Casting and machining motorcycle risers

[LukerParticipant @luker]

Some interesting machining and casting I did recently for my bike. Thought it may be of interest…

[LukerParticipant @luker]

[Michael GilliganParticipant @michaelgilligan61133]

Very impressive … thanks for sharing it

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

I enjoyed it too. Just the right length for breakfast coffee, and a good sell for motorbike pleasure!

Struck me how much more fun it is driving on a near empty road. Judging by the shadows the test run was filmed early or late in the day – or is it always that quiet in Durban?

In rural England it's muck spreading time, with queues due to enormous tractors hauling gigantic tanks of fermenting excrement. And making it worse the weather is good enough for groups of push-cyclists to be out 'commanding the road'. Fortunately caravan season ends before muck spreading! On top of this lot, there are rush hours as well. Driving round here can be frustrating because there are too many other road users.

Dave

[HopperParticipant @hopper]

That's cool. I need to do exactly that on my Honda VFR800. Very similar set up and getting harder to ride with every year. I guess I had better start looking at making a furnace.

[not done it yetParticipant @notdoneityet]

I went the other way when I was a regular biker – from standard handlebars to clip-ons. No doubt, by now, I would be using a more sit-up riding stance!.

Let’s face it, Blackbirds were not introduced for touring around town! The supplied kit was more appropriate for its expected purchasers back then. This was an era when my nephew was, err, travelling around on a Blackbird at high speed and usually with ferocious acceleration at every opportunity.

Good to see some proper ‘12” to the foot’ machining, as well as the casting, on the forum.🙂. Likely better than buying in the ready-made items, too.

[Anonymous]

I had a Blackbird, best bike I ever owned after I pioneered the FI loom fix that did the rounds of all the forums. Heavy lump pottering about, comes into it's own as a hyper tourer. I used Vfr Vtec bars on mine the 1" or so lift made a big difference.

Edited By Bezzer on 29/10/2022 16:03:46

Edited By Bezzer on 29/10/2022 16:04:31

[LukerParticipant @luker]

Thanks guys.

Dave; I'm very lucky where I stay, the roads are generally quiet and the trees line the roads so you drive in the shade. I did cut out most of the traffic bits in the video though.

Yep, I've also had to fix the loom. And the cam chain tensioner, which is a fantastic design, pity the manufacturer didn’t put much effort in keeping to tolerance. After re-machining the problem bits the tensioner has given me no issues. Its a good thing I can make things because parts are getting very expensive and more difficult to source.

I agree, I don't use the bike as the designers intended. I was considering getting a cruiser but my bike is apparently worth nothing; besides when I was walking round the bike shop looking at what’s available I was rather disappointed. One particular bike (completely out of my price range, and something I wouldn’t be seen driving out of pure embarrassment) had some of the worst welding I’ve ever seen on the exhausts. The welds were sensitized and there was clear over penetration. The Blackbirds welding still has the discoloration with no corrosion after all these years. I was not very popular when I pointed that out to the sales guy! Needless to say I decided to take my worthless bike and modify it to suit me…

[Tim StevensParticipant @timstevens64731]

Just a thought – I would be reluctant to use anyone's home-cast risers. The steering controls can be loaded severely whenever a quick swerve (etc) is required (as well as every time the bike falls over). Has any comparitive testing been done to be sure that hone-cast risers are up to scratch?

A further point – the slotted clamp is not as strong as using a pad bolt in a non-slotted hole. Pad bolts are neater too.

A pad bolt is a stud threaded at one end, with a cut-out in the side, towards the other end, to match the radius of the steering tube where it will clamp. Tightening a nut on the thread pulls the radius hard against the fork tube, and pulls the opposite side of t he hole tight, too – so plenty of friction.

Not my idea – used on Vincent front forks 1950 – 56. (but they were not teles).

Regards

Tim Stevens

[Robert ButlerParticipant @robertbutler92161]

Uncomfortable if you come off without gloves, ask me how I know.

Robert Butler

Edited By Robert Butler on 29/10/2022 18:38:11

[LukerParticipant @luker]

Posted by Tim Stevens on 29/10/2022 17:41:10:

Just a thought – I would be reluctant to use anyone's home-cast risers. The steering controls can be loaded severely whenever a quick swerve (etc) is required (as well as every time the bike falls over). Has any comparitive testing been done to be sure that hone-cast risers are up to scratch?

A further point – the slotted clamp is not as strong as using a pad bolt in a non-slotted hole. Pad bolts are neater too.

A pad bolt is a stud threaded at one end, with a cut-out in the side, towards the other end, to match the radius of the steering tube where it will clamp. Tightening a nut on the thread pulls the radius hard against the fork tube, and pulls the opposite side of t he hole tight, too – so plenty of friction.

Not my idea – used on Vincent front forks 1950 – 56. (but they were not teles).

Regards

Tim Stevens

Hi Tim. I understand your reluctance to consider using home-made items, albeit a little odd in the context of this forum. Unfortunately I don’t share my free body diagrams, hand calcs or numerical checks simply because people aren’t generally interested in such things nor will they understand mesh dependency checks or sensitivity analysis, etc. An experienced design engineer would have noticed the lofted upright designed to distribute the stresses to the lower ring, as well as the curved geometry to drastically improve strength while using less material (improving castbility). This of course all falls apart if you don’t grasp the fundamentals of casting aluminium and you get fade, or gas pickup or casting inclusions due to poor riser and ingate design. Again an experienced foundry-man would notice the lack of casting defects typically evident in the region of the ingate.

