Why did my Ariel seize? Part 2: Assessing and repairing the damage. Good progress made.. 

With the state of the top end you should definitely strip the bottom end, it could be bodged as well, I’m just trying to get you to do more videos because I find them very entertaining, thanks keep up the good work

As it was running well, I’d leave the bottom-end and ride it for now, and possibly strip it in the winter if you think it needs it. Too much riding time can be wasted in the garage (ask me how I know!). Les

Thanks for taking us along with your rebuild. I love Arel motors. We fix everything with J-B Weld here in Texas. Cheers

I love it when a plan comes together. Bang the top end on and see how it runs. Then strip it all down in the autumn if you have too.

Adrian, one solution is to look back to the past before helicoils when engineers turned up an internal/external threaded bronze insert. This method was used by BLR engineering at Surbiton, Surrey having done a few for me.

It's a shame that someone before you did such sloppy work on such a beautiful machine. Well done sir.

love to see old iron kept running

Get out there and strip it down in the winter :)

Don't strip the bottom end, as if it gets noisy, it will give you a winter project. A man of your calibre can deal with that. Plus it will give you the opertunity to see how the JB weld fairs under the summer riding. You can take measurements of the position of the centre of the JB weld threaded hole with respect to the other three bolt hole centres if you need to rework it.

I would flush the crankcases and look for glitter. If there was nothing untoward, I'd go ahead and put some more miles on the bike. A winter strip-down will tell you how well the top end rebuild has succeeded as well as revealing the health of the bottom end.

Assemble and enjoy the rest off summer, then strip the bottom as a winter project!!!!

Good work! Do the job once and for all!

Interesting videos Adrian! A 90 year old friend who is an accomplished vintage m/cycle engineer said in reference to your engine that someone may have fitted an alloy piston made in Italy or Australia! The alloy is a bit 'leady' and he did say that you need 6 or 7 thou clearance. Interestingly, he said that there are no pistons made in the UK anymore.

I would never have thought of using a Helicoil in JB Weld! I HAVE used JB Weld on my truck to fix the Differential (where someone had not shimmed it properly and caused a side bearing to fail), and it's held for 15 years now! I expect that your fix will be as good as permanent!

Adrian I'm sure you are aware but ACCU is a great place for all types of fixings and ancillaries including Imperial nuts & bolts

Thanks for the video. I have a 1937 VH with the later enclosed valve cylinder head so pretty much the same as yours. Looking forward to the bottom end strip.

OOOhhhh a Lister DK, very nice, I had one once, it had a radiator as well, right now though I just have a standard D.

With the amount of booger on the top end I would crack the bottom open and have a look. I still say some hack started to rebuild that thing and found out they were over their head. Slapped it back together to get rid of it quick. You might get lucky and the jackwagon stopped at the topend and the bottom is fine. Good luck on whatever you pick. For the rocker covers JB weld works great. I had a chevy v8 that had 2 out of the four bolts on the valve covers strip and I jb welded studs in place. Never leaked a drop after my roadside fix.

I would leave until after the summer as it was running fine. Enjoy the summer then investigate, after the horror of the top-end you can't risk leaving it too long.

great job lad keep it going

Great job. If bottom end not broke don't fix it, wait until winter if needed. Mike.

26TPI is cycle thread, I used to get taps and dies from place down on south coast (Tracey Tools in Devon) Never found JB Weld to work well on things that get hot but it is one of the highter heat epoxies. I would strip it, even if you want to get out there on it, failed big end, main bearings or timing side will ruin your day. You can check crank for proper alignment, make sure magneto base isn't worn strange shape and needing shims, (either mag or crankcase) and check the oil pump isn't too filthy or worn out

As already stated by someone else, coarse threads for cast iron aluminium etc ie soft metals. Don't use bolts. Turn the bolts into studs. UNC on one end for the cast iron and UNF on the other for head nuts. JB Weld bad idea. I use JB Weld and am a fan - but not in this instance. Do the job correctly. Plug the old hole first with a threaded plug of cast iron - whatever size fills the hole. Use high temperature Loctite. Then same routine as before - drill tapping size through rocker box bolt hole and tap thread. If it were me I would also convert the rocker box bolts to studs. Less wear on the threads in the head.

