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I have an early 6.5 hp Intek engine on a walk behind. This looks like a Quantum but is OHV. It has trouble starting and when it does start it lets out a puff of smoke. Engine model 11A602-0151-E1 I have done the following:

Reset the magneto gap to .010
Cleaned the Carb and changed all intake gaskets
Change the spark plug with a new and set gap to .020
Using fresh fuel
Changed the primer bulb
Set valve lash to .005 on both intake and exhaust.

On a cold start it takes a minimum of 4 pulls to starts it Sometimes as many as 8.

On a hot start it can start right up with one pull.

When it starts it will let out a puff of smoke for a few seconds. I assume it is rich gas that did not fully burn. However I realize it could be a leaky valve seal. It runs good once started. No smoking or any issues.

I have not pulled the head to look at the cylinder wall or inspect the valve train. I am thinking that may be my next step but I wanted to post the problem before I dive in to that.
I do not have a leak down tester. Otherwise i would have tried that by now.

Any thoughts?

First thing I would check is the float height. With the carb inverted the float should be level or slightly tilted down for easy starting.

Rivets said:

First thing I would check is the float height. With the carb inverted the float should be level or slightly tilted down for easy starting.

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That is a good trick to have in your back pocket. This is a primer style carb and I could test out the low fuel in bowl theory by pumping the primer a few extra times and see if it fires up. If even for a few seconds. But I will take a second look at this. Thanks

Rich/Gas would be Black smoke, oil from a leaky valve seal would be blueish

What grade oil are you using?

nbpt100 said:

That is a good trick to have in your back pocket. This is a primer style carb and I could test out the low fuel in bowl theory by pumping the primer a few extra times and see if it fires up. If even for a few seconds. But I will take a second look at this. Thanks

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Add to that blowing through the inlet
If you have a pump, the float upside down should hold 4-7 psi without leakage for at least 5 minutes
Otherwise just blow through it holding your breath but please stop before you urn blue .

mechanic mark said:

Results

www.briggsandstratton.com

What grade oil are you using?

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SAE 30

bertsmobile1 said:

Add to that blowing through the inlet
If you have a pump, the float upside down should hold 4-7 psi without leakage for at least 5 minutes
Otherwise just blow through it holding your breath but please stop before you urn blue .

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That is a good trick to have know as well. However, i Do not believe the carb is flooding.

I think it is time to remove the head and do some inspection.

Check for vacuum leaks. This Intek has a manifold that runs to the other side of the block from the carb. Check both sides with WD-40. If engine smooths out or smokes you've found your leak.

nbpt100 said:

I think it is time to remove the head and do some inspection.

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Should be done anyway to remove carbon in the cylinder and head.

Notice the last 2 items in the below list from your manual........

slomo said:

Check for vacuum leaks. This Intek has a manifold that runs to the other side of the block from the carb. Check both sides with WD-40. If engine smooths out or smokes you've found your leak.


Should be done anyway to remove carbon in the cylinder and head.

Notice the last 2 items in the below list from your manual........


View attachment 58196

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I have done everything , if possible, on this list.

nbpt100 said:

I have done everything , if possible, on this list.

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Even pulled the head and de-carbonized the cylinder and head? Checked/adjusted the valves? Cleaned the cooling fins?

Vacuum leak check?

You said you cleaned the carb and changed all gaskets. Perfect time to check for vacuum leaks. You've been in there fiddling with it.

Verify your primer is squirting fuel into the carb. Remove air filter cover and filter. Look into carb throat. Push primer bulb. Watch for fuel squirting up vertically from lower center area of carb (emulsion tube).

I've had some good engines that take 4-6 pulls like yours. Told myself don't be lazy and pull the rope. Not that big of a deal. We all need as much exercise as we can get.

Remember fresh gas, good spark, good compression, & fresh air at air filter are needed to start engine. I know Manual says valve adjustment is .004 to .008 & you set both at .005, why not set both in middle at .006. I always use high test gas & Star Tron fuel treatment or B&S fuel treatment. Also try a different multi-grade oil instead of straight weight. 10w-30 or 5w-30 I use Full Synthetic 5w-30 in my B&S 20 h.p. Vanguard & change filter every time, either Valvoline or Pennzoil because they've been around more than a century. Walmart is where I purchase oil, has best prices.
Auto parts stores loan tools out with a deposit which you receive back when you return tool, so no cost to you.

Thanks for all of the ideas.

The smoke I see on a cold start is whitish grey smoke so I believe it is oil. Which leads me to suspect leaking valve oil seals. One or maybe both. It may be a compression issue but I can not test compression as I do not have a leak down tester. It does seem to have plenty of power once started. I do not believe there is a vac leak. Primer bulb is new and working as it should. I can prime it 3 times as recommended or 6 x and it seems to behave the same way. I am leaning towrard a compression issue. I need to pull the head inspect everything. Cylinder wall, valve guides, seats and seals. If the cylinder wall is scored it is likely junk. I am not going to hone it and put in an over sized pistion. I can get a decent used engine for that total burden. I dont mind changing valve guides and or seals along with a new head gasket. This was a newly acquired machine and it may have been run with low oil.

Could this be a partially sheared flywheel key?

mechanic mark said:

Remember fresh gas, good spark, good compression, & fresh air at air filter are needed to start engine. I know Manual says valve adjustment is .004 to .008 & you set both at .005, why not set both in middle at .006. I always use high test gas & Star Tron fuel treatment or B&S fuel treatment. Also try a different multi-grade oil instead of straight weight. 10w-30 or 5w-30 I use Full Synthetic 5w-30 in my B&S 20 h.p. Vanguard & change filter every time, either Valvoline or Pennzoil because they've been around more than a century. Walmart is where I purchase oil, has best prices.
Auto parts stores loan tools out with a deposit which you receive back when you return tool, so no cost to you.

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Pennzoil? I wouldn't put that crap in my ex-wife's car!

Or, come to think of it... I would.

lefty2cox said:

Could this be a partially sheared flywheel key?

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Partially sheared flywheel key will kick back when you try to start it.

Like Slomo said take air filter off and look into the throat of the carb as you push the primer, You should see gas spurt up the main nozzle into the throat of the carb. If not it is probably the air filter base warped since the primer system goes through it. Part no. 692673. Seen this many times.

nbpt100 said:

Thanks for all of the ideas.

The smoke I see on a cold start is whitish grey smoke so I believe it is oil. Which leads me to suspect leaking valve oil seals. One or maybe both. It may be a compression issue but I can not test compression as I do not have a leak down tester. It does seem to have plenty of power once started. I do not believe there is a vac leak. Primer bulb is new and working as it should. I can prime it 3 times as recommended or 6 x and it seems to behave the same way. I am leaning towrard a compression issue. I need to pull the head inspect everything. Cylinder wall, valve guides, seats and seals. If the cylinder wall is scored it is likely junk. I am not going to hone it and put in an over sized pistion. I can get a decent used engine for that total burden. I dont mind changing valve guides and or seals along with a new head gasket. This was a newly acquired machine and it may have been run with low oil.

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wow you can't check the compression on a push mower engine and get a true reading since it has a compression release. The best way to check it is to pull the plug wire off and ground it to the block some way. Activate the operator presence handle which releases the fly wheel brake. Turn the blade backward until you feel compression then turn it about half turn back. Then snap it backward against rotation, if it bounces back hard it has good compression. Be sure and keep your hands out of the way.

My philosophy KISS If I am talking to my wife it is keep it simple sweetie. You are thinking too difficult.