Slow burn project - JDM style RZ YPVS

[JonW]

Dec 5, 2020 6:45:37 GMT 1 mak595 said:

The lad a bought my 350 barrels off for my RZ has a pair of mint JDM 250 middle fairing panels that dont have the lower holes to mount the belly pan, i did ask if he was selling them but he's hanging on to them....probably quite rare in the uk

Cool. Closing the holes is easy really on the std panels but nice to see someone seeing value in stuff like this.

[JonW]

You can only know so much with something like this when stood in front of the seller. At some point you need to take a gamble.

To mitigate the risk I checked the cases and looked up the exhausts, turned the flywheel and everything moved freely but with no kicker and gear lever anything else would be hard. The clutch was in there as it was firm on the lever and there was oil in it. Felt the tops of the pistons with finger (being sure not to spin the flywheel at the same time as we know from the other week) and didn’t feel any detonation. Tried to use my Aldi boroscope but couldn’t see a thing with it. Nothing new there really, the angle isnt ideal. Almost all the fixings look OEM and there is minimal damage to the clutch case, tho the oil pump cover is trashed. Someone left the throttle cable connected to the oil pump by cutting off the OEM 51L throttle cable. Very much a wrecker trick, why undo when you can cut etc. They had cut the oil pipes as well of course. No chain damage and nothing un-towards with the cases at all. The dipstick hadnt been ‘pliered’ which is a good, but rare, sign. The clutch cable holder had been removed but I guess the wrecker did that and didn’t bother to put it back when they pulled it out of the bike. All good info... You can learn a lot from that stuff.

Deal done and with it home I needed to strip it to see what I had got.

The bottom is quite oily. There was almost no spooge from the PVs tho. Weird.


First good discovery was that the newspaper stuffed up the inlets and exhaust was in Japanese and from 2014. So this was an import engine and not one that had been removed from a bike in Aus. That bodes very well indeed. Aussies use and abuse stuff. Can say it without fear of slander as its a fact we all know down here lol.



So someone felt this engine must be worth stopping dirt getting into. That’s good news. It was a long time ago in a far off country though, a lot of dust has floated around it since.

It was a simple task to remove the (still pliable!) inlet rubbers and reed valves and while there is dirt in the cyls, there is always good news when you get to see that extra port. Thank you Yamaha for working with Boyesen, even if it was for just the one year.



Whipped the head off and all bolts look to never have been apart. Head has no det marks and bore measures as Standard. Cool. Left piston solid as a rock but right piston rocks a little mid-bore, so rebore quite possibly needed, maybe 2 oversizes. Ive no problem with that. Will let the pros advise me on that of course.





Cylinders off and pistons don’t look that bad really. So not massive miles, but not low miles either.



Then off with the pistons... Im finally getting to use my new Ballards tool, why on earth didn’t I buy one of these before. Cheap as chips and a lot less hassle than what I used to do.



To be honest the crank feels fine, side to side and up/down. Its dirty and probably has rust in the bearings from sitting but Its not blown up so that’s good. It will be pulled apart anyway, so no big deal but nice its not dead already, I usually seem to buy engines like that.

Flywheel come off with a nice clean pop with the Aldi big rattle gun and looks new. The stator looks ok too.

Drained the oil. Looked to have hardly been run since it was poured in and only a bit of haze in it.

Then the engine decided to fight back. The clutch cover bolts were done up tight. Im a huge fan of the Vessel screwdrivers as you know and my Impacta No.3 took care of them, two were ruined by some previous (quite recent) failed attempts at undoing tho, but I was in...

Clutch pack off... Steels are a bit rusty so some moisture must have got in, that would account for the light haze in the oil. Big clutch nut was less than finger tight with the lock tapped back... That’s not good. No real idea why as yet, but maybe that made noise after a clutch refurb which sidelined the bike. You hear stories about how over the yearrs that the Japanese would just leave stuff on the side of the road when they were done with it as it was worthless. No one stole it and it just sat and sat. I reckon my Evo was like that. Eventually it was seen and then bought (or actively sold to, or even just collected by) a company who salvages vehicles and then auctions or scraps them. In the case of my Evo, its a very low mileage bit of ‘scrap’ lol so was auctioned. Maybe this bike was simply dismantled after a crash, who knows. I suspect Old Gold brought this engine into Aus with one of their shipments when their Japanese connection found it either for sale or in a bike shop or parts place.

