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Hi all ive worked on a lot of different briggs motors but never had this much trouble with an engine.
Its a 17.5hp intek 31G777 motor fitted in a ride on mower. Ive replaced the con rod and cam shaft,
timed it up all ok like I normally do set the valves up but no start.
Its backfires through the carb and wont have it at all, tried narrowing the clearance on the inlet to
compensate for the combustion release and its doing something because the exhaust is warm.
Any ideas where I should look next???
John

ehl said:

Hi all ive worked on a lot of different briggs motors but never had this much trouble with an engine.
Its a 17.5hp intek 31G777 motor fitted in a ride on mower. Ive replaced the con rod and cam shaft,
timed it up all ok like I normally do set the valves up but no start.
Its backfires through the carb and wont have it at all, tried narrowing the clearance on the inlet to
compensate for the combustion release and its doing something because the exhaust is warm.
Any ideas where I should look next???
John

Click to expand...

As long as the timing marks on the cam to crank is ok then it may be a valve issue (requires ground). A leak down test would tell you quicker.
If you had the flywheel off then the key could have sheared knocking timing out due to bolt not being tight enough.

It also could be a head gasket problem.

Thanks pugs the key had sheared,starts fine now but revs high all the time even after ive reset the cable control

The governor arm should move yeah?
Do I reset the governor like normal, undo the screw and turn the shaft clockwise till it stops then re tighten the screw?

You turn the shaft in the same direction the governor shaft turns when you move the throttle from idle to full throttle.

Cool ive set the governor up however it doesn't return from full revs when I move the control to idle. ive overhauled the carb so nothing sticks,
it all works fine when not running but the butterfly on the carb isn't returning to idle while running, could it need a helper spring fitting?

If everything is connected correctly, like making sure the governor linkage isn't hooked up to the carb incorrectly, and the governor arm is adjustment correctly, sounds like the governor gear inside the engine isn't working.

are the governors prone to sticking? I fitted a new one with the new camshaft because it was damaged.

ehl said:

are the governors prone to sticking? I fitted a new one with the new camshaft because it was damaged.

Click to expand...

No they are not. Like ILENGINE said it has to be something inside as in not fitted correctly.

This is what im looking at, ive got the timing marks right and the governor fitted correctly I think.

Can the governor be set with the sump off so I can see where ive set the arm to?

the sump actually needs to be on because the governor gear can shift around when the sump goes on, which will change the setting. From the picture it looks like the shaft would turn clockwise, to set static setting. I have had a couple engines that I have to hold the shaft in place while tightening the governor arm because the weight of the governor would change the setting.

Make sure you have the linkage in the correct hole on the carb, because on some carbs it is possible to connect in a different hole, which changes the direction that the governor operates. The governor will try to open the throttle as opposed to closing it.

Thanks for the advice ILENGINE and Pugs

the little R clip on the governor shaft was missing and the shaft had slid back through the casing and was missing the governor completely.

That and I did have the carb linkage in the wrong hole on the governor arm :wink:

It runs great now, something to watch for though.

Ehl