[Bilgemaster]

You need to check a few things first , check tappet clearance as the sea foam may have cleaned some crud of your valves therefore making them a bit tight now, and check points gap and spark timing are all good things to eliminate and know where your at anyway, possibly have a look in the carb something maybe floating around now from the sea foam cleaning it off

I believe "Mr_84" may have noted the likeliest culprits to check: pushrod clearances or fuel system or carb blockage. Though I'd likely leave any fussing with the points or timing for later, so as not to needlessly complicate diagnosis.

Like him, my hunch is also that the SeaFoam has either eased off some crud from the valve face or seat or perhaps added a dislodged chunk there from the combustion chamber, most likely to the exhaust valve, affecting compression, or had dislodged some fuel system crudlet that's now somehow clogging the carb.

If it were my Iron Barrel, I'd do the following in this order:

• Check pushrod clearances, adjusting if needed. Leave access cover open for now.
• Remove carb float bowl, check fuel line from tank petcock for clear running, clean carb bowl, float needle and its seat with spray carb cleaner (wear safety glasses!), also blasting cleaner up into jets from below, then button the carb back up
• Remove spark plug and pour a couple of ounces of SeaFoam into hole, replace plug and kick it a few times (ignition and fuel off) with the decompressor engaged to coat whole combustion chamber, and allow to marinate, perhaps overnight
• Check valve pushrod clearances again and replace cover--being sure not to overtighten
• Try starting again. It may smoke like hell, and you may need to pull the spark plug to clean fouling.
• Once started, run at fast idle for several minutes
• Allow to cool and check pushrod clearances again, adjusting if necessary

That might cure it, but if it's a valve grundging or "carboning up" issue, you might want to triple down on the SeaFoam in your fuel to help ease out any remaining cruds. If that is the case, a bit of vigilance to the valve pushrod clearances over the forthcoming weeks would be wise. Occasional compression checks might also be advisable.

Frankly, a lazy man's "SeaFoam Decoke" might be in order to help clear out more of any carbon buildup you may have. I described my own successful SeaFoam "Bodger's Decoke", along with its "steam cleaning" here:
https://forum.classicmotorworks.com/index.php?topic=27655.msg353669#msg353669

Good luck, and let us know how it goes!

[Sunbeam63]

I'm very pleased with all the responses. I'm getting a consensus on here that it is likely related to fuel, which makes me feel better, because I was worried it was mechanical.

Nonetheless, I'll need to take the proper steps to remove culprits. I like the plan Bilgemaster laid out, so I'll start with that. Hopefully by the end of this weekend I'll have an update to see who had an accurate guess!

Also, Seafoam was shown to me by an old boy (a fabulous mechanic by the way), who swore by it.

Regards,

Solomon

[axman88]

I've seen it written that Seafoam is mainly napthalene (~75%) mixed with isopropyl alcohol (~25%). 

The MSDS seems to agree, more or less, although it's hard to say exactly what the hydrocarbon cocktail is, without more advanced research than I'm willing to do.  https://seafoamworks.com/uploads/2019/01/Sea-Foam-Motor-Treatment-SDS-v20161205-ENG.pdf

So, it IS fuel, of a sort.  I'm sure anybody's 1892 naptha launch would be very happy burning a steady diet of the stuff. https://en.wikipedia.org/wiki/Naphtha_launch

I think Seafoam does seem to do some good, in fuel systems, as lazy man's carb cleaner, a couple ounces every few fill-ups, or the smokescreen de-carbon treatment.  I use the plain liquid stuff.  If it needs to be sprayed, I put some into a trigger spray oil can and have at it.

If one got started using mass quantities, I suppose they could mix it themselves and save big bucks over the fancy, aluminum bottled, brand name stuff.
https://www.acehardware.com/departments/outdoor-living/sporting-goods/camping-goods/82079
https://www.walmart.com/ip/UltraCruz-Isopropyl-Alcohol-99-1-Gallon/403367851

I'd be hesitant to use 70% isopropyl, which is much cheaper, because the 30% is probably water.

This guy uses diesel fuel in his mix:  http://hildstrom.com/projects/seafoam/


 

[Seipgam]

If all was good before using the Seafoam stuff then most likely caused by that.  As others have said it's probably moved some crap down stream into the jets.
I would pull the carby off and give it a good clean, making sure all the jets and fuel passages are clear.

Geoff.

[allanfox]

Seafoam is an engine cleaner.  You can Google it.  I hadn't heard of it until recently.  From what I've read on Seafoam's website, it doesn't contain any chemicals or abrasives that would harm an engine.  I'm not likely to use it, though.