Clutch basket has what I would say is low wear and the gear is solid to the basket.

Anyway... Easy stuff done... Next some toughies. The clutch bearing and shift drum retaining plates were a nightmare and again the Impacta was a godsend, but these lil buggers still needed heat. The joy of a JIS driver is that it bites further and further into the slot and will never lift out, while of course the Vessel impacta version I was using was also working as an impact driver. Heat and hitting went on a while but the screws all came out and are still like new.

With the cases apart and the gears look great and they were bagged once the old 16T (weird) sprocket was clamped in a vice and the drive nut spun off with the rattle gun. Easy as...

Next one was a strange one. The shift shaft adjuster cam wouldn’t come out. Someone had red loctite’d it in place I think. I pretty much ruined the slotted head with my attempts and in the end heated it more than I felt comfortable with and then rattle gunned the lock nut out until it ran out of thread, locked into the shaft and spun the thing out. You can still buy these cheap enough to not have to worry about keeping them.

With that out I could pull out the shift fork shafts, but the one under the shift shaft adjuster wouldn’t shift. I guess the edge had been galled at some point in the messing with the adjuster. No problem. tap tap tap... and it popped the alloy plug out of the case and I slid it out the other side instead after taking off the undamaged (but missing one screw?!) neutral plate.

Finally I had base cases. The usual clutch plate sludge and some thing that is either dirt or rust, tho no rust on anything other than the clutch pressure plates, so maybe its some good old red aussie dirt as its also in the crank wells. Good news is no spun bearings.



Cleaned the crank wells up and wow, as you can sort of see in the pics there are no det marks... That’s super rare lol.

Next step is to take the cases / covers and cylinders / head to my mates workshop and clean all the dirt off using his pro parts washer. I can then box the cleaned up parts and start to gather a list of what is needed.

A little note on doing this... I bloody love ripping motors like this apart. Its a 1984 engine. 36 years ago it was someone’s pride and joy. They picked it up from the dealer and had something brand new, not just another ypvs but their own one. It was also the new 'F1 250' the RR, with the new engine and exhaust setup. They ran it in, probably babied it for a bit... until they ranted it. Carved corners and beat their personal bests getting through the city. Missed gearchanges and even made some more serious mistakes on it, or suffered the mistakes of others. Yep, just normal riding for us bikers. All those memories they kept locked up in their head... And some of those stories have tell tales that also reside inside and outside of this engine. As you strip an engine apart it speaks to you. It tells you how it was looked after, if it failed and how it was repaired. Then later how it was removed and stored. All that info helps those of us who repair and restore work out what is needed and what has to be done. A great way to spend an afternoon I reckon!

[cnkxu1]

Note to self: Find old Japanese newspapers to wrap parts in.

[midlifecrisisrd]

Result on the condition of that

16t front sprocket is standard on the 250

I never realised that. Thought it was just the 41t rear but the 3hm1 book said 16/41

Steve

[JonW]

Dec 5, 2020 12:07:15 GMT 1 midlifecrisisrd said:

Result on the condition of that

16t front sprocket is standard on the 250

I never realised that. Thought it was just the 41t rear but the 3hm1 book said 16/41

Steve

Ahh yes course it is, I just checked the 51L parts book and yep youre right. I always think 17s but usually im building 350s lol

Yes the condition is very good. Always a gamble but sometimes you get lucky. Only a few missing parts and only a few bits mullered, so not too bad at all

[donkeychomp]

Loved that last paragraph. And it's so true. When you look at a bike, it's not just a 'thing', it has a history and someone else's history behind it all. Well said mate.

Alex

[JonW]

Dec 5, 2020 22:48:07 GMT 1 donkeychomp said:

Loved that last paragraph. And it's so true. When you look at a bike, it's not just a 'thing', it has a history and someone else's history behind it all. Well said mate.

Alex

Thanks Alex!

--- UPDATE ---

Small update on the engine. Two things:

1, the brown stuff in the crankcase is old fuel. It was a devil to remove but i got it out with a scraper.

2, I did notice the clutch nut was loose (finger tight) and looking at the clutch parts there is only one of the big spacer washers present. I reckon this bike got something big like a new crank but they lost one of those washers. Ran it up and it sounded awful so switched it off and left it. That would account for the clean oil at least.

