CB500 Two weeks into ownership update

[Roxy John]

Following the warm welcome I received in the "Introduce Yourself" section, I thought I would provide an update on things I have discovered so far, with my '75 CB500K1.

(Firstly, many thanks to those who responded to my first post, especially Oddjob and Bryan, who have taken time to provide lots of info).

The bike landed in my garage on Monday 23 January, having been driven up from Kent by a pal from work, whose friend had rebuilt the bike in 2018 but he sadly became ill in 2019 and hasn't used the bike since then. On the face of it, the bike looks really nice, so I'm hopeful of a bit of a tickle-up in the garage (who isn't?) and we should be in business.

First thing was to give her a clean and determine which bits needed attention - she hasn't been ridden or cleaned since tackling a few laps of the Isle of Man in 2019 so there was a bit of road-splash but nothing too serious.

It was apparent that there was a bit of rust in the tank - not too bad, but worth some action. I drained the tank and although the fuel was quite orange, there was no jelly or black nasty stuff in there, just a few tiny flakes. I did some research and it seemed as though the easiest and potentially less problematic option was to try a citric acid solution and see what happened. I bought some citric acid powder online (it's about £6/kg) and mixed up enough at 1kg acid to 10 litres hot water and brimmed the tank, leaving it overnight to do its' stuff, then drained it and re-filled with the same and again left it overnight. I had read about "flash rust" appearing immediately following draining this from the tank, so mixed-up a litre or so of petrol with a dollop of 2-stroke oil ready to pour-in after emptying-out the acid solution.

I emptied the solution into a big white bucket and it was pleasing to see it had turned a bit orange and had some small flakey bits in it but no big lumps of anything. I shone a torch inside and it looked much better, so poured in the petrol/oil mix and sloshed it around for a while, then emptied it out, flushed with another half litre of neat petrol, then filled the tank with fresh Esso Supreme 99.

I drained each of the float-bowls and again, some slightly orange but clean petrol filled my little tin up, so rather than disturb the carbs, rubbers, airbox and all that lot, I instead crossed my fingers and remembered it's a Honda.

As mentioned in my Intro thread, the throttle and clutch cables seem quite stiff; the throttle cables had been passed down through the gap in the tank-side of the clocks then along the right side of the frame  , so last night I re-routed the throttle to make it run a bit easier; I sent it around the steering head, through the hole in the frame where the coils sit and on to the butterfly jobby - there is an improvement but the throttle still won't close on its own... further investigation required - I've got some WD40 silicone arriving today so hopefully a squirt of that might help; if not, I'll order some new cables. I'm not sure where I need to send the clutch cable yet so any advice gratefully received!

A new battery (together with 4 lites of mineral and an OE filter) arrived from DS earlier this week, so having popped the battery on charge on Tuesday, the temptation to give it try was too great to resist.... I had poured some light oil and several squirts of spray-lube down the plug holes a day or two after delivery and for a few days after, so having tried a few tentative gentle hand-prods on the kickstart with the plugs out during the last week, I was happy that everything was (hopefully) free.... I had cleaned and gapped the plugs while they were out and the previous owner installed electronic ignition, so I hooked it up last night, connected a temporary fuel supply, kicked it over a couple of times with fuel off, then fuel on, hit the button and she burst into life, immediately chiming-in on all four. As Captain Millyard might say, I was well pleased with that.

I'll warm her through over the weekend and change the oil & filter so everything is fresh.

The right hand pair of exhausts don't line up at the balancer pipe - I've read about bracket alignment being something of a dark art, so will have a look and see if I can suss-out what's wrong there. Failing that, I have got several hammers, so I'll sort it one way or another.  Again, any advice on this would be most welcome!

Anyway, that's plenty of rambling so I'll update if anything interesting happens over the weekend!

Bonjour for now, Phil.

[Oddjob]

Talking of the Millyard but on the bike show last night he mentioned using Molasses to clean a tank of rust and old fuel. He said 1 part of Molasses to 9 parts water, he didn’t say hot or cold but I’d imagine hot. Leave for a while and drain out.

Never heard of that before.

[Oddjob]

Just looked molasses up as a rust remover and to be fair it seems to be on par with Evaporust but considerably cheaper. The main problem is how long it takes, around 7 days looks to be good but longer if possible, it doesn't appear to harm metal as well, unlike Evaporust which will the longer you leave it. As far as I recall Molasses is just black treacle and you may be able to find it in Tescos or Asda for instance. I'll be having a look for some next time I'm shopping. It also doesn't appear to promote flash rusting afterwards but a swill with some diesel might be a good idea for a tank.

Holland and Barratt sell 454g of Molasses for £2.50 which is cheaper per litre than Lincoln Molasses sold at Farm stores. After some calculation I work it out to you needing 3 jars to completely fill a CB500 tank which IIRCC is around 3.1 gallons. I suppose you could store it afterwards and use it again.

[McCabe-Thiele (Ted)]

What evidence is there that Evaporust will harm good metal?
The blurb says it just breaks the bond between the rust & good metal.
I've left the odd washer in Evaporust for months with no apparant ill effects.

[K2-K6]

Molasses is noted as between Ph 5~7 and so effectively located on the acid side of neutral.

Looks like you'll control the final Ph of tge mix by how the ratio to water will affect it.

White vinegar if you want to up the acid level.

