Motorcycle General Discussion

[Mike PooleParticipant @mikepoole82104]

The telescopic fork is still the fork of choice on most bikes including the upside down version. None of the alternatives have successfully displaced it other than on a few niche models. Much work has been done to help minimise the shortcomings of the telescopic fork like anti dive and complex spring rates and damping. Hub centre steering and the various link systems all suffer weight and wear problems so the humble tele has more or less prevailed. Twin discs must help to balance out the twist effect of a single sided setup. If you can brake hard enough to get the back wheel in the air without falling off then it’s probably working quite well.

Mike

[Bill PudneyParticipant @billpudney37759]

I did a college final project in 1991 which ended up being called "Motorcycle Suspension". It required determining what loads are applicable to motorcycles on the road, it ended up demonstrating that braking loads are the major loads in normal use. It also demonstrated that compression of the front forks under braking reduces the stability of a motorcycle at exactly the time that maximum stability is required. To determine what order of magnitude these braking loads were a series of braking tests were performed from 30 up tp 100 kph. These tests established that…1/ The "old Wives tale" about the front brake doing 75% of the braking is about right. 2/ That extreme braking was indeed a tense affair because of reduced stability 3/ That under the right conditions "stoppies" (where the rear wheel comes off the road surface) are feasible on a single disc road bike.

I had felt for some twenty years prior that telescopic forks were somewhat limiting, and ended up proposing a system similar to the Hossack/Fior layout which ultimately was more or less copied by BMW with their Telelever .

The snag seems to be that motorcyclists are very fashion conscious and want something that looks like what the motogp riders use, and motogp manufacturers are hooked into suspension providers, who are mainly interested in selling stuff.

cheers

Bill

[duncan webster 1Participant @duncanwebster1]

Clive's right, it was Roe. I like the look of the Hossack setup referred to by Bill, but as SWMBO won't let me have a bike anymore I'll just have to dream

[Bill PudneyParticipant @billpudney37759]

Like Duncan I don't have a bike anymore. Sadly after a lifetime of motor bicycling I was on my way to work one day, when I realised that I was just going through the motions and wasn't enjoying it any more….no more fun. It was like getting a bucketful of ice cold water over your head. I still fancy a 650SS, or a G80CS engine in a featherbed, or a Silk, but realistically those days are gone. Just, mainly happy memories!

cheers

Bill

[Peter Jones 20Participant @peterjones20]

Interesting how far this has gone in only a few days..

I was working in Honda/Yamaha/Triumph/MZ/SILK dealers then moved across the street to Suzuki/BMW/Vespa (?) dealers. (later dropped BMW, didn't want to be a 'boutique' dealer before it was even invented) Did a bit of work on the K series, 750 was quite a nice bike and K100 would do crazy high miles (one customer did about 245,000 )

Switched back and forth every few years as general managers believed they didn't need me to run things after I got workshops running properly.

I have 'first hand' experience of majority of the bikes mentioned (nearest Kawasaki dealer was 20+ miles away so did quite a few of those as well.)

Suzuki GT750, wasn't just fork 'problem' the swing arm was incredibly flexible, it was just a bad design and would wallow around even when in good condition (probably the real reason it was called the water buffalo?)

Always found CB750 too wide and heavy the extra torque was Ok but dragging bits around in corners limited it's use for me, my 591cc CB550F1 was much better for all around use

Also had 550's F2 and K3 ( 550FourK ) at the same time (still have original 1977 F1 don't remember what happened to the others, my brother had the FourK for several years.

Really don't remember much about FJ900, 'we' sold a couple but the earlier XS 1100 and later FJ1100 were much 'nicer' bikes for hooligans (anyone remember the 'Martini Yamaha XS1100?) that was a lot of fun as you could drift it very easily in second gear and have it completely sideways at 50~60 mph.

Sold a lot ofYamaha 600 Diversion but GSX-R was mainstay at dealers

Early-mid 80's after the GSX-R 750 was launched was when things got worse rather than better. Apart from cost cutting, the 'weight savings' using less material became a selling point.