I do wonder how bad this would sound lol. Nothing looks to have wobbled enough to contact anything else but its a worry. Still available tho, so I'll buy one. Only way to find out if its any good. I bet its fine. Strong engines


--- NEW Stuff ---

I inch ever onwards... Dejan supplied me with an airbox. The good news is that after all this talk of Brazilian bikes, I now have a part that is from Brazil.

Its a little known fact that when Yamaha moved production to Brazil they changed some of the part number prefixes as well to show that these were made in Brazil. They were for the 1YH bikes and as such they are prefixed with that code. They are generally the same part, just made in South America. Of course there are some differences on some parts... lets not blindly drink any Kool-Aid lol

So while my new-to-me 4CE airbox proudly states 1YH where it would say 29L or 51L between the outlets, it's an exact copy of the 51L of course as its Brazilian made version of the ones used on the RD/RZ from 85-on. So just what I need and I like the fact weve already been talking about the Brazilian market short mid panels, so it seems 'fitting'.

I did look for some pics of the airbox as Ive already stored it away, but I didnt have any from Dejan's ebay listing. oops.

[JonW]

Think I may have answered the question as to all the brown sticky stuff in the gearbox. Its clutch plates.

I think when you forget to add the 2nd washer in the clutch mech all sorts of nasties can happen, but the main one is that the clutch plates wear fast as they touch and bounce back and forth. When I stripped them (and put them straight in the bin) the steels look thin and are rusty and while the frictions looked ok, one had snapped across in one place. All the springs were very worn, 33.7mm, should be 3.7ish. I know the springs are 99% of the time junk in these engines but wow in the 33s... mad.

Anyway Ive worked my way through a lot of this engine now and think Ive probably reached the end of what I can see (and bin). The rest will get reused.

Ive started to clean parts up and they can all get boxed for later.

[JonW]

The burn is still so very slow on this one... there is news though.

I finally found a set of half decent side panels for this build. Originally I wanted to fit my Quality Works FRP tail with the early ypvs triangle rear light and had sorted out how to do that at the tail end, but i realise now that wont work with the 86-on tank at all without major work and this is a brand new panel which really shouldnt be cut up. sigh... So Ive gone back to something more like standard bodywork as Im not keen at all to import another tail from Japan for this, it cost waaay too much last time.

So the side panels I chose were the 3HM units as they dont have holes for the grab rail.

This use of the 3hm design offers two things for this project... 1, saved me from having to locate a grab rail (lol), 2, gives me a cleaner look which was what I was after



Just got to locate a joiner piece now... Ive asked in the Wanted Section, fingers crossed

[JonW]

No luck on the joiner as yet... :/

Anyway, I have 'progress' as I just had some good news from my ‘crank guy’. Seems weird writing that, he’s certainly not a crank lol. Anyway. Seems when it was stripped the crank I pulled from this engine is really good and any years of sitting were done in garages that didn’t have damp, salty sea air, floods etc. Maybe the wads of Japanese newspaper were the key, who knows. Either way this was fantastic to hear. In fact he didn’t even think the thrusts really needed to be changed.

Ive never had such good news about a crank really. Wow. Of course I’ll change the mains anyway as I bought some NOS ones a while back when they came up on ebay, we do like a little peace of mind

So my assertion that this engine had done very little work before being pulled from the bike holds true. What a shame the owner (or his mechanic) did the bizarre thing with the missing clutch washer and let the plates turn to junk. Ahh well, its simpler and cheaper to sort the clutch than the crank!

[JonW]

Ok, this update was posted in the 'What did you do today' thread, er, today...

---
In the time it takes to have a baby... er, a tank I bought from Dejan has arrived in Aus. Haha

Ok, there is a bit more to that story of course... But the gist is that in mid December last year Dejan boxed and sent me this tank.

After a few months it had got as far as Singapore but the tracking had stalled and the tank proceeded to have a lengthly holiday in a Warehouse in Changi Airport. Perhaps it was allowed out on occasion to visit the Jewel (which is great if you havent been), but I doubt it...

Then one day it was unexpectedly returned to Dejan. Apparently there was no way to get it the last 7 hours of flight time to land in Aus. Argh, soooo close, yet soooooo far.

