Why did my lovely Trials Ariel seize up? A top end strip reveals a litany of horrors... 

Thinking the same myself 😕

I'm thinking the same. After you found the mistakes on the outside of the engine, you could've assumed that the rest of the engine also has a lot of bodges.

Horrendous isn't it? 😕

Thank you 😊

Whatever works and gets you home it's a great solution 😁

Whatever keeps the oil where it belongs. A friend went to Syria by 650 twin Yamaha in the eighties. She broke the rev-meter shaft right where it exits the engine on a particularly bad piece of gravel road - oil spilled, there was no time to lose and she put in an old, seasoned barkless pine-twig she found on the spot. It swelled tight with the oil within an hour and kept everything separated (oil and atmosphere, that is) for over twenty years until the engine got a thorough overhaul - and the rev-meter back working.

@@manfredschmalbach9023A brilliant fix 😊

Ive had to stuff my tire full of weeds when I got a front flat out in the bush. W/e it takes to get you home is Never a bad thing :) Cheers.

@@fetus2280 Not heard of that one before! 😁

Absolutely right. Certainly have been some bodges in its 74 year history. It will be sorted though, one way or another 😊

Thanks. Currently puzzling over some of it, but most is in hand... I hope! 😁

A new head... Nice! 😁

@@t20racerman nowadays I would have no thoughts but to make a new oversize valve guide or sleeve a stripped thread or drill out a broken bolt but he bought it without telling me in advance and who was I to argue.🙂

As a lad in the 1960s, I had a succession of such bikes that had been bodged, butchered and neglected. As you say, they were worth little at the time, and when we lads got them, they were essentially the, worn out, discarded, ride to work transport of the working man. I did my share of wrecking, stupidly using ill-fitting open ended spanners during needless strip downs, and meddling. My greatest occasion of sin was my obsession with 'de-coking' engines that before I got started on them, ran perfectly well enough. That and neglecting ever to change the oil on the grounds that it seemed to change itself by leaking copiously from a range of engine case joints. Oh - and squirting gasket sealer into joints in huge amounts and blocking oil ways. I had no idea and listened to people of my age or near it who knew no more than I did.

@@Tonyv1951 You and many others did damage, but the bikes were then of little value, not wanted, and without people doing there best to keep them going, they wouldn't have survived to this day!

@@Tonyv1951 reminds me of a journalist I knew, who related a tail of going to a petrol station with attendants, if you remember those days, and askiing for a pint of oil for her Norton, he is supposed to have said, "shall I pour it down your trousers now or would you like it in the bike first?"

Some good points there, and I agree with you - I feel I need to strip all of the engine down to see what other horrors await... 😬

Thank you - It really is a lovely bike. 😊

So nice 😁

@@t20racerman don't get me wrong, exterior parts were all messed up! Wrong mudguards front and rear, terrible repaint, mirrors with imperial thread bolts braised onto the bottom of them forced into the metric threaded hand grips... *shudder* But at least the engine and gearbox were unmolested, and fired up after I'd rebuilt the carbs.

After several decades of use and abuse, it's amazing how many have survived this long! 😊

Retire? Bikes are for go, not show! 😁

@@t20racerman Understandable. We don't see Ariel bikes much in the US. I don't think many were sold here if any. Maybe not as rare in the UK?

@@twwtb Used to be fairly common. Not like BSA & Triumph were, but still plenty around

Euthenase the critter so someone can practise taxidermy? Yuck!

They are such nice bikes. 😊

Thank you 😊. Yup I'll get it sorted, maybe not as good as new, but sorted nonetheless 🏍️

Thank you. 😊

It was a new piston - that's what the previous owner told me. The bore though was tapered and far too tight, so no wonder it nipped up on me. Will clean out the sludge trap, and considering stripping the whole lot down 🙄

Thank you 😊

Thank you. Next video out v shortly 😊

@@t20racerman Nice, looking fwd to it :)

Its a lovely old bike, and yes, it'll be back on the road soon enough one way or another 😊

Hi there Phil - nice seeing you the other day 😊 Have you tried Draganfly in Bungay for the A7 bits? They have loads of stuff

@@t20racerman Yes, they were the people who normally have gasket sets but were out of stock. Since Brexit it is a nightmare trying to get stuff posted to Croatia so that's why I waited until I was there.

@@Phiyedough Happy to post them to you if Dragonfly send to me

Yep. Premix in old four strokes makes a difference. It was common to do this on short circuit bikes back when JAP was the motor of choice. Especially when running A. Also, oil rings were not used.

@@bruceparr1678 It might be a good idea to increase the jet size if you mix in oil as the oil displaces fuel...so the actual fuel to air ratio leans out? No oil=all fuel Some oil=less fuel

@@JohnSmith-yv6eq Only about 2% less fuel.

