Author Topic: Float bowl plug (Read 2071 times)

Mossy · « **on:** January 23, 2023, 10:18:13 AM »

Hello everyone,

I'm new to this forum so thank you for your indulgence if you've been asked this a million times.

I have a 73 Honda CB350F that was given to me. It's been sitting for 30 years and now I'm going to restore it. The first thing I noticed was the completely rounded off oil filter bolt.
I welded a nut to it and spun it right out.

Next, I removed the carbs to clean and rebuild and found sheet metal screws in some of the float bowls' threaded holes. I've ordered a heli-coil kit so I can repair them.

Now I found that at some point, a gorilla snapped off one of the float bowls' plugs. I made a jig to attach the bowl to and set it up in my Bridgeport. I ran an endmill down through the center of the broken plug stub. I'll try an EZ out lightly but not enough to snap that off in there. Sorry for the long-winded backstory. My question is can you please tell me what the thread is on those bowl plugs? I'll heli-coil that as well if I damage the threads at all.

Thank you

bryanj · « **Reply #1 on:** January 23, 2023, 11:52:20 AM »

Probably easier to fit another used bowl, all i can sugest as to thread is remove another drain plug and check that.

Mossy · « **Reply #2 on:** January 23, 2023, 12:06:28 PM »

Thank you, Bryan. I may try to source a used bowl.

robvangulik · « **Reply #3 on:** January 23, 2023, 01:35:35 PM »

Those plugs are 6 mm. with a fine 0.75mm. thread.

BenelliSEI · « **Reply #4 on:** January 23, 2023, 04:15:36 PM »

I have to admit to having trashed a few! Tried heat, soaking, drilling, reverse drills, easy outs, you name it! I have two or three sitting around if you are successful. Please share your results.....

Mossy · « **Reply #5 on:** January 24, 2023, 04:30:33 AM »

Thanks, guys. I'll post the results as I can't seem to find a replacement readily available.

Mossy · « **Reply #6 on:** February 05, 2023, 11:43:13 AM »

Hi Gents,
If anyone is still interested, I just finished the broken float bowl drain screw repair.
It took some time but it worked out in the end. I initially thought I could simply Heli-coil it and be done. After installing the thread insert, there wasn't much of a counterbore left for the o-ring to seat on for a good seal.
I scrapped that idea and bored that thread out of there. I then made a plug for a .004 interference fit. Then it was time to wait for a 5.25mm drill bit and 6x0.75 tap. The repair appears to be good now.

MauiK3 · « **Reply #7 on:** February 05, 2023, 01:02:28 PM »

Impressive work!
Welcome aboard, keep the posts coming. There is a lot of help available here.
We love photos.

robvangulik · « **Reply #8 on:** February 05, 2023, 01:25:11 PM »

Well done, looks impressive. Steel plug?

Mossy · « **Reply #9 on:** February 05, 2023, 03:11:42 PM »

Thank you.
I used aluminum as I felt it was safer to match the parent metal rather than risk galvanic corrosion down the road.
I do have some Ti6Al-4v Titanium that would be safe to use but it can be tough to tap and I have 1 M6x.75 tap.

BenelliSEI · « **Reply #10 on:** February 05, 2023, 03:19:51 PM »

Well done! I have two or three more if you want a “set”. Happy to send them along if you want them!

Mossy · « **Reply #11 on:** February 05, 2023, 03:57:12 PM »

Thank you, Benelli, that's very generous. I'd certainly attempt to repair them. Do you need any for a project?

70CB750 · « **Reply #12 on:** February 05, 2023, 05:25:32 PM »

How did you press the plug in?

Mossy · « **Reply #13 on:** February 05, 2023, 05:33:44 PM »

Heated the bowl and froze the plug. I was able to tap it in before it cooled enough to seize.

70CB750 · « **Reply #14 on:** February 06, 2023, 02:42:23 AM »

Great job, sir.

Mossy · « **Reply #15 on:** February 06, 2023, 03:36:12 AM »

Thank you. I was hoping that would work. If not, I figured I'd have to make a fixture so I could actually press it.

newday777 · « **Reply #16 on:** February 06, 2023, 03:59:45 AM »

Quote from: Mossy on February 05, 2023, 11:43:13 AM

Hi Gents,
If anyone is still interested, I just finished the broken float bowl drain screw repair.
It took some time but it worked out in the end. I initially thought I could simply Heli-coil it and be done. After installing the thread insert, there wasn't much of a counterbore left for the o-ring to seat on for a good seal.
I scrapped that idea and bored that thread out of there. I then made a plug for a .004 interference fit. Then it was time to wait for a 5.25mm drill bit and 6x0.75 tap. The repair appears to be good now.

2 thumbs up for you!

BenelliSEI · « **Reply #17 on:** February 06, 2023, 05:35:51 AM »

Quote from: Mossy on February 05, 2023, 03:57:12 PM

Thank you, Benelli, that's very generous. I'd certainly attempt to repair them. Do you need any for a project?

I’m pretty sure I’ve got a few that I snapped the screw head off. I’ll look today and see what I have.

MauiK3 · « **Reply #18 on:** February 06, 2023, 06:56:25 AM »

Would you be willing to tell us a bit about your machinist background? Not many work with titanium. As you know, it can be difficult to work with.

Mossy · « **Reply #19 on:** February 06, 2023, 08:03:14 AM »

Thanks, Benelli.
I worked in Aerospace parts for 20 years but mostly machined Inconel (which can be a chore as well.)

Later I moved to medical device.
For implants, most are made of Ti, Co-Cr, 316L and PEEK. Most of the PEEK implants had to have radiographic marker pins so they could be seen in xrays/fluoroscopy. Those pins were made of Tantalum. I didn't do anything with that though. It's very soft.

Instruments were made largely of 17-4 and 416 SS. In medical I was on the quality side but have a home shop. We were free to take the remnants home so I did a lot of machining (and learning) on Ti and SS.

BenelliSEI · « **Reply #20 on:** February 06, 2023, 09:30:51 AM »

I do have a complete set, that came with a large pile of parts. They are two “rights” and two “lefts”. One is butchered, two are snapped off and I guess the last one was “I give up”!

I don’t need them, if you do, yours for postage. John D.

Mossy · « **Reply #21 on:** February 06, 2023, 10:51:24 AM »

Sent you a PM Benelli.

On another topic, could you guys please tell me where I can buy a replacement for the gasket that goes between the tank and petcock? My Google-fu doesn't seem to be strong enough to find one. Thank you.

MauiK3 · « **Reply #22 on:** February 06, 2023, 02:02:30 PM »

I just took a look at Yamiya, the 350 and 400 have different cocks and the gaskets are not the same. They are out of 350 stuff. Dang

MauiK3 · « **Reply #23 on:** February 06, 2023, 02:05:28 PM »

Interesting stuff working with the exotics.
When I was working on nuclear submarines we dealt with a lot of cool stuff like inconel, titanium, high tensile steel etc. One of the most interesting to me was nickel-copper-aluminum also known as K-Monel. Great stuff.

Mossy · « **Reply #24 on:** February 06, 2023, 02:43:50 PM »

Thanks for looking Maui. I may have to try cutting one out of some type of rubber gasket material.

I've never worked with K-Monel. Sounds interesting. We also used Hastelloy and Waspaloy. Waspaloy was used for turbine engine blades. I didn't do anything with it but the guys that did said it was some tough stuff. I believe it has a very high nickel content.

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Author Topic: Float bowl plug (Read 2071 times)