This is one of the problems of Covid that people dont expect or know much about I think around the world. Australia reduced the amount of people who could come here last year. Incoming persons were limited to basically only returning Australian citizens although it seems if youre a Hollywood star (or an annoying Big Brother contestant from the UK lol) you can come and go as you please. hmm... Anyway, limiting people who arrive to around 2000 or 3000 a week killed Airmail. Killed it dead. 3000 people was less than what landed before 7am most mornings in Sydney before Covid and thats just one point of entry to Aus...

Of course not everyone was screwed, Fed Ex has its own planes and other carriers repurposed some of their passenger fleet to take up some of this demand, but still flights are limited and airmail is really quite slow now, in and out of Aus. Postal organisations also removed all their cheap options of course. Why allow people to buy something cheap when the costs have gone up and the supply/demand ratio is stacked towards 'demand'?

Anyway, long story short: Both Dejan and I waited... and Waited (capital W)... Eventually he got word from his local post office that posting to Australia would be switched back on this month and within 2 weeks the tank is here! Wahoo!

Considering its done enough miles to have been all the way round the world now I think we did ok, the handling only bent the side panel grommet mounts and they can bend back. Dejan's great packing was the key to that of course.

Anyway, Massive thanks to Dejan for his hard work and also for the deal on the tank. I know what I'll be doing the rest of this week... now where did i put that paint stripper and DeoxC I bought last year??? haha.

[JonW]

So, Let's have some 'before' shots, so we can see what we started with:

My initial reaction is that it looks like a very good tank externally. Very few dents and its not too heavy so doesnt feel like its full of filler. These tanks are actually very lightweight and removing the paint makes them weigh almost nothing, unlike the earlier models.

Internally its quite rusty and of course has flakes moving around when shaken. This was expected of course. The tank was well described to me when I bought it. Exactly what you need for distance purchasing.

So, the pics... Ive tried to focus on the dents where I can here, these are not glamour shots!















One thing the pics dont show is the smell of old fuel haha... eugh!

[JonW]

So like all gentlemen would, I decided that now this beauty was home it was time to get her clothes off!

What followed was a bunch of hours with the heat gun and some serious paint stripper with various paint brushes, wire brushes and scrapers.

Since there was no filler and also no primer, Im saying this was OEM paint!

This is what we have to work with next :
(once again, these are not glamour shots, they are to show me what i have to work with and fix etc)

[JonW]

So, wow... very nice actually. The dents you could see with the paint on were the same when the paint was removed. No filler or big dents is really great news.

I protected the exterior with a product called Dry Coat which stops rust. It will get some in the next stage but no sense letting it run riot over the outside of the tank if we dont have to.

Both sides near the seams do have small rust patches... these will need to be watched to see if they are just surface or pin holes course.





So let's test those areas in the only way we know... lets eat the rust from the inside!

I like to do this in two stages. With tanks that stink of old fuel and also have quite a lot of rust I like to start with vinegar. It eats the rust and the smell quite well and is cheap as chips... smells like em too lol. The 2nd stage will be completed with DeoxC. I know in the uk the cost of DeoxC is minimal, but here its very exy so I prefer to keep it in as good condition as possible and only let it complete the job and not get contaminated with old fuel, oils etc



Lets see what happen....

[donkeychomp]

That tank looks surprisingly good Jon. Fingers xxd.

Alex

[JonW]

Yes it does Alex. Im really pleased with it. Compared to my other F2 tank it's a thing of beauty. You might recall that the one for my F2 resto had been in multiple accidents and was a proper 'football', needing a lot of dent pulling which was days of work with the glue gun and the PDR tools. I probably cant improve (and certainly not remove) the dents on this one to be honest, they are too sharp and small for the methods that I use from the outside, but i'll try and see what i can do as you never know until you try of course.

It's always a gamble buying an old tank. You never quite know what is under the paint as so often its been redone after an accident and contains big dents and thick filler etc. You have to go by what you see and that means looking inside and when you see a lot of rust inside it doesnt fill you with confidence, but you still never really know until you "strip 'n dip" it.

Anyway, yes 'so far so good'. My fingers are also firmly crossed here, thanks for also crossing yours, its appreciated!

MORNING UPDATE: I just checked it and after about 18hours its holding and the vinegar is slowly eating the rust as there is gentle bubbling of the gas this produces. This part of the process will take some time and I'll keep checking it of course.