@@JohnSmith-yv6eq Leans it out by a similar amount as a 2000' increase in elevation.

It also clears out carbon deposits in the combustion chamber. 640:1 of TCW-3 two stoke-oil is the ratio to use in all four-stroke engines, even cars.

Thank you 😊 I neglected my motorcycle RU-vid channel for a few years as I was busy with my Narrowboat one (@narrowboatadventures), but I'll be building it back up this summer. Hopefully a fair few more similar videos to follow 😊

When it gets hot the rings expand, and the gap will close up, not expand. If the gap gets bigger then compression suffers.. If the gap closes then the engine seizes.

I've measured the ring gap and it's fine, but the bore is far too tight for the piston, and tapered too!

Thank you - and welcome along! Ariel repair video not made yet...as I still haven't repaired it! A BSA one coming shortly though 🙂

It'll get repaired one way or another. So many abused engines on these old bikes, but without people like me, determined to put them right, we'd have a lot less old bikes out there :-)

I agree it's a tad lean on the main jet (I'll go up a size) but I've now had the barrel/piston clearance measured accurately and it's way too tight. Add high speed, heat and a lean mixture and there's only one outcome! 😭

I've had monoblocs and concentrics. My A10 has had both fitted in the past. Its a concentric now. Both pretty straight forward carbs

So many bodges! 😭 Glad you enjoyed my video. More to follow soon

That's how I feel - it's a tad weak on the main jet and worth going up a size, but it's not weak enough to cause a seizure.

I’d say the plug colour is OK, certainly not weak but I might change my mind if I saw it in daylight!

@@t20racermanbut how often are you on the main jet?

@@raymondsanderson3768 Not that often, but I think going up a size would be advisable. Mixture seems spot on for the rest of the carb range 😊

@@t20racerman In my view the mixture is too lean at high revs. Tight piston no help there either. I would be checking the needle profile - main jet seems fine at low to middle revs but lean up high, so you could perhaps raise the needle, or fit one with a thinner diameter in the high range. I had a similar issue many years ago with three 1 3/4" SUs - the engine would idle perfectly, run beautifully up to 3,500rpm, then lean out above that. Spent hours in the SU needle catalogue to find the needle I thought would suit, then had to order them from the UK to be sent to me in Tasmania :) Luckily they were perfect, just a smidge on the rich side all the way to redline from 3500rpm.

Not far off right. A tad weak on the main jet I feel

You, me and many others too I believe having read through the comments!

Thank you 😊

They certainly do

The solid inserts are called Time-serts. Brilliant solution, but not available in the 5/16 x 26 size I need for the rocker cover bolts. I can helicoil the stripped one though. The cylinder head bolts are way bigger than standard - 7/16 x 18 and the barrel threads can't be helicoiled back to standard from that size. I'll have to work with what's there.

​@@t20racermanif you have enough room making your own "timesert", ie a solid I'd and od threaded insert is an option. Best to use the same pitch inside and out and careful alignment when screwcutting the od or you have to make the insert overly large to allow for a mismatch in threads, but still possible. Metric threads are easier this way as taps are often available in the next size or two up but with the same pitch just like BSB or Cycle. Loctite 648 is good enough to hold the insert in place to give the same effect of the timesert's swaging feature.

@@t20racerman Wurth Timeserts are only quoted in metric. The closest metric equivalent to 5/16 x 26 would be M8 x 1.0 if they were available. I think the timeserts would have been the favorite repair for the regularly removed bolts but you are stuck with Helicoil. Helicoil would be the favorite for those bolts that did not require regular removal like the head bolts To stop the Helicoils from winding out peen the edge of the thread hole, still allowing the bolt to start in the thread. You can't use Loctite as this would ooze through the threads to lock the bolt as well Personally, as you have damaged threads all round (the tight bolts will have damaged threads) I would bite the bullet and Helicoil the lot, its just not worth skimping. A Helicoil is far stronger than a straight tapped hole due to its oversize and method of locking under load so Helicoiling the lot will be of benefit, they should not be considered as a repair but an upgrade. As for the head bolts just stay with the 7/16 x 18 with Helicoils as you have already stated that perfect authenticity is not the goal but using the machine is. I would have suggested scrapping the bolts and refitting with studs and nuts to get the most reliable arrangement since currently the tapped holes are into castings that doesn't lend itself to frequent dismantling but I appreciate that unless you remove the engine each time for a head removal or a valve check then the stud route is not practical. I see that the exhaust valve appears somewhat large. Normally for best gas flow the exhaust valve is sized at 85% of the inlet size and where this occurs elsewhere the opportunity to increase the inlet valve size (only) has netted advantages. Is the piston OE because the bore is worn, as you say with a lip but it is too tight at the bottom. The piston is for the most part scrap as the ring land for the middle ring is crushed so a new oversized piston in a rebored cylinder will probably be required. I would shoot for 5thou per inch of bore for the ring gap for an air-cooled engine and 1.5thou per inch for the piston clearance as they are prone to large fluctuations in temperature

