Tiger Cub Intake Manifold // Paul Brodie's Shop 

It is nice to know that my old acquaintances Trial & Error have other friends too.

I love the even-tempered way you approach engineering. "It is a manifold and not a nuclear reactor, so we are ok!"

I think a couple of degrees to each flange face ought to do it or perhaps a little more work but cooler might be a piecut....no, one more would be better... 2 piecuts and Tig welds all the way around. Your signatures are these parts we see being made with ease. The crazy expensive mixed with the certainty of handmade is a look that adds the best kind of value, a personal touch. Time to wait patiently for the chosen solution.

I purchased the same Phil Irving book when I was 15/16 yrs , I got that intrigued by inductions and exhaust systems that I saved my money and when I was 18yrs old in 1977 I imported into a Australia a Superflow flow bench Colorado USA , i then spent the next few yrs flow testing and modifying every type of cylinder head I could get my hands on , I was fortunate to meet Phil once , was a brilliant Australian engine engineer Great episode Paul 👍👌even tho I am probably the same age , I am picking great ideas /hints from you , can never stop learning 👌Cheers Chris

Fun to watch! Bringing back teenager memories of filing instead of using the mill and lathe I wouldn’t own for 40 yrs.

Like Bob Ross for metal fabrication and such. Love watching these videos.

2 stroke tuners handbook is another good one

nice work! but to fix the carb clearance something nice would be to put some angle on the flanges so the carb is more upright compared to the cylinder... I think it would look better too.

.....one problem at a time.....how true!

I really don't understand why people thumb videos like this down. Just move along if you don't like his style. Some people are just miserable lol Enjoyed the video, Paul. Thanks!

Hi Paul, I can see a MKII manifold coming along soon!!, MKI looks good though.

In my late teens i had tuning for speed on permeant loan from our local library - it is still relevant today - How many books are still relevant after 50 years

C'mon lads, let's all buy Paul & Mitch a coffee, they need it after that new little issue at the end lol.

Paul you are an artist when it comes to machining & lathe work.

Mr. Irving owes you a coffee - his book just landed in my Amazon cart :-)

I've seen many trials Cubs here in the UK fitted with the concentric carb. But the engines may have been fitted into frames that had more left engine offset. This allows the chain to clear 4.00 section rear trials tyre (tire). My 1961 Cub runs a Amal Monobloc carb, I've not taken if off yet to measure it's size. I enjoy your vids please keep them coming.

Saw that coming mate. I’m looking at a similar tight spot with the carb conversion on my CCM F650 Dakar. It’s clear why no one has ever done it…! If you make a V cut into the thin diameter of the manifold (and weld it together again), you can angle the carb downwards closer to level, and clear the top tube. That will allow you to use one of those angled cable tube extension thingies. Nice work as always. Thank you for sharing your Tiger Cub adventures.

The frames were brazed in an open fire pit / forge. There’s a factory movie from the mid fifties out there on RU-vid somewhere that shows it..

Hi Paul, Chris here from UK. Love your shows and learn something every time.

Some nice nuts can be made by cutting the head off twelve point bolts. Drill and tap and you have nut with a flange that you can get a box end wrench on. Nice job on the manifold

Paul, you make a fine job to keep those great classic engines alive. Good tutorial. Well explained.

Paul, thin those flanges a tad for more clearance , they are pretty beefy .

Irving's Tuning for Speed has appreciated on the garage book store that became somewhat popular. I'm holding on to mine until it's worth at least 12 gallons of gas, 11 sets of decals, 10 big bandaids.... ... and a pocketful of Iridum spark plugs......

You could cut your adapter and weld it back together at a slight angle. 😂 That would fix it.

Whenever I say to the wife I have nothing to do she says "read Tuning for Speed". My copy was bought in the sixties along with Motorcycle Engineering. Phil Irving knew his stuff.

You are now my favourite guy!

from what i can remember the sports manifolds were angled so the carbs were level

One problem at a time 👍👍😎👍👍

Hi Paul Brodie. And Mitch too.

You are a true craftsman Paul

Enjoyable as always . Love watching you machine something up . Love the comment about the reactor . Mate used to say its joinery not a airlock door on the shuttle. I'm sure you have already decided on a way out of the cable access problem already so I look forward to seeing that . Thanks from the UK.

Great videos Paul. Love your work. I started on Cubs at 13 years old, so this is a great project to see. I have a 26mm Concentric on a tapered manifold. It runs perfectly throughout the rev range, and much better than the original 15/16 (24mm) Monobloc. The standard manifold is canted to level the carb somewhat from the 25° barrel incline. Good luck; this will be a great Cub. P.S. Depending on your CR and exhaust I'd start with a 200 main jet on that carb.