Me and you both!!

[ddavidv]

Ford's Motorcraft line of chemicals has a very similar product that is less expensive than Seafoam. I used it while trying to fix a pinging issue on my truck. I think it was the PM-5 injector cleaner but don't hold me to that.

My $20 Amazon borescope attached to my laptop clearly showed the internals of my engine. May be worth having one of those before pouring chemicals into your engine, unlike myself who bought it afterwards.

[cyrusb]

I've seen it written that Seafoam is mainly napthalene (~75%) mixed with isopropyl alcohol (~25%). 

The MSDS seems to agree, more or less, although it's hard to say exactly what the hydrocarbon cocktail is, without more advanced research than I'm willing to do.  https://seafoamworks.com/uploads/2019/01/Sea-Foam-Motor-Treatment-SDS-v20161205-ENG.pdf

So, it IS fuel, of a sort.  I'm sure anybody's 1892 naptha launch would be very happy burning a steady diet of the stuff. https://en.wikipedia.org/wiki/Naphtha_launch

I think Seafoam does seem to do some good, in fuel systems, as lazy man's carb cleaner, a couple ounces every few fill-ups, or the smokescreen de-carbon treatment.  I use the plain liquid stuff.  If it needs to be sprayed, I put some into a trigger spray oil can and have at it.

If one got started using mass quantities, I suppose they could mix it themselves and save big bucks over the fancy, aluminum bottled, brand name stuff.
https://www.acehardware.com/departments/outdoor-living/sporting-goods/camping-goods/82079
https://www.walmart.com/ip/UltraCruz-Isopropyl-Alcohol-99-1-Gallon/403367851

I'd be hesitant to use 70% isopropyl, which is much cheaper, because the 30% is probably water.

This guy uses diesel fuel in his mix:  http://hildstrom.com/projects/seafoam/

Can you light it with a match?

[Bilgemaster]

I'm very pleased with all the responses. I'm getting a consensus on here that it is likely related to fuel, which makes me feel better, because I was worried it was mechanical.

Nonetheless, I'll need to take the proper steps to remove culprits. I like the plan Bilgemaster laid out, so I'll start with that. Hopefully by the end of this weekend I'll have an update to see who had an accurate guess!

Also, Seafoam was shown to me by an old boy (a fabulous mechanic by the way), who swore by it.

Regards,

Solomon

Glad I could help... hopefully. If it does turn out that those possibly SeaFoam-loosened cruds from the fuel tank gunking up the carb seem to be the culprit instead of carbon sloughing off in the combustion chamber causing valve issues, which may be fairly apparent if there's even the least bit of crapulosis seen when you peer into that float bowl, then you might consider reducing or impeding those crudlets in several ways.

One thing I've been meaning to do with my own '05, but have just never got around to, is to mount an inline fuel filter, as has been recommended in many past threads. The perennial advice found in them seems to favor filters of 10 microns filtration or better, though my hunch is that most ANY added filter would be preferable to none. Hitchcocks does offer a couple of options with unspecified filtrations, a fancy chrome one with a cleanseable reusable filter and a single-use one, both shown here: https://accessories.hitchcocksmotorcycles.com/Amal-Carburettors/Petrol-Pipe-Fittings?ext=F&search=Fuel+filter+inline. Obviously, other inline filter options abound online or at your local parts joints or Wallyworld. Some choices specify their filtration specs (i.e., 10 or 40 or 100 microns seem common--the smaller the number the better the filtration), but most don't. Perhaps someone else here can recommend a specific "good one" for our carburetted "Iron Bellies" with a link for online purchase.

It turns out you probably already have  an inline fuel filter incorporated at the base of your fuel petcock that you can rinse out. Mine's shown in place on the tank and then disassembled after cleaning in the attached photos. With the fuel tap set to "Off", you just unscrew its base with a 13mm wrench/spanner, taking care to set aside its rubbery round sealing gasket, go to town with some spray carb cleaner and maybe a little screwdriver or brush for any stubborn chunklets, and just button it all back up and test for leakage.

One trick used by me and many of my fellow amphibian Amphicar motorists in addition to inline fuel filters is to slap a big magnet or two onto the bottoms of our steel fuel tanks, which are also obviously quite prone to rusting given our bizarre predilection for aquatic motoring. These magnets will attract and hold those iron oxides quite firmly in the fuel tank, keeping them from finding their way into the fuel lines until such time as the tanks can be cleaned out or resealed from time to time. I use big old fashioned black ones for the Amphicar, but a handful of these rare earth 5/16" diameter type (https://www.harborfreight.com/10-piece-rare-earth-magnets-67488.html) popped strategically around the bottom of your fuel tank would probably work nicely and be inobtrusive. I also pop those little ones, sometimes a couple, onto the outer heads of all my various vehicles' oil drain bolts, including the Bullet's, to magnetize them throughout and thereby catch and trap the odd ferrous bits floating by within until the next oil change.

