WB32 settings

Kirk Deason · Posted: Wed Oct 12, 2011 7:15 am Post subject: WB32 settings

I cannot get my new JICA started. I have a fully charged battery in my external starter and it *seems* to be spinning the engine pretty fast. I have spark (confirmed by grounding the plug on the head), I have fuel (plug is wet after turning over for several seconds), I took the head off and looked at the cylinder and piston (seems fine, not seized, etc).

I am almost sure my carb settings must be off. I searched this site and the rest of the interwebs and found some recommendations of about 1.5 turns on the low and .25 to .5 open on the High. I have gone as low as 1.25 on the low and .25 on the high but it still won't start.

I am at 8oz castor/gallon with MS98. Current plug is NGK BR10EIX

I know there is a ton of experience out there with this carb and motor, and would appreciate any knowledge sharing. Eg: do you crack the throttle when starting, or leave it closed? If so, just a hair or wide open? Do you need to quickly change the low end settings once it is running (ie: richer?)

One more thing, I do NOT have the kill switch wired up, I was assuming I could just choke it to stop the motor, any problems with that theory before I take it for a shakedown?

Kirk

al nunley · Joined: 13 Nov 2006 Posts: 3038

The 2 cycle is the simplest of engines, if it has compression, if it's getting fuel, (with the right air/fuel ratio) if it's getting spark, (at the right timing), if the engine is air tight, it's going to run. As with any engine, there are things you need to check, it’s not just a matter of gas and go.
Have you tried a new plug, they go bad sometimes. Yes, there is spark when the plug is out of the engine, but maybe not when installed in the engine due to the compression pressure.
By the way, have you checked the compression?
We always carried a new plug and plug wrench to the starting grid, just in case.
It’s possible it’s too rich, have you tried pinching off the fuel line when it doesn’t fire right up?
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting

Kirk Deason · Posted: Wed Oct 12, 2011 7:55 am Post subject:

I KNEW you would ask about compression! (I always get hit with the question I am unprepared for). No, I did not check that. I will also try a new plug, I took the current one out several times to dry and clean it with some brake cleaner, wipe it off and try again.

OK good tips, I'll report back with results.

Thanks, Al.

Walt Gifford · Posted: Wed Oct 12, 2011 7:56 am Post subject:

You're flooding it. The crankcase is full of fuel and the mixture is so rich it can't achieve combustion. Also, your plug could be fouled. Cleaning with brake cleaner will make it foul faster. Even though it sparks outside of the engine, inside the engine is a different environment that inhibits spark. Try a ND-W27ES-ZU fine wire. Also, only run your engine on the stand long enough to prime the carb which is about 3 seconds, anymore and you're just fouling the plug. When you see macho man reving his engine and smoking out everyone please feel free to laugh.

If the engine gives you some resistance when cranking it has enough compression to start.

When starting you have to have a sense for what the engine needs. If the fuel is not up to the carb it might need a small choke to help the carbs fuel pump get it up. Choking is rarely necessary when everything is working right.

If the fuel is getting up to the carb then usually all you need is to crank it while pumping the pedal. If you get a sense that it's flooding then hold the pedal all the way open, keep it there and crank it until it starts and clears out then modulate the pedal to control rpm and keep it running. It will not idle at race settings.

Once the engine is running all you have to do to shut it off is lift off the pedal and it will flood to a stop with the racing needle settings.

When you come off the track don't let the engine wind down slow and die because that will flood it too much. Just before it dies rev it once to clear it out and let it die quick. Next time on the grid it will fire right up.

Hope that helps,
Gif Cool

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FAA certified jet engine and aircraft technician
Nicholson Speedway class champion 2001
Yamaha KT100 Service Center
40 years karting experience

John Mulvihill · Posted: Wed Oct 12, 2011 2:45 pm Post subject:

I'll second Walt. You probably have a crankcase full of gas.

Shut off the gas and crank with the throttle wide open to see if you can get it to clear out and fire.

Worse comes to worse, try an automotive spark plug (HOT) to get it to start, but only on the stand. Not under load. Don't forget. Instant stick.

John
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I bowl overhand..........