The 'Sport Tourer GSX-F (later Katana's) were a much better handling bike with the perimiter frame but were way too heavy (particularly the GSX600F) 750 top end was direct swap as bore spacing and crank main bearings were same on all model SACS motors (even 1100 and later 1200 Bandit)

(plus, I have a 750/600 motor 'in the shed)

Little bit of modification though and even 600 was Ok to about 135., 750 was good for around 155 (it was most powerful 750 on the market at the time – below 10,000 rpm) All the sport 750's were more powerful but had to be revved harder

That's all for now, been breaking stuff in workshop although welded parts are not quite as tough as if they were made from chill cast steel then 'repaired' by being built up with MIG (no after treatment or normalising) Surprised how hard even A36 gets though.

[colin wilkinsonParticipant @colinwilkinson75381]

Mike, I agree most models have settled on telescopic forks but must take issue about the niche models bit. The most manufactured bike in the world, over 100 million, the humble Honda C90 and its derivatives had leading link forks.🙂 . My three Greeves race bikes, like most Greeves have leading link forks. Surprising how many have survived considering they closed in the early70s, although road bike production ceased earlier.

[Graham StoppaniParticipant @grahamstoppani46499]

Posted by duncan webster on 18/01/2021 00:30:02:

Clive's right, it was Roe. I like the look of the Hossack setup referred to by Bill, but as SWMBO won't let me have a bike anymore I'll just have to dream

Duncan,

as the old saying goes, "it's not what you know, it's who you know". An old friend of mine who's an ex-Cosworth employee was given the Triumph Hossack prototype as a gift by Keith Duckworth's widow.

Triumph Hossack

He was allowed to pick any vehicle he wanted from a selection stored in a hanger. He wasn't allowed his first choice, a helicopter, and was told not to be silly!

[Mike PooleParticipant @mikepoole82104]

Posted by colin wilkinson on 18/01/2021 05:57:54:

Mike, I agree most models have settled on telescopic forks but must take issue about the niche models bit. The most manufactured bike in the world, over 100 million, the humble Honda C90 and its derivatives had leading link forks.🙂 . My three Greeves race bikes, like most Greeves have leading link forks. Surprising how many have survived considering they closed in the early70s, although road bike production ceased earlier.

It’s funny the thought went through my mind about the Honda as I wrote and nearly mentioned it. On its own it probably proves leading link is the most popular system in the world.

Mike

[John OlsenParticipant @johnolsen79199]

The Honda leading links like the C90 are adequate for the style of bikes they were mostly used on, but because they depend on the fairly small axle to brace them against twist they would not be very good for anything with sporting pretensions. We had a Honda Benley 150 in the family once, I was keeping it going for my brother in law to ride. It wasn't a young bike then, being a 61 model in use during the mid seventies. It had a very comfy ride, and good anti dive geometry, which was a bit disconcerting for those used to teles, but fine in practice. It made an interesting comparison to the Tiger Cub that a friend had at the time, with its four speed gearbox, electric start, indicators, overhead cam engine and so on. Also quite similar perfromance although it wasn't built as a sporting bike, that was what the 125 version was for. The 150 did not have a centre main bearing and was a 360 crank like the British bikes, although with a more sensible horizontal split case.

John

[Ex contributorParticipant @mgnbuk]

compression of the front forks under braking reduces the stability of a motorcycle

By steepening the steering head angle – can be used to advantage for a quicker turn-in.

I was working in Honda/Yamaha/Triumph/MZ/SILK dealers

Brooke Listers in Bradford by any chance ? The only SIlk dealer I knew of – though I only saw them in passing while buying parts for my Garelli Tiger Cross. More expensive than a CB750K7 IIRC.

I hated the "funny front end" on the R1100RS that I test rode at the time they came out. I couldn't feel what the front wheel was doing & frequently locked it at slow speeds. A really rather unpleasant motorcycle in many regards.