I should note that if the tank hadnt been as nice under the paint and if it does have holes then I will not be blaming the seller of the tank at all. The risk was all mine. Im happy I was buying from someone who knew what they were looking at and could advise me what they saw literally half a world away from me. That mitigated the risk, but in the end it was me who bears the risk of buying an old fuel tank from a bike/era that's known to have rusty tanks due to thin metal/design etc. My pics here are just me showing you guys how it this work pans out in this thread as Ive not really done much in the way of forum updates for a while as Ive been working on other things and the arrival of this tank excited me, plus its journey to get here was a good story. And we all enjoy a eood story on here, especially one with pics haha With so few tanks available to us now more and more of us are going to have to take risks with purchases like this and then go through the work to clean and repair them before putting them back into use.

[JonW]

DAY 2 UPDATE:

Another 24 hours and the old fuel smelling soup of vinegar and rust flakes is doing its job. When probed with a long screwdriver (lit by a torch) through the filler I can see/chip big flat rust flakes off the metal inside. I could lift small areas yesterday, today they are bigger. The vinegar seems to be creeping under this layer of rust, allowing it to detach in large flakes. This is good news I guess, but probably means the rust was quite thick and not just a surface coating. Tho looking at the before pics you could predict that I think from the filler neck.

I'll leave this another 24 house and then start shaking it with some nuts-on-a-wire (er, painful!) to scrape along the inside to help loosen the more recalcitrant areas.

One mildly amusing thing did happen: I came into the garage and looked into the bottom of the tub as could see liquid at the bottom. Immediately i thought id had a seam failure or pin hole and my heart sank a little. But no, the morning sun on the garage had warmed the air gap around the filler and when that expanded it had pushed the vinegar level up the filler 'tube' area, it then overflowed and went down the drain hole and out the drain. Crisis easily averted lol. Downside is that my nice clean steel tank now has light streaks of surface flash rust from the vinegar. I always knew it wouldnt stay looking so pristine as it did in the 'just had its paint removed' pics as i dont have enough deoxC to totally submerge it when i get to that stage so it will get tide marks on it anyway.

FWIW I squirted some DryCoat down the overflow to help protect it from flash rusting while i continue to let the vinegar do its work. This will be fully submerged in the DeoxC later of course. WAs musing about the interesting design of that overflow and I cant imagine how much fun it would be to have to try and replace that pipe as it runs through the inside of the tank. If it failed it would of course allow fuel to just run out of the tank... has anyone ever had that happen i wonder? I guess the tube is thicker steel than the tank by quite some margin so maybe not... Perhaps the smart move at that point would be plug the top and treat it as a spare fuel tap thats always on lol.

[midlifecrisisrd]

Fingers crossed this tank survives lol

I haven had a steel overflow tube fail but I had one block solid due to it rusting

Not a big problem you'd think but if left out in the rain the water would seep past the cap outer seal and have nowhere to go untill you opened the cap and it goes straight into the petrol ☹

Steve

[JonW]

Thanks Steve!

Yes, I think the idea of the overflow is a good one, but wow replacing it would be tough on one of these. lets hope that isnt ever needed.

I was thinking, of course if it did fail you'd just plug/cap the ends. wont fix the issue of rain tho...

[JonW]

DAY 3 UPDATE:

Tank rechecked, no perforated seams or 'elbows' as yet. Phew!

More of the rust is lifting and I gently probed the extra long screwdriver around inside to chip off the rust and lift chunks down by the seams as that still feels like its 'baked on' in places and I want the vinegar to get under it to lift it off. Its interesting as when the rust lifts off it leaves a nice shiny and slippery surface that the screwdriver skates over, but when it hits the baked on rust you can feel its all rough and grabs the screwdriver with its rough surface. But, if you can pop off the rust chunks off the steel then its smooth as silk underneath immediately. Anyway, the probing and freeing of more rust chucks didnt hole the tank so thats good.

I do wonder if some of what im calling rust here is actually partly a mix of dirt/rust and old fuel thats turned into 'varnish' that is coming off. It doesnt stay as big chunks like a liner would, instead its falling apart in the vinegar and it does look 'rusty', but rare to see it come off like this and leave such a nice clean surface. hmm...

Another day would have this pretty good i think, tho needs to be upside down to do the 'roof' and I think I'll let the DeoxC handle that, Ive done 70+% of the tank with the vinegar and I bet the DeoxC is chomping at the bit to have a go at this lol.

