Gas Tank Cleaning?
Printed From: Unofficial Allis
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Forum Name: Shops, Barns, Varmints, and Trucks
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=148936
Printed Date: 29 May 2025 at 12:37am
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Topic: Gas Tank Cleaning?
Posted By: CrestonM
Subject: Gas Tank Cleaning?
Date Posted: 29 Mar 2018 at 5:59pm
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Hi guys! I'm working on tuning up an excellent surviving original 1966 Honda 305 "Dream" motorcycle. It hadn't ran in over 20 years, but after cleaning the carburetor and hooking up an auxiliary fuel tank, I got it running (kinda). The bottom of the fuel tank has varnish in it (There was about a quart or two of gas in it was all), and I've heard a lot of different methods to get it out/dissolve it. Some say pour in lacquer thinner and let it sit. Some say acetone, muriatic acid, apple cider vinegar, or even water and Oxi-Clean. Every review I've seen said they are all easy methods, but does anyone here know for sure? I know putting some rocks or bolts in the tank and shaking it helps quite a bit, but if I can keep from doing that, I'd like to, because of the difficulty I've had in the past with getting everything back out, especially with baffles.
I'm a little hesitant about any major chemicals, as the paint and chrome on the tank are superb, and I don't want to mess it up. I said earlier it's "kinda running"...It will start right up with the kick starter when some throttle is applied, but when I let go of the throttle it dies. Runs great as long as I hold the throttle a little bit, but when the RPMs get a little low, it quits. I need to do some more investigating and see if it's sucking air somewhere it shouldn't. I may get the propane bottle out to test that. (release the gas around different points on the carb and see if engine sound/RPM changes to verify leaks) This is the first time I've ever done any involved work on a motorcycle, so it's all kinda new to me. Although most of it seems like "regular" engine stuff, just smaller than what I'm used to. Thanks! |
Replies:
Posted By: DiyDave
Date Posted: 29 Mar 2018 at 6:04pm
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Drop a couple feet of light duty steel chain in it, and rig it up in a paint shaker... You can always fish the chain out, wif a strong magnet.
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Posted By: Dakota Dave
Date Posted: 29 Mar 2018 at 6:11pm
| I use a piece of dog chain and diesel fuel. Rinse with soap and hot water. And blow dry with the shop vac. |
Posted By: Thad in AR.
Date Posted: 29 Mar 2018 at 6:32pm
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Chain and roofing nails. Strap it to a concrete mixer and let it run. I’ve had good luck with mutator acid but I’d be hesitant to try it while wanting to save original paint. Mc carbs and manifolds can be a pain to seal up. Inspect the intake very close. Dreams were very cool bikes. Good save👍 |
Posted By: CrestonM
Date Posted: 29 Mar 2018 at 6:38pm
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Thanks, Thad! Dad got the bike at a garage sale back in the 70s or 80s I believe, but it's stayed tucked away most of its life. I had never seen it run in all of my 20 years, so I'm excited to get it road worthy again, even if it's not quite a Harley I was surprised to see it has 20,000 miles on it. Seems pretty high, but the bike looks nearly new.