Honda ditched the pressed steel leading link fork on the C series bikes quite a while ago – the whole range is telescopic forks now. Another rather strange bike to ride, with the front end rising under braking & IIRC they had no damping.

I have an MZ ES250/2 with Earles forks, but it came to me in bits and that is where it remains, so no riding experience on that type of suspension. Not certain why MZ had the Earles forks on the ES range – possibly because they were offered with a factory sidecar for which the Earles fork has advantages. Certainly not because MZ couldn't make telescopic forks, as other models in the range had them.

Forks with no seperate bushings don't seem to have any particular longevity problems. Mrs B's R65LS has covered around 100K miles with no more than a couple of sets of seals & regular oil changes. I did notice a stain on one stantion, though, where closer inspection revealed that the hard chrome plating has worn thin & the steel is starting to rust. Re-chrome time soon – but after 35 years or so I don't think that is too bad. IIRC Honda started with the non-metallic bushings to reduce stiction. MZ do something similar in their un-bushed fork by recommending the addition of molybdenum dispulphide suspension to the fork oil.

While various "funny front ends" have come and gone, I guess the "inferior" telescopic fork survives because to does enough fo most riders most of the time & is easy & inexpensive to make.

Nigel B.

[Mike PooleParticipant @mikepoole82104]

BMW have a history of innovative front ends but what did the put on the hyper sports RR1000? Good old telescopics, upside downies with some trick electronics. Seems to be successful on the racetrack although the various lever systems give a very good touring ride.

Mike

[Nigel McBurney 1Participant @nigelmcburney1]

I have always preferred pivoted or leading link forks, A relative had an Invacar which had Greeves trailing link forks,with the rubber spring units and no dampimg,I always thought this was a really god set up,very good ride ,needed no lubrication ,no metal to metal wearing parts,later when I was about 15 I made a set of leading spring forks for my dirt track pedal cycle,using parts cut from old cycle frames,with spring units made from frame tube with triumph cub cut down fork springs,they worked well but proved to lack strength,I then had a 1953 Dot trials with early Metal profiles forks,they were light but useless,around this time I tried out a Dot with the full length Earles type pivoted front fork,gave a good stiff ride but were heavy and tended to flop from side to side as all the weight was behind the spindle,DMW had a similar set up on their competition bikes but was a better set up and so much lighter steering,so I really favoured link type forks, so my next bike was a new Greeves trials with the rubber sprung leading link forks,with Girling hydraulic damping,never needed any attention,steered very well on or off road . the next Greeves had similar forks with improved HT tubing and better fork trail.that bike a 1961 TD trials had a hard life it was ridden in over a hundred trials and was my work and pleasure transport for over three years,and in that time new dampers were fitted and a set of the rubber units. by doing that the forks were good as new,no bent or worn fork tubes. In their day they were very good forks, and though I never rode one their road machines they had by all accounts superb road holding.Fashion,the availabilty of better steel tubing and the need for increased fork travel to be competative against the foreign CZ bikes.with leading lik forks the problem was increasing the fork travel ,Greeves tried with their steel sprung "banana" forks but eventually went to Ceriani forks.

[HopperParticipant @hopper]

You guys who thought early Japanese superbike front forks were spindly and wobbly should have tried riding a 600lb Harley Superglide fitted with the same things (made by Showa but unbadged). Or even the 500lb Sportster with same forks. We called them "Flexiflyers". I swear you could feel that front wheel coming back underneath you with a big handful of brakes. (Which were equally woeful but still capable of bending those spindly Flexiflyer forks.)

It is amazing what machinery can do in the hands of a 19 year old.

