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| Nobby the Bastard |
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Nobby the Bastard
Harley Gaydar
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| The Shaggy D.A. |
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The Shaggy D.A.
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| Nobby the Bastard |
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Nobby the Bastard
Harley Gaydar
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| PeterC |
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PeterC
Derestricted Danger
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 Posted: 01:11 - 12 Mar 2020  Post subject: |
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| Teflon-Mike wrote: | England and America. Two nations divided by a common language!
Seems we are communicating on skew paths... howebler.....
https://www.caferacerz.com/wp-content/uploads/2017/07/honda-cb125-cafe-racer-2-slideshow.jpg
Just puling that from your examples, it looks like it started life as a like a CB125TD-C, of which I have one or two examples in various states of disassembly. (actually the file name now I have copied it actually calls it Honda-CB125-Cafe-Racer!) |
That one is actually a lot more extreme than I was planning on going with mine. Don't get me wrong, its a beaut, but in terms of appearance I was leaning more to something a bit more like these:
https://s1.storage.2banh.vn/image/2013/08/20130829_ac3a8f33099fcab72defddb968b99426_1377768276.jpg
https://cms.kienthuc.net.vn/zoomh/500/uploaded/quanghuy/2017_07_26/4/xe-no-gia-re-sym-wolf-do-brat-cafe-cuc-chat-tai-ha-noi-hinh-7.jpg?watermark=kienthuc
| Quote: | The frame has been hacked though; I can tell you that much. Its been sawn off just behind the carburettors and a new sub-frame to support the seat grafted in.
This could, and probably has been welded, but getting a bit crafty, could have been a bolt-on, that probably has been welded up to suit, but could be constructed in many ways and not necesserily from tube, but perhaps sheet, folded and riveted... that could be done in my back yard with no particularly specialist tools.. just a big hammer, a vice a drill, and maybe some pliers.. you dont even need a fancy rivit tool if you use propper rivets and form the ends to grip with a hammer and die, or even just a hammer! |
Will keep in mind, in case I decide to tackle something that ambitious..
| Quote: | The main stresses the frame is carrying are between the steering stem supporting the forks, through the back-bone that goes over the engine, down to the rear swing... American/English game... we call it the swing-arm.... I think you call it the rear-fork... but same thing... beam that the back wheel goes up and down with. That bike has a 'mono-shock' and the suspension forces squash a spring thats supported at the top by a lugg on the main tube that comes down from the top tube, and is squashed at the bottom by a linkage hinged off the bottom of it.
That 'custom' seat-sub frame is taking virtually no structural stresses, as far as containing the torque the motor may make (which is pretty pitiful!) Its just supporting that part of the riders weight NOT supported by the foot-pegs or handlebars. |
I wasn't so much worried about that part: what I was looking at is that when bikes start getting larger engines there's often a part of the frame that goes down underneath the engine, apparently to hold the engine stable. On smaller bikes like my SYM and the CB125 whose frame it copied it just bolts onto the front of the engine. I was worried that putting a larger engine on would require that part of the frame going all the way under to support the engine, that without it to hold things in place the stronger engine pulling on the chain would be twisting the frame, creating stresses its not meant to handle.
Part of why I figured a 250cc engine might be safe is that examples like the CB250RS and the Nighthawk have similar frames that bolt onto the front and don't go all the way under the engine to attach back around to the main frame.
https://images.cmsnl.com/img/partslists/honda-cb250rs-1980-a-france-frame-body_mediumma000141f28_b63e.jpg
https://i.ebayimg.com/images/i/272444941195-0-1/s-l1000.jpg
On the other hand, if you look at the CB360 frame that thing goes all the way under, which leads me to believe the frame needed extra support there to handle the torque created by the output of the stronger engine:
https://i.ebayimg.com/images/i/311566423826-0-1/s-l1000.jpg
I'll admit, My guess as to why they'd do that with those frames and not the 360 could be entirely wrong, but it seemed to make sense when comparing the frames and how the engines attach up.
| Quote: | Chopping up frames is NOT that scary, if you have some idea about structure....
Meanwhile, on hat bike, and I presume yours, it has what's known as a 'Semi-Stressed' engine. The 'frame' has no bottom rails under the motor, the engine itself bolts into the hole between the front down tube and the main spine, to make up the 'structure'...