Obviously, if your tank is really crusty within, unlike mine, especially if you use fuel with added water-attracting ethanol, which I don't, then cleaning out and possibly sealing that fuel tank might be a sensible long-term solution, and there is much guidance to be found on this in this Forum's archives--everything from raiding the pantry for white vinegar rinses to multi-part wonder potion stripping and sealing kits.

In terms of avoiding fuel tank rusting in the first place, it is always advisable to keep the tank fairly full. This reduces the amount of air within with its water vapor that can condense, drift to the bottom and commence wreaking havoc. This is greatly exacerbated if ethanol-containing fuel is used, since that ethanol eagerly binds up with that water into a nice cloggy caustic snot. In really advanced long-term cases, such as I discovered in the carb of a little used fixer-upper outboard I'd bought, that snot will eventually fossilize into something resembling British Demerara sugar or that "Sugar in the Raw" stuff they have at Starbucks.

[Sunbeam63]

I managed to pull off the carburetor and clean it with carb cleaner. I also adjusted the pushrods. The intake needed to be shortened just slightly and the exhaust needed lengthened just slightly. Let some seafoam sit in the cylinder over night. Took the bike out this morning to get it warm and ran fine as usual. Brought it back home and let it run in the driveway, and same noise/symptoms. The only additional thing to add this time, is that now it manages to make that noise even at idle, without any throttle.

To answer some other questions; after I added the seafoam, while I didn't drain the tank, I did add more to the tank to dilute any leftover seafoam. I also have always had a fuel filter on the bike. I recently replaced the inline filter when I worked on the bike last winter. That project was for removing the starter, changing the drive sprocket, and doing cosmetic changes to 'backdate' the bike to the '50s. While I had the tank off, I actually cleaned it out at that point. That project had nothing to do with timing and no changes to the carb. It ran good for the last 8 months until just now.

axman88 correctly noticed that it backfired back into the airbox when it died (something that it's done since I've owned the bike). He asked if it helped to run the bike with the choke on or enrichment. It does not run better with the choke on, but it does run better with enrichment.

Since the bike was warm, I put on a compression tester, and I managed to kick out 90psi. My original thought (fear) was that my valve timing was off somehow and a valve is bouncing off the head, but if that's the case, compression would be lower, right? If it's still fuel related, the issue has to be within the carburetor still.

Loved hearing the trick with magnets on the Amphicar. Keep the thoughts/ideas coming. I appreciate the mentoring.

[Paul W]

90 psi is a low reading. I still think you have a valve gear problem.

The intermittent nature of the noise makes me suspect that this might be a loose valve seat or a sticking valve or rocker.

[cyrusb]

90 psi is a low reading. I still think you have a valve gear problem.

The intermittent nature of the noise makes me suspect that this might be a loose valve seat or a sticking valve or rocker.

Isnt 90psi the 6 to 1 compression ratio of a stock bullet? Throttle wide open?
Edit ;actually 6.5 : 1.  Strangely, 350's have an 8.5:1 ratio.                                 

[Paul W]

Yes, my 350 gives a compression pressure of 130 psi. I don’t think I’ve ever had any vehicle giving a reading as low as 90 though.

If 90 is standard for a later 500, then fair enough but I don’t think a fuel problem can result in a clattering noise like this one seems to have.

[cyrusb]

The pressure is simply calculated by multiplying atmospheric pressure by the selected ratio.
 So 14.7 psi at sea level times 6.5 Enfield Spec for Iron Barrels = 95.5 Hence I call it "The Oil Lamp"
 As far as the video goes, all I hear is a backfiring bullet, even coughing out the carb.May be a lean condition For some reason the microphones of cameras always pick up the high frequency clatter of the valve train . A video of my 500 would and has sounded the same. Eh, who knows?

[Sunbeam63]

So looking at my shop manual, it does call out 6.5:1 compression ratio, or 110+/-5psi (recommended).

With that said, I kicked the bike (cold) like a man this time, and I got 120psi.

[Mr_84]

As cyrusb says very hard to hear on the video , coughing and backing is time to eliminate the ignition system check points gap and spark timing , or maybe you could describe the noise other than what everyone is hearing on the video . If everything spark wise checks out I guess you will going down the road of somewhat Paul W is talking about next