Edited By Hopper on 18/01/2021 11:08:13

[SamsarandaParticipant @samsaranda]

Clive, you mentioned the front suspension set up of the Ariel Leader/Arrow, I owned a Leader for some time and found it had very good road handling and was comfortable on long distance rides, I was in the services and commuted long distances on weekends. I did have one very disconcerting episode with the front suspension, the front brakeplate had a bush where the front spindle passed through, unbeknown to me the bush on my front brakeplate had worn and it was enough that when I applied the brakes one time, the front wheel locked solid as the brakeplate had moved on the spindle, only slightly but enough to lock the brake solid. The result was that even though the bike was two up, the whole bike pivoted around the front brake spindle, depositing myself and passenger in a heap on the road, both fortunately relatively unscathed. The necessary repairs entailed a new front wheel assembly and complete front forks, despite this unfortunate episode I regarded the bike as a brilliant piece of engineering and well ahead of its time, pity that Ariel never managed to put the four cylinder variant that they prototyped into production.
Dave W

Edited By Samsaranda on 18/01/2021 11:47:09

[Peter Jones 20Participant @peterjones20]

Posted by mgnbuk on 18/01/2021 09:58:26:

compression of the front forks under braking reduces the stability of a motorcycle

By steepening the steering head angle – can be used to advantage for a quicker turn-in.

I was working in Honda/Yamaha/Triumph/MZ/SILK dealers

Brooke Listers in Bradford by any chance ? The only SIlk dealer I knew of – though I only saw them in passing while buying parts for my Garelli Tiger Cross. More expensive than a CB750K7 IIRC.

Nigel B.

I hated the "funny front end" on the R1100RS that I test rode at the time they came out. I couldn't feel what the front wheel was doing & frequently locked it at slow speeds. A really rather unpleasant motorcycle in many regards.

Honda ditched the pressed steel leading link fork on the C series bikes quite a while ago – the

 

 

 

Friend had a Garelli Tiger Cross. His father was a dentist so had more cash than most of us.

I worked at Leslie Griffiths/Waterton cross motors in Bridgend South Wales plus Two Wheel Services across the street

TWS were more into road racing though (8th place in Production TT around 1970 on a T500)

Later they sponsored Ian Lougher befoire he got some works rides.

Personally I liked the BMW telelever for chasing around, it handled better than the GSX-R1100 up to ~130 ish on 'B' roads.

 I only ever saw one Ariel Leader, it was parked in a garden on my way to school, never saw it running though. As a 9 yr old I was quite impressed when a modified 'Arrow' did 126mph (in 1966.)

Edited By Peter Jones 20 on 18/01/2021 19:15:15

Edited By Peter Jones 20 on 18/01/2021 19:16:14

[MeunierParticipant @meunier]

Hmmm, 80 was quite achievable on an un-modded 'Gold' Arrow if you dropped flat on the tank, as Pc… X divsn stated in Acton Magistrates Court in 1963. You realise you may be in trouble when the audience in the courtroom go "oooh" and "aah" when aforesaid PC tells of pursuit on his SpeedTwin for five miles at speeds in excess of (…) before catching up with the defendant.
3mths ban led me to change to cars shortly afterwards.

My chum bought the Leader and I bought the Arrow from Pinks of Acton and we put in many pleasant and reliable miles on them (and a shot of Redex please)

DaveD

[duncan webster 1Participant @duncanwebster1]

………………

Personally I liked the BMW telelever for chasing around, it handled better than the GSX-R1100 up to ~130 ish on 'B' roads.

……….

Peter,

I'd ask a moderator to delete this if I were you, Mr Plod might be watching!

[Peter Jones 20Participant @peterjones20]

Pretty sure 'Statute of Limitations' would apply for something like speeding. (there are very few things where it doesn't apply, murder being most obvious)

It's why I don't have an issue with my avatar on sites. (or a problem relating these stories from the past,)

My 1977 CB550F1 at 100mph, rolling over to 100,000 miles many years before mini sports cams were even thought of (1982)

If I can find it on the various hard drives I've had over the years I'll change my grandsons picture to something more 'fitting'

The BMW/GSX-R happened around 1995 when I worked for Motorcycle World in Talbot Green (South Wales).

