New Dude Killed His Scoot By arigold (Read 2,402 times)

[arigold]

I got my scoot running consistent after replacing all the vacuum and Fuel lines. Noticed white smoke after changing the oil and didn't think much of it. I was so happy it was running dependable I just thought maybe I was burning a bit of oil.

The exhaust stud has been broken and unsealed for quite sometime. It makes it loud but is dangerous to the valve seat.

I was running down the road and it died. It lost compression and now it won't start.

Did I Kill it...? Should I do a top end rebuild?

I don't know what to do.

Please help.

[Scooter Doc]

The broken stud can be harmful to the exhaust valve if the leak is large enough to let cooler air in after you turn off the scoot. Repeated exposure to rapid temperature change can damage the valve and seat. Also, might you have filled it with too much oil? That can damage the rings. I prescribe checking the compression to help diagnose your problem, it's possible it's the rings and not the head. In that case you'd waste a lot of money on a non-fix. You can get a compression tester at auto parts stores, dirt bike shops, scooter shops, and here:
search.harborfreight.com/cpisearch/web/search.do?keyword=compression+tester
So do the test and let us know what you get. Any other Docs have a suggestion?

Hook up a compression gauge and open up the throttle all the way. Crank the scooter until the needle on the compression gague stops moving. This should take no more than 5 seconds. Very roughly, 100-125 psi is good, 125-150 psi is very good, and 150+ psi is great. If you don't have this level of compression then you have bad valves and/or bad piston rings. If you want, you can add a teaspoon or so of oil to the engine through the spark plug hole. Then try the compression test again. If compression is higher, then it's likely you have bad rings. The oil will seal the rings and give you better compression. If compression is the same, then you have bad/misadjusted valves.

[phaze]

sounds cooked to me, got to love blowing a motor, just hope it stayed together and nothing is in the bottom end thats the exspensive part

[arigold]

Thank you for your replies....


I posted the same query on another forum and got 0 feedback. Much appreciated.

Will throw a compression tester on there today and let you know immediately.

When you say "nonfix" what exactly do you mean?

[arigold]

Opened her up to do the compression test. This is what I found. What is missing here?

After getting the spark plug out. I tried screwing in the compression tester and it wouldn't fit. Too large. The spark plug is a wee little thing.

Weird because it worked on my 2T 50cc....

[Scooter Doc]

This one has 12 and 10mm:
www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95187
By the way, what kind of scooter is that?

[arigold]

It is titled a Konced 150. Very much like the TNG LowBoy. I love the style of this scoot. It has a retro trash look that gets lots o' compliments.... So far she has two names. The "Blue Canoe" and the "Hardly Davidson"

Because it's a chinese scoot and for various other reasons I am having lettering made for the side that says.... "Scooter Trash"

I don't have the extra $25 to buy another compression tester at this moment. So I suppose I will have to wait.

Riddle me this?

If it has good compression. Then what?

If it doesn't? Then what?

[arigold]

As far as step by step... no.

On my 2T 50cc I just hooked up the compression tester and turned it over as many times as I could.

[Cruiser]

Apr 10, 2010 14:53:33 GMT -6 arigold said:

Opened her up to do the compression test. This is what I found. What is missing here?

After getting the spark plug out. I tried screwing in the compression tester and it wouldn't fit. Too large. The spark plug is a wee little thing.

Weird because it worked on my 2T 50cc....

To answer "What is missing here?" It looks like part of the emissions hardware. This means part of the exhaust is going right to the atmosphere and besides being loud it could cause a burnt exhaust valve as noted on earlier posts. Here is a picture of what is missing. It is the chrome tube thing with a valve device on the end of it. Did you remove it?

www.partsforscooters.com/164-183_GY6_EGR_Valve_Cover?sc=9&category=613

[arigold]

I didn't take it off. It just wasn't there. The guys that put in the new engine about a year ago didn't do the best job. I guess it rattled off. I don't know.

[arigold]

If it burnt the exhaust valve... is the exhaust valve and the missing part all I need to replace? What other damage can that cause?

[Bashan]

Good catach Cruise, I didn't see the opening until you mentioned it and I mag'd back to see the whole attachment. That's the port for the PAIR system, Pulsed Air Injection Reburn, it pulses raw air into the exhaust gasses to help burn them and supposedly lower emissions. If the system is removed you're supposed to block that opening off or at least leave the squirrel pipe and reed valve on. That port goes directly to your exhaust valve and I feel the cool air rushing in damaged it, JMO. Here is a diagram of it, the system IS ugly: three hoses, a canister, an extra intake nipple, the squirrel tube on the valve cover, etc. It's understandable why they took it off, but to leave the exhaust valve exposed was boneheaded. You asked what damage it could do and what you'd have to replace; probably the valve, seals, and polish the seat. I would think just buying a rebuilt head with valves installed would be a lot simpler. Diagram:

[Cruiser]

His picture opens up OK for me, JR. The head you linked to at BPNW is out of stock, but they suggest you use their high performance head starting at $199.99. If a head is needed, this one is available at $49.99.

www.partsforscooters.com/Cylinder_head_gy6

Gotta do that compression check!

[arigold]

So instead of risking screwing something of this caliber up. I took it to the local shop.

They pushed me into a whole new motor. They said it would be easier to just swap it out instead of rebuilding the top end to find something else wrong...

What do you think?

New Motor... $480 shipped. From Joel @ MRP
Labor... $120

Shiny new motor that won't die and someone I can hold responsible when something does happen....

Priceless.

[runningslow]

That's pretty much the route I'm taking. I'm doing the labor myself, but I'm going to have a shiny new motor to work with.