OT - Troubleshooting a Scooter...

[Jim Saraceno]

A buddy of mine aquired a motor scooter some years back (5-7). The story he tells me is he drove it several times then put a charger on the battery, the battery "got fried" (I'm assuming it boiled out), he replaced the battery and it has never started again. As we were talking about it, another guy said he was concerned that some wiring had also gotton fried. I'm a little unclear as to why he had the battery on a charger and what could have caused the battery to get fried. Anyway I told him I'd have a look at it.

 

The new battery was completly dead so I re-charged it. It has an electric starter which turns the engine over but there is no sign of any firing. Right off the top it sounds like there is no spark but that is only conjecture. The gas is 5-7 years old so I know it's not very good but it does not have that "Varnishy" smell yet.

 

I'm going to go ahead and start taking things apart so I can get access to the engine and obviously the first thing to determine is whether it is missing fuel or spark and then go from there.

 

My question, because I've never worked on scooters or motorcycles is... Are there any little quirks about scooters that I should check before I do the normal checks we would do to get our cars running?

[Don Coatney]

Contact forum member DCurrent as he is the scooter guru

[Scruffy49]

Unless it is an older Vespa, other older European make, or Honda (not Spree) made out of real metal, it isn't worth the headaches. If your friend just has to have it fixed up, troubleshoot it like any other chainsaw engine, assuming it is a 2 stroke... If it is a four stoke, treat it like a late model OHV Kohler engine. If the engine is turning over with the plug out, and will blow your thumb off the plug hole, you most likely have a dead coil. And unless it is a rare model that is being rebuilt for show, a Kohler coil works fine, as does a Kohler regulator/rectifier assembly.

 

Go to http://www.dotheton.com/forum/index.php?board=76.0 Lots of info on updating motorcycle/scooter electrical systems.

Edited November 2, 2013 by Scruffy49

[DCurrent]

Jim,

 

First off tell us what make and model it is along with year and so on. I hate to say that if it's a Honda you will have no trouble at all getting it to start as I usually work with older American makes most of the time. Ya just can't beat the Japanese cycles when it comes to setting around.

 

The first thing id do is drain that stail gas. The carb may need a cleaning, but id take the chance at just changing the gas. If this scooter is new enough it should have a drain screw at the lower end of the float bowl. It may even have a hose running to the bottom of the scooter from the bowl. If so put a pail under it and unscrew the screw so that the gas begins to exit the bowl. Flip the tank petcock to reserve and this should drain all the gas from the tank. 

 

Fill the gas tank with new fresh gas of high octane. Turn it over again! Is it firing? If not, pull the spark plug and inspect for gas. If it's wet that's a good sign the carb is doing it's job, but the spark might not be igniting. Lay the plug, still attached to the wire, on top of the head or a good ground. Turn the scooter over and inspect it for a spark. Is there spark?

 

Report back.

 

Darren   

Edited November 2, 2013 by DCurrent

[greg g]

I have also found that these little two strokes are sensitive to spark plug condition.  If you have compression and spark at the plug lead, I would change the fuel/lube mix, put in a new plug and start from there.  If it doesn't respond then I would removed disassemble and clean the carb, and any fuel lines /filters that may be present.  Some of these may have a vacuum line to the fuel tank that opens a check valve to allow fuel to flow when the engine runs, other have a manual fuel shut off, make sure which ever is operating properly to allow fuel from the tank to the carb.

[Plymouthy Adams]

first off what CDI ignition does this have...I assuming it is such..is it AC or DC unit...quick test...battery in, key on, does the headlight burn..if not..it is ac inductive CDI and you have a sensor coil under the flywheel..odds are the ignition unit is fried...common problem..most are easy to obtain and some between 5 and 12.00 on the average with cdi and coil combo for less than 18.00 delivered.

[Jim Saraceno]

Thank you gentlemen. To answer a few of the questions... It is a Cinese made "PopCycle" manufactured by Loncin and made in 2005. I realize it's a pretty much junk and it may not be worth messing with but it gives me something to do on Thursday's "Mantivities" night where a group of us get together, build things, go have dinner and a couple of beers then topped off with whiskey and cigars.

 

CDCurrent, I'm thinking that is exactly the way to go. No sense in taking a chance of gumming things up with bad gas. Then test for fuel and spark to see where that takes me.

 

I have no idea what type of ignition it has. I know with the key on, the blinkers work (so I assume the headlight does also). I have a parts drwaing and it lists a "regulator assy." and a "unit/coil assy". I honestly didn't think about the possibility of it being a 2 cycle motor. If it is, I'm probably screwed, I've never had much luck with those. My first guess is the ignition is fried but who knows. Test, then replace if bad... Right?!

 

It will be next Thursday before I have a chance to play with it. I'll let you know what I find. Thanks again for all the suggestions!

[Jim Saraceno]

Oops! I haven't posted on this forun since it changed format. I see I posted it in the wrong section and got moved over to the proper section. Sorry, I'll know better next time.

[Plymouthy Adams]

CDI ignition  box and trigger is dependent on AC or DC ....to get the correct box this has to be determined and yes it could well be a 4 stroke engine..lots of these Chinese knockoff are copy of base Honda engines and pretty much emulate their control circuits..the blinkers. horn and brake lights will work off the battery..they also have a regulator/rectifier assembly...again..ignition box will depend on AC/DC...weed out is headlight if you do not know for certain..no headlight key on but will come on engine ruinning...the systems is AC

[Dave72dt]

Some of those little bikes and scooters had a separate run/stop switch on them in addition to the key switch.  They do go bad and they have been left in the STOP position more than once for the occasional DUH moment.

