The Blue Falcon—a dune buggy thread!

[rmaynard 15,428]

The carburetor is different than the old Kohler's I'm used to, but easy to clean. Just like the Kohler, there are places to look for trouble. One in particular is the pilot jet. It's the smaller removable jet accessed after removing the bowl. Mine was totally blocked. Cleaning it with a tiny piece of wire finally opened it up and the engine ran great afterwards.

 

Edited June 23, 2020 by rmaynard

[Achto 27,506]

After coming to the conclusion last Sunday that you are still have a spark issue I did some research on this engine. Before you order a new CDI box try replacing the small wire terminals that go to the + & - posts of the ignition coil. A read some complaints about the factory crimp being bad on these causing an intermitted spark issue. Let me know if this cures the issue.

[PeacemakerJack 10,738]

Thanks Dan, I pulled both off and was hopeful when I noticed that the ground female plug was somewhat loose.  I crimped it tight with a pliers and installed.  Started it, and took off.  It was going pretty good until I got into the higher RPM range and it started misfiring again.  If I let off the gas it would idle just fine, then I could start going again but if I gave it more than 1/3 throttle it would start missing and eventually would die.  At any point if I hit the accelerator pedal hard, it would kill it dead😡!  So...I keep looking.  I will say this Dan, it seems like the wiring is a MAJOR ISSUE with these Chinese karts.  Grounds seem to be problematic, connectors are cheap, and the wire itself isn’t great...this buggy is too much fun to let it sit because of a hiccup like this.  We will figure this out!

[Achto 27,506]

22 hours ago, PeacemakerJack said:

 If I let off the gas it would idle just fine, then I could start going again but if I gave it more than 1/3 throttle it would start missing and eventually would die

 

It sounds like re-crimping the terminal changed the symptoms. If they are just common ring terminals try cutting them off and replacing them. The loose terminal that you found may have caused the wire to heat up & corrode inside the terminal. A new term should put you on fresh wire again. 

[WHX?? 48,788]

Just a thought her Jack but cutting out the wiring and just replace. . Can't be too much??? 

[Achto 27,506]

15 minutes ago, WHX24 said:

Can't be too much??? 

 

The wire harness is a bit more than one would think. The box that houses the CDI box is littered with wires, fuses & relays.

[PeacemakerJack 10,738]

10 hours ago, Achto said:

 If they are just common ring terminals try cutting them off and replacing them. The loose terminal that you found may have caused the wire to heat up & corrode inside the terminal.  

They are spade connectors on the ignition coil and I’ll try putting new ones on it.🤞🏻

 

10 hours ago, WHX24 said:

Just a thought her Jack but cutting out the wiring and just replace. . Can't be too much??? 

Unfortunately, there is quite a bit of wire in these little machines as Dan stated.  I’ll post a picture of it sometime soon here.  However, if I can’t source the problem sometime soon, that may be an option I’m forced to consider.  

[WHX?? 48,788]

Is this the correct CDI? For that kind of money I would be tempted to try it. Also maybe dealing with multiple problems like wiring spark problems and fuel issues as Bob mentioned? 

 

https://www.scooterpartscatalog.com/stock-cdi-100-153.html

Edited August 20, 2020 by WHX24

[Tractorhead 9,064]

Hi Jack, 2 questions

Have you a timing flasher light aside?

is it a original diaphragma carb or a exchanged?

 

the timing flasher is my primary tool to see if ignition occurs really problems on higher Rpm.

 

jack up rearaxle an test it with and without engaged Gear.

look for a visible spot on the Engine, if no available dismount the cvt enclosure and flash it directly on the Enginepulley.

If a mark is on it, you will be fine and each fail in revolution is immediately seen.

after that you can simply decide if it was an Ignition fail or a fuel fail.

 

Most of Scooter engines be similar to the buggy Engine you have,

i found troubles in worse connectors rotten pins on the Key or also troubles in the suction carbs.

the diaphragma they they be mostly used while smoother throttle response, but they be horribly in setup sometimes.

the diaphragma witch pulled the piston up on that Suction carbs can have a small rip or even dried out,

that results in worse reactions and sometimes in wobbling response while running.

 

When you rev the engine slowly up, was the troubles allway‘s in the same rpm range or did they happen in a wider rpm area,

When the allway‘s close to the same rpm, that can point you on a worse Ignition pickup either.

