Liduno's vertical 250 By Bashan (Read 2,449 times)

[Bashan]

I've been PMing back and forth with a guy name Liduno about his vertical 250. He's got an electrical problem straightened out but now the engine bogs with throttle. He has:
1. Adjusted the valves
2. Checked the plug
3. Cleaned the carb
4. Checked the airbox for leaks
5. Checked fuel flow
This is a buggy not a scooter. I don't know what else to tell him, I'm out of ideas. He has extensive experience with bikes and some GY6s but not the 250 if I remember right. Liduno, add to what I said if you can think of anything.

[Alleyoop]

Well bogging when given throttle is to much air not enough fuel, has he adjusted the carbs fuel mixture? He would need to turn the fuel ratio mixture screw counter clockwise.
Alleyoop

scooterdoc.proboards.com/thread/1499/4ts-carb-tuning

[Bashan]

I can't remember but I'm sure he will chime in soon enough. He did discover a 110 main jet which is kind of anemic.

[Alleyoop]

Question I would have is was running good before or was it always bogging. That motor has a 30 or 32 mm carb and they feed a lot of fuel, I don't think someone changed out the main jet in that carb.
Alleyoop

[Bashan]

Here's a quote:


I took it for a little beat run across the street behind the sears, it ran good for about 5 minutes. Coincidentally that's about how long it takes for the automatic choke to fully extend, checked that today after our talk. It worked on the black wire so I left it there.

After a wide open run from one end of the lot to the next, it bogged down and would only idle. Any throttle input resulted in a big bog, and I noticed the header glowing red.

He has not adjusted the A/F

[Alleyoop]

WOW!! Header glowing read that sucker is RUNNING LEAN AND MEAN. Well he best start to turn that screw counter clockwise. Don't forget when you twist the throttle you are opening the butterfly allowing a lot of air in and exposing all of the tiny fuel outlets(usually 4) that are fed from the Pilot jet to have fuel sucked out of them. The main jet at this point is doing squat it is all on the pilot jet.
Alleyoop

[JR]

Jan 8, 2015 18:48:13 GMT -6 Bashan said:

I can't remember but I'm sure he will chime in soon enough. He did discover a 110 main jet which is kind of anemic.

If it is a 30mm carb most of them come in a range of 120 to 130 but you need to remember this is a buggy and geared lower and runs slower than the scooters thus the lower jet.

If he's got a glowing header his jet isn't too big for sure.

JR

[cyborg]

partially plugged jet or jets ,,,sit for a long time and get varnish built up in the jet bores??

[liduno]

Thanks for all your help so far Bashan. I think I would have given up on this thing if not for your wiring help..lol

So I will try to make this short but include as much info as possible. I got the buggy not running[coolster cf moto 250]
With lots of help from Bashan I got it running. It ran well for about 5 minutes till the auto choke fully extended then it just lost all rpm, it would idle fine but bogged when I gave it gas. Plug was the color of coffee with cream.

There was some backfiring when I got off the gas but it had an exhaust leak, so I wasn't sure if that was a symptom of being lean or if it was just the leaky exhaust.


My first thought, like a lot of the posts above, was that it had a lean fuel condition. I welded up the exhaust, cleaned the tank, petcock, carb and adjusted the valves. Now it starts and idles better than ever, hot or cold. But it still bogs when I hit the gas, hot or cold.

I took a squirt bottle of water to the intake and all the hoses, hell I soaked the whole carb to no avail. Being sure I had a lean condition I upped the main jet to a 132, having seen other 30mm carbs with this size jet at sea level. It still bogged.

Bashan advised me to check the slide, to make sure it was operating properly. so I jacked the wheels off the ground and disconnected the air box so I could see the slide.
I noticed it revved a little better with the air box disconnected. Up to this point everything pointed at a lean condition except for the improvement when I took the air box off..lol Plug still looked lean after revving it up with the air box off. If I put the box back on it wont rev.

I did not adjust the air/fuel mixture because it started and idled so good at 1-1/2 turns out.

It has 30mm keihin carb, the float level is at 18mm, 132 main jet. I forget but I think the idle jet was a 38. The slide needle didn't seem to be adjustable so it is where ever it comes from the factory.

[Alleyoop]

Cool, start it up and let it warm until the enricher shuts off the extra fuel then start turning the fuel mixture 1/4 at a time counter clockwise. You want the highest the mixture to get the HIGHEST IDLE you can lower the idle using the IDLE SPEED screw if after the adjustment it is idling to high. It should idle anywhere from 1500-2000, the 250s due to the bigger motor like to idle around 1800 or so.
If it bogs giving it throttle it is LEAN and at this point the MAIN JET is not active it is all on the PILOT JET up to around 35-40 mph then the main starts to come on.
Alleyoop

[liduno]

11:23 pm here so I will check it tomorrow but I was under the impression the main jet came into play almost as soon as the slide was open?

[Alleyoop]

No in reality the main jet actually comes on around 3/4 throttle , the air pressure in the venturi has to build up and push the diaphgram up to raise the needle out of the defuser.

[Alleyoop]

No in reality the main jet actually comes on around 3/4 throttle , the air pressure in the venturi has to build up and push the diaphgram up to raise the needle out of the defuser.

[cyborg]

Did you check the carb diaphragm?,,,may hav a tear or small pinhole not letting the slide lift correctly,,,,just a thought

[liduno]

Jan 8, 2015 22:38:33 GMT -6 Alleyoop said:

No in reality the main jet actually comes on around 3/4 throttle , the air pressure in the venturi has to build up and push the diaphgram up to raise the needle out of the defuser.

Good to know. I will give it a shot tomorrow.