@@clivewilliams3661 Someone good advice there. I'm definitely going to leave the head bolt size as 7/16 x18 as the threads cleaned up really nicely, although I'd have preferred a finer thread. Re the rocker cover bolt threads, I'll see what threads can be reused , and find a solution for the others. It's a shame it's such a mess, but all can be made good one way or another 🙂

No. Just clean it up and replace the rings if they're damaged. It's not gonna be doing thousands of miles at high revs.

Your BSA doctor is spot on! 😂

Hi there. Thanks for subscribing, and welcome to my little world 😊

@@t20racerman Awesome channel mate👍🏻

That was handy! Yup, I definitely need to inspect the bottom end.

Thank you 🙂

Hi there 👋 Thanks for watching and I hope that you enjoyed it

Thank you - I agree. 😁 Just got to fix it now...

Thank you. Glad you enjoyed it. But what a mess my Ariel is... 😢

It does, and it will again shortly 😁

Oh dear... 😁

It was tapered and far too tight too. 😕

Nice! Maybe show him my video too - might bring back some memories 😊

Thank you! More to follow soon

Nice bikes, but I don't believe the bodywork protected the rider from rain that much! 😁

I'd checked it a few times before, although not on a proper 'plug chop', and it was absolutely fine. Definitely a tad weak on the main jet though it seems. I'll go up from a #200 to a #210 when I rebuild it. 😊

Thank you, and thank you 😊

Thank you. Glad you enjoyed it. My head bolts are 7/16 x 18 BSF threads which will make fine torquing of the head somewhat difficult! Not ideal, but at least they are all in reasonable condition. Ran a tap down them and they cleaned up nicely. Have to work with what I've got now.... New bolts on order.

Interesting. I hope not too!

If the machine shop was worth it's charges they would have increased the clearances for an aircooled engine. I have a 1968 YG5-T 80cc that was overbored one size over (0.25mm..?) and the shop that did it mostly bore car engines and hadn't factored in the need for looser clearances because of the hotter running conditions, So it had some beginnings of a soft seize when running fast. Also running a smidge richer on the oil injection, and a slight increase in main jetting and raising the metering needles during break in. Good things to do.

Yes, it was definitely a clearance issue on mine. Had it accurately measured up and it was way too small

You do have to be very careful when getting rebores done - as you say, old air cooled motorcycle engines aren't the same as water cooled engine cars

What a beautiful bike. My Dad had a Red Hunter during the war, commuted from Kits Coty to Chatham Dockyard on it.

@@TrustMeiamaD.R. Very popular bikes back in the day, and extremely reliable too 😊

Hi Louis. Nice to hear from you - and you certainly weren't the worst! :-)

Thank you :-)

Glad you enjoyed it

Thanks, glad you enjoyed it. Yes, it'll take some sorting, but hey ho, if we're going to buy and ride motorcycles from decades ago, we have to expect these things I guess. 😊

Thanks. When I measured the piston clearance it was far too tight, and the bore was tapered too. As for the head bolts... 😱😱 It will get sorted though, one way or another

I'm putting off stripping the bottom end for that very reason... What lurks in there? 😬 A job for the winter methinks

He clearly had little mechanical skill 🙁

We mostly say 'carbs' here too 😁

Glad you found me! 😊 Classic bikes really are wonderful, but you have to be prepared to do a bit of maintenance. Have you seen my "A fast thrash in the countryside on a BSA" video? So nice to ride. Will be filming another video today - out on my BSA. 😊

@@t20racerman I will hopefully take a look later on on the big TV. Just trying to edit my own little vid from Prescott at the moment and there were some amazing classic bikes being put through their paces on the hill.

Sounds nice. JAP made some great engines 😊

@@t20racerman I loved it :)

I'm not mad on the idea of moving to metric. I'll assess everything carefully and work out the best solution - best as in effective and not too expensive. As you would know from racing - what works is what you do! 😁

Sounds nice. 😊

😁

There are a lot of engines out there that have been butchered, sadly :-(

A bit harsh!!!

Some very interesting comments there, thank you. A colder plug is certainly something to consider, although when I've checked it other days (albeit not a proper plug-chop) it's looked spot on. I'll definitely go up a main jet. Having UNF head bolts in BSF threads sounds plausible as I found the barrel threads cleaned out lovely with a BSF tap, but a die on the Allen bolts (just to see) was very tight, despite being the correct size. Yup, it's an A10 - a pretty special one. Check out my BSA playlist to see more. I'm also relaunching this channel, so more BSA vids (along with other stuff) coming soon. 😊

Maybe. The oil certainly used to seep out!

