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Cpto116

By God please help! 1999 Suzuki LT80 not Running

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Hello all, I am new to The Forum and like some of you I suspect, I have joined because of an issue I am encountering with my childs ATV.

 
So I just changed the top end on my daughter's 1999 lt80. I put new Reed's in and a fmf fatty pipe along with reducing the main jet to a 90. (At the recommendation of Eric at Midwest Mini)
It started fine it ran fine and I did two heat Cycles on it before riding it. Once I was riding it I got a little more than half throttle and the engine just died.
I can't tell if it was starved from fuel or if there is something wrong with the top end. This is the first time I've ever done a top end job. It starts up just fine and runs at idle but when riding it for any length of time like greater than 5 minutes the engine just boggs down and cuts off while riding it. When you try to pull start it it feels like the Piston is semi seized but, it still starts.
Once it starts it seems as if it's starved for power, then it's cools and after 20 minutes it starts right back up again and rides great for 5 or 10 minutes.
please someone help me make my daughter happy and let me know what they think the problem could be

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3 days ago · #1
 
By God, someone please help
 
So I just changed the top end on my daughter's lt80. I put new Reed's in and a fmf fatty pipe along with reducing the main jet to a 90. (At the recommendation of Eric at Midwest Mini)
It started fine it ran fine and I did two heat Cycles on it before riding it. Once I was riding it I got a little more than half throttle and the engine just died.
I can't tell if it was starved from fuel or if there is something wrong with the top end. This is the first time I've ever done a top end job. It starts up just fine and runs at idle but when riding it for any length of time like greater than 5 minutes the engine just boggs down and cuts off while riding it. When you try to pull start it it feels like the Piston is semi seized but, it still starts.
Once it starts it seems as if it's starved for power, then it's cools and after 20 minutes it starts right back up again and rides great for 5 or 10 minutes.
please someone help me make my daughter happy and let me know what they think the problem could be

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3 days ago · #1
 
By God, someone please help
 
So I just changed the top end on my daughter's lt80. I put new Reed's in and a fmf fatty pipe along with reducing the main jet to a 90. (At the recommendation of Eric at Midwest Mini)
It started fine it ran fine and I did two heat Cycles on it before riding it. Once I was riding it I got a little more than half throttle and the engine just died.
I can't tell if it was starved from fuel or if there is something wrong with the top end. This is the first time I've ever done a top end job. It starts up just fine and runs at idle but when riding it for any length of time like greater than 5 minutes the engine just boggs down and cuts off while riding it. When you try to pull start it it feels like the Piston is semi seized but, it still starts.
Once it starts it seems as if it's starved for power, then it's cools and after 20 minutes it starts right back up again and rides great for 5 or 10 minutes.
please someone help me make my daughter happy and let me know what they think the problem could be

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It almost felt like the Piston was seizing. I'm going to disassemble it today to take a look and see what I can find. I will post some pictures later maybe you guys can help me diagnose it.

It didn't sound like the Piston was hitting the head at all. As a matter of fact the bike ran great after I did the install. Although, I did have to use the stock head with the new cylinder. The cylinder head that came with the Niche kit would not seal properly. Once I started it with the correct cylinder head on it I can feel air coming out between the head and the base

Edited by Cpto116

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I did torque the head down quite a bit though period way more than the specified amount I'm sure.

 

I had first only torqued it to about 9 pounds but once I started the machine I could feel the gas is coming out between the head in the base where the gasket is so I tore it down a bunch more. Do you think that could be the problem?

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A leaking base gasket can cause a lean seizure as well, but usually not that quickly. To test you could start the machine and spray carb cleaner around the base. If your idle changes, you have a leak.

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I will try that today although I don't think it's a base gasket leak I didn't notice it when I was checking.

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I added your ATV info into your topic title and moving to suzuki forum. So it rides fine for 5 or 10 minutes but then dies out? When it dies out if you spray some gas or starting fluid into the intake, will it stay running?

  • Thanks 1

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Thanks, I'm new to this forum stuff and not all that good with computers so it'll take me a little while to figure it all out. I wound up putting the original cylinder head back on the bike and the original cylinder I just rehomed it with the original piston and new rings. It made all the difference in the world the bike runs like a scalded dog!

 

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It is seizing imo. Does the auto injection oiler work? Which way did you point the arrow on the piston? Did you rebuild with a china kit?

Anyways (just read last reply) how did the cylinder look? Intake side stuck and grooved the cylinder eh...??

Watch the plug going with the 90 main.

Should check the compression on the honed cylinder. :)

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Okay so here's the update, I took it all apart and it does in fact look like the engine was having a heat seizure. There was some minor scratching on the cylinder wall and on the Piston itself. I took the original cylinder wall and re-honed it and used some new Chinese piston rings. Now the bike runs great. Thank you all for your help I truly appreciate it.

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