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Corroded Carb Blues. #730803
04/04/18 2:59 am
04/04/18 2:59 am
Joined: Feb 2018
Posts: 41
Oklahoma
T
Tracey Spear Offline OP
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Tracey Spear  Offline OP
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T
Joined: Feb 2018
Posts: 41
Oklahoma
69 Tbolt project.

I've started teardown

the carburetor slide and body are one, can't be budged, and the alloy is so soft I'm afraid to get rough with it.

I'm thinking Oklahoma humidity has taken it's toll. Where the needle passes through the main jet I could see a blob of white corrosion, as if moisture formed on the needle and dripped down. I haven't removed the bowl yet, just setting aside parts for now.

Is corrosion that bad worth messing with? Or should I start sourcing a replacement?

Thanks

Tracey

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Re: Corroded Carb Blues. [Re: Tracey Spear] #730806
04/04/18 3:26 am
04/04/18 3:26 am
Joined: Jun 2013
Posts: 93
Texas, USA
R
Ray Elliott Offline
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Ray Elliott  Offline
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R
Joined: Jun 2013
Posts: 93
Texas, USA
If you know anyone with an ultrasonic cleaner, even a cheap HF model, give them 15~30 min in there. Simple Green is an acceptable surfactant, cut it 5:1. It'll knock all the crud loose. You'll have to use a brush & air to finish up.


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: Corroded Carb Blues. [Re: Tracey Spear] #730850
04/04/18 3:38 pm
04/04/18 3:38 pm
Joined: Mar 2006
Posts: 1,301
Magnolia, TX
htown Offline
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htown  Offline
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Magnolia, TX
Get a new AMAL Premier carb. Time you buy all new parts for the one you have you will be at least halfway to the cost of a new one. Odds are you will damage the slide bore getting it apart and will have air leaks with the bike never running right. Also, it's dang near impossible to get the internal passages completely clean if it is that plugged up.
I went down the same route with my 70 Thunderbolt. Wasted money on all new carb internals, bike still ran like crap. Bought the Premier and it ran like a top. Great thing about the Thunderbolt, only one carb to buy. I've restored 5 bikes and ended up replacing the carbs with new ones on all of them after futzing around with the old ones. Ouch on the Trident. It's a fact of life that amals the slide and bore wear and there isn't much you can do about. A lot of people used to have them sleeved, but again the cost for that work is almost as much as a new carb.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Corroded Carb Blues. [Re: Tracey Spear] #730860
04/04/18 5:43 pm
04/04/18 5:43 pm
Joined: Sep 2004
Posts: 796
Farnham, Surrey, UK
gunner Offline
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gunner  Offline
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Farnham, Surrey, UK
I've heard that soaking the carb's in citric acid will remove the white corrosion, just don't leave it too long or it might attack the metal. An even better option is to boil the carb's for a few minutes in citric acid as the heat will help expand the metal and allow penetration of the acid.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: Corroded Carb Blues. [Re: Tracey Spear] #730861
04/04/18 6:00 pm
04/04/18 6:00 pm
Joined: Nov 2012
Posts: 624
Isle of Wight, UK
K
koan58 Offline
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Isle of Wight, UK
From your description of the carb, I wouldn't waste much time and no money on it. You've plenty more things to be getting on with, in the meantime do the carb soaking advised, nothing to lose.
Establish what bits you need before ordering, it is easy to waste lots of money in carriage costs if you are disorganised about it.
If you can keep to it, keep notes and pics of what you find as you dismantle, and a master list of serious matters - easier said than done I know!

Re: Corroded Carb Blues. [Re: Tracey Spear] #730867
04/04/18 6:30 pm
04/04/18 6:30 pm
Joined: Feb 2018
Posts: 41
Oklahoma
T
Tracey Spear Offline OP
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Tracey Spear  Offline OP
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T
Joined: Feb 2018
Posts: 41
Oklahoma
Thank's all for the advice.

Last evening I looked at the AMAL Premiere and have pretty much decided to replace. Anodized sleeve and better idle circuit, seems like a no brainer. Especially after reading the section in Brown's book about the corrosion. I've only just started teardown, so it will be quite a while before carburation becomes an issue. New carb with better specs and reliability vs all the problems this corrosion could cause, not to mention the thrill of stuck full throttle, no thanks.

