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NickL #846511 04/19/21 10:29 am
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I have a 23 I was collecting. For another 4 speed, I had one of the seconds and one of the 1st and need the other two. Ben and Paul's A65s have C/R now and they are so much better. The ball ended plungers do not fit the 5speed apparently. I'll see if I can find out who has them. If you have it out to fix the box definitely fit one. The Firebird doesn't need C/ratios 21-47 is easy to pull in any gear. I still think you should try a head on your thing.

Ben got a pair of 34mm PWKs the other day for under $100.

I have a stock '71 twin carb head I tested the other day because it's actually ported like a '68 Spitfire, though with 30 not 32mm opening. I just compared it to a std 70 port which should be 109cfm, if that's the case the 71 is 122cfm and if they were all like that BSA were on track. A friend in the US did a 13.01 quarter on a 71 with open pipes @ 99mph. He said a '70 was a second slower and the head may be a lot of why?.

A misfire or broken clutch cable can destroy those gears. And I expect the weight of a sidecar and passengers doesn't help. I had 1st jumping out, and it's not very satisfactory on full noise. One of the causes was me, stress, having your foot hovering over the lever and easy to bump, so must kept the toes on the peg till the red light was on, then move it. And keeping the foot away, you have a good millie second after the red frown

That sliding gear on the lay shaft could go deeper into first with the welded track and the shaft location meant the dogs in the other direction were also fully in. It fixed it.

I once had a couple of gears with rounded dogs built up and recut, they are std and I never used them because I got others. I think they were sprayed with hard facing. They could be undercut so load pulls them together, that's how the 5speed is but neutral needs getting while moving because it's not possible stopped.

I don't know how much heat the gear takes doing the dogs, it may effect hardness if it was really heated? But I don't know what was the case. But good gears with rounded dogs may be worth salvaging. Maybe you could put 'heat ban' on the gear except for the dog area?


mark
British motorcycles on eBay
NickL #846552 04/19/21 10:53 pm
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I have actually put rake on worn gears dogs before but it goes through
the hardening and they burr up very quickly. It was a very laborious
process to do, i didn't have them re induction hardened which i should have.

By moving both shafts when you setup the box, you can get full engagement.
The two big further improvements to my old outfit were the outrigger and
speeding the box up by fitting a 33 tooth engine sprocket. This one has
the outrigger but we need to get a 32 tooth engine sprocket sorted out.
(33 has to use pre stretched chains)

With a solo, you don't drift around corners on full noise over bumpy tracks
pulling twice the weight, you don't spin the wheel up when pulling away etc.
Sidecars are very hard on gearboxes and the a65 one was never really
a very well engineered unit to start with. It's the reason i was looking at
cutting the back of the motor off and using a modified triumph box on my one.
It's always the same problem, 2nd and 3rd sliding gears are pushed out
of engagement by the torque, this starts the rounding of the very poor dogs
and this just gets worse as they are used. Probably a 5 deg back rake would
have made the box 80% better but without spending heaps of money, i'll
never know. (The unhardened version i did was around 8 degs, it was better
but as the dogs were soft it didn't last long.).Starting from scratch the mainshaft
should have been 1/4 inch larger in diameter, AMC/triumph type dogs and
selector cam plate etc etc. You don't just get a box out of a c15 and make it bigger!
The blokes at beezer knew this but they were never going to get it sorted.

Please let me know who makes those plungers, i'll definitely give one a go if
you think they are that good, otherwise i'll just fit an old valve spring into the
plunger eh?

NickL #846648 04/21/21 1:20 am
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https://www.ebay.co.uk/itm/BSA-A50-...ll-gearbox-plunger-57-3660-/274588653499


Try this Nick.

Do you know why the outfit smokes a bit? Might it have a crack in the JB? A light up the port in the dark with the R/cover would show it. My brothers had a little patch under the valve spring that came out. I fixed it without removing the head and he's had no problem for 6 or so years.


mark
NickL #846671 04/21/21 9:18 am
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NIck,

Try Morries Place for the 2nd gear for a quick solution. They should be listed in site sponsors above. As you say, they are starting to get hard to find and so priced accordingly.

Ray


BSA 1969 A65F
BSA 1966 A65H
Triumph 1968 T120
Kawasaki A1R
& too many projects!
NickL #846747 04/21/21 9:40 pm
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Mark, i fitted a set of rings which i wasn't happy with when i put it back together
after morgan park. They had cooked the motor a little there running with a split
inlet rubber. I have another set of rings for it, i doubt it's the port leaking as i went
through those very thoroughly when i had the head off and valves out.