[Scruffy49]

That's the first thing to go on my street motorcycles, the red switch. Followed by the clutch and kickstand interlock switches. A set of cutter/strippers and a few wire nuts later... no stranded in the back side of nowhere w/o cell service at midnight in a downpour.

 

I miss points and kick starters. I've decided I hate my 1998 built, can't be retrofit with either major missing component street bike. And my dual point kick only Honda is beyond repair, the bottom end ought as well be welded up solid, NOTHING moves in that engine/gearbox unit...

[DCurrent]

I wondered where this thread went. Someone moved it. I just thought by chance someone did. I rarely check these other forums. Looks like ya haven't had a chance to piddle with it anyway. If ya had other things to do I'd steer you away from this scooter. The Chinese built scooters are a bit more of a hassle than they are worth. Forget getting parts for them. Hopefully you will just have a simple problem with it. I'll try to remember to check back although there are plenty of guys here that can help you trouble shoot it just as well as I can.

[Plymouthy Adams]

parts are a dime a dozen on the internet..

[DCurrent]

When dealing with Chinese stuff your going to need a dozen of them.

[Jim Saraceno]

I finally had a chance to play with the scooter. I removed the sparkplug and there was spark. I then disconnected the hose to the carberetor to drain the fuel, no fuel. I removed the fuel filter and there was no fuel to the filter.  At the gas tank there was a fitting that had two hoses on it, one going to the fuel filter and the other had a plug (from th factory) in it and connected to nothing. I pulled it, it has a fine mesh filter inside the tank but that did not appear to be plugged. I don';t understand what this fitting is or why there is no fuel passing through it. Does anyone have any insite for me here?

[Jim Saraceno]

I found a parts manual and that thing is the fuel petcock. It shuts off the fuel unless there is a vacuum on the second hose. I see there is another hose with a similar plug near the carburetore so I'm guessing someone cut the fuel line and put the plugs in and I'm hoping if I reconnect them everything should be fine. I'm totally baffled why that would happen. It's my understanding that this scooter has never had any work done to it so I'm quite confused about this situation.

 

My buddy who owns it is out of town so when he gets back he might be able to clarify some things.

[Don Coatney]

Just a wild guess but that device may be a pulsating fuel pump. My lawn tractor has such a fuel pump. It has a gas in  from the tank, gas out to the carburetor, and a line that connects to the valve cover where it picks up vacuum/pressure pulses that activates the diaphram and pumps gas. If the diaphram fails it may allow fuel to enter the crankcase and that may be why the line on the scooter is cut and plugged. But as I said this is a guess AKA SWAG.

[Jim Saraceno]

That makes perfect sense Don. My brain couldn't quite comprehend a pnematic petcock but the pulsating fuel pump just makes sense. And the cut and plugged line very well could indicat a diaphagm leak. I'll put a vacuum pump on that fitting and see if it holds a vacuum.

 

Anyone have any idea how much vacuum these things would be rated for? I''d hate to blow the diaphragm by putting too much pressure on it.

 

btw... Is there no spell check when we make forum postings? Man, I'm in trouble if not!

[Don Coatney]

I would not go lower than 3-4 inches. If it holds that for a few moments I would think it is good to go.

[Jim Saraceno]

Thanks Don, I'll try that.

[greg g]

On my old Kawasaki MC.  The tank feeds the carbs via gravity.  But there is a line that runs engine vacuum to the petcock.  This automatically stops the flow of gas when the engine stops. So if the fuel tank is above the carb, and fuel would normally flow via gravity, that line might be a shut off.  If that is the case, then gas should flow to the carb, and the engine should run with the vacuum line plugged, as a testing bypass. However leaving the petcock open and gas flowing to the carb with engine off could lead to flooding if the needle go stuck open.

 

 What is the engine configuration on this thing?  2 stroke, 4 stroke single, twin?

[Jim Saraceno]

So the part manual lists it as a petcock. The fuel tank is above the carb and it should be gravity fed so maybe you are right that the vacuum line is an automatic shut off. Regardless, I'm sure the two hoses with similar plugs in them must have once been one hose and I have no idea why someone would cut and plug that hose. As I said before, I was under the impression that it has had no work done to it but I can't see how it could have ever run with the current configuration. My buddy won't be back in town until next week so maybe he can clear up some of my questions.

 

I'm going to put a vacuum on it to make sure there is no leak in the diaphagm and if all goes well, I'll re-install the petcock, connect vacuum line to the intake manifold, put some new gas in and see what happens. I only work on this on Thursday nights so it will be next week before I know any more.

 

This is a 4 stroke single cylinder 50cc scooter engine. Everything I read tells me its a piece of Chinese junk not worth messing with but as long as I'm having fun with it I'll keep at it. If nothing else I'm learning a little about scooters.

[greg g]

So with spark (assuming it is firing at the right time) and gas and compression, one would think it would fire if not start and run.

[Jim Saraceno]

That's what I'm hoping for. I checked the petcock by putting some vacuum on it. It held so I'm assuming we should be good to go.

 

I'll be really interested to see what my buddy says when I tell him what I found.

[Jim Saraceno]

Okay, problem solved and scooter running! The problem turned out to be the vacuum hose from the intake manifold to the petcock had been cut and plugged. After talking with my buddy about how this could have happened we came to this conclusion...

 

He bought this scooter on a whim, started it up, drove it once around the parking lot, let it sit and it never started again. At some point someone had it running (there are 45 miles showing on the odometer) then we are guessing they cut and blocked the vacuum line for shipping. The dealer should have reconnected it during dealer prep but apparently didn't. There was a little fuel left in the hose and fuel filter, enough for my buddy to start it up, do his test run and that's it.

 

Thankyou to everyone for insight and suggestions as knew nothing about these scooters. As ussual you guys got me going in the right direction!