I'll throw more change in the jar.

Re: Corroded Carb Blues. [Re: Tracey Spear] #730921
04/05/18 5:02 am
04/05/18 5:02 am
Joined: Mar 2006
Posts: 1,301
Magnolia, TX
htown Offline
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htown  Offline
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Posts: 1,301
Magnolia, TX
Just looked at Lund machining, sleeving is 80$ per carb for a 900 series carb. Also with the Premier you get the Stayup float and vitron tipped aluminum needle which deal with ethanol better. So:
resleeve 80
new anodised slide 45
new needle and jet 25
new main jet 5
stayup float kit w/aluminum needle and gasket 50
total $205 plus you are still stuck with the crappy pressed in idle jet and the hassle of sending the carb out to be resleeved and waiting for it to come back.
In the US you can buy AMAL MKI concentrics for around 200$ from most of the reputable parts vendors.


1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Corroded Carb Blues. [Re: NickL] #730930
04/05/18 7:24 am
04/05/18 7:24 am
Joined: Aug 2014
Posts: 1,535
OZ
Triless Online content
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Triless  Online Content
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Posts: 1,535
OZ
Nick, you told me not to believe what you write once , then you have, obviously, what must then been a sagacious lapse !
I really hope you can make it to Halls Gap later this year !

Re: Corroded Carb Blues. [Re: NickL] #731015
04/05/18 7:53 pm
04/05/18 7:53 pm
Joined: Feb 2018
Posts: 41
Oklahoma
T
Tracey Spear Offline OP
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Tracey Spear  Offline OP
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T
Joined: Feb 2018
Posts: 41
Oklahoma
Originally Posted by NickL


I suppose you could apply the option to all the bike really. Gearbox is worn, new one only $1500.00. Crank needs a grind, new one only $1000.00
Clutch $1000.00, Rods $750.00. Spokes, so you may as well go for new wheels $1750.00 etc etc
I'm sure you'll have a nice bike at the end of the day.
How much is a new bike????????


Dang Nick! You just saved me a lot of money. This bike has < 6000 miles, so all the original 40 year old components should be totally reusable. Right? Why replace compressed valve springs, when I can save money and just stretch them back to original length? And all the 40yo rubber, heck a little Armor All will make them look like new. And those 40 year old tires should be just fine at 70mph. Tread's good, no need to replace. Right?

Good grief, we're talking a $250 carburetor! Or I could spend months carefully going through this old bike, and just for spite, insist on cleaning 40years of corrosion from the carb. And after all those months of work, I can slap that old carb on it and enjoy another few weeks trying to sort out all the problems.

Or I can save a few bucks, maybe eat a few burgers instead of steak. Then when it's all sorted out I can mount up a new carb, fire it up, and with and with a great big grin, ride off into the sunset.

Re: Corroded Carb Blues. [Re: Tracey Spear] #731039
04/05/18 9:38 pm
04/05/18 9:38 pm
Joined: Oct 2007
Posts: 1,537
Auckland NZ
Ignoramus Offline
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Auckland NZ
without actually seeing how bad the carb is its hard to recommend what i would do .........personally if it wasnt that bad i would free it up clean it out and give it a go , you might be surprised.

one thing i wouldn't do is resort to sarcasm on this board,,,,,,,,but im old fashioned like that.


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Corroded Carb Blues. [Re: Tracey Spear] #731050
04/05/18 11:01 pm
04/05/18 11:01 pm
Joined: Aug 2001
Posts: 3,910
argyll. scotland, uk
gavin eisler Offline
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gavin eisler  Offline
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Posts: 3,910
argyll. scotland, uk
If you were going to buy a new carb why did you ask about the old one. My 71 still has whats left of the original carbs, I have only had to replace , throttle slides 6 times , bodies twice , float bowls once , needle jets 6 times, float valve needles 3 times. Still on the original floats, jet holders and carb tops.I like AMAL carb rebuild
ability. At 6K miles the carbs wont be worn out , they may be V corroded beyond repair, its hard to tell from here, if you poke out the welch plugs you can get to most of the tricky passages.I would reject them if there was serious corrosion around the two small pilot jet drillings in the choke floor.