Ray, i think Baxters is the only place with those gears now but luckily i still have
a couple and Bill, the guy who owns the bike has a few. A mainshaft 1st 16t is
what i am missing for another spare box.,

Tom there were about 5 revisions to the camplate over the years, the one in this
bike is the later stepped one thickest and best cut of all of 'em. Shimming the top
or moving the shafts about is all part of setting up the A65 box, i know from bitter
experience. Unfortunately i chucked my cut away gearbox section made years
ago when i was racing, that was helpful with the setup.

NickL #846807 04/22/21 2:12 pm
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I'm saying nothing about a 16T. Except I'm sort of needing the other one. Do you know what size the motors in the Triumph and Norton are Nick? Watching the videos I can see what's so fun about an outfit, it's a team, and you share the fun and accomplishments.

I started doing another Lightning head. They are pretty easy because they don't break through. It's got std 40.5mm valves but is flowing pretty good. I noticed an interesting thing. I did one port and tested it, kept having to turn the vacuum up to keep it on the test vacuum as I stuffed with it.

If it flows better the vacuum drops because the air goes through easier, but you test at a set pressure. Anyway it got good numbers, I put a stock port on and the thing wouldn't even adjust back enough without opening another air bleed. But I thought I'll see what vacuum is actually needed to pull that much air through the old port and the thing was flat out, heaps more inches of vacuum and it was still reading low. Higher than before but still crap and far below the new port. I probably should have switched the 4th vac on to see if it would do it or pop the circuit breaker. Or just pull the water right up the wall.

I had a thought about this, and what it may be doing, because the Firebird is very interesting. If you increase the total flow of both cylinders enough, the amount of air to burn can approach that of another stock cylinder being added. And how close can that be to having that effect. If the air is travelling at higher speed in quantity it's going to push harder into the cylinder before the inlet valve shuts while the piston is rising on compression. HP is dependent on how much air is in there when it fires. Why blowers are used. Or big displacements, they create more vacuum to pull the air and overlap does the same. It doesn't necessarily need higher rpm to do that because the port is pretty small. A big port doesn't do the same thing because the gas speed is slower and it's inertia is less. Or looking at it another way the boost pressure is less. And up till it runs out of air the more it revs the more it gets. The Firebird also does not ping at all no matter what. A65s with std pistons often can. And maybe the charge enters better?


mark
NickL #846868 04/22/21 11:36 pm
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Matt's passenger had to leave after the first practice session on Saturday so
the guy who we press-ganged into swinging had never been on a classic
outfit before. He normally passengers on modern outfits. He was lost when
they first went out for practice but we showed him how a front exit works
and he did his best but struggled moving from left to right. Matt went onto
the grass once or twice and had a couple of interesting moments but managed
to get in front and stay there most of the time. The triumph is an 840 and the
Norton is a 920 both on methanol, the vinnie at the back is still a work in progress.
I got him to fit an EI and it actually runs now but he has to get the fuel side sorted.
I don't understand some blokes, he had never owned a vincent before and he
bought this one. He has spent about a zillion dollars on it and it has 1200cc bloody
great carbs, methanol etc etc. Why didn't he start from scratch, they produced good
power as a standard bike. Surely just put it into lightning trim and start from there?

Lap times were not that brilliant over the weekend by anyone. Matt's were the best
but not as fast as he had done before. A last minute change of passenger will do that.

The gas speed thing is important as is the inlet track length as far as cylinder filling
goes. Getting good turbulence in the combustion chamber is the way to stop pinging,
that can be helped by the way the chamber is filled.

NickL #846885 04/23/21 4:23 am
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Don't be slow Nick.

https://www.ebay.com.au/itm/1142620...RHsNIeBV5ovWYKh4qJ6uZm6B6XtkORCcuP60Kjnw

16T 1st.

First test of the left port heaps better than the right, and I think I know why. ridiculous with a std 40.5mm valve. Improved conversation quality. Man what have you got done to that! Stock, stock etc, stock valves, just matched the ports to these nice chrome slide 34mm carbs, nearly $100 the pair new. Way too big Man. Yea I know... where's a hill.

In a discussion amongst enthusiasts in popular theory the big things on meths would win hands down. Certainly humorous for us who love our BSAs. What's it like on long straights?