I can see why you are torn regarding whether or not to strip the whole thing. If it was mine I’d check the big end for play in both directions. If no wear then reassemble and enjoy.

My W/NG nipped up after a rebore. The bloke who bored the barrel gave only 4 thou clearance. I honed the barrel out an extra thou or two, cleaned up the piston and she's running as sweet as a nut! Lesson learnt, always check the piston to wall clearance.

Hello Adrian, 1 On ringed piston engines the bores should be substiantially parallel. If tapered as your trusty Arial was the rings will expand and contract with each stroke, which could well lead to fatigue cracking of the rings but will certainly wear out the piston ring grooves. 2. I don't like helicoils as it is possibe to ping out the end of the coil whilst screwing in the bolt or stud , especially if working blind and the bolt goes in at an angle. Also the top end of the helicoil has to be a turn or so below the surface or again the bolt or stud can lft out the insert end. 3. What I have done is do a bit of research and find a thread bigger than the bolt which has its minor dia. a bit bigger than the original thread major dia. Then tap the housing out that size and make an insert of the same material as the housing or maybe a stronger grade, leave the threaded end on the bar and screw that in tight into the housing. Saw it off above flush then in the Mill, mill it back to almost flush then diamond file down to flush. Next fit the mating part and spot through with a drill that is a close fit in the mating part's hole. Remove the mating part and next drill a small hole down at the intersection of the insert and the housing and turn up a slightly tapered pin to be a press fit into the hole. Press in, cut off excess and finish flush. This axial pin then stops the screwed in insert from ever turning. Set for centre of the spotted through hole and drill and tap for the original size. Smallest insert I have done is 10BA on a 1947 model aero engine crankcase, so should be a lot easier on motor bike sizes! For cast iron parts the inserts could be made from mild steel though cast iron could be used. Best to use mild steel for the axial pin. On my 500 DB Gold Star the big ends as fitted by others never seemed to last. 2 years at best. So when the timing side crankshaft broke I fitted the new shaft myself after getting it nickel plated to bring it up to be a press fit in the steel flywheel and also fitted the new roller big end myself, corrected original BSA manufacturing faults as I went (conrod big end bore had a false start so was tapered) and that assembly went for many years and did not fail..

Change your gear case oil and inspect. If you want you can have a sample tested. Unless you have crankshaft seal issues put the top end back together and Ride!

Doubt it applies to four strokes (maybe it does?) but I have a Fireblade but recently got back into two stroke scootering again (Vespa PX200E). Learning this time around, I realised most of our seizures on Lambretta's/Vespa's back in the 80's were because we tuned them but did not understand two stroke mixed fuel is: 1 Fuel. 2 Lubrication and most importantly 3 COOLANT!!!! We ran them lean for "power" but never understood this critical knowledge about fuel being a coolant! Immediately they began to nip up we'd do the worst possible thing and close the throttle, depriving an already overheated engine of its coolant!

Unless the casing is a leaky basket, I would check slack on the crank bearing, and if ok assemble top end.

I would definitely strip the bottom end, given what you have found so far. That is good news about the head bolt threads as they are the most critical ones on the whole bike.

I have just read down the other comments and see someone already made the same suggestion as me . Also those look like stainless bolts on the rocker covers , and where used in cast iron can pick up threads after time .

my enfield 350, I use the same head barrel sealing lapped in ,,,18000 miles no probs !

you dont need to strip the bottom end but you need to pull it out of the frame , inspect it thurerly ,conrod play , distribution , oil pump , if its all ok just fit it back and go for the races . cheers!

The mixture looks fine to me.

As other say “ Leave it alone ! “

leave it for now and enjoy it as you say it was running well so🤞

Definitely strip the bottom end. The previous owner was obviously a criminal. You cannot possibly rely upon any aspects of that engine. Good luck.

Gearbox on my MZ ts150 is a bit noisy, but the gears go in fine, so I changed the oil and left it, still going strong. So don't beat yourself up, get out and ride it. If it starts to feel iffy it will keep you occupied in the winter😂

It's just a couple of hours work to remove and strip the bottom end. And if it's all good another couple to reassemble it. Any issues and you'll be glad you did it. At least you'll ride confidently. On the other hand if you don't do it you'll be second guessing yourself every time you kick it over.