Steve O'Hara · Posted: Wed Oct 12, 2011 9:33 pm Post subject:

Kirk,

Remove the spark plug and wrap the plug cap in a towel and tuck it away from the motor so there is no chance for a ground, disconnect the fuel line, hold the throttle wide open and spin the engine with your starter fully charged for 15 seconds.
Place a towel over the head to catch any excess fuel that blows out through the spark plug hole while spinning the motor.
Put a new plug in and reconnect the plug wire.
Check the pop-off pressure on your carb to see if it hold pressure and if so how much ( if you don't know how to do this search this forum to read up on pop-off settings, how to measure and how to change)
If you check the pop off and it will not hold at least 8psi you need to fix that before you try to start the engine. If this is all new to you find a local racer or shop to take the carb to and watch and learn... it is simple.
Once you have verified that the carb has at least 8psi pop off, reconnect the fuel line and set the low speed needle at 3/4 of a turn and the high speed needle at 1/2 turn. More pop off pressure is better, I recommend you set it at 15 to 18psi.
To start the motor hold the throttle wide open and crank the starter until it fires up. With those carb settings the engine should idle like a chain saw. If the idle speed is too low or high adjust the idle with the idle adjustment screw on the other side of the carb.
When you get the kart on the track and start driving fast you will want to open the low speed needle to 1.25 turns. If you are a novice driver and not pushing the engine real hard you can open to just one turn. If the engine 4 cycles (blubbers, misfires) at the high speed end of the track you fine tune with the high speed needle in very small steps.
Good luck.
Steve O'Hara

Kirk Deason · Posted: Thu Oct 13, 2011 12:39 am Post subject:

Thanks, everyone, for the tips. I got some new NGK BR9 and BR10 EIX plugs, and Walt, I orderd four of the ND-W27ES-ZU plugs. I put the BR9 plug in, removed the fuel line, held the throttle wide open and cranked it until the starter battery wound down (twice) in an effort to clear out the crankcase. I got a couple of pops out of it but nothing promising.

I checked out a few cylinder pressure testing gauges at sears (but didn't buy yet) and will be now, also, looking at a pop-off gauges.

I'll post progress.

gregg boyce · Posted: Thu Oct 13, 2011 5:05 am Post subject:

Kirk,

I've been starting mine with just a crack of throttle. I'm at 1 on the L and .25 on the H. and I'm @ 500ft vs 5000ft for you. You can close the L side down alot more to get it going. Once you're moving richen the L till it runs clean.

GB
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My imaginary friend says your crazy.

Walt Gifford · Posted: Thu Oct 13, 2011 7:02 am Post subject:

If it sits for a while it can dry out. If you're sure it's dry put about 3cc of fuel in the spark plug hole. If it fires up for a short burst then connect the gas line and try a normal start. If it fires a few time and quits you might have a bad crank seal or ignition problems. Clean all the electrical connections and ground and look for a crank seal that's popped out. Is your pulse line connected ok?

Gif Cool

_________________
FAA certified jet engine and aircraft technician
Nicholson Speedway class champion 2001
Yamaha KT100 Service Center
40 years karting experience

Ron Towles · Posted: Thu Oct 13, 2011 7:12 am Post subject: Check fuel connection

Wonder if the fuel line and the pulse line are swapped? Fuel goes to brass colored connection, pulse line goes to silver connection. Would not be the first time I've seen them swapped.

Kirk Deason · Posted: Thu Oct 13, 2011 4:06 pm Post subject:

The pulse and fuel lines are not swapped, they are correct. Compression tester and carb pop-off gauge have been ordered.

Kirk Deason · Posted: Wed Oct 19, 2011 8:12 am Post subject:

I got my compression tester yesterday and tested it out on the JICA. I did it several times and saw readings of 48-50psi each time. I am still waiting on the pop-off/carb tester to arrive.

Is 48psi acceptable or normal?

Brad Linkus · Posted: Wed Oct 19, 2011 8:38 am Post subject:

Should be at least 120-150psi, you need at least 100 to start an engine.
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John Mulvihill · Posted: Wed Oct 19, 2011 9:39 am Post subject:

Hi Kirk,

48 lbs isn't good.

Did you have the throttle open while you were spinning the motor with the starter?

John
_________________
I bowl overhand..........

Kirk Deason · Posted: Wed Oct 19, 2011 11:19 am Post subject:

Crap. I retested with the throttle closed to confirm--same issue. 50psi. Makes me want to throw things.

Well it appears we are closing in on the root cause. And now I know the value of, and how to use, a compression tester.