I know Paul enjoys his. He does rallies and things and drones along for hours. Guys on new stuff kind of look down on it, 'What have you been sitting on?' 'No no no they they won't do that!' 'Ha ha' 'The think would blow up'. But they forget they are at the same rally and everyone goes home sometime. And they will be rounded up with the A65 on cruise speed. One guy had a newish Triumph with pipes, sounded great, set up on a dyno 60hp at the wheel. Couldn't match the old thing on hills and big straights still no go.

Last edited by Mark Parker; 04/23/21 4:50 am.

mark
NickL #846890 04/23/21 6:45 am
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Cheers Mark, i'll get onto that gear.

Matt says it just keeps pulling now, he needs to get a better rear tyre as
it's 'lighting up' all the time, off the line especially. Looking at sorting a 16in
car wheel and making a hub, that should give him some choice of rubber.
It's a fair job as he has to run a drum brake but we'll see. Means making
a new swinging arm too. I doubt it will be done for the titles this year but it
is on the cards. I have still got 32mm venturis in the carb at the moment,
they will go to 33 for the titles, means smaller air correctors with the weber.
Still a few improvements to make, but a bit at a time is good. Making sure it
holds together is important, seems good so far except the gearbox but i think
he's just going to have to live with that like i did. He's found another a10 crank
so that's a good move, we'll get it drilled for end feed and a bearing fitted etc.
He's got a later t'bolt head which i think he spoke to you about, it's in much better
condition than the one that's on there, we'll see about getting it welded up and
stubbs put on.

I agree with you, those old bsa things never did much did they?

NickL #846898 04/23/21 9:01 am
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I was actually interested in what a 650 would do with some rpm.

Balanced to 56% the guys testing balance factors for BSA said it was the best, and smooth around 6,000 but the factory chose to stay with 70% because it wasn't so lumpy down low. Down low means lower frequency which may mean fillings staying in and maybe it's not that bad, not like 7000 at 70% high frequency. If the testers said 56% was better, why not go with it, at least on the Spitfires and get some owner feedback. They just paid specialists to study it with a bunch of engines. Did people really get around at 50mph? Because I do not know any of them. If I knew I was drilling the Firebird in the right place I'd do it through the sump.

If Matt eggs the stubbs and has them a tad lower we can get a bit more out of it, enough that it should be noticeable. Ben's thinking of getting one for his 750 RGV because the carbs are closer together in the limited space and he can use the std RGV fuel tap because there is room. He bought some PWK 34s which are also much lighter on the throttle than the 38tms. And his wrist I think is the main reason.

But if we do that I think he needs to dyno it with the big head first, just to see where it's at.

Always good developing stuff in stages. I don't know if a bolted 90degree would sustain full noise for an extended period but they seem strong. I would not bother with a long stroke just add rpm. I have a map for the crank if you want to try one. There is no shortage of stock cranks.


mark
NickL #846966 04/23/21 10:57 pm
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Maybe with a solo i would agree with you but with an outfit the increased stroke
and lower revs makes for increased torque, that gives better drive out of corners
and less wheelspin etc. I agree you would be able to happily see a 650 revving to
8 or maybe 9k but to sustain that the flywheel would need to be lighter or the crank
would need to be offset. They would break otherwise through flexure. What i would
really like is a set of bigger barrels and run 80mm pistons. That setup just suits the
engine really well.

NickL #846988 04/24/21 5:00 am
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I like what he's doing with the smaller motor it makes what he makes it do more special. Like being stuck with a Thunderbolt head, that kind of adds to the whole deal. If he's using around 6,000 56% is supposed to be good there, naturally I haven't tried it, but definitely would if it wasn't such a big job..

I think 80x74 would be the best on a solo and 90 smooth and can rev, though a stock bore and stroke might be more fun. And cheaper. If you want to try a 34mm Lightning head with 34 PWK, around $100, 150 main jets about $20 more, split cable, anytime with changing nothing else just send a head and std valves I'm sure you would be surprised. See if you can figure out why it does what it does. It doesn't have to rev, just feels strong by 3,000 just with a bit of throttle in top, or stronger with more. You don't need to go fast it's just really nice till you hit the vibes. But different bars may be better because there's not
a lot in the seat and pegs but the instruments blur.

I could get this finished and make it at least as smooth as an old 3cyl.

[Linked Image from i.postimg.cc]

The old pommy git seems to have that weber working really nice.