I am thoroughly your vids! I love Tiger Cubs. Had a few in my younger days and still wish I had my old T20M

Nice work as usual! You’re pretty brave, power tapping!

I can't wait to see how you tackle the carburetor positioning problem. I love your videos, they are very informative.

Nice work, it will be interesting to see how you solve the interference problem 👍.

Oh yeah just got my 1kg carb right here

On the Norton Commando using those type ofAmal concentrics, the manifolds are curved to bring the carb closer to horizontal with respect to the bike frame. Could give you the carb top clearance needed. Also, the manifolds have studs threaded into the carb side flange, so the carb only needs a washer & nut each side to attach and no clearancing needed on the manifold body. When you stated you would not be planning to remove carb often, I chuckled! Can't tell you how many times I've have to remove mine! Those older, non-Premier types have non-removable pilot jets and a bad reputation for stubborn clogging of the pilot jet circuits.

I had an Amal monibloc carburettor with a extended float bowl just like the points cover he made.on sports cubs in the UK 🇬🇧 they came as standard Carburettor.

Excessive heat is one of the major problems of Cub motors, as they were based on the 150cc Terrier, and fin area is marginal at best. One of the issues related to this is fuel vaporisation, which is made worse by the low-quality carbs that are often fitted. The fuelling difficulties cannot be cured completely , but can be improved a great deal by using a better carb, which is spigot mounted into a rubber intake hose.

Hi! you could make a custom carb slide cover with the cable off to the side a little so it misses the frame. and without a choke cable thread.

I agree with Gerald, that Phenolic spacer is pretty thick as well, you could get the carb a lot closer to the intake port and gain some room for the cable routing, awesome job on the manifold though, it is great watching you work Paul.

Nice work. That throttle cable location is going to bug you till you come up with a Paul approved solution.

Hi paul and mitch. Ye iv got that book too. Ye make this work look so easy.an mitch ur video work is great.

Funny thing Paul, Neil Young relates that his first job was stacking books in a bookshop; maybe it is a Canadian thing!

That is such an awesome bike.... I'd love to build one like that but I want a high powered electric QS 273 3.5t motor and Kelly 72200 controller running 80v Greenworks batteries so they can be charged and swapped out quickly.

I use a thickness collection of sheet aluminum to check wall thickness. Put scrap between driver's side thumb and index finger and the adapter wall between passenger side index finger and thumb. My middle finger and thumb combination are only used for calibration..... I think your thickness mover outer is a cool tool.

Nice work, if you put a slight slope to the one face the carb would sit flatter and give more room for the cable and allow to mount as one combined piece. But you probably know this. I found this very interesting as i recently restored my 1967 Cub.

Always fun watching you make these parts! I make nuts for exhaust flanges out of tubing and weld an allan head to the end. I don't think that would work for your application due to space limitations in the other direction but might be useful in the future. Another excellent video! Thank you!

I was taught the inside of one stud to the outside of the second stud gives you the center to center as in your manifold mounting studs. This assumes that both studs were of equal diameter and saves my from a math error!

Hi Paul 😊 i’ve just finished watching the Amazing Aermacchi Build, Now starting the Cub renovation, you showed in this video how do you get the centres of the manifold studs, there is an easy way that doesn’t involve math ….. you just measure from the outside of one stud to the inside of the other this will give you the centre to centre measurement

Its a manifold, not a nuclear reactor. Gold.

Having ridden a tiger Cub extensively in the early to mid sixties, I have a fond memory of them. II appears to me that the bike you have is abit of a mongrel The frame may be a swap over , or a one-off. The motor is not from circa 1958, but most likely a bastard version or an up-grade from a newer model. The ignition breaker was not offered by Triumph until model year 1964 and was a very welcome modification.The proper contact breaker assembly was mounted vertically in the right engine case with an internal clamp secured with a crew through the outer case cover. Th i arrangement was unreliable as it ouuld slip and cause the ignition timing to change while it was running.The frame is missing the triangular gusset welded over the jumcture of the under-tank tube and the front down tube. Some of the cubs could develop a crack in the front down tube without it. I thoroghly enjoyed your treatment on the manifoldWe never had the equipment to do such work. I hope your project runs good and is reliable for you.

Now that he's really set the hook in me, I want to see how he engineers the fix on the throttle cable location. He's so great!

Don't forget to true up the face of the carb. They are essentially a heavy lump of plasticene being shaken to pieces, and the flange is always bowed, leading to air leaks.