I don't have a concrete mixer, but I have heard of guys using tractor wheels. Jack up one side, strap the tank on, and let it go for a while. I think the G would be a good candidate for that. I made an attachment a few years ago for using it to roll up long lengths of garden hose, and it worked quite well. Do you think a tiny bit of sealer on the O-ring that seals the carb to the engine would help if it's leaking there? |
Posted By: johnkc
Date Posted: 29 Mar 2018 at 7:08pm
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If you’re going after varnish only, not rust inside the tank. don’t use the chain or nuts and bolts or anything just use a degreaser, citrus-based to start with. I use a chemical called Powertune by Mercury/ Quicksilver that is very good at cutting varnish. Get it at a Mercury outboard dealer. ------------- I support the development of hybrid automobiles and alternative fuels as I need DIESEL fuel for my ALLIS CHALMERS! |
Posted By: steve(ill)
Date Posted: 29 Mar 2018 at 7:15pm
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a little sealer on the o-ring cant hurt... new O-rings are even better !! The old carbs have a throttle slide ( like a piston) in the bore that the cable pulls up... there should be a screw on the side half way down.. Turn it in a turn or two and it lifts the piston up and increases idle speed... do this AFTER checking for leaks.. You can always lower it back down later if things seal up and the idle gets too high. ------------- Like them all, but love the "B"s. |
Posted By: JW in MO
Date Posted: 29 Mar 2018 at 7:34pm
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The chain, ball bearings, rocks etc... idea is good for old tractor gas tanks but you don't want to use that on a 305 Dream gas tank. They are square with lots of corners and you could easily damage it, they are waaaay too collectable for that. I would not use muriatic acid either but I would not be afraid of acetone or lacquer thinner. Neat looking old bikes, should be a lot of fun, enjoy. ------------- Maximum use of available resources! |
Posted By: Thad in AR.
Date Posted: 29 Mar 2018 at 7:38pm
Don’t be runnin 60 all over on dry old tires when you get it going. I keep us posted |
CrestonM wrote:Posted By: CrestonM
Date Posted: 29 Mar 2018 at 7:51pm
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Ok, thanks. I guess a parts store would probably have the gas-resistant O-ring? One thing I noticed about this O-ring was I got a little carb cleaner on it, and it immediately twisted up. It took me a while to finally get it where it would press flat in the groove for re-assembly (Didn't have another O-ring at the time and just wanted to see if it'd run).
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Posted By: CrestonM
Date Posted: 29 Mar 2018 at 7:55pm
Just swish it around in the tank, and maybe scrape the bottom with a stick? Will it hurt the paint if any gets on the it? If it does, I'll be sure to immediately wipe it off, but I imagine I can keep it clean. Also....would the acetone/lacquer thinner eat up the rubber fuel line connecting both sides of the tank? (It's a new line...the old one was rotten) If so, what would you recommend I plug the holes with? I'll try to get a pic this weekend for y'all to see. Hopefully I'll get it ready for a little test drive around the block.
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Posted By: im4racin
Date Posted: 29 Mar 2018 at 9:05pm
| I would say that if it won't idle then the idle circuit in the carb is plugged. Have you had the carb apart and cleaned? After that many years of sitting the same varnish in the tank is in the carb passages too. Is this 2 stroke or 4 stroke. If it's 2 then cleaning the carb is not up for discussion. It's mandatory. As for cleaning the tank I just use hot water pressure washer. The time required to clean depends directly to the amount of varnish and water temp. Ours gets nearly to boiling. I had to wear insulated gloves to tip the tank over to drain out! |
Posted By: CrestonM
Date Posted: 29 Mar 2018 at 9:41pm
| Before it was parked the engine was ran with the fuel petcock off and allowed the gas to run out of the carburetor, so it was relatively clean already, but yes I did clean it. It is a 4 stroke engine. |
Posted By: shameless dude
Date Posted: 29 Mar 2018 at 10:53pm
| you gonna put a mud tire on it? |
Posted By: weiner
Date Posted: 30 Mar 2018 at 5:06am
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My word! My first bike was the little brother, 150 Dream. You meet the nicest people on a Honda. ------------- Real heros wear dogtags, not capes. |
Posted By: PaulB
Date Posted: 30 Mar 2018 at 5:34am
Creston: Harleys are nothing but “hound dogs” I see the pansy owners of them letting them ride in the back of pick ups all the time  If they were truely a motorcyclist, they’d be in the saddle  ------------- If it was fun to pull in LOW gear, I could have a John Deere. Real pullers don't have speed limits. If you can't make it GO... make it SHINY |