Last edited by Mark Parker; 04/24/21 10:24 am.

mark
NickL #847057 04/25/21 12:25 am
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80 x 74 was the nicest version of the engine i ever ran, balanced on edges at around 60%.
Back then i just couldn't get enough power out of it, revved to 8k no problem. That's why i
would like to do an offset version of that one day. I'm pretty sure now that with help we could
get 75bhp from that setup. I could never get more than about 64 in the 90's.

First up though is working with what we have, we need to get a rear tyre with decent rubber sorted.
Plus a gearbox that holds together for more than 2 meetings. (something the factory boys never did!)

NickL #847081 04/25/21 7:53 am
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What you have seems to be working. I guess you know it should make best power around 8,000 probably. If you could get your hands on an A70 crank. If it has a bearing outside the alternator it may help prevent it flexing as well. If you get a piece of wood between two bricks and put your foot on it the ends come up. If you secure the long overhang it is more difficult to bend. My friend runs a 74mm with steel pin with blower on Nitro. For very brief periods.

P4 would allow 80X74 and 744cc if it was solo the 4 speed would last better. A Rickman would allow all round discs and decent front end. It would be hard to beat even with the big inch multies I would think. A modified Rob North style as well if one could weld it up. Ben's got an OIF he wants to run so rear disc is not allowed and it's just more expensive setting up a drum rear, because a stock wheel would be pricy plus limit sprocket choice. So Jap has to be it even though I have a Rickman hub and disk. Available then but not allowed like the forks.


mark
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With the early cases there is no solid support for a crank outrigger bearing
but i may have a look at doing something. Finding a good A70 crank is very
near impossible now, we may as well go to that chap in the 'states who has
some A10 suitable for A65 ones on the shelf. They look like a very nice job
but they are not cheap and we have to keep this in the realms of reality.
If we had a sponsor who was wanting to loose some tax money somewhere
things may be different but you have to draw the line somewhere.
Running this engine up to 8k would see it lasting very little time, the crank is
50+ years old. (mind you, when it was jumping out of gear last week i think
it probably saw over 8k a few times.......)

Last edited by NickL; 04/26/21 11:36 pm.
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Hi

Not trying to but-in. For mounting an out rigger Brg on these cases, although you never said if it was the original three long stud type! Or the next ones with the alloy bracket. Guess if its the first of them, you could machine a flat on the casing to accept the alloy bracket and allow you to clamp it down to fit the out rigger in place of the alternator.
Or (not so good) mount the Brg into the primary cover and make a shouldered crank nut, which slides into the Brg when fitting the primary cover.

my tuppence worth

John

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Yes John, we have to 'appear' to be abiding by rules so pre 62.
The cases are the very early type, a pain but i think we can do
something as you say getting the removable carrier to put the
bearing mounting in. At the moment i am mulling over fitting the
later type gear quadrant with the bigger bearing area, it's a lot
better than the original which is just the shaft coming through the
timing cover. It means i need to sort out the stops as the early ones
used a forked arm onto a peg outside the inner cover. They dropped
it quickly as it was pretty bad. He is going to run this 650 engine at
the July meeting so i'll get a chance to put a set of decent rings
into the 750 and sort the g'box out once i've finished this smaller
engine. I used the smaller version of the combination needle race
in this one (30mm ID) and it's come up quite well. It does mean you
don't have to set end float etc so a little easier to assemble.
Blimey, it's nearly May, who said that when you retire time is plentiful.....

Keep chucking your tuppence worth in, it's always valued.

Nick

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Does Matt want a head for the 650? Or can you use that one? A 650 really interests me because of what the F/bird's like. More rpm should sort of get the same hp from a smaller engine.

I also have a question plenum chambers have a frequency apparently which has an effect. If I put a big box over the head and cyl on my bench it flows a bit more, not normally, but when its near max on 3 vacs. Why? I can see it flows more because the main vacuum drops. Your test vacuum, and that drops when more air goes through and effects vac in the cylinder. It has two big holes in the box for the flow meters. I don't think it reads wrong but makes it flow more, because if you restrict air going in it flows less and the vac goes up. So harmonics in the box or something makes it breath better than with it off and it's obviously not moving just room air?

Maybe a big air box with cold air ducted from the front could enhance it?


mark
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Kevin Cameron can tell you how that works:


I tried to make it work on my bike here:

http://www.landracing.com/forum/index.php?topic=11874.0

Tom


Life's uncertain - go fast now!
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I can only think of a plenum/air box being a bit of a pain. But if it was easily put on and off I think you could test it on the bench and see when and if it worked watching the main vac. But it would not tell you what's happening with a running motor which may or may not be important.