I have some decent only part used valve springs if you need them.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Corroded Carb Blues. [Re: Tracey Spear] #731065
04/06/18 12:58 am
04/06/18 12:58 am
Joined: Mar 2006
Posts: 1,301
Magnolia, TX
htown Offline
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htown  Offline
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Posts: 1,301
Magnolia, TX
If the bike has 6000 miles on it odds are the bore and slide are worn. He stated that the slide was stuck in the bore. A likely possibility is that freeing it will damage the slide or bore further especially if any force is needed. Who ever owned the bike before may have overtightened the flange nuts and the bore may be warped. So now you are at a decision point. Worn bores leak air so in order to restore the bore you need to have it sleeved so you are out 80 bucks. At 6000 miles the needle jet and needle need replaced another 25 bucks. You try to reuse the plastic float and needle. All the gas in US has at least 10% ethanol. Yes, I know there are some places in the boondocks that sell nonethanol along with marina's and airports. Not very convenient if you ride more than 200 miles a year. Or there is race gas, 10 bucks a gallon. Maybe the plastic float and needle survive the ethanol or maybe you can't figure out why your bike runs like crap. So if the ethanol eats the float, then another 50 for the ethanol proof kind. So now you have 150+$ in the carb and it still doesn't run right because the internal passage to the idle jet is still plugged.
I rest my case
and not in a sarcastic way but based on my experience restoring a few of these crates.
but as the stock brokers say "past performance may not be an indicative of future results"

Last edited by htown; 04/06/18 1:03 am.

1978 Bonneville T140E
1974 Trident
1970 BSA Thunderbolt
1971 Norton Commando
1972 Norton Commando
1973 Norton Commando
1974 Norton Commando
2004 XL 1200R Sportster

Everything will be alright in the end. If its not alright, its not the end.
Re: Corroded Carb Blues. [Re: NickL] #731068
04/06/18 1:51 am
04/06/18 1:51 am
Joined: Oct 2007
Posts: 1,537
Auckland NZ
Ignoramus Offline
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Ignoramus  Offline
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Joined: Oct 2007
Posts: 1,537
Auckland NZ
Originally Posted by NickL
one thing i wouldn't do is resort to sarcasm on this board,,,,,,,,but im old fashioned like that.


As if i would...............
Who needs to be a 'restorer' when.....
You too can be the proud assembler of a kit of of new bits. Just like Airfix eh?



i wasnt referring to your post Nick


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Corroded Carb Blues. [Re: Tracey Spear] #731080
04/06/18 6:22 am
04/06/18 6:22 am
Joined: Feb 2018
Posts: 41
Oklahoma
T
Tracey Spear Offline OP
BritBike Forum member
Tracey Spear  Offline OP
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T
Joined: Feb 2018
Posts: 41
Oklahoma
No worries NickL. I take work, finances, and such seriously, this stuff, not so much. But one can't have a dig and not expect one in return.

My first real motorcycle was a '75 Bonnie, it was love at first ride. After a while I sold it to get a '74 Commando. After a while kids came along and wife put an end to my riding days. Now at 58, my darlin' found this bike on Craigslist, knew it was worth much more than seller was asking, and snatched it up for my Valentines Day present. Lucky me. Other than handlebars, near as I can tell all the original parts are there. But I'm not a mechanic, and this is my first total rebuild. Sooner or later I'll get this all sorted out, learn much, and if all goes well, one of these days ride off into the sunset with a great big sarcastic grin.


Last edited by Tracey Spear; 04/06/18 6:25 am.
Re: Corroded Carb Blues. [Re: Tracey Spear] #731087
04/06/18 7:45 am
04/06/18 7:45 am
Joined: Sep 2008
Posts: 802
Skudeneshavn Norway
S
Stein Roger Offline

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Posts: 802
Skudeneshavn Norway
Things aren't always clear cut and easy.
I've been playing with these things for over 40 years and have accumulated at least some knowledge along the way. For a "layman" a new instrument might just be the right choice.