 

 

[Achto 27,506]

2 hours ago, Tractorhead said:

Have you a timing flasher light aside?

 

We ran it last Sunday until it stopped running. We installed an in line spark tester and cranked it over. We found that the spark was intermittent, when it did spark the engine tried to start but then the spark would fail again. This is what leads me to believe that it has a spark issue not a fuel issue. 

[PeacemakerJack 10,738]

thanks @Tractorhead for the thoughts.  These are all great items to check.  One by one, we will test these as needed if we don’t get the result we are desiring.  As Dan stated, we definitely have a spark issue.  When I’m confident that we have that taken care of, if the problem still exists, we will take a look at the carb.  The carb is brand new and has only be on the machine since I brought it out of storage.  It is a factory replacement and so it is the vacuum style.  I have the original carb that came on it but I would need to do a massive cleaning as it sat with old fuel in it for about 3 years

Thanks for the link Jim,  I already have a performance version of this on its way, along with a performance coil. These are upgrades that I wanted to do eventually anyway.  A good excuse to take care of them now.  Mine is the AC version whereas Bob’s was the DC style.  I am still going to put fresh connectors on the wires attaching to the coil before I exchange it...🤞🏻🙏🏻

[rmaynard 15,428]

On my grandson's kart, we also had a problem with one of the engine kill switches. It was the one on the dash. The kill switches work by grounding the trigger circuit. The small connector on the back of the switch came loose and contacted ground killing the spark.

 

Just for info purposes, here is a good wiring diagram for the DC CDI system.

 

[Tractorhead 9,064]

 

Good tip with the Killswitch Bob,

an generally exchange of the crappy chinese round single connectors is allway‘s a good idea to prevent any further troubles.

I did this on my Quadbike in the past and never had troubles since, used 6,3mm Flat connectors fully insulated.

A shot of Vaseline into the connectors before connecting together and they last forever,

even at harder Racing competitions on MX Trails.

 

 

The harness connectors on the CDI’s mostly be usable, just take a closer look ahead inside the Connector‘s  metalclamps

on Vehicle side, if the ain‘t worn - means bend up.

If they bend up, i use a micro flat screwdriver and re bent them carefully to fit snug again.

 

Edit: Ah, forgotten,

also take a closer look at the Engine Pickup for the CDI on the Flywheel.

This must be snug and with a gap of  0,011-  0,019in or  in metric 0,3 - 0,5mm  as far as i remember right.

 

Drove yesterday a 18 To. truck something 600km far while Sohn moves near Saxony

so i‘m today not at home we are at MIL‘s  House, 

but if i‘m back home i can take a closer look of the given gap what shall not exceed.

 

 

 

Edited August 21, 2020 by Tractorhead

[rmaynard 15,428]

Just wanted to add something else. If you start to chew up CVT belts, DO NOT buy the cheap ones on eBay or Amazon. We have gone through at least 6 cheap belts in less than 200 miles. We replaced the last one with a genuine GATES Powerlink belt. No problem after at least 100 miles. Make sure that your belt has the Gates logo.

 

GOOD GATES

 

SUSPECTED FAKE GATES BELT

 

 

 

 

 

 

[Tractorhead 9,064]

This AC Ignition CDI is based on just a few Wires they be required.

 

one is the AC wire for selfpowering the CDI directly out of the Engine ( protected by a Fuse sometimes what sits in the fusebox)

one is the Stop ground wire - goes to Ignition key and mostly to one or two killswitches

one is the Pickup line directly from Pickup to CDI ground sometimes different handled.

one is for the ignition coil

and one is a fixed ground wire.

 

At https://www.buggydepot.com

you can find that Schematic, that shows nicely how simple the electrical Engine wiring is.

 

[PeacemakerJack 10,738]

Thank you guys for all the great insight.  The best I can figure, I believe we solved the problem tonight.  The racing AC CDI showed up and it changed everything.  Immediately you could tell a difference in how it started and ran.  Caleb drove it hard for about 30 minutes without issue and then Judge and Claudia took a turn.  It sure seems to be working well now.  Good throttle response and it moves—quickly! So...I need to make sure all other maintenance is up to date and let these kiddos play!!!!

[Achto 27,506]

Great news Josh! Now you can sit back & watch your lawn turn into a dirt track. 

[Tractorhead 9,064]

Now it seems, there is a need for a FEL

to turn the previous Garden into a Racetrack.. 😎😂😂😂