V1 Engine noise

it's CEV. it must have just been loose. It's fixed now though. Is it possible the wrong kind of spark plug or spark plug cable could have dislodged it? I don't want to test my theory and end up having to pull it apart again. I also didn't use a flywheel puller. after i did it, i read that is a bad thing to do. i just slightly edged around the back of magneto with a flathead screw driver to loosen it enough to pull off. (edited)

Re: Minarelli V1 Engine noise

its not the woodruf

Re: Minarelli V1 Engine noise

okay, i thought i was done with this thread but my ped won't start now. I drove it around the night i got the noise fixed. took some peddling to get started but it ran good. took it to the car wash last night because it was leaking oil all over my garage. washed it, dried it, started up fine but after driving about 4 blocks i pulled up to my house to drop the towels off before going for a ride, and when i slowed down at my driveway it died. started back but was sputtering. drove about 2 blocks and it died at the stop sign. had been adjusting the throttle, making sure spark plug was dry, could get it going but was at a real low idle at full throttle. i couldn't make it half a block without it sputtering out. today it won't start at all.

Re: Minarelli V1 Engine noise

You have to check the fuel flow.. out of the tank to the carbie, then .. check the carb... I would already took the engine off and but new condesner or cdi on the engine. There 30 some years old engines stuff goes bad when you think "oh I am going to get this running" Have to update the ignition and make sure the gas tank is clean and so on.

The noise could be bearing noise. Its old probably needs rebuilt. (edited)

Re: Minarelli V1 Engine noise

Update: I took the carb off, check fuel flow, pulled front end (real clean) and exhaust (nasty). Checked flywheel one more time. I also adjusted the breaks on the real axle because it was a little loose. I thought it could be affecting the chain and flywheel. IT'S ALIVE!!!

Starts up real easy, but, whenever the rear wheels stop spinning it dies. I'm reading up online but wanted to keep y'all posted and see what you think. I'm determined to get this thing on the road again ASAP!

Re: Minarelli V1 Engine noise

What was the noise, very interested

Re: Minarelli V1 Engine noise

Darrell Gabbard /

he said there was dust/debri inside the flywheel.

Re: Minarelli V1 Engine noise

there wasn't any dust in the flywheel. but there were scrapes on the inside of the magneto. It must have been hitting the coils because i just took it apart and put it back together the noise stopped. maybe the flywheel was loose?

I'm taking the engine apart tonight and going to clean everything. It's still leaking oil so i bought new gaskets for it.

Re: Minarelli V1 Engine noise

#1. Get a new mechanic. Anyone who would think that is a rod knock ought not be calling himself a mechanic. He wasted your time and money taking the engine apart.

Re: Minarelli V1 Engine noise

Sorry, Kyle, nothing personal.

When I saw the video tonight and heard the noise, I could tell it was something rubbing, nothing to do with a rod knock.

Re: Minarelli V1 Engine noise

I'm very glad you got it fixed, let's ride

Re: Minarelli V1 Engine noise

Darrell Gabbard Wrote:

-------------------------------------------------------

> too tight of a chain seems to vibrate a rediculous

> noise through the engine also. start buying parts

> to do engine rebuild over the winter.

My chain was too loose causing it to slap against the chain guard, you could check that.

Re: Minarelli V1 Engine noise

I'm back everybody. Figured if i'm gonna be riding this thing i should probably start working on it myself. So to learn this thing inside and out, I'm doing an engine rebuild, but I've ran into a couple issues.

1. someone mentioned the woodruff key. There is no woodruff key, so it's on order.

2. When installing the crankshaft the manual says to install it with the arrow facing towards the exhaust (which means down) but that makes the side with the slot for the woodruff key go to the clutch side. (I didn't dismantle the crankshaft and piston at all so i know i didn't install the piston wrong.) Can someone look at this picture and tell me if there is a way to know if the piston/crankshaft/rod are installed properly?

thanks!

photo (3).JPG

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