LT50 not running - Any suggestions? - Suzuki ATV Forum
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post #1 of 10 Old 11-03-2018, 03:43 AM Thread Starter
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LT50 not running - Any suggestions?

Hi team, I picked up a LT50 for the kids and it worked for a little bit-enough to swing your leg over and then nothing.

So I went and swapped the spark plug and new tank of gas, no joy. It would start but only rev high. I took the carb apart and cleaned it all out as the tank has some rust in it. Petcock filter still looks good and is letting fuel through. Also ran wire through the jets again thinking of the rusty tank.

When taking the carb off I noticed the gasket between the carb and motor is split.

I put it all back on the bike, it would start with the choke on then die immediately. Touching the throttle would kill it, it also wouldn’t start without the choke.

I pulled the plug out and found it wet so assuming too much fuel?

I’m puzzled at this stage and not too sure what to look at next, any help would be great.

Thanks,
Brad
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post #2 of 10 Old 11-03-2018, 06:56 AM
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Hi Brad, sometimes those little two strokes can give you fits trying to make them run. I used to work at a Suzuki dealer when those little bikes were current. You mentioned that the gasket or carb boot was cracked. That will need to be replaced or repaired. It will suck in air making it hard to start and keep running. Being that the spark plug is wet with fuel, possibly the float and needle valve assembly not sealing and flooding the engine. Make sure the needle valve is moving freely and not sticking and is stopping the fuel flow when the float is at its highest level. Does the oil injection system still work, or are pre-mixing? If so make the ratio is correct. Most of those littel quads came with a restrictive washer where exhaust pipe bolts to the head. It restricts the exhaust flow limiting the power for the little riders. If its still in there, loosen the bolts and remove this washer. It will allow the engine to run freely and stops all that excess carbon build up. The speed of the quad can be controlled with the throttle limiting screw on the handle bars. Hope these ideas help, and good luck.
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post #3 of 10 Old 11-03-2018, 12:32 PM Thread Starter
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Hi Benjamin,
Thanks a lot I’ll give it a go, it has the exisiting oil tank in place and by all accounts works - you can smell the mix when it does fire up.

Cheers,

Brad
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post #4 of 10 Old 11-03-2018, 07:22 PM Thread Starter
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Right, got the gasket sorted with some gasket paper and got it as about as good as I could.
It ended up starting and then dying, same old.

With the airfilter off I placed my hand over the air intake and it fired up, no for long but off choke and ran for a while longer than previously with the choke on.

I tried this again however noticed a bit of petrol on my hand I.e appeared to be getting too much fuel.

Took the carb off and undid the bowl to adjust the float cut off. I bent the metal tab that triggers the cut fuel cut off up so the float didn’t have to get so high before stopping flow.
(Previous day I had tested the float simply by removing the bowl, leaving the fuel line attached to the carb and seeing if the fuel would stop as I moved the float up and down - it worked, however not to say it does when operating under normal conditions).

I put it all back together and it started up, no choke, and it ran, however it seemed to be reving a bit high/not what id deam an idle. It ran for say 5 seconds and then died.

Tried starting it again however no joy. I then checked the plug to find it wet again (cleaned it at the start of the day).

I looked down the carb from the air filter to check the needle seating in the jet, it appears ok to my untrained eye, moves freely in and out.

From the above, restricting airflow seemed to work, so does this mean too much petrol is getting into the carb? And therefore the needle possibly isn’t seating correctly?

Am I also right in assuming the jets must be clear if too much fuel is getting in?

Cheers,

Brad
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post #5 of 10 Old 11-04-2018, 01:38 AM Thread Starter
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Had a couple of goes writing this reply as the phone died.
Went back, and looked around for any air leaks that jump out to me, tightened up the bolt that clamps the carb to the elbow leading to the head, but only slightly.
Tried starting again, no luck.
So checked the bowl and dumped fuel out of there but no fuel came out, so undid the carb for the ?th time today to adjust the float, did this a few times until got fuel running out of the drain plug for the carb.
Then the better half came out, still didn’t start after multiple attempts.
Better half left, not encouraged by my progress.