Posted By: Stan IL&TN
Date Posted: 30 Mar 2018 at 7:40am
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Another option would be to just add an inline fuel filter and just add gas to the tank. In theory over time it should dissolve the old stuff and if any flakes off you will have the filter to catch it before it gets to the carb. I have restored a couple of 70's Hondas and cleaned and sealed the tanks but didn't have to worry about keeping the paint intact. You will be running some risk using any chemical unless you are very careful. ------------- 1957 WD45 dad's first AC 1968 one-seventy 1956 F40 Ferguson |
Posted By: CrestonM
Date Posted: 30 Mar 2018 at 8:09am
Thanks Stan. I need to do a little cleaning at least, as the fuel peacock is full of junk I believe. It was very hard to open/close, and when I got it open, nothing would come out. I’m going to try and remove it, but I just hope it’s not stuck on too bad. Don’t want to break something getting it off. Fuel filter idea is good, as it doesn’t have one right now, although I’ve been told the fuel stem in the tank has one built in? |
Posted By: CrestonM
Date Posted: 30 Mar 2018 at 8:10am
Nice to know! Dad almost bought a 150 back when he was 18, but didn’t go through with it. A little later he got this one. |
Posted By: TDF
Date Posted: 30 Mar 2018 at 8:15am
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Between me, my two brothers, and my Dad, we currently own 125 motorcycles, and have had numerous others in the past. And one heck of a lot of them had varnished up and rusty tanks. Have tried all most all the methods previously mentioned, but the one we prefer is to take the tank down to the local carwash, and use the powerwasher and spray out the inside. You have to keep working the tank around to different angles, and letting water out of the tank, but that blast of water will rip the rust and varnish right off. Wear old clothes and pick a warm day because you're going to get wet. TDF |
Posted By: Stan IL&TN
Date Posted: 30 Mar 2018 at 8:19am
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If the fuel petcock has a small bowl on it then it should have a small round screen mounted in it. On the 70's Hondas anyway. After the small bowl is off then you will see the petcock mounting screw which holds the petcock to the bottom of the tank. Again that is for a 70's Honda so it might not be the same on the Dream. ------------- 1957 WD45 dad's first AC 1968 one-seventy 1956 F40 Ferguson |
Posted By: CrestonM
Date Posted: 30 Mar 2018 at 8:57am
From your description, that sounds right. I know it has the bowl on the bottom, but I haven't tried taking it off yet.
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Posted By: HudCo
Date Posted: 30 Mar 2018 at 9:56am
| we made a right angle nozzle and angled wand for our steamer cleaner just for gas tanks a few years ago realley speeds up the cleaning , i think what works the best for getting the varnish loosened up is plain old e10 gasoline, for the black goo hot water and crystal drainO, just rusty ones we just strap them to the cement mixer with clean crushed rock |
Posted By: CrestonM
Date Posted: 30 Mar 2018 at 11:27am
| You know, I've heard guys say E10 or even E85 (use E85 for soaking only) will eat up varnish. I always figured it would do the opposite and clog things up, as I've heard it's hard on engines and carbs that sit for long periods of time. I never usually buy E10, especially for things that sit, but if it will work for cleaning the varnish out, I will give it a try! |
Posted By: Tbone95
Date Posted: 30 Mar 2018 at 11:39am
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Creston, when you get that one done, you can take a vacation up here to MI and get my '71 CB 500 Four running good. 3 squares, a queen bed, heck, I'll even let you keep an eye on calving. And I got a daughter.......but be a gentleman!
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Posted By: CrestonM
Date Posted: 30 Mar 2018 at 10:03pm
Hahaha, all very tempting incentives, but I ain't going nowhere up north this time of year! Too dang cold for this southerner. It's been in the 60s/70s lately, but supposed to dip back to the 30s on Easter. Oh...got to thinking about your "incentives" and forgot to post the update! Got the petcock off, and it was all corroded looking inside. It's currently soaking in Berryman carb cleaner. I washed the tank out with a garden hose, and I guess I was wrong. There really wasn't much varnish in there, but there is light surface rust. I'm thinking of sloshing some Ospho around in it tomorrow (Phosphoric acid) and hopefully that will fix the light rust issue. Any ideas/recommendations? Or just blast the inside with a pressure washer and not bother with the acid?
