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Discussion Starter #1
Just got in a briggs twin model 401707-0130-01-78022812 runs great untill drive or pto engaged then boggs down to almost dieing, Have gotten into it much yet but think its got points and kinda sounds like the condenser is bad I realy need a mauel on this so i can find the problem, anyone have one ? ED
 

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You sure it's running on both cylinders?


Sent from the MTF Free App
 

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I can send you a Service Manual at address below, put in proper format and remind me, model number and what you want.

Walt Conner
wconner5 at frontier dot com
 

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Discussion Starter #6
Ok heres what ive found so far , replace fuelline from filter to carb, its was brittle and was spliced with the wrong size union, after that wouldnt hardly run atall, after recharging the batt was back to running good (unless under load) pulled right plug wire and it slowed down but kept going , pulled left and she dies, when running rough before recharge any plug pulled would kill it, compression check with both plugs out to get the most RPMs was 70 on right cyl 75 on left cyl. first thought it was fuel related then points/condenser now not sure where to go I know Larry in Tx has a few of these any thoughts? this is 35 years old and wondering if she's just wornout .
 

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If the engine is hard starting, runs rough, misses or lacks power, perform a cylinder balance test to determine whether both cylinders are operating to their full potential.

You need a tachometer, two ignition testers, screwdriver with insulated handle.

Attach ignition tester, between the spark plug lead and each spark plug.

Start and run engine running at top no load speed and note spark at ignition testers. If the spark is equal at both ignition testers, the problem is not ignition related.
A spark miss will be readily apparent. Now note RPM of engine. Ground out one cylinder with screwdriver by contacting alligator clip on ignition tester and a good
ground on engine. Note RPM loss. Then ground out the other spark plug and note the RPM loss. If the difference between the two cylinders does not exceed 75 RPM, the amount of work the two cylinders are doing should be considered equal.

If the RPM loss is less than 75 RPM between cylinders and the engine runs poorly, the problem is common to both cylinders.

Things that affect both cylinders are Carburetion, Crankcase vacuum, Ignition timing.

If the RPM loss is greater than 75 RM, this indicates that the cylinder with the least RPM loss is the weakest of the two cylinders. Look to that cylinder for a problem like a fouled spark plug, leak in spark plug wire, head gasket, intake manifold (a leak at either end of the intake manifold will affect one cylinder, not both), valves, rings, piston, cylinder.

The cylinder balance test will also detect a cylinder that is not functioning. When grounding out one cylinder there will be no RPM loss. When the other cylinder is
grounded out the engine will stop.
 

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Discussion Starter #8
Thanks MWP for the link it helps forgot the mention that it seems to have a lot of crank case pressure,
 

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If you have crankcase pressure than you have other issues as well, you should have negative pressure, or vacuum inside the crankcase. You may need to replace your breather.
 

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Discussion Starter #10
was thinking it was bad as I got a push pull effect on the breather hose ie vac /press thanks agin but will this cause the low power when under load?
 

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Discussion Starter #13
Heres an update after the cyl bal test, cyl leakdown, compression and ign tests I decided to go with my gut feeling , found the fuel pump was rebuilt but was missing a spring, also cleaned the jets and replaced the fuel line and filter and now shes got full power , makes me mad when I dont go with my first thoughts but its out of here (almost) still cant get the battery to charge Im thinking the rectafier is bad as I get a spark when I plug it in when its not running , so thinking a blown diode. got to take the tins back off to check the color of wires . ED
 

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Discussion Starter #14
This thing is driveing me NUTS! I ran it over 1/2 hour under ful power and load no problems , guy took it home and said it started to do same thing after 5 mins. so brought it back, Ive been looking way back in the old posts and when she starts her missing, its popping fuel back out the carb so now leaning towards intake valve not seating all the time , going to order head gaskets and go from there , am I onto something or just spinging wheels agin?
 

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Note the last paragraph of my large post. You mentioned that when you pulled the plug on the right, it slowed a bit, but when you pulled the plug on the left, the engine died. Now assuming you put the plug wire back on the right side before you pulled the plug on the left, that would indicate that the right cylinder is not working properly. The engine should be able to run on one cylinder with RPM loss. You need to check for things like: a fouled spark plug, or a leak like in the spark plug wire, head gasket, intake manifold (a leak at either end of the intake manifold will affect one cylinder, not both), valves, rings, piston, cylinder.
 

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I would check valve clearance. Did the guy add fuel? Could he have added some water?
tom
 

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Discussion Starter #17
When I checked the plugs I added 2 new ones, no change, yes pulled 1 plug wire at a time , no fuel added, Ive ordered the head gaskets but wont be in til next week, I did notice oily (burnt) between head and block on no. 1 cyl.I also checked the plug wires for nicks,cracks ect.so all I can think of is head gaskets or valves.:Disgus: i did check intake for leaks
 
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