So I thought about the air, and covered the air filter with my hand and it started. Revved up and then died as I took my hand off the airfilter. So I tried it again and left my hand on the filter for a while longer and low and behold back into life.
Took my hand off and as it started to die I half covered it and away it went.
I left it running for a bit on the jack and altered the throttle screw bringing the revs down a bit.
I left it running, revving it a little for a couple of minutes. I then stopped it and easily started it again with no hand on the filter. So got my daughter to have a go around the backyard and was able to restart it easily.

However I left it a couple of hours and it was back to being stubborn.
Not starting at all.
So I dumped the fuel from the carb, out it on prime briefly and then back to run, it would fire but not run
Eventually I put a rag over the air filter as couldn’t get my hand on it due to the plastics, stuffed it as tightly as I could and it started.....
It ran for a bit then died so I did the same again and away it went. I had no time to keep playing with it however getting an idea that blocking the airfilter to start it works until it’s warm, then once warm we are away.
I can’t put my finger on why it’s apparently working when starving the airfilter.
Does this allude to an air leak somewhere still?

Daughter loved it when it was going, the dog not so much, ohh well.

Cheers
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post #6 of 10 Old 11-04-2018, 08:47 AM
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Hey Brad, glad you got the little quad started. The fuel you are seeing on the spark plug may be from the excess fuel in the engine from flooding. The two strokes draw in fuel under the piston when its on the up stroke and then as the piston is on the down stroke pushes the fuel mixture through transfer ports in the cylinder walls to the top of the piston. When two stroke engines flood badly enough, a fair amount of fuel can be under the piston and repeatedly foul the spark plug. Sometimes it takes a while to get that excess fuel out of there. Putting your thumb over the sparkplug hole while pulling the starter will help blow out some of that fuel. Unless youve got a basket full of spark plugs it sometimes gets to be a pain. I usually spray spark plugs with B12 aerosol carb cleaner. It works good to clean the carb and jets and helps dry out fuel fouled spark plugs. Also did you check on that washer in the exhaust? Im not 100 % sure that Suzuki used them, but I know Yamaha did on the Trizingers. That washer would restrict the exhaust throttling back the power of the engine. Mostly it just caused so much back pressure and carbon build up the engine wouldnt run very long with out fouling sparkplugs and oily carbon on the piston. If you have to clean the carb again, if you havent already, remove the jets from the carb and make sure all the little holes in them are clear amd the ports in the carb that they screw into are also clear. You can check it by spraying carb cleaner through them. Just some more ideas, hope you get it going. The kiddos will love it. Good luck!
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post #7 of 10 Old 11-04-2018, 11:36 AM Thread Starter
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Thanks Benjamin, I'll have a look at the washer tonight and have a go getting any excess fuel from below the piston.
Yes thinking I'll strip the carb down again and give it a good clean and report back.

Cheers
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post #8 of 10 Old 11-05-2018, 01:02 AM Thread Starter
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Hi Benjammin, stripped the carb down and letting it soak overnight - will see how it is tomorrow and report back.

Cheers
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post #9 of 10 Old 11-06-2018, 02:38 AM Thread Starter
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Very wuickly, I stripped down the carb completely, taking off the choke component and the rubber seals. I got a can of carb cleaner and basically emptied it into a container deep enough for the carb to sit and submerge the area the main jet sits and the central cylinder of the carb (sorry technical words escape me) as there was a bit of crap in there. Also took apart all the jets for them to soak.
I let it sit over night and took a toothbrush to it, cleaning out the main cylinder.
It was hard to start for a couple of times then I again blocked the airfilter but it was a lot easier than previously to start.
I turned it off and restarted, again easier.
I’ll report back in 24hours, leaving it a day and seeing how it is.

My wife’s sceptical of the results...
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post #10 of 10 Old 11-11-2018, 10:03 AM
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Well Im curious, any progress with the little quad?
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