I guess so - but tapered too! 😱

@@t20racerman True...bad work or tools...or both!

That definitely sounds like a possibility.

He owned it for 12 years! Said he'd restored it, fitted a new piston (!) but couldn't get it going... No wonder huh?

Whoever assembled it didn't seem to know much at all :-(

Obviously a bit tight too then. 😊

Not sure where its from, but now I've measured accurately the clearance between it and the cylinder, its was always going to seize when hot 🙁

No, they were in place. I've had the bore honed to the correct size and it cleaned up a treat. 😊

Thank you. The bore was VERY tapered (it's been measured now) and will hone out. As for the rest... 😱😭😭😭

It was way too tight - and tapered too! No wonder it nipped up 🙄

Hi there. Yup, work to do. Not a huge fan of helicoils, although they are fine in some situations. Still working on a strategy...

Ariel recommend 5-7 thou on these! It was clearly too tight with that big cast iron barrel. I had a 441 once - nice bikes :-)

@@t20racerman That sounds right dis similar heating considered, had a 500 International with cast barrel. I have used the daily runner 441 36 years or so many barrels LOL! Wish they were more like my 72 R60/5 swb barrel wise.

Yup, quite a big air leak! The threads on these should be: 3/8 x 26 for the head bolts and 5/16 x 26 for the rocker cover bolts MY head ones are 7/16 x 18 BSF which is quite a difference.

It's about right, but with the experience I've had, I'll try a bigger main jet and see if that's better or worse.

@@t20racerman All depends on how long you actually run on the main jet. irc a freind back in the late 70s with a B25 starfire said in was runnining the best it ever did moments before the piston smeared itself around the barrel.

@@kevinwilliams4899 On my racing 2-strokes, if ever they ran superbly flat out, you'd worry - and re-jet after the race if it survived. Had to have a barometer in the tool kit because if the air pressure dropped, you'd seize up unless you re-jetted. Crazy times!

@@t20racerman If only they had had EFI and MAP sensors then.....

Modern fuels are more difficult to read the plugs by !!

Already done the brakes, wheels, clutch etc. Just the bottom end left to worry about. I'll strip that in the winter

@@retiredbore378 The brakes are certainly 'interesting' 😁

Yes, Draganfly Motorcycles in Bungay. Massive range of parts. 😊

I'll probably have a couple of M8s where the damaged rocker cover bolt threads were. Will look at putting in time-sert inserts. The head bolt threads in the cylinder have already been opened up to a bigger size, and I can't change them now. They cleaned up ok, so I'll use them - but with decent bolts to hold the head down

Look at my other videos and you'll see my 1967 Suzuki T20, and my 1980 TZ350 😁

I don't think helicoils will be strong enough for the head bolts - but fine for the rocker cover bolts. The cylinder threads cleaned up nicely - they've been taken up to 7/16 x 18 BSF by a previous owner, and although 18tpi is a little too course for head bolts, I'll use what's there if it works

Thank you 😊. Yup, some dodgy work on this bike over the years. They weren't valued as classics though back then, just an 'old bike' that needed fixing (somehow!) to get hit going again. Bound to be the odd dodgy repair over it's 74 year life 🙁

It's definitely what I should do. Tempted to wait until the winter though - rebuild the top end now, use it, then strip in the winter. Haven't decided yet

Oh my gosh... :-(

I'll go up one on the main jet as its a tad weak there. It's fine through the rest of of the rev/throttle settings though. 😊

I'm still working on the best solution for the threads. I love Time-serts as they are SO good, but cycle threads not availiable, whereas helicoils do come in the correct thread sizes The BSA is a heavily modified A10. I'm releasing a video of it this afternoon - thrashing it around the countryside! More to come. Also, do check out my channel playlists as there are a few of my BSA..

Shouldn't be a problem on one of these. Check out my BSA video dropping today...

Make sure you watch the next video to see - when I've made it! 😁

The pressure in the carb is lower than outside, so it definitely would draw air in through there. Not a lot, maybe, but it was a consideration 😊

Agreed - but 5/16 x 26 BSC timeserts not available

@@t20racerman ok, didnt know that. I assume you are trying to keep the bolt sized stock? Even though the bike is kinda not ? Personally I would just change to metric. Specially as most would never know. But either way, hope you success.

It took some work to get it going I must admit. It's run beautifully since though (apart from seizing!), so I'll build the top end back up, use the it through the summer and have a look at the rest in the winter. But yes, no big sense of confidence in the rest of it! 😬

I agree, but on plug checks when not on the main jet it was fine. I'll be going up a main jet size as its definitely weak at the top end of the throttle settings