The pad-bolt is brilliant and is used extensively in other applications on all my bikes. Specific to the Blackbird uprights; the clamped ‘ring’ is locked in place by a ring clip at the top and located to the bottom yoke by a small tab, so the required gripping force isn’t that great. Incidentally my pattern was symmetric with the LH and RH tabs machined flat respectively.

I’m a firm believer that anybody can do anything with a little reading and just giving it a go! The notion that ‘home made’ is not as good as ‘professional’ is (in my humble opinion) an absolute fallacy.

[duncan webster 1Participant @duncanwebster1]

What happened to a bit of bent tube clamped to the headstock? Much simpler

[Tim StevensParticipant @timstevens64731]

Hello – me again

I agree with Luker, and in particular with his view that ' The notion that ‘home made’ is not as good as ‘professional’ is (in my humble opinion) an absolute fallacy.'

I was not intending to imply that Luker should not rely on his 'home made castings' but more to bring home the notion that others, with less experience, less skill, and perhaps too, less access to facilities, might be inclined to try their hand at similar components, not realising that while what was shown was indeed 'home made', there was rather more to it than that.

Best wishes to you all

Tim Stevens

[Michael GilliganParticipant @michaelgilligan61133]

A very valid point, Tim … and well-made

The opportunities for doing a job like that wrong are legion.

MichaelG.

.

Edit: __ This is worth a look: https://www.researchgate.net/profile/Sunarto-Kaleg/publication/332620161_The_failure_analysis_of_bike_brake_lever_Observation_on_crack_propagation_and_stress_analysis/links/5ebdf92692851c11a867d3f7/The-failure-analysis-of-bike-brake-lever-Observation-on-crack-propagation-and-stress-analysis.pdf

It’s only six pages, including the pictures.

Edited By Michael Gilligan on 29/10/2022 21:14:41

[Bill PudneyParticipant @billpudney37759]

I thought about suggesting that the risers be at least tempered to ensure that they were not in cast condition (T0) Then it occurred to me that the rider obviously never falls off as he doesn't appear to use gloves, so the risers will never be stressed in an emergency situation.

If this was for my motorcycle I would have used a high grade bar or plate material, 2024 T4 or 7075 T651. The machining would have been more challenging but not too difficult.

Nice bike and a nice project though. Best of luck

cheers

Bill

[LukerParticipant @luker]

Hi Tim, I never took your comment to imply I should not rely on my castings. I very seldom take issue with any comments on what I do; in fact I appreciate the feedback. I will always point out that anybody can do anything and anything is possible with the correct knowledge. It’s a fine line to walk giving caution versus dissuading people from trying. The idea is to show that something is possible which will give most people the confidence to give it a go; by reading up further. The necessary technical knowhow is probably outside the scope of a forum and more suited to formal articles/books (the benefactors of this site for example).

I have the same facilities and skills as most people, lathe etc. My furnace is not a commercial furnace, but home-made so the tools required to make a furnace are well within the average home machinist arsenal.

Michael; read the abstract, thanks for posting. Shows quite nicely how a commercial ‘professionally’ made item can fail . That’s probably been duplicated many times over so there may be a few faulty brake levers out there. It actually speaks to the point made about hardening the alloy, which I decided against to improve the fatigue life of the handles at the expense of strength (but this was designed for).

Bill; Gloves, jacket, jeans, riding boots and the front wheel on the ground is the norm!

[HopperParticipant @hopper]

Overthinking perhaps? It doesn't matter if the casting is strong enough to survive if the bike falls over and or slides down the road. Most of the rest of the bike's sticky-out bits will not survive either. Even falling off the stand when parked is enough to snap clutch levers and footpeg mounts etc and smash fairings. I reckon the casting would stand up OK by comparison.

And steering input even when quick swerving is not going to snap alloy that thick. It is limited to the force a pair of human biceps can supply through a pair of human hands. Not exactly metal-snapping kind of forces. I can quick swerve my similar Honda VFR800 with just a finger and thumb holding each bar. No great forces involved on these modern bikes where counter-steering is used..

I would have total confidence in such castings. After all, old Burt Munro got his Indian up to 200mph with homemade cast alloy pistons.

[DalboyParticipant @dalboy]

Motor bikes are not my cup of tea but a good job on the risers.

Some good points raised in my limited knowledge on these things so can't make a judgment on whether they are suitable

Posted by Luker on 29/10/2022 18:48:29:

 

I’m a firm believer that anybody can do anything with a little reading and just giving it a go! The notion that ‘home made’ is not as good as ‘professional’ is (in my humble opinion) an absolute fallacy.

I remember someone saying to me years ago

"Do you want the job done properly or Professionally"

And it always made me laugh

Edited By Dalboy on 30/10/2022 09:32:03

[Nick WheelerParticipant @nickwheeler]

Posted by Robert Butler on 29/10/2022 18:37:49:

Uncomfortable if you come off without gloves, ask me how I know.

It's bad enough to come off a bicycle when not wearing gloves.

[old martParticipant @oldmart]

I would be wary of castings used in a critical stressed application. We used to make aircraft undercarriage folding supports for electrical and hydraulic lines out of castings. Every one cost £100 to have X rayed even though they were not stressed members. We ended up saving a lot of money making them out of rolled plate, much more swarf, but they could be crack tested in house using dye penitrant, and were stronger than any casting.

[Author]

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