I know it would have been a lot more work but personally I would have made the manifold with a gentle bend in it, this would have given you clearance for the choke and throttle cable, also the carb is less likely to flood if its level, jetting it can be a bit easier and you are less likely to have the engine run rich when you are braking hard because the fuel won't spill out of the idle circuit into the air stream. Yes a straight shot at the intake valve will give more power than a bent intake but I bet there isn't a dyno that is sensitive enough to even measure the difference on a Cub engine. Anyway watching you machine stuff up sure beats doing the work that I'm supposed to be doing!

i had that book in the 60s late 60s. my brother and i used it to help tune my bsa b31 350 73 standard with tuning and lightener we got 80 mph approximately bigger card longer inlet manifolds and a bellmouth just saying good look

I think there's a slight twist in the standard Cub manifold, it's hard to see, but if you put it on upside down , the carb pokes out the other side of the frame top tube.

Perhaps you could fashion a cap for the carb that has everything where it needs to be? That damaged frame, I hope you fix it--even if you don't run it. Likely, that frame forging itself would not be a good thing to repair, but perhaps one could be made either from billet or welded metal. I am really enjoying your channel. Thank you. If you have to put in the welding music, you must. Sigh. Presently, I keep up with 135 youtube channels, dealing mostly with engineering, science, and mechanics. I come to your channel not for welding music, but instead for your skill, creativeness, experience, and expertise. [My uncle had a 1959 Triumph 500 frame, with a 650 Bonneville engine (AFAIK). I grew up helping him work on it. It was an old award-winning 1960s show bike called the "Bonnie Bandit." Oddly, he had the entire frame triple-chrome plated. I should hope that all the hydrogen was baked out of it. The tank and fender appeared like custom parts. I always wanted that bike, but wanted it outfitted more leaning toward a cafe-racer, with disc brakes and handlebars somewhere below the shoulders. It was very nicely balanced, with most of its weight low. I remember, once we went to the parts dealer, where I saw in a glass display case, an oil pump, for around $200, in 1980s US Dollars! ] Perhaps, models could be made of the old engine parts and investments could be 3D printed--for brand new engine parts.

cool stuff! Thanks.

I love watching the work on the Cub. I really do wish the camera would do a lot of extreme closeups

You guys are great !!

I wonder if making your adapter a little shorter would help with the fit of your throttle cable? Thanks for the video, great stuff! Hi to Mitch.

The threads on the Cub cylinder head carb studs are not 1/4 BSF. They are 1/4 BSC (British Standard Cycle.). Sometime in the 60s, BSC was changed to CEI (Cycle Engineering Institute ) but the thread remained the same. While 1/4 BSF and BSC/CEI share the same diameter and 26 TPI pitch, the BSF has a 55 degree thread angle (ala Whitworth) and the BSC/CEI is a 60 degree angle. While they are often unknowingly interchanged, they tend to be a tight fit as evidenced when you needed a wrench to tighten your "custom" nut. BTW, there is an OEM Triumph nut that will work perfect on that stud. Correct thread, small BS wrench size and proportionally longer in length. I'll look for the part number. As always, nice work on the manifold👍🏻

When I was in school, I read every book I could find on motorcycles, I was only 11-12,

Beautiful work, as ever, but i wonder if that is one to cut and weld at a slight angle? Many thanks for posting another entertaining video.

Remove swingarm check for "twist" also..axle holes maybe flogged out causing wheel lean

you see like phil irving when you challenge the old god edward turner you are asking for trouble

G'day Paul, Thanks for another great video, but I just need to pass on a comment. It might have been Mitch's point of view, but it looked like the rear mudguardwasn't centralised in the seat frame. My eyecrometer is good like that, & has saved me from some badly crashed motorcycles. Andrew

18.10 Bison Bial, spiral self-centering chuck MADE IN POLAND !!!

Ok , Ive watched a lot of your videos , and after watching you file corners again , Ill offer you a suggestion, instead of rolling the file round the corner the way you do , following the curve . try rolling the file the totally opposite direction , ie , the way you work in the vise , the un handled end of your file tends to go down hill as the handle end comes up ,,,, do it the other way , handle comes down and free end up. sounds crazy ,,,, but give it a go , and let me know what you find . I thing you will get smoother corners and a better finish and a lot less effort. The guy who showed me that technique forty odd years ago was a master of old school bench fitting, be interesting to hear how or if it works for you , ? T

I was thinking you might modify the frame That’s where stuff gets sticky What do you do Make a knew mor complicated manifold or take the easy route and modify the frame I liked the previous comment thinning the flanges moving the carb forward Or cut a piece of tubing and weld it into the frame making room for cable 😃 this will be interesting What will you do ?

Love the work and videos. I'm sure it will be overkill and expensive, but would you consider making that part of a super light material like titanium?