Premiers are nice, but not always easy to tune in. On a TR6 I'm trying to dial in, I think I'll need a bigger idle jet as it won't respond correctly to the air screw and it can be a bitch to start from cold at low ambient temperatures. Some suggests replacing the #17 idle jet with a #19, which is the next step up.
Things like that can really confuse you if you haven't had much experience with carburetors.

New carbs built to the original specs are still available, and they're cheaper too. For most people they will last for many years and give good service. Set the air screw to 1,5 turns out and chances are it'll be fine.
I would consider getting one of those.

On the other hand, I'm usually able to get good service out of almost any old Concentric, most will run well with a new slide and needle jet, provided all passages and the idle jet is open. I've thrown away all the brass float needles and replaced them with either the old nylon version, or the new Viton tip aluminium ones.

The plastic floats haven't given me any grief so far, things may change now that Ethanol content is being increased from 5% to 10% here as well.

Re: Corroded Carb Blues. [Re: Tracey Spear] #731122
04/06/18 3:28 pm
04/06/18 3:28 pm
Joined: Nov 2012
Posts: 624
Isle of Wight, UK
K
koan58 Offline
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koan58  Offline
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Isle of Wight, UK
No need to make any decisions or spend any now, get it dismantled to see what else maybe of concern. Then you can judge as to how realistic a proposition it is to resurrect or not.

All I'd say about the carb is as it's corroded enough to lock it solid, the small passages will take some clearing, and when the slide is freed from the bore I'd be surprised if the area in which it was seized wouldn't show bad wear (just where it is so important for mixture at low throttle). But you may be lucky, so it's worth cleaning and checking first.

Even with a sound engine, one's enjoyment can be spoiled by some simple things, for instance a sad carburettor or sad ignition system. These things are behind a large number of the posts for advice on these forums, as failing to pay attention to these can effectively ruin a lovely bike for a haporth-o-tar.

These old bikes will run with such systems in poor condition, but the difference is obvious when they are right.

Re: Corroded Carb Blues. [Re: koan58] #731240
04/07/18 4:46 pm
04/07/18 4:46 pm
Joined: Aug 2001
Posts: 138
SoCal
P
Phil R Offline
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Posts: 138
SoCal
Originally Posted by koan58


These old bikes will run with such systems in poor condition, but the difference is obvious when they are right.


So true. I had my Tbolt "out & about" one time when I found it's performance, especially at low speed, to become increasingly very poor.
I finally pulled into a parking lot to check things over and was surprised to find the carb (AMAL Concentric) hanging loose enough on it's two studs that you could jiggle it back & forth.
The bike still ran though.......Ahh the beauty of simple technology!

Re: Corroded Carb Blues. [Re: Tracey Spear] #731247
04/07/18 5:31 pm
04/07/18 5:31 pm
Joined: Nov 2012
Posts: 624
Isle of Wight, UK
K
koan58 Offline
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koan58  Offline
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K
Joined: Nov 2012
Posts: 624
Isle of Wight, UK
Had a similar experience with my stopgap norbsa down the A4 to Newbury in 1978. When I had to slow to ~40 it started playing up, but opening the throttle seemed to improve matters, but this got progressively worse over the next few miles, till I had to stop and check. The right carb was free on its studs. That was a 99 motor, I've never had anything like it on a Triumph. They prefer to lose their rockerbox caps instead!

Re: Corroded Carb Blues. [Re: Tracey Spear] #731262
04/07/18 7:40 pm
04/07/18 7:40 pm
Joined: Aug 2015
Posts: 1,160
Bolton Lancs UK
A
Andy Higham Offline
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Andy Higham  Offline
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A
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Posts: 1,160
Bolton Lancs UK
A tip for Triumph rocker caps, BSA pre-unit oil tank caps and primary chaincase caps.
Replace the fibre gasket with an "O" ring, it stops them unscrewing themselves.
How many of us BSA riders have felt the warm wet feeling on the back of our right thigh?


1955 BSA B31 500cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350
1967 Greeves 360 Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc "Llareggub"
2003 Aprilia RSV Mille "Lo Stregone"

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