Couple of questions about my carb

[scrisp]

I'm almost finished rebuilding my carbs and just had a couple of final questions.

1. What type of paint do you use on carbs? Is the special marine paint or would i just use regular paint from the hardware store?

2. I've attached a picture of a nut that got lost somewhere along the way. It was off when I removed the carbs and I could not find it in the hull. Anybody know of hand what size and thread that would be? I looked through my shop manual and didn't see it listed or even shown anywhere.

 

[mikidymac]

Why was the throttle shaft nut removed? There is no reason to remove it. It is going to be a little difficult to replace as it is a thin nut, stainless and metric. There should also be a lock washer.

Make sure you follow the Carb Rebuild Thread exactly.

The paint never sticks very well due to years of oil and grease but if you really want to try gloss black Appliance Epoxy from Home Depot/Lowes.

 

[scrisp]

Why was the throttle shaft nut removed? There is no reason to remove it. It is going to be a little difficult to replace as it is a thin nut, stainless and metric. There should also be a lock washer.

Make sure you follow the Carb Rebuild Thread exactly.

The paint never sticks very well due to years of oil and grease but if you really want to try gloss black Appliance Epoxy from Home Depot/Lowes.

I don't know what happened with the nut, it was off when I removed the carbs from the hull. The bellcrank was kinda flopping around on there.
No wonder the throttle response was not as good as my XP.

I was able to find the exact nut in stainless and the correct thread. It is an 8mm 1.0 fine thread. I found it at Menards believe it or not.

I'll see if I can find sine paint the next time that I'm at Menards or Lowes. Thanks!!

 

[mikidymac]

You will need a stainless lock washer also. If you don't have enough threads use some blue loctite.

 

[scrisp]

You will need a stainless lock washer also. If you don't have enough threads use some blue loctite.

That what I ended up doing, the locktite.

I read through your carb rebuild thread and did the popoff. It was kinda low, 23psi, but was within the okay range for an SPX, so I went with that. They were both the exact same pressure using the original springs and arm. I tried the springs from the Mikuni kit and one was a bit lower, and the other ended up making it pop at 45psi or so, which was way outside the range on the other website, so I swapped it back to the original springs. I did the pressure test and they both passed with flying colors.

Thank you for all the help!!

 

[burtshaver2021]

That what I ended up doing, the locktite.

I read through your carb rebuild thread and did the popoff. It was kinda low, 23psi, but was within the okay range for an SPX, so I went with that. They were both the exact same pressure using the original springs and arm. I tried the springs from the Mikuni kit and one was a bit lower, and the other ended up making it pop at 45psi or so, which was way outside the range on the other website, so I swapped it back to the original springs. I did the pressure test and they both passed with flying colors.

Thank you for all the help!!

Kits from Amazon?

 

[mikidymac]

You were correct. DO NOT use the springs in the Mikuni kits.

 

[scrisp]

Kits from Amazon?

Yes, from Bay Area Motorsports (or possibly Powersports) on Amazon. They were the genuine Mikuni kits. The only problem that I had was that the little rubber grommets were hard and I tore 2 of them trying to get the little clear discs in place in the fuel block. It was as if they had been sitting a long time in the shelf and hardened up. I ordered 2 replacements from Partzilla and they were very squishy like rubber should be. They popped right in with no issues.

 

[burtshaver2021]

Yes, from Bay Area Motorsports (or possibly Powersports) on Amazon. They were the genuine Mikuni kits. The only problem that I had was that the little rubber grommets were hard and I tore 2 of them trying to get the little clear discs in place in the fuel block. It was as if they had been sitting a long time in the shelf and hardened up. I ordered 2 replacements from Partzilla and they were very squishy like rubber should be. They popped right in with no issues.

I think all the kits come with the wrong springs except from OSD marine, pretty sure they put the kits together themselves so they have the right springs in the kits. I know that Bay Area Powersports does sell aftermarket carb rebuild kits as well, always have to be careful as the marketing can be deceiving when it comes to them be genuine Mikuni,

 

[burtshaver2021]

I was just looking on Bay Area Powersports website for a carb rebuild kit for 787, all I could find was Vertex/Winderosa. Hopefully I just couldn’t find the genuine Mikuni kit and you didn’t get Vertex.

 

[scrisp]

I was just looking on Bay Area Powersports website for a carb rebuild kit for 787, all I could find was Vertex/Winderosa. Hopefully I just couldn’t find the genuine Mikuni kit and you didn’t get Vertex.

These are what I received...

 

[burtshaver2021]

These are what I received...

That looks like the good stuff,

 

[mikidymac]

Those are genuine mikuni. Just make sure not to use the new springs in the kits.