"Do it once - Do it right" Of course, do the bottom end. You won't regret it 😊

Have a good look at bottom end too…just to satisfy yourself all is OK. You’d hate to have to pull the motor apart again later.

some of the bikes had a thin copper ring as a gasket I dont know Ariel it was like shim stock anneal then tighten down, run the bike and check

Trouble is if you don’t strip the bottom end you will always be listening for something, and hearing noises that are not there , if it was the winter you wouldn’t think twice

Hi Adrian, I well recall my late Dad, a very experienced mechanical engineer, explaining to me that coarse threads were used to secure studs in cast iron blocks and fine threads were used on them to secure the head for the reasons you explained. So, how were the original factory fitted heads secured? With fine threaded bolts? If so assuming the barrel is cast iron my Dad would have said they were wrong. The lass or glad who fitted the larger bolts coarser threaded bolts may well have been worrying about the old fine threaded ones stripping out of the barrel under load. Since the threads cleaned up easily they must have been formed well, somehow muck has got down them over the years. And, while I'm at, what was with that hole in the top of the carb? I'm amazed that no cylinder gasket was used, but who am I to argue?

I cant believe you used JB weld to hold a bolt, not once in history has glorified epoxy body filler ever done the job. The hole needed to be cleaned out properly and welded up before retapping to the correct size.

Hi I know it's a bit li g winded but now the barrel is tapped 7/16 × 18tpi unc I think I would make custom studs with that thread form for the barrel with a 7/16 × 26 this at the other end This would give the same clamping force per unit torque as was originally required if you continue with a corse bolt the clamping g force will be reduced for the same torque applied, just a thought it's what I would do coarse in castings fine with a nut

JB Weld has a quoted tensile strength of 5,020 psi. That's less than a third of aluminium and anything between about a half and a twentieth of cast iron. Just don't over tighten the rocker cover bolts to avoid pulling the helicoil insert out. The insert will be fine with the wear on the threads but will not be as firm as one screwed directly in, if there was a decent hole to screw it into!

You know the score Adrian, if it were me and I didn't investigate the bottom end it would forever be preying on my mind !.. While you've got the engine apart anyway you may as well go the whole hog and make sure it's all sound rather than have it fail later and have to repeat the process.. But of course, that's just what I'd do, and it's not my bike or my riding time I'd be sacrificing !..

if you change the tread pitch don't you get different clamping force for a given torq number ?? Keep up the good work

Hi strip the bottom , who knows what you will find , like the top end? Many thanks enjoyed the video. From Nr Chester

Perhaps it could use a rebore?

If someone told me Adrian was the first cousin of both Sean Lock and Cristopher Lloyd, I might believe them.

Don’t take a chance having got this far, strip and check that bottom end now.

Is it just me, but does that Ariel head look sort like a cross between a HD Ironhead and a Knucklehead from the top?

Enjoy it but strip over winter

You gotta open and clean the bottom..you will have debris from the seizure .... you just had a new piston and cylinder work..which you can destroy if you don't do it properly....

Go on, strip the bottom end! If nothing else for peace of mind....

Split the crankcase, split the crankcase, split the crankcase....... Pleeeeeeeaase!!😢

Did you gap the piston rings?

Excuse the Aussie ignorance… but what is ‘firefly’? Regards Robert PS Given the bodgey-ness of the top end, I’d go for the bottom end rather than risk it.

why would the tight barrel decide to cause trouble after all these years of not?

I would........

Any news on the sick Ariel Adrian ?..

Off subject but do I spy a set of Suzuki T250 barrels behind you right ear ol ? 🤔

Next job - fix VM30 😎

Strip it down and check it out. It won't take that long and you eill have peace of mind instead of sitting on the bike every time you go to ride it saying to yourself I should have done the rite thing when I had it down that far.

Naaaah! Ride it till it breaks then you'll know where the problems lie.

Whilst you have it stripped so far……

If you really love the machine do it properly, and once.

You have no choice really. Horrible place to be. You need to strip it down. If you don't strip it down, ride it and then something catastrophic occurs, that you could have avoided by stripping it down now............how will you feel then?

Just run it the rest of the season, if something major was wrong with the bottom end you would have ventilated cases by now anyway!