Honda HT3813 plug fouling

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Old 08-07-06, 09:48 AM
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Honda HT3813 plug fouling

My HT3813 recently started to experience a high level of carbon on the plug. Changes plugs cleaned the air filter and still have heavily carbonized plugs after only a half hour of operation. Are there adjustments that can be made? If so is a proceedure availabe. Thank you in advance. Heavily sooted in Connecticut
 
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Old 08-07-06, 12:37 PM
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clogged air filter

You need to replace the air filter. Honda filters use a finer paper that will trap finer particles that can not be cleaned out causing a rich run and carbon build up.

AJ
 
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Old 08-07-06, 03:35 PM
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Will give it a go

Thanks for the suggestion, will give it a go and advise results.
 
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Old 08-07-06, 06:34 PM
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Well, AJ beat me to it. His advice is accurate.

BTW: Nice little mower you got there. They don't make em like that anymore. Liquid cooled, smooth, and quiet. And expensive to repair, lol.
 
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Old 08-09-06, 01:24 PM
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Still sooted

Changed air-filter as recommended. Cleaned the plugs. Runs better but still carbonized after an hour of heavy cutting. Noticed I'm using more gas than before. Is there be something else that neeeds ckeaning or adjusted. Like you said its not cheap to repair. Recently had the drive shaft replaced. Thanks
 
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Old 08-09-06, 10:00 PM
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Check the choke to make sure it's opening fully. If so, you may want to look at the inlet needle, seat, and float. You may have a flooding carb. Does it seem to lack power? If so, you could also have a jumped timing belt. (one tooth off).
 
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Old 08-10-06, 09:10 AM
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Cheese - What should I look for in determining a faulty float or inlet needle. This happened right after the mower was down for 4 weeks having the drive shaft replaced. Could the timing belt orientation have been upset at that time? Is it difficult to reset the timing belt? Please advise.
 
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Old 08-10-06, 08:31 PM
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Hondas don't seem to have much trouble with the needle/seat leaking, and this carb is not gravity fed, so I really doubt the needle is the problem. It could be though, but it's hard to diagnose it on that engine unless it is blatantly leaking. You could fill a smaller fuel tank with gas and connect it to the carb and place it higher than the carb and watch to see if fuel gathers at the bottom of the intake. If so, the needle/seat are leaking.

To check the timing belt "timing", remove the valve cover, and the spark plugs. Use a long thin screwdriver and put it in the plug hole until you hit the top of the piston. Rotate the engine by hand (I usually turn the fan blade) and watch the screwdriver. Make sure it stays loose in the hole and doesn't bind or scratch the piston/cylinder. When the piston comes to the topmost point of travel, look at the valves. Both should be closed. If you rock the engine slightly one way and the other, the rocker arms should alternate pushing one valve down or the other. The spot where both rocker arms are centered, the piston should be at the topmost spot in it's travel. If it is off just a hair (and that's all it will be if the belt is off by one tooth) then the belt timing is off. If you do this, and the valves don't react anything close to what I described, turn the engine over once more and when the piston comes up this time, the engine will be on the right stroke to perform this check. The peak of the piston and the change of rocker arm movement must correspond exactly with one another.

The timing belt could possibly have been upset during driveshaft replacement. Especially if some trash fell in the cover onto the belt. The trash can collect where the belt wraps around the crankshaft pulley (where the driveshaft is connected) and will get smashed between the belt and cogged pulley on the crank when the engine is turned over. That allows the engine pulley to slip on the belt just a tad sometimes. I found that out the hard way! If it's never been changed before, it might be time anyway. Problem with that is that it's quite difficult. You either have to remove the engine and then the timing covers, or contort your arm and remove most of the components behind the dash, take the motor mounts loose, driveshaft out, and a lot of other things out of the way to be able to squeeze your hand into the small spots at the back of the engine. I prefer the latter, but I'm good with my hands. Some people prefer to take the engine out.

If you do wind up going into the timing belt issue, take a look at the water pump pulley. Most times when a timing belt is needed, the cogs are nearly worn off the water pump pulley. Regrettably, you have to buy the whole pump to get the pulley.

I think the belt is around $90, and seems like the pump is near $150.
 
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