Before that I will fit a bung to the filler hole (I found one of the expanding rubber bungs I use for leak down testing the Athena cyls fits!) drop in the wired nuts and give it a shake this arvo, tomorrow i think i will ditch the vinegar and rinse it out and see what its like, either strain the rusty chunks from the vinegar and go again or move onto the DeoxC bath.

[stirling11]

Phosphoric acid has a bit more grunt than industrial vinegar, it also does not attack the steel

It’s present in good old CLR, however it will be a bit expensive to fill the tank, unless you can get it in bulk or get 26% phosphoric from a local chemical supply company

The phosphoric will also passivate the steel so it won’t flash rush until you can get the deoxc in there

It might be worth a crack

[JonW]

No, no, honestly as I said above I'm totally good for a real chemical as I have DeoxC made up and ready for use, its what ive been doing tanks in for a while now. I just prefer to get the worst out with vinegar as its cheap and plentiful so its totally sacrificial in my mind. 60c/litre from most supermarkets, so 20L is only $12 (£6)



FWIW Never underestimate the power of cheap white vinegar, it will impress you for its ability to help with the old fuel smell and the rust, it does take time tho, but we are locked down now til end Sept at least, what else am i going to do?!

As said, when the worst of the rust has been eaten/lifted etc I will rinse with water to get the last of the bits out and then submerge the tank in DeoxC to finish the job, that is a much better product and doesnt flash rust like vinegar. But to store the tank after I will then totally stop the rusting with Dry Coat



For anyone in Aus wanting some of this, Repco have been selling it off cheap, last few that i bought were $2, RRP was $16.99.

Anyway, This is a pic i took today... it looks to me like a Politician's afternoon delight. Ahem...

[midlifecrisisrd]

We all know that's yer anal beads and butt plug 🤣

Steve

[abar121]

Lol at the screw in Butt plug.

Just by packets of citric acide from an Asian shop.

It's a lot lighter and more effective than vinegar as you can up the strength. Dirt cheap.

[JonW]

Honestly Im covered on the chemicals to do do this...

Guys, family forum.... haha!

[JonW]

Progression to stage 2.... Empty out the (now red wine looking) vinegar and (m!)any solids.

Obviously the Politician's "Rip Starter" (! as a mate called it, he knows better than me I suspect lol) has done its job and knocked off a lot of the loose rust chunks when the tank was shaken... Yeah, there was quite a lot of them, which isnt too exciting, but as we know 'better out, than in'!

This is about 3/4 of what came out.







What is bizarre tho is that the inside is really quite clean and shiny where these chunks have popped off (they really do pop when you prod them with a screwdriver), that makes me think some of this is actually old fuel varnish, but it does feel like rust when squished between thumb and forefinger.

Ok, there are still areas/patches that have rust of course, but 90% of it is clean steel now, sadly no pics of the inside as its not really easy to do.

So, onto stage 2! DeoxC



You'll see my method of raising the level, akin to that story (maybe it was a parable, not that ive any idea about such things) of the bird dropping stones in the glass of water to get a drink we were told as kids... and they say I never listened back then, pah!

[midlifecrisisrd]

A lot of that must be varnish Jon

If that much was pure rust there would be a hole big enough for a finger in it

I left my 385 sitting with fuel in it unused for 4 years. It had some 2 stroke added as I always do to stop any rust.

When I drained the tank it was fuel of red scales

Steve

[abar121]

That must be an old liner coming out!

Coming along nicely

[JonW]

Interesting thoughts guys, I do think its part rust and part fuel varnish, it was really quite thick all on the insides, hence why there was so much of it in the bottom of the tub when the vinegar was flushed out. It is a weird one tho, Ive never got so much stuff out of a tank before and Ive done plenty, so it is a thick coating.

I dont think Vinegar would lift any liner, another reason Im saying this is rust/varnish.

I will say that this tank really stank of old fuel, defo it had been in there years and then dried out fully. You could not put your nose in the filler without gagging. The vinegar now stinks of it still even now its out and no longer smells of vinegar at all, but after a rinse with water before moving to the DeoxC the tank itself just smelt of steel that had been cleaned with Vinegar.

FWIW I'm always happy to sacrifice vinegar for that kind of job, I once totally killed the properties of a large (and expensive) amount of a product called Metal Rescue with what was already in a tank; a combo of Kerosene, 2 stroke oil and old fuel. I plan never to do that again, I was gutted.

[stirling11]

Run a magnet over the "rust"

That will soon tell you how much is rust and varnish