Thanks Tom I will look at the links. The sound doesn't work on this so I have to use a different computer.


mark
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Mark
I have the original head here off the bike, the one that was ported to buggery
and cracked. (i'm innocent, it was before my involvement!)
After i repaired it and put a couple of plates in the inlet port floors + some guides it
was quite good and ran well with the two 32mm mk1's on. Standard valves.
The stubbs come out at centres close enough for me to use the weber on it, so i'll
do that, just slightly smaller main jets. Matt rides this engine like it's a 2 stroke so
i'm happier now i've done the bottom end. I set an ignition up with a rev limit at 8k.
for it It does make good power actually, but you do need to rev the old thing to get it.
The cam doesn't start working until around 5k but just keeps going. That's how he's
blown it up in the past. It's done properly this time with an end feed, big barrel studs,
new rods, decent oil pump etc. Should be a nice little engine, with it's 10.5-1's in it.

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Nick

If you can machine the crankcase to centralise the alternator/out rigger carrier, then you can also increase the OD to allow you to carry larger engine sprockets. Three counter sunk hole to fit the mounting to the crankcase, then another three holes to lock your out rigger into, this way you can give it clearance for the larger sprocket! To make it one piece there is going to be a lot of swarf, so might be a case of make the crankcase mounting and weld the three leg to carry the out rigger on.

John

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I have this Lightning head I'm messing with with a reading of 164.4cfm at std lift and with a stock valve. Only one side, so I need to fix the other and match it, its close. And make manifolds. It may be out a bit but not by much. The stock port smoothed a bit will not go anywhere near it even with 4" of extra vacuum it gets stuck at 135cfm, that would be like a big motor and big cam sucking on it. And hp is burning air. When on the test vac I have to open a vac port because the control doesn't adjust back enough.

If you felt what the Firebird was like you would probably be as excited as me and want to run a stock cam and strengthen the clutch. I do not know how it would compare to the big fire breathing opposition, but really it could possibly be on terms. High comp should help it, I'm not sure about a cam. Cams are about getting additional air at rpm and the thing could have enough for 80hp at lots of unmentionable rpm with a stock cam. But the midrange is great and it needs drive. The vibs suck not the hp. It's got small pipes and stuff but it's ridiculous. Can you imagine the jumping up and down we might be doing if Matt put a 650 first past the flag? If you use the 750 head I could do a better one for it.

I have O/s exhausts in the Firebird as well as inlets. And would suggest that for the 750.


mark
NickL #847265 04/27/21 8:09 am
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John, yes i see what you mean, i'll look at making up a carrier that is sensibly shaped, or i'll be knee
deep in swarf......

How big did you go with the valves Mark, i never really achieved anything by increasing exhaust size,
but i was running a bigger cam, that was on my old 880-900 thing. 30 deg seats was a good gain on my
original 650.
I'll get that head we have welded up and send it down as soon as i get a chance, i'm up to my neck at
the moment, i stupidly took on an automation project for an old customer and it keeps growing........ plus
i'm trying to get bits sorted for this 650 motor and chivvy Matt into sorting out a rear wheel and tyre etc.

Nick

NickL #847269 04/27/21 10:04 am
Joined: Apr 2005
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MAP make slightly O/size inlets and exhausts 42mm and 37mm. The std exhaust is 35.8mm so not much difference, but helps on a low seat, and might do something? Same price $30us. They are out of 42mm, which are good with a swirl pattern, I polished one of to see, but the swirl pattern flows a fraction better frown so Firebird has the one swirl valve in the worst cyl to get them closer.

If you put a bearing out there on a carrier it may mean it can handle high rpm longer. If the 750 can drive past these big outfits or match them maybe a 650 pulling a bit more rpm can as well. 8,000 should be reasonable but with a stock cam the engine isn't peaky just pulls and keeps going, and it's important for it to drive early because there is no risk it 'will' rev. If it's doing what I suspect, it's getting boost, intake forcing in with speed and volume, and size doesn't matter so much. It would be interesting to explore how far that may work, we don't really know. Even with static 9-1 compression, actual cyl pressure may be quite high.

I've worked on a 350chev with a big blower and belt through the bonnet and dual 4 barrels on top, the throttle response just blipping the throttle on the Firebird reminds me of that, it's very sharp and instant. One of the kids does that on the throttle when he's on it, and it can attract the wrong type of attention. I just let it idle without rap rap. Especially in town.

We might find a 650 just cannot do it, but what fun if it can.


mark
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