Late 80's, Motorcycle News had a 'help' feature with Somerset Police trying to contact a motorcyclist who had 'lost' luggage on M4. It may have been me as I dumped panniers after they caught fire aaround 160+ on a modified FJ1100 I had borrowed (gonig to Donnington Park, via Essex )

There were traffic camera in operation but resolution wasn't so good back then (luckily for me) 'Smoke screen' may have also helped?

That's another story though

Had a good friend in South Wales Constabulary who was' traffic cop' and 'armed response' who would tell me 'stuff' now and again. (he's been retired about 15~16 years now.)

He had some good stories about 170mph police Jaguars (one time only then full engine re-build-almost got suspended for that ) and 130mph all day everyday in the Rover SDI without a hitch, 150mph chases in the Volvo estates with 'blues and twos' going

I've been living in Florida last 21 years and would use Florida driving licence if anything did happen which is pretty unlikely

[Pete RimmerParticipant @peterimmer30576]

Posted by Peter Jones 20 on 18/01/2021 19:10:46:

Personally I liked the BMW telelever for chasing around, it handled better than the GSX-R1100 up to ~130 ish on 'B' roads.

Is that because 130mph was about all any bike fitted with telelever could ever manage?

I'll agree about the handling though I'm on my third tele-lever bike.

[Peter Jones 20Participant @peterjones20]

Yep, didn't get on motorway or dual carriageway very often during 'road tests' even though it was only about a mile away so don't know top speed of the older telelever bikes.

The late model/new high cam 4 valve motors are supposed to be good fer over 150 although I've only ever ridden a slightly modified one around a housing estate after fitting a new starter motor and ring gear. Surprisingly easy compared to earlier R series)

There was an issue with the starters though as the location could easily be 'off', alignment was by a rather loose 6mm dia pin on crankcase. Startrer motor would move just far enough to disengage then shred teeth off both parts, lock up and break nose off starter. I still have a broken 'nose' here somewhere, maybe I'll post some pics?

. Reassembling anti-lock braking system was probably more involved (swing arm had metal brake line bracket to it with no way to finagle things out)

[IanHParticipant @ianh]

Has anyone any info on what is on the inside of the jet block on an Amal type 27 carb?

I would like to know what is going on inside the jet block but am a bit reluctant to have a go at taking the carb I have apart – it looks like it is soft soldered together. I can see the pilot circuit, but what I suspect is an emulsion tube is largely hidden inside.

Ian

[Pete RimmerParticipant @peterimmer30576]

Posted by Peter Jones 20 on 20/01/2021 00:10:38:

There was an issue with the starters though as the location could easily be 'off', alignment was by a rather loose 6mm dia pin on crankcase. Startrer motor would move just far enough to disengage then shred teeth off both parts, lock up and break nose off starter. I still have a broken 'nose' here somewhere, maybe I'll post some pics?

Yep, I've both wedled the starter nose bolt lug and repaired the ring gear on one of mine. The ring gear teeth were missing about 1/3 of the tops in a couple of places so I carefully mig-welded the tops of the teeth, turned the OD  then dressed a grinding wheel to the tooth form and ground them back into shape.

Edited By Pete Rimmer on 21/01/2021 00:20:19

[SteviegtrParticipant @steviegtr]

Posted by Pete Rimmer on 19/01/2021 22:29:09:

Posted by Peter Jones 20 on 18/01/2021 19:10:46:

Personally I liked the BMW telelever for chasing around, it handled better than the GSX-R1100 up to ~130 ish on 'B' roads.

Is that because 130mph was about all any bike fitted with telelever could ever manage?

I'll agree about the handling though I'm on my third tele-lever bike.

Yes the GSXR-1100 was a dog to handle. The fork rake was all wrong. Some guys grafted the engine into a GSXR-750 frames which was much better.

Steve.

[bernard towersParticipant @bernardtowers37738]

If you think telescope are bad try riding mine with 1/4 elliptic front end!

[garyParticipant @gary44937]

hello ian h i remember seeing a good cross section of a 276 carb on you tube. enter cross sectioned amal 276 carb and you might find it. gary

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