Modern Vespa

HI I am hoping someone can help me with a problem I am currently having with my Rebuild.
The other day while I was riding I lost power on my 300 GTV. the bike would still go 50 but had lost considerable power.

I took the motor apart tonight and I found one of the Exhaust valve adjustment nuts was gone. I search high and low in the head, hoping it was laying around there somewhere. No such luck. I could only assume it is at he bottom of the timing chain tunnel. I have removed the oil pan and tried to fish it out. could not see it anywhere.

Has anyone had this issue before?
Any suggestions on how to fish that nut out.
Will it find its way into somewhere where it can do catastrophic damage.

Any help is appreciated.

I am going to Harbor freight tomorrow, and see what they have for small magnets to retrieve things like this.

Forgive the uninformed obvious...

Turn the motor so the timing chain tunnel is underneath and blow with some compressed air or a can of brake and parts cleaner?

As a kid I made a superb electromagnet out of a length of 6mm steel threaded rod with insulated bell wire wrapped around it in the threads. Connect to a dry cell battery cluster and poke around in the tunnel.

What happened to the associated valve?

I will have to review how to make a magnet. That could be the polarization I need.
I have manually turned the motor over and have not found anything easy way to get under the timing chain. When I do turn the engine over and it is at TDB, there seems to be some areas to poke around. I can try that tonight.

What happened to the associated valve?
The valve seems in good shape, but I am replacing the Piston, Cylinder and Head with a new Malossi head, so I did not pay close attention to it. The valves I believe have enough clearance from the Piston, and also with it in the closed position I would think it was ok.

The original head is on the left, Malossi is on the right. Rockers and cam have been moved over. The rest will be done once I retrieve the setting screw.

Am I the only one this has happened to?

You may have to remove the oil seal to get it out. This is what it looks like https://scooterpartsco.com/vespa/gtv-300-and-sei-giorni/gtv-300-engine/oil-seal-for-vespa-piaggio-aprilia-with-piaggio-engine?zenid=tuta01in9f4d1oofvm4gvjbn64. Scooterpartsco might even have the tool as a loaner. I highly suggest you get the tool.

If I remove the Oil pump and slide the chain to the side, would I be able to get a magnet up there to retrieve the nut?

In order to remove seal would I have to split the case?

you won't have to split the cases.

don't freak out, I promise you can overcome this.

lemme put some coffee in my face and I'll write it out for you

so you've already got the oil pan off and can't find it. you've got the head off, so I'd go ahead and pull the barrel as well. more than likely it's slipped into the channel next to the chain. so if you've got the pan and the barrel off and can't find it, after poking around and flipping and flopping the motor and blowing compressed air... then I'd surged removing the water pump. pull that the the sump plug and you may find it just chilling out in the bottom. so, pull the plug and the screen first. then pull the water pump. you should be able to see all the way through.

I doubt it's behind the timing cover because it more than likely would've gotten lodged in the the chain or the cog and jammed everything up tight. so save that for last. also removing and installing that seal is a giant pain in all nine assholes without the special tool.

my guess is that it bounced into the head and then kicked off for a ride down next to the chain is sitting in the void.

I can get some pics tomorrow with pointers if you haven't found it by then.

good luck!

When you say barrel: I assume you mean the Cylinder and piston? Yes I have removed that already. The Malossi rebuild is a larger piston and new Cylinder.

I pulled the Oil and screen out during the search. I left the plug out until completely dry. I took a flashlight and my strongest reading glasses but saw nothing there. I will double check the oil that came out and see if may be it came out there somewhere.

I have not pulled the water pump yet. I didn't know there was a plug hidden underneath it. I will try that as we..
Thank you

you need an inspection 6mm camera. lots available that use the usb ports and plugs into a lap top to view. check amazon , harbor freight might have them as well. some come with attachments like mirror to view 90 degrees and retrival hooks

Well I am glad to report Said Valve set nut has been found and removed from engine case. Crisis averted. Now to figure out how this happened in the first place.

I did the valve adjustment last week and I am very certain I tightened both the intake and exhaust valves to the correct values, and tightened them accordingly, Apparently something weird occurred on the exhaust valves or rockers. I checked the other exhaust valve and it was loose as well, while the Intake valve set screws were nice and tight.

Great! Glad to hear you found it. Any sign of it having been ground up? If so, you may want to flush the engine out really well with kerosene to try to get any small metal shavings out.

As far as "how did it happen?"... well, we all make mistakes. I did not properly tighten a push rod on my old vtwin a few years back. A couple days after I had worked on it, the push rod loosened up while I was running at highway speed and, like you, sudden power loss. I use a lot of blue painters tape to remind myself when I'm working these days. I know at age 60, I'm not as sharp as I used to be. I have learned to work a little slower than I used to and be more methodical.

-Craig

Glad you found it.
My last foray into the abyss involved a broken ring in an Enfield crankcase. Each tiny shard that the magnet found was a step toward redemption.

Good points. I will do that while I am waiting for the Oil sump gasket to get here.
I put a New Piston in last night, and new Head. Fingers crossed this is the last time I have to work on this bike until after Cannonball next summer.

It broke down on me, during the ride last year and left me stranded in Michigan. Purchased a new one and finished the race. However I want this bike to go the distance.

What is the benefit of using Kerosene as opposed to other types of oil?
Is it a price thing?

Kerosene or diesel fuel is used to free little shitties from hugging the engine cases or other parts and allowing them to flow out. obviously, after doing this you need to carefully replace it with something lubricious like oil.


Most of the time I have heard of people with your problem they wound up shaking a diesel filled crankcase like a maraca.

Thank you all for your replies.
It always impresses me the amount of knowledge on this Forum.

I will take to the shaking the bike like Maracas tonight, and hopefully riding like the wind by Saturday.

it's possible that you over-tightened the lock nuts, I've seen them back off due to that before. but odds on you didn't tighten them to begin with.

great suggestion on running kerosene thru to collect any shrapnel. have a look at the nut at the threads and make sure everything is ship shape before knocking it all together and sending it down the road.

Price is one good reason. Kerosene is much cheaper than most motor oils. But the primary reason is because it's thin and will flow through the engine quickly. This facilitates flushing any little bits out. Finally, any residue left behind by Kerosene will be compatible with your oil.

-Craig