[K2-K6]

Looking further into product and found this

"Evapo-Rust uses a chelation agent, most likely EDTA (ethylenediaminetetraacetate)." From independent sources.

My understanding of edta from using it is to convert oxidised metals into soluble state to effectively remove them from substrate. In which case products containing this should just leave the non-oxidised alone.

Seems to be Ph 6.1 for Evaporust.

[Oddjob]

I watched a test on YouTube where they tested the effects of various solutions on various metals, alloy, metal shavings, rust on steel, rust on iron, and even the effect they had on painted surfaces. All the parts were weighed before and after. The best were Evaporust and Molasses, Apple Cider vinegar and White Vinegar were also in the test. The vinegars peeled the paint off in a few days, so did the other 2 but took a lot longer with Molasses having the least effect, something to consider if paint is present and you don't want to harm it if at all possible. The vinegars gave the fastest results for the rust but were overhauled by the other 2 as time went by, Evaporust looked like a clear winner at one stage but Molasses just kept getting better and better the longer the test went.

In conclusion the winner was Molasses, because it gave a every so slightly better result than Evaporust and mainly because it was SO much cheaper per litre. I have 5 litres of Evaporust and I know how much that cost me. When weighed the molasses seemed to have eaten away less metal, Evaporust was second, neither ate much TBH and neither affected alloy in any way.

The vid was quite good except the fella spoke far too fast, why he including water in the test is beyond me and they was also a form of Hydrochloric acid used which didn't come out well at all.

All in all, it may be worth giving Molasses a try, it seems to work as well as Evaporust but costs about 1/6th of the price. Can't argue with those figures. 

[McCabe-Thiele (Ted)]

FWIW one odd thing about Evaporust is it turns Gudgeon Pins black and stains Chrome work.

[Laverdaroo]

How strong was the Hydrochloric acid Ken?
I ask as I always use a one litre bottle of Hydrochloric for all the derusting I do and it strips rust in minutes. I get it from the Swimming pool shop labelled as Muriatic acid and costs about 9 quid. for fuel tanks its brilliant as swish it about for 10 mins and the inside is as clean as a whistle and down to bare metal. Touch of a wash out with some water followed by a bit of cherry diesel and its done. Takes less than an hour and under a tenner!

Builders merchants stock similar but its for cleaning drains (found in sealed plastic bottles in a sealed bag behind the counter usually and I found that to make it effective you wet the part you're cleaning first and dunk it in and watch it fizz like crazy. There's an exothermic reaction and it warms up as it goes, giving off hydrogen gas so do it in a well vented space, it can cling to your chest summut rotton and you'll cough like a donkey if you get a lung full of that.

gloves and goggles or specs a must and a vapour mast deffo!

Bloody good though!

[Seabeowner]

If the bike goes as good as it looks I'm sure you will be well pleased. I see you have a choice of dip switches!? The one on the right is the correct one.
I'm also researching the molasses as I have one very rusty tank that I got cheap from DK.

[Oddjob]

Muriatic acid was the exact one they were testing Roo, couldn't remember the name without looking again, it was extremely aggressive, it virtually dissolved the alloy test piece so if you've left the petrol tap on for instance it would wreck that, on steel it cleaned off the rust pretty quick but then went on to start dissolving that as well, on iron it created huge craters in the surface. After about 1 week all the Hydrochloric acid had off gassed off and it slowed right down. I would not advise using that at all after watching how it affects stuff, they used metal filings as one of the test subjects, both the vinegars dissolved them, the muriatic did as well but a lot lot quicker. Molasses and Evaporust didn't really affect them.

This is the test I watched, boring bloke but good tests except for using water, really, what did he expect.

https://www.youtube.com/watch?v=_dzlE9-9DVE

[Laverdaroo]

If they were putting things in for days I'm not surprised they were pitting like that. I dip stuff for about 5 mins max or when the water has stopped reacting and fizzing like buggery. Have an inspect and if it needs another go, go again. You get to suss the times the more you do stuff. I once left a carb body in the hydrochlric over night and came in to find what resembled a carb body but made from a grey crunchy bar. I've had brilliant results runing a current through it and a bit of sacrificial steel in there as a cathode via electrolosis  but its a messy old job.

I never put any ally in now after that although some test bits Idid simply all came out black so I quickly knocjed that on the head, I always feel that ally is able to be 'nannied' back where corrosion and rust is a pig to shift physically and so justifies the aggressive approach.   I have a gallon tub of good old B&Q brick acid under the bench also which I use to soften powder coat on frame bits, swing arms that sort of thing. You can leave that for a few days and the black slime just washes off with a bit of pressure but saves hours for me. It doesnt tend to effect the ally in calipers though and just makes the black paint slide off in about 12 hours. Means I can strip, clean, scragg up and etch prime in two evenings and get it all out the way faster.
I've got that caliper from Johnny to sort and i'm on with making brackets for the horn, speedo etc etc at the min so once all done the sheets will be out and paint the lot in one hit. I'm surprised he was leaving them in there for that long though. TBH I could only watched 5mns before he started to sound a bit like my old RE teacher and I had to give it up

I watched a similar one where a bloke does about 20 different ones, including coke, pepsi, alsorts. Similar results and exactly the same with the water test...............both the test samples got wet!....

[Oddjob]

I think the time frame was to give time for the Molasses etc to work but also I suspect to show what just leaving parts to soak can do to them if you’re not careful