Can this motor be saved?

[zogthegreat]

Thanks mckutzy!

 

[zogthegreat]

So I'm finally finished with painting and assembly:

It looks good, but it seems to be lacking a certian Je ne sais pas quoi.

Ahh! Much better!

 

[Nosandwich]

So this answer to the title to this tread is YES???

 

[zogthegreat]

Hmm, I'm having a strange problem. I put on a new carburetor and tried to start the motor and the carb started leaking gas out the throat. I figured that there was a problem with the float or the needle, so I swapped out the carb for an old one that I know is good and I had the same problem. I took both of them apart and they look OK. Any suggestions on how I'm messing this up?

 

[mckutzy]

Gaskets are potentially broken....

To clarify... Next to the filter or the motor side?...

 

[zogthegreat]

Gaskets are potentially broken....

All of the gaskets are new, however I did reuse the spacers on both sides.

I'm seeing the dripping mainly from the motor side, but when I remove the air filter mount, I see a large amount of gas/flooding in the carb throat on the air filter side also:

I think that I have the gaskets installed in the right manner, I'll recheck tomorrow morning.

 

[zogthegreat]

OK, I'm going insane here!

I borrowed a carburetor from one of the groundskeepers lawnmowers and I have the same problem!

I know that I'm missing something basic here but I can't figureout what. Here is how I have the gaskets setup:

There is a gasket on the cylinder head, it's gray, so it's hard to see. I checked a diagram from partstree.com and the only thing that I see that's different is the gasket that goes between the carb and the spacer for the air filter:

 

[supermanotorious]

you shouldn't have fuel just pouring out cause the flanges aren't sealing, have you checked the carb bowl? made sure the float needle is seating properly?

 

[Nosandwich]

Yeah, needle/seat....or bad float.

Now, back to football....

 

[zogthegreat]

It's alive! My creature, it's ALIVE!!! Bwahahaha!!!

Well after trying 4 different carbs and getting the same results, I decided to try something different. The head that I was using was the one that I had ported and polished. I pulled that head and swapped it for a non-ported and polished and the motor started with the second pull.

Now, of course, comes the question "why". If anything, I should have needed more fuel coming into a ported head. Does anyone know what the problem here is? I really would like to use the ported head for my summer project with my daughter.

But at least I know that I don't have 4 bad carburetors!

IT'S ALIVE!

[url]https://youtu.be/1qNeGSJaQ9Q?t=138[/URL]

 

[Whitetrashrocker]

Did you check to see if you damaged the valve seat when you were doing the P&P?
Did you lap the valves?
Did you take any material off the head to raise compression?

 

[zogthegreat]

I did lap the valves, I'm of the school that if you have a head off, lap the bleeping valves. I also used Prussian Blue. Essentially I did it like I would a car head.

As for the head surface, it looks fine to me, but I will go get a piece of glass to be sure.

I didn't remove any material from the head surface. The head that I swapped was actually from a Honda GX160, so I think that it's slightly smaller than the stock clone head.

I'm going to dig out the other 6.5 clone head that I have and test with that today.

 

[Whitetrashrocker]

Sounds like you know what your doing. What about valve train? Is the lash set right?

 

[KartFab]

Just a few personal thoughts on porting:

if you hogged out the port runners, you killed port velocity, inadequate port velocity doesn't give a strong vacuum signal at the carb, resulting in a lean condition, and poor mixing of air/fuel. If you buy an extra idle pilot jet, you can drill it out and see if it makes any difference.

If you nicked a seat, you lost compression, so it wont run.

If you set valve lash at the wrong spot, you could get non-start.

Head gasket could not be working/blown.

Just thoughts, maybe none of them are correct, or the actual problem.

 

[zogthegreat]

Sounds like you know what your doing. What about valve train? Is the lash set right?

LOL, thanks, but if I knew what I was doing, I wouldn't have to ask for so much help!

I set the intake for 0.004 and the exhaust to 0.006. With the Honda 5hp head, motor runs fie with those settings.

Just a few personal thoughts on porting:

if you hogged out the port runners, you killed port velocity, inadequate port velocity doesn't give a strong vacuum signal at the carb, resulting in a lean condition, and poor mixing of air/fuel. If you buy an extra idle pilot jet, you can drill it out and see if it makes any difference.

If you nicked a seat, you lost compression, so it wont run.

If you set valve lash at the wrong spot, you could get non-start.

Head gasket could not be working/blown.

Just thoughts, maybe none of them are correct, or the actual problem.

I don't see any nicks around the valve seats, when I used the Prussian Blue, they looked fine. I thought that I went fairly conservative on the porting, (compared to what I have seen):

I left the valve stems alone, I mainly worked on getting the roughness off, making sure to leave some roughness for the intake.

I agree that I should be running lean with the port and polish, that's why I'm confused about the flooding. I used the same head gasket for the Honda head, so I can eliminate that.

 

[Whitetrashrocker]

Ok Zog. Riddle me this.

You had a leaky carb, you swapped on a new carb, it leaked also. You even borrowed a working carb and it leaked now too?

Then you swap heads and now it runs?

What happened to leaky carbs?

 

[zogthegreat]

I tried all of them with the new head and they ran fine, (I actually tried 4 different carbs).

This is why I'm confused, (well, one of the reasons! ), if one or two carburetors had flooded, OK, I have a bad float or something. But swapping the heads removed the flooding on the carburetors. That just doesn't make any sense to me.

 

[Whitetrashrocker]

Yup. It's the Gremlins!
No other way to explain how a head change can effect a carburetor float.