You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
8hp flathead 190707 intermittent miss
- Thread starter Oddjob
- Start date
I solved it. You were right to question the linkage. It is set up the same but the holes in the arm of the throttle shaft were switched. The little one for the return spring was on the bottom and the bigger one for the throttle linkage was on top (farther away from centerline of shaft). So the linkage wasn’t moving far enough to close the throttle plate inside the carb when the governor arm pushed it. I enlarged the small hole enough to get the linkage in and used the large hole for the spring. Voila. The oem throttle arm only had one hole that the spring and linkage shared so I had no template to follow. It is amazing what a huge difference it made moving the linkage into a hole less than 1/4 inch away.Have to be careful with some of the chinese aftermarket carbs on some engines because the throttle linkage in the carb is set up backwards. So the governor can think it is closing the throttle to limit speed but is actually opening the throttle.
Thanks ILENGINE for putting me onto the linkage, and thanks to all who replied with helpful advice.
Every carb has one or more.Is there a passage on this carb that is hard to see?
But not recommended in soft brass.If you have a torch cleaner set, those work a little better.
Agree with this.Can you manually hold the China carb at idle?
Agree with this. Would recommend bread tie wires too.Make sure the pin holes in the emulsion tube and main jet are clean.
A 1984 engine will need de-carboned. Meaning cleaning all the carbon from the valves and head areas. Valve lapping probably a great idea. Valve lash another recommended task in yours and every other engine manual out there. This is in every engine manual out there.
Solid fuel delivery AT the carb inlet needs looked into. Drain into a glass jar looking for water and trash. Flush the fuel tank out while you are there. Probably full of water, debris, leaves, grass, bugs and such.
Weak ignition coil needs to be ruled out. Seen them spark ok at low revs, fading out in mid and high revs. Need an open air gap type spark checker.
Dirt/trash in the fuel can. Easily passes into the carb at EVERY fill up. Make sure you have a new style fuel can spout that is sealed. Open top fuel can spouts need throw away.
Solid fuel delivery AT the carb inlet needs looked into. Drain into a glass jar looking for water and trash. Flush the fuel tank out while you are there. Probably full of water, debris, leaves, grass, bugs and such.
Weak ignition coil needs to be ruled out. Seen them spark ok at low revs, fading out in mid and high revs. Need an open air gap type spark checker.
Dirt/trash in the fuel can. Easily passes into the carb at EVERY fill up. Make sure you have a new style fuel can spout that is sealed. Open top fuel can spouts need throw away.
I just reset valve lash a few weeks ago and while I had the head off I cleaned all the carbon off. The Chinese carb works well now that I put the throttle linkage in the hole closer to the throttle shaft. Today I set rpms at 3600 and the engine runs smoothly and it idles at 1800. I restored this machine from stem to stern 2 years ago. Great machine. Thanks for your input. Appreciate all the advice the pros can offer.A 1984 engine will need de-carboned. Meaning cleaning all the carbon from the valves and head areas. Valve lapping probably a great idea. Valve lash another recommended task in yours and every other engine manual out there. This is in every engine manual out there.
Solid fuel delivery AT the carb inlet needs looked into. Drain into a glass jar looking for water and trash. Flush the fuel tank out while you are there. Probably full of water, debris, leaves, grass, bugs and such.
Weak ignition coil needs to be ruled out. Seen them spark ok at low revs, fading out in mid and high revs. Need an open air gap type spark checker.
Dirt/trash in the fuel can. Easily passes into the carb at EVERY fill up. Make sure you have a new style fuel can spout that is sealed. Open top fuel can spouts need throw away.
This engine is on a 1984 Snapper RER. I have not been able to get it to smooth out. I have cleaned the carb very thoroughly and replaced the gasket. I have recently adjusted the valve clearances. It starts easily. But it runs like a hit and miss engine. I just put in a Chinese clone carburetor and the miss disappeared, BUT it ran way too fast. My tach recorded 4900 rpm and was slowly climbing. I tried adjusting the high speed screw but could not get it to slow down, so I shut it down. I checked the governor arm and it was properly adjusted. I put the old carb back on and the miss returned but the tach showed 3200 rpm. Did I get a defective carb? Can a carb make an engine overspeed? I thought the governor would prevent overspeeding. Could I have a bad governor? Why would it govern speed with one carb but not the other? I have cleaned a lot of carburetors but I can’t help but think I’ve missed something on this one. Is there a passage on this carb that is hard to see?
Could be a coil, or points and condenser, or the end in the spark plug wire gets rusty. Good luckThis engine is on a 1984 Snapper RER. I have not been able to get it to smooth out. I have cleaned the carb very thoroughly and replaced the gasket. I have recently adjusted the valve clearances. It starts easily. But it runs like a hit and miss engine. I just put in a Chinese clone carburetor and the miss disappeared, BUT it ran way too fast. My tach recorded 4900 rpm and was slowly climbing. I tried adjusting the high speed screw but could not get it to slow down, so I shut it down. I checked the governor arm and it was properly adjusted. I put the old carb back on and the miss returned but the tach showed 3200 rpm. Did I get a defective carb? Can a carb make an engine overspeed? I thought the governor would prevent overspeeding. Could I have a bad governor? Why would it govern speed with one carb but not the other? I have cleaned a lot of carburetors but I can’t help but think I’ve missed something on this one. Is there a passage on this carb that is hard to see?
andrewslarge
Well-Known Member
Congratulations!!!! Thanks for posting your solutionI just reset valve lash a few weeks ago and while I had the head off I cleaned all the carbon off. The Chinese carb works well now that I put the throttle linkage in the hole closer to the throttle shaft. Today I set rpms at 3600 and the engine runs smoothly and it idles at 1800. I restored this machine from stem to stern 2 years ago. Great machine. Thanks for your input. Appreciate all the advice the pros can offer.
Gord Baker
Well-Known Member
Try the Sea Foam, Have tank near empty, Shot glass full into 1 qt/l of Fuel. Run for 10 minutes and let sit for 3 days or so. Worked for me after cleaning the carb did not.