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LT80 - Fouling plugs

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  #1  
Old 10-09-2018, 12:22 PM
Weekend Warrior
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Post LT80 - Fouling plugs

Hi all,

Looking for some advice, the 2000 LT80 I rebuilt kills plugs, LT80 and other game me some advice, so to summarize:
- original carb cleaned and rebuilt, stock settings
- change the oil to 2 cycle oil for air cooled engines
- Change to the NGK iridium stick plug equivalent (BPR7IX?)
- Checked reed valve, - no cracks
- no air leaks at the carb
- 150+ PSI compression, don't see any leaks around head gasket or cylinder gasket
- new clutch rollers (probably not related)
- exhaust does not have the restrictor and not clogged
- 91 octane fuel
- Starts great and runs great for quite awhile before the plug dies
- I clean all the carbon build up on the plug and sometimes I get reuse the plug

So after some more research, my son does poke around slowly (he is only 7 with limited space):
1.Would going to a BPR6HS (hotter?) plug help burn that what I assume is oil carbon build up ?
2. Would switching to mix gas (32:1?) help with this maybe ?

Thank you in advance.
 
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  #2  
Old 10-09-2018, 01:24 PM
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This may seem odd, but would the diameter of the oil line from the pump to the carb make it flow more oil ? That line on my 87 LT80 has a really small inner diameter compared to the 2000 LT80. Just a thought.

thinking out loud...
 
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  #3  
Old 10-12-2018, 03:37 PM
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I think the pump flows the same amount of oil...if the ID was smaller that may cause a problem, but not larger. I found going to the iridium plugs helped a ton on fouling. I'm curious if your carb is starting to show it's age and the wet float levels are a tad to high causing excess fuel to spill into the cylinder when driving slow...if you have a manual petcock then you can just crack it open (I only open mine to the screw) to limit the fuel flow. I'd also be curious if your choke is closing completely...that will also dump more unwanted fuel into the equation...
 
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  #4  
Old 10-15-2018, 06:56 AM
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Originally Posted by DirtDevil101 View Post
I think the pump flows the same amount of oil...if the ID was smaller that may cause a problem, but not larger. I found going to the iridium plugs helped a ton on fouling. I'm curious if your carb is starting to show it's age and the wet float levels are a tad to high causing excess fuel to spill into the cylinder when driving slow...if you have a manual petcock then you can just crack it open (I only open mine to the screw) to limit the fuel flow. I'd also be curious if your choke is closing completely...that will also dump more unwanted fuel into the equation...
Iridium plug didn't make a difference , That being said, I changed the plug just to make sure it would still start, and it won't. Got spark, Got fuel, I can feel compression with my thumb over the hole. Had a tornado come through my srea so all my shop contents are not in a shipping container, so I'll have to wait to work on this .

Hoping the engine isn't blown, it's a new chinese top end. maybe I'll have to spring for better quality if that is the case.
 
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Old 10-15-2018, 12:04 PM
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Do a compression test (throttle wide open) and tell us the number...my experience with the Chinese top ends hasn't been good...just poor machining...
 
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  #6  
Old 10-15-2018, 02:47 PM
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I was 150+. maybe I can dig the tester out. ugh
 
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  #7  
Old 10-16-2018, 12:11 PM
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150 is very good...maybe too good...I'd be curious if you blew a head gasket...that was my experience with the Chinese kit...kept blowing head gaskets...
 
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Old 10-16-2018, 02:39 PM
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Originally Posted by DirtDevil101 View Post
150 is very good...maybe too good...I'd be curious if you blew a head gasket...that was my experience with the Chinese kit...kept blowing head gaskets...
Re-Read 1st post.
 
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Old 10-17-2018, 03:26 AM
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Most of the LT50s and 80s I work on run remarkably clean for two strokes. So, either you are running rich and getting fouling that way, or too much oil. I rather like the separate oil system, but the easy way to find if it is over oiling is to remove the oil pipe and run on 32 to 1 premix. Blank the hole into the carb off, and see what happens. This would tell you if it is an over-oiling problem, or the air/fuel mixture.
 
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Old 10-26-2018, 01:27 PM
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Originally Posted by merryman View Post
Most of the LT50s and 80s I work on run remarkably clean for two strokes. So, either you are running rich and getting fouling that way, or too much oil. I rather like the separate oil system, but the easy way to find if it is over oiling is to remove the oil pipe and run on 32 to 1 premix. Blank the hole into the carb off, and see what happens. This would tell you if it is an over-oiling problem, or the air/fuel mixture.

Thanks, i will try that. I'll remove the plastic thing that turns the oil pump also.

Won't start now and turns over really easy, so I think DirtDevil mentionned I may have blown the head gaskey as 150psi is too high and the chinese kits are not machined right. I might have to spring for a kit from LT80 as many mentionned it's better
 
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