Author Topic: Just bought 85 fl350 was running and now wont start  (Read 6384 times)

jasweett

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Just bought 85 fl350 was running and now wont start
« on: October 25, 2012, 05:47:57 PM »
I just bought 85  FL350. It would start every time almost without choke and run fairly well. One of my guys at the shop was running it up and down the alley and said it seemed to be running rich so of course he thought he could lean it out. He reached down thinking he was turning the air mixture screw but was turning idle screw instead. what ensued was back fires and not being able to start again. He never touched the air mixture screw. I just bought two new spark plugs we pulled the air cleaner box off and check the reeds, the reeds looked fine but soaked in gas. Want to try and set the carb back to a baseline stab a new plug in it and try again in the morning, any input for baseline or any other pertinent info would be much appreciated as I am trying to go riding Sat. Thanks Super newbie

hoodlum

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Re: Just bought 85 fl350 was running and now wont start
« Reply #1 on: October 25, 2012, 06:36:34 PM »
I hope this doesn't sound really sturid,but have you tried re-adjusting the idle screw?Have you checked the compression? Have you done a leak down test?

LiveWire

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Re: Just bought 85 fl350 was running and now wont start
« Reply #2 on: October 26, 2012, 06:54:42 AM »
The standard jetting does tend to be rich on the low end with a 52 slow jet. That is why the choke is not needed. The screw at the back of the carb is an air bleed. You turn it out to lean out, but won't get it to clean up even at 3 turns out.

I doubt adjusting the idle has anything to do with it not starting. Based on what is common, I would bet the rings are stuck giving low compression and that the crank seals are leaking.

jasweett

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Re: Just bought 85 fl350 was running and now wont start
« Reply #3 on: October 26, 2012, 07:59:30 AM »
We have tried turning the idle screw a quarter turn at a time, but was wondering is their a baseline setting. The guy I bought from had gone through it completely seals and all. No compression or leak down as of yet. As soon as he messed with screw is when it was back firing and would not start. changed the plug and continued. We thought we might have fouled the plug so I got two new ones last night and want to start over. But a baseline would help for idle screw.
Thanks

LiveWire

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Re: Just bought 85 fl350 was running and now wont start
« Reply #4 on: October 26, 2012, 09:56:56 AM »
The baseline for idle setting on a new carb is backed out so it won't idle. It would be dangerous to do otherwise. You tun it in until it will idle without holding the throttle. You have to blip the throttle and let it back down because the screw won't force the slide up. It is just a stop for slide when coming back down.

Changing the idle setting will not make it back fire. The only way I could see turning the idle screw would cause anything other than a change in idle speed is if it was cranked in really hard which spun the slide and broke the little plastic nub off that aligns the slide.

jasweett

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Re: Just bought 85 fl350 was running and now wont start
« Reply #5 on: October 26, 2012, 04:37:47 PM »
Thanks for info, we are checking the slide now. We did try turning all the way out while feathering throttle but no luck.  Took the pipe off and cleaned to get any raw fuel out. Put a spark tester on and we have spark. The reeds look fine nice and tight no gaps or distortion. New plug. When cranking sounds solid sounds like compression. The only thing we get is a back fire.

Factory 45

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Re: Just bought 85 fl350 was running and now wont start
« Reply #6 on: October 27, 2012, 04:23:36 AM »
Get the backfire figured out quickly...backfiring a 2 stroke can do some serious things to your engine. The quick high pressure from a backfire can and will blow the oil seals right out of their journals. Then no matter what you will be hard pressed to get it running at all without doing the seals over.

As it has been suggested a compression test...followed by a leak down test should be performed. My suggestion would be to do at least a comp test before you go further...dont keep trying to start it if it consistantly is backfiring.

Just because the stuff is "new" doesnt mean it was assembled correctly :)

Get a comp gauge and a shop manual to go further...and find your baseline for the carb. Why are you having to clean fuel out of your exhaust...and your reeds are soaked with gas? Is the carb leaking fuel down into the crankcase because of a leaky float valve? Is the crankcase full of extra fuel? If the previous owner sold it to you...im sure it hasnt gotten much use...and this was one of the first rides...ESPECIALLY because your guy said rich...Im saying you may just need to douche the carb and fuel system...possibly replace the float valve. DRAIN ALL THE FUEL from the tank...try to strain it through a PPG paint strainer to check for grit/particals...and make sure the float valve works to meter fuel. If not it will drown in fuel...fill the crankcase and pipe...and not start until it is drained. What are your plugs looking like...sopping wet with gas?

Getting the crankcase empty from fuel will require you to raise the buggy from the rear with a hoist...the idea is to essentially "dump" out the engine with the exhaust headpipe removed. IF Im on the right road with the fix...and you need to do all this including dumping the crankcase out...be sure to drain the counterbalancer oil before you tilt the buggy around...if the oil mod has not been done...oil may end up in the mag/ignition side of the crankcase and eventually waste your starter motor. 
« Last Edit: October 27, 2012, 05:28:27 AM by Factory 45 »

odypilots

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Re: Just bought 85 fl350 was running and now wont start
« Reply #7 on: October 27, 2012, 12:53:46 PM »
I found my 350 manual, and the smallest main jet it shows is a 138 (for the warmest temperatures, and highest altitude), up to a 145 (for low temperatures, and low altitudes). Air screw; 1 1/2 turns out to 2 turns out. Needle clip shown in all positions for different temps and altitudes.
The usual 'my two cents' disclaimer applies. :)

LiveWire

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Re: Just bought 85 fl350 was running and now wont start
« Reply #8 on: October 30, 2012, 06:48:48 AM »
If the diaphragm in the fuel pump has a hole/crack in it, the engine will just suck fuel straight into the bottom end.

jasweett

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Re: Just bought 85 fl350 was running and now wont start
« Reply #9 on: November 10, 2012, 01:40:44 PM »
Found problem. key on shaft had sheared causing the timing to be almost 180 out. Thanks for all the info.