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Posted By: Ted J
Date Posted: 31 Mar 2018 at 8:51pm
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I'm surprised that Coke didn't get in on this thread Creston. He is kind of our resident expert on OLD bikes. My buddy had a 66 dream and I had a 66 Scrambler. WHAT a world of difference!! Wish I had that bike back.... Gave me a BIG (at the time) hospital bill and some VERY nice in house hospital treatment from SEVERAL girls... If it didn't hurt so bad, I'd of loved the attention. I'd use 1/4 or 3/8 nuts. You can reuse them for ever!! They are easy to get out of the tank with a magnet and get the tank nice and clean. GOOD luck, they are a lot of fun to ride. Back in the day, they were the BIG bikes...LOL ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: Tbone95
Date Posted: 03 Apr 2018 at 8:02am
| I got my gas tank all cleaned up nice a few years back. I started with the nuts trick to knock the bigger looser stuff off. I bought a kit of stuff called Kreem I think it was...clean, etch, coat the inside of the tank. I think I did something good, but maybe not. The project sort of died off after that. A buddy owed me a bartering favor, and he was supposed to clean the carbs. He sort of halfassed it and it ran for a little while then the floats stuck and flooded it. I had friggin' gas pouring into the air cleaner before I limped home (from the parking lot across the street!) Sighhhh.....I sure wish I could get that bike in good shape. |
Posted By: Walker
Date Posted: 04 Apr 2018 at 4:29pm
| Varnish, pad it good with rags then bungee it to a rear tractor wheel add some clean gravel and go for a ride. Rust, go to TSC and get a gallon of Milk Stone Remover mix with water and let her sit over night. |
Posted By: Michael V (NM)
Date Posted: 04 Apr 2018 at 7:37pm
| I had/still have a IIRC a 1974 750-4,, good runnin machine back when I was in the motorcycle gang lol... haven't thought about it much til now ...its dust covered in the back of the barn.... |
Posted By: CrestonM
Date Posted: 15 Apr 2018 at 10:59pm
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A little update...I rebuilt the carburetor today. It really wasn't bad looking, but I gave it a bath in carb cleaner anyway. Put it on the engine and rigged up a temporary little fuel tank. Started up and ran well after making a couple carb adjustments! Next was the tank...I took a 10" length of chain and tied a wire on the end of it. Dropped the chain in the tank and proceeded to shake it around for a while, then moving the chain to the other half of the tank and repeating the process. After I was finished all kinds of rust powder came out! I couldn't believe it! Took an air hose and spent about 10 minutes blowing it out, and when I looked inside everything was pretty clean looking! Went ahead and put some "Ospho" in and shook it around to coat the inside. After draining and letting it dry, it seems most of the remaining rust was converted to the black iron phosphate, so hopefully, that will help the rust issue quite a bit. The chain really did get most of it out. Hopefully next weekend I'll get the fuel valve installed and the tank back on the bike.
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Posted By: Ted J
Date Posted: 16 Apr 2018 at 5:13pm
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Good luck Creston! IF you happen to find a 66 or 67 Scrambler, let me know. I'd bet one of my grandsons would like to have a ball on one.... ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: shameless dude
Date Posted: 17 Apr 2018 at 10:55pm
| do they work good in the snow Ted? |
Posted By: Ted J
Date Posted: 18 Apr 2018 at 12:30pm
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Heck yes!! But you better have a snowmobile suit on,,,the ground is kina hard. You can do all kinds of stuff with a bike you can't do in a car or truck in that 'Pretty'. WOOHOO ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: Ted J
Date Posted: 18 Apr 2018 at 12:30pm
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Creston, did you get that tank done yet? ------------- "Allis-Express" 19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17 |
Posted By: CrestonM
Date Posted: 18 Apr 2018 at 3:48pm
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Nope, I'm away from home for the week. Not sure if I'll be home for the weekend or not. School is getting pretty intense right now with semester reviews/finals approaching. Luckily summer will be here before too long. Then I'll have more time to mess with it. It's cleaned and ready to go, I just have to put it on the bike.
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