If the engine is out or not properly bolted in, then the whole frame can twist or bow, and this would the much more of a worry than any extra stresses than a bigger motor might apply! |
And apparently if I had just read a little further I'd have seen that we were getting to the same point. So I know that I was right to worry about some engines not working with that type of frame, but it looks like if I go with one of the ones I was looking at with the similar type of frame then the engine should be able to handle the stress as both were built to bolt in like that. Good to know. Also those Nighthawk 250 engines are common as heck and pretty cheep, so that's one to keep in mind.
| Quote: | As said I have a bunch of them 125 twins littering the yard, and I have dropped a 200 twin into a 125 frame, because they are bolt for bolt interchangeable... as is the 250 'Benley' twin I believe. |
The 150 engine in the SYM is a single, but I'm guessing that if the 200 twins bolt to the same frame as the 125 twins bolt into the same frame as the 125 singles then a 250 single from the RS or double from the Nighthawk could also bolt into those same frame.
| Quote: | The engine sort of hangs off the rear down tube on plates that are welded to that and clamp round the back of the engine. At the front, a U shape bracket connects the front engine mount to the down tube, and a V-Bracket hangs off the back-bone and stresses the structure to the cylinder head. |
Ok, so all that seems to basically jive with what I was finding studying those diagrams. Didn't necessarily have the vocabulary, but yeah.
| Quote: | Like I said, most of the small honda motors, whether singles or twins share common mounting bolt pattern on the engine, and many of them will bolt like for like between the frames. |
And THAT is the information I was looking for.
| Quote: | Where they wont, its no great shakes and still don't need a welder, just a hammer, vice and hack-saw to bend up bottom brackets to mate the front of the engine to the down tube, or the cylinder head to the spine.... and as long as you have some common sense and awareness to make sure it all bolts up tight and will contain the stresses, it's likely all 'good'. |
Good to know, but as I stated I'm specifically doing what I can to find an engine which is as plug-and-play as possible for that frame. Plus, the more I look at it the more I'm liking the idea of a Nighthawk engine; they were still making the bike until '08 so I won't have to deal with a 50 year old worn out engine that lost its compression. I wouldn't even be surprised if they still make replacement engines for them.
| Quote: | In similar manner, I mentioned the old Tritons, the marriage of a Triumph Bonaville engine into a Norton 'Featherbed' frame, the original 'Cafe-Racer'. Typically that marriage of moor to frame was done with adapter plates cut by hacksaw and hand drill from a bit of Duralamin plate, to match the bolt holes on the motor to suitable boltholes on the frame... its not exactly high end CNC engineering, just old fashioned common sense and 'craft'.... |
That sounds amazing, but finding Norton anything around here isn't exactly doable. It would probably be possible to find the new Bonny engine no problem, but those new ones don't come cheap and I'm guessing that applies to the engine as well.
| Quote: | You REALLY dont need to have a fully equipped garage and Mc Toolkit to do this sort of stuff, JUST the know-how.... and that is where you are most lacking, I think. |
As I said, I did a lot of work on my old Vespa: at least enough to know how to replace brake/clutch cables, tires, adjust carbs, that type of stuff. Also occasionally with the maintenance on the old BMW R65 I owned. On that one I really needed a laptop handy to pull up diagrams and vids for the tasks when I needed clarification I couldn't get from the Clymer guide. On some of the repairs I'd take it to the shop to double check my work and make sure I wasn't missing anything, but I wasn't a total slouch.
I get that a project like this is a bit of a step up from general repairs like that, but so far (with a few trial and error exceptions) I've not run into a project I can't self-teach on and get some decent results.
| Quote: | Lets Hot-Rod a CB125 Super-Dream, like that one... just cos I have done it a couple of times!
As said,there's a whole plathora of small Honda engines that will drop straight into a 125-TD frame, bolt for bolt, this is REALLY not a big problem or issue. |
And that was the info I was looking for, thank you.
This is REALLY not a big problem; there are a plathora of engines from the small Honda range that will drop in bolt for bolt.
The problems start when you look at the chain run, and the sprocket on the engine is 1/4 inch out of line to the one on the back wheek, or the exhasut that matches the enginedoesn't have any bracket to hang from at the silencer(muffler?) Or the carburettors dont line up with the snorkels for the air-box, or the ignition system for the engine doesn't match the ignition system on the frame.
THIS is where you start to get vexed, and whatever your grand plan at the outset, and your optimistic hope that an engine will just drop in like the one you took out starts to fall apart.. and when you get aroundt o solving these sort of niggles, you realise, that it die=dn;t really matter what engine you started with.. IF you had known.. you probably wouldn't have bothered....and now you do, well, the hassles involved the pains spent worrying about engine compatability really weren't worth the worry... As you still had to faff about with hack-saw and plate and drill, and fettling to fit.... you probably didn't save much if any effort, picking an allegedly 'interchangeable' engine over anything else.... and you could have probably slapped a Jowa speedway engine in there more easily, if only for the fact that you had no pre-conceptions and expectation that it 'should' bolt up, and could buy half made adapter plates off the shelf and saved your self a lot of head scratching to first you you needed an adapter, and more blood-sweat and pains trying to find suitable material and then cut and file it to shape!
Like I said, its all on the learning curve... where do you want to start?
Sensibly, for the learning pick a standard bike, and restore it to the book. First there IS a book, and what to do is laid out in easy to follow step by step instructions. Go custom and you have to write the book as you go.... then adapt that.
That is where you start on the learning curve, if you dint want to turn your pride and joy into a pile of scrap that sits around for the next decade or so, while you ponder the 'problems' you have to solve....
