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dctaz37

1990 Suzuki LTF4WD Not starting (unknown year)

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Hi, I am working on a machine for my neighbor LT250 fwd and have several problems. 1)I don’t know what year it is because I can’t locate the serial number.2)The starter doesn’t work when I push the button. It is in neutral, the parking brake is on and the key is on. The neutral light and reverse lights do not come on. I can bypass the starter button with a wire to the solenoid and it turns over. 3) There is spark and fuel but it won’t start. I already cleaned the carb. 4)The compression seems low because when I put my finger over the spark plug hole it does not push my finger off. They spent 500 bucks a while back and one of the items the guy did was adjust the valves. Not sure if this could be the problem. It lasted a month after they got it back and it has been dead since. Any help would be much appreciated.

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ihi i have one of these quads if the starter doesnt work, you probably have a bad ground or the battery might be bad. also if the valves arent adjusted right it wont star and might mess with compression depending on how far out of adjustment they are.

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The starter button itself, or the wires that send current to the solenoid are probably resonsible for the start button not working. As far as in not starting, I would say that the lack of compression is the problem. The best thing to do would be to get a repair manual and start tearing the motor down and see what needs to be fixed and if it is worth fixing.

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I ran wires directly to an external battery and it cranks over. The neutral light doesn't come on so I was thinking that the neutral safety switch might be the problem. I also noticed 3 broken blue wires that go somewhere to the rear of the machine. I don't have a compression tester but if I put my finger over the spark plug hole it is easy to block the air. When I do the same test on my yamaha big bear, I can't hold my finger to block the air. They only ran it a few hours after it came back from repairs so I can't see the valves being out of adjustment being the problem. If I take it apart should I change the piston and rings? Will the damage be obvious? I have the manual so I'm assuming I can follow it. They don't have the money to pay someone so I am doing this as a favour.

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the three cut blue wirees i believe is either neutral safty or a sensor try unpluging the left switch and key switch it should have spark once that is done. got my quad like this not too long ago. didnt seem too have much compression but then when i put gas in the cylinder and checked for spark it had lots of compression everyone told me the feeling of compression with pull start doesnt determine anything also if you unplug the stator and it has spark your stator is bad. and if its good and for some reason unplugged there will be no spark.when you get it running and it smokes you will need rings/ piston do you know if it smoked before it stoped running

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There was actually 4 blue wires so I fixed them but it didn't change anything. No neutral or reverse light. The wires went to a switch that screws in the diff. I have spark and was able to crank it over by running a hot wire to the solenoid. That is when I determined there was little compression so it was cranking over fast. I'm not sure if it smoked or not but the repair guy said he changed the oil and when I drained it it was black. I already tried the gas in the cylinder. I'm going to worry about the starter later once I can get it running. I have removed the head and will get to the cylinder out shortly. The question now is 1)how do I figure out the year? 2)do I replace the piston and rings or just the rings?

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you will need both piston and rings/do you have any pics of the quad i may be able to identify also there should be a number on the motor and one on the rear plastics under the seat be careful pulling the jug and other stuff off once you get the piston and rings replaced you will need to have it timed send me the numbers you find

Edited by dirtlover
because

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You need to figure out where you are losing the compression. To answer your earlier question, yes, the problem should be obvious enough that you can see it. If it is the piston, rings or cylinder walls, there will likely be evidence of excessive wear. You will need to have the cylinder bore measured to determine how big the bore is so you know what size piston to buy. If the piston/rings are the problem, it may be best to have the cylinder bored to the next piston size up from what is in there now depending on what the cylinder walls look like. Your problem may be as simple as a head gasket. You could also be leaking compression because the valves aren't sealing or closing, so, improper adjustment could be leaving one of the valves open thus leaking compression out of the cylinder. Start by removing the valve cover and checking the valve lash. If that is ok, remove the head and inspect the head gasket and look down into the cylinder to check for signs of wear on the cylinder walls. Also look at the valves and seats. Since the compression is so low, you should easily be able to spot the problem.

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The piston, rings and cylinder look okay. I brought them to a machine shop just to verify my opinion. He said to pour some liquid in each of the ends of the head to see if the valves are seted properly. If it leaks he said there is a problem. I am going to check if the valves are seated properly next. I'm not sure what valve lash is.

I'm back, the valves let a tiny bit if liquid through but the guy at the machine shop said it would be no big deal. Should I get the tool to take the valves out? I found th serial number,

JSAAJ45A4L2107789 Model LTF4WD. The book says that vin means it is a 1990, what do you think? How about the motor size? I have an old invoice and it is listed as a 250 but I couldn't find anything on the machine to back that up.

Edited by DirtDemon

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In the future just go ahead and make a new post instead of editing your last one to add info.

It is a 250. If you want to remove the valves yourself, it would be easiest with a valve spring compressor. A vavle grind should not cost you too much, new vavles, seats, seals, springs, retainers and cotters should only run about $100 from the right place, if you bought everything. The machinist should be able to recommend what all to replace. Good luck.

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Ok, I'll make sure I make a new post each time.

Do you think the valves really need to be addressed? I cleaned them up with cleaner and they look pretty good. At this point I'm thinking either the gasket was toast as it looks pretty rough or the guy who adjusted the valves did it incorrectly. The guy at the machine shop said the cost to do the valve job just for labour would be $85+tax. He said a little bit of leakage from the valves shouldn't be a big deal.

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When you say the valves let a tiny bit of liquid through, how long does it take for the liquid to seep through to the other side. If it comes right through, then I would say yes, it needs to be addressed. If it takes a while for it to seep through, I personally would still fix it. It may still run for a while, but probably wont be long before it doesn't. If the valves can't keep a little bit of water from running through, then how are they supposed to hold 120 psi of air and fuel? If it were me, I would clean up the head, get a valve grind, and replace the valve seals. Here is a link to a site that will do the valve grind, cut the valves, install new seals, set the valve lash, prep the gasket surfaces, check the guides and springs, and provide new gaskets probably for less than $175U.S.Services

Or you can clean everything up, replace the gaskets, set the valve lash yourself, and it may run forever, who knows.

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The liquid takes a few seconds to start getting through but it is a tiny bit seeping, overnight the intake chamber does not empty. I rented the spring compressor and removed the valves and cleaned them up. They look pretty good, the exhaust seat is a little pitted but the intake look pretty good. I just don't want to spend money if I don't need to.

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The biggest problem there is that since the exhuast seat is pitted, the valve does not make as good of contact with the head, and therefore, cannot conduct heat away as well. If you put it back together without repairing the valve seat, it may run ok, but you may also end up burning up a valve and losing the head of said vavle in the cylinder. At that point, you are looking at much more costly repairs. IMO, it is worth the extra time and money to just fix it right. Especially since this is an air cooled machine.

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I hear you, i'll take it in and have an engine place recommend/service it. I would hate to do all this work and not have the thing run. I still don't think that was the problem for it not running. I cleaned up the valves and the exhaust valve had a lot of dirt on the top.

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I took the head to a machine shop and they are going to grind the vavle seats. The intake valve is worn out so I ordered that and I figured I might as well get rings while I'm doing all this.

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Thanks, I'll let you know when I get it back together. I still have to figure out why the electronics don't work. I can jumper the solenoid and the starter cranks. I think the start button and solenoid are toast. I was thinking that I could just bypass the start button with a switch and wire in a generic solenoid. I also think the neutral switch is bad as there is no neutral light when it is in neutral. Not sure on the cost for the original solenoid, neutral switch and start button but I'm guessing it would be cheaper to install what I suggested.

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