HT-R3811 Choke

Mr-Mom

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I have an old HT-R3811 Honda riding mower. It's a great machine, which I've owned for many years and we use it for mowing and towing a small, home-built trailer. The trailer is key for picking up leaves and garden waste. We use the mower and the trailer late into the fall to finsh fall cleanup prior to the first snow.

Last spring I put a new air filter on the mower. The machine was way overdue for this, but since doing it, I'm having starting difficulties. The throttle on this machine has "start" way at the top, then down to fast run, then down to the bottom for idle. Historically, to start, you move the throtttle lever all the way up and turn the key - always started right up. Since putting the new air filter on, this does not seem to work. In the start position, the mower won't start. If I move the throttle to the idle position, it will start and run very slowly, but stalls as soon as you start to advance the throttle to a running speed. Being very judicious in letting the machine warm up a bit at idle speed, then slowing advancing the throttle, I can get it to run. This gets more difficult as the weather gets colder. Warm starts are not an issue.

I suspect that before I put the new air filter on the machine, it was a bit "choked" all the time due to poor airflow through the clogged filter, hence, it started well. Now, with full airflow, it needs a real choke mechanism.

I cannot find any information on how this choke mechanism works. I do not have a workshop manual and cannot find one online. I've looked at a parts diagram for the carburetor, but that was of little help. I cannot find a parts diagram for the throttle mechanism, so I do not know how that connects with the carburetor and ties into any choke mechaism there.

Any suggestions on what to look for and how this choking mechanism works?
 

Rivets

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Remove the air filter. When you move the throttle control cable to the start position look to see if the choke butterfly is fully closing. I’m guessing you will find that the butterfly is not fully closing. If that is the case you will find a clamp anchoring this cable. Loosen this clamp and push the cable forward until the butterfly fully closes and tighten the clamp. This should solve the problem.
 

Mr-Mom

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Remove the air filter. When you move the throttle control cable to the start position look to see if the choke butterfly is fully closing. I’m guessing you will find that the butterfly is not fully closing. If that is the case you will find a clamp anchoring this cable. Loosen this clamp and push the cable forward until the butterfly fully closes and tighten the clamp. This should solve the problem.
OK. I'll pull the air cleaner off and have a look. I did remove it and have a look earlier, but I did not see any obvious parts (like a choke valve) that seemed out of order. Do you know how the cable works to activate the throttle and the choke? I looked at the cable today and it did seem to have a bit of slack. Perhaps that is part of the issue. Thanks for the reply.
 

Mr-Mom

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Fixed! This was pretty simple. I watched the video
, which did not discuss the choke but at least gave me a glimpse of the assembly before diving in. The fuel tank has to be removed, which is simple, and the air cleaner mounting has to be removed - also simple. Once this is done you can see the throttle control mechanism, which is fairly complex. The mechanism was filthy with grease, grass and dust. This may have been part of the issue. I cleaned the mechanism and could observe that when the choke should have been engeged with the throttle, it was not pulling closed. There is no adjustment for this so I pinched the "U" bend in the rod, which in effect shortened it. This was enough to make the choke work properly. The rod in question is the one on the bottom of the attached photo.

The machine now starts and runs has it always has. When it is cold, pull the throttle lever all the way to the top and turn the key... varooom! I don't think the air cleaner had anything to do the problem. It was just an issue of age, wear and dirt. Lots of dirt.
IMG_2334 (1).JPG
 
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Rivets

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Glad to hear you got it fixed.
 
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