Here in the UK, there has been an awful lot of development work on Cubs, in relation to use in "P65" trials. Modern frames, billet wheel hubs, billet cartridge forks, are all commonly used. A great deal of work has been done on the motors, with some being taken out to nearly 250cc. A very common modification is fitting an 18 mm sleeve in the intake port, to increase gas velocity and improve carburation and running at lower engine speeds. The Cub intake port is overly large and poorly shaped, which is the main reason the restrictors are used. Caution should be used in relation to Amal carbs, as they are very low quality and wear out quickly, which will lead to all sorts of running problems. Heat is a big problem on Cubs, bearing in mind the motor is based on that of the Terrier which was only 150cc. The factory used to advise works trials riders, to ride through any puddles they saw, to help cool things down a bit..........lol With carbs mounted direct to the head, there can be problems with fuel vaporisation and also issues related to vibration. Most serious competitors here are using spigot mount Dell Orto's, and manifolds with rubber intake sleeve. A good carb which is rubber mounted, will improve the performance of a Cub enormously, and all the parts needed are available off the shelf here in the UK. Of course no need to worry about carb issues, if bike is not actually going to be ridden or used very much, but if it is then sorting out the carb and ignition properly is a very good idea............... Finally, with carbs mounted at acute angles, there may be problems with fuel level and resultant poor running, so if you intend to use an Amal carb, I would suggest getting a new one, so running issues related to carb wear can be ruled out.

26 tpi threads per inch was commonly called cycle thread when l was dealing with motorcycles, all diameters were 26 tpi. BSF the no. Of tpi depended on the diameter of the bolt or threaded rod as l recall. However there was a size where both were the same no. Of tpi but l cannot remember what sizes they were but two different spanners fitted the nuts maybe one was 1/4 and the other 5/16 or 3/16. It was a long time ago in the late 1940s or. 50s.

Manifold came out beautiful. You'll need to remove the air slide (choke) plunger I've had that same Phil Irvin book since around 1978 when I got a second hand one. The early remote float carb, even though small diameter will flow a lot more air than the mono-bloc or concentric of the same size or larger as it's a 'smooth bore' carb and acts about 5mm larger than actual size at full throttle but with better pick up due to higher gas speed at low rpm. They do have issues with fuel delivery on sidecar outfits though, I remember my father building a dual float chamber for sidecar use. Isn't 26TPI a British Standard Cycle thread? The lightweight carb is aluminium for a trials cub, the others are zinc die-cast (probably Mazak?) so much heavier. About the only thing that beats them for weight are the remote float early carbs cast in brass, often nickel plated (but look really good and 'vintage' when polished)

You remind me of the great Burt Munro. 😎❤ Btw, my mom's dad's name was Boyd. Be glad you're not called Brody. 😄

👍👍

The horizontal top frame tube on the Cub looks all wrong. Why didn't they make it angled to join the steering head tube higher up? (would have solved your throttle cable routing, too!)

I have a disappointed, I was certain that you were going to use the cub as a 4 speed Supercharger for the Aermacchi.

Thanks I like your show !!!

Why do I have a feeling you are going to remake this one?

Love your content. What do you use for cutting oil?

Use a brake noodle on the carb.

The concentric and monobloc designations should be stamped on them, a 626 even concentric could well be too big for the 200cc engine in the venturi area, too much air being drawn in no matter what main jetting you use, unless racing or whatever. The very small carb may have been for a 150cc Terrier, predecessor of the Cub? Some of the Cub manifold adaptors are angled. Monobloc 376 types are fitted to later cubs, jettings can be found in many places.

You need to have the float bowl level or you will not have a proper float operation and your carburetor will have abnormal fuel air ratio fluctuations. Make a new manifold to accommodate a level carburetor and it will solve you choke and throttle cable problems.

I see what yo yo up to at 15:30.

Measure one stud. Zero the digital caliper, and measure over the two studs. No math involved.

Paul, that Triumph Tiger Cub Bible costs around 500$ 😆

Did you put the adapter on upside down causing the carb clocking to be out?

you make 45grades choke and gas cable

A slight downward angle on your manifold might have helped. Still non of us are perfect Eh! Paul even you!!!!

Measure far to near. The outside of one stud and the inner side of the other. Done, no math.

😎✌

What's the reason for such a long inlet manifold?

spin the carb top around to clear.....i think.

Hi Paul, I have the same issue with my cub and a concentric carb, did you fix the issue?

Carb maybe correct..head may have been ported

The engine maynot "drive" oversized carb at low rpm...not enough suction

I bought a new Triumph T20SH Sports Cub in 1965 and the wheels on that were not 'in-line' either.