Meanwhile you say that you need this bike readable to get to and from.... remember the old addage, IF IT ENT BROKE----DONT FIX IT!
So why you want to make it broke, and plan getting someting that's not broke to use whilst you break it!?!?!?
Keep what you got, un-broke, and get something that's already brake to do the deviouse to! And if you want to use it, keep it to a known 'standard'; and start at the bottom of the learning curve, with a straight resto.. THEN when you have learned a few things, you might start doing a few mild mods along the way, and you might if you want more start over to do more, or do them to something else....
B-U-T your ideas as is, like that the manageability and MPG are some-how attributable to and proportional to the engine displacement.. are pretty nebulouse... You have the ambition to make art... but, are also both a bit lazy and dont want to have to do too much to make it, or step far from your comfort zone and take a chance.....
How much is a Van Rental?
That seems to be a pretty big excuse to looking for anything other than whats already right under your nose.... the USA is a pretty large land mass, and onlyt a little bit of it was hit by Hurricane Katrina... there are plenty of motorbikes ion other bits of the continent to buy... heck, there's folk buying them up, sticking them in containers and flogging them here as project bases, or booking a fly-drive holiday to go buy one your side of the pond, 'cos manufacturers chasing the $ flogged so many of them in the US in years past!
SERIOUSLY, if you are pondering a 'project'... re calibrate your perceptions!
IF you are too lazy to look a little further afield than the town you live in, and find ways to go get from that further local... then the immense hassle of a project is going to be enormous, and beyond you. If the expense of hiring a van or paying shipping is a deal breaker, then, again, you do NOT have what it takes to take on project! The cost of hiring a van or U-Haul for a week-end to go see and get a bike, are frankly a drop in the ocean of the all in cost of seeing a project through. The cost of incidental tools or materials you find you need along the way, are frog in the saucepan kind of costs that aren't often expected or planned for and have a habit of ramping exponentially... And its these sort of pit-falls that are the most common cause or project bikes ending up languishing at the back of sheds or yards never finished... you you bin warned.
For where you are at... I would seriously recommencement that you reel in the aspirations and ambitions a bit.... A straight to the book resto, is probably more than enough of a learning curve here and now, let alone trying to piggy back nebuliouse geekster ideas of hipsterisation into the bag.. and STILL if you are going to limit yourself to the bike you got or whats on your immediate door-step... you probably dont have what it takes to see ANY project through....
So think long and hard about what you really want to achieve, and how much you are prepared to put in to get that out, and rather than MAKING problems before you even start, spouting excuses for why you HAVE to hack the bike you got, and cant go buy anything else to bash about... look at the problems with that, and start there trying to solve them, rather than dodge them.... Just think... if that is how you start, trying to dodge problems, how you going to handle it when the flat seat you like in the catalogue needs that custom made sub-frame to fit it... and that begs some other way of mounting the rear shock absorbers, and the tail lamp and the indicators and and whatever other consequential problems ensue, that you had hoped to titally dodge at the beginning.
THIS is where it starts, PROBLEM SOLVING... that is even where most of the 'fun'is to be had. Not in the bragging rights of 'Well, its CUSTOM' and spouting hipster ideals of individuality... and if you are NOT prepared to tackle problems right here, right now at the very start? It dont bode well for any others along the line.... does it?
End of the day, its your project, its your money, and its you that got to live with it.... B~U~T........ you really are not heading towards achieving anything with the ideas you have got, and the constraints that you yourself are imposing, and the excuses you are already making for NOT doing anything different, all point at disappointment....[/quote] |
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| Teflon-Mike |
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Teflon-Mike
tl;dr
Joined: 01 Jun 2010
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| Posted: 04:23 - 12 Mar 2020 Post subject: |
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It really does seem we are talking different languages.
The CB125T and I presume what you have has a 'stressed' engine, that forms a part of the 'frames' actual load bearing structure.
If you look at schematics of things like the Yamaha R1, they have a 'beam' frame, pioneered by Bimota whey back when. It's essentially a U shape with the head-stock at the bottom of the U and the swing arm pivots on the ends of each beam leg; the engine then hangs from the U by a bracket from the cylinder head and bolts on the back of the gearbox. If you think that the stresses imposed by a 20bhp nighthawk motor might overwhelm a frame with no craddle rails under the engine, how the heck do you think that an R1 with 160+bhp manages?
The pertinent bit of my discourse here was, that of the Honda engines that might fit this frame with little adaptation, as the engine itself is a structural member of the frame... if it isn;t bolted in properly then the frame will flex! What engine here don't really matter too much, and you could probably wallop in something as over-engined as a CB900 engine, with suitable adaptor plates... and even with the 90 odd horse power that makes, the critical thing ass far as stresses go ISN'T how many cc's the engine has or how much power it might make, but whether the 'structure' and all the bolts that clamp it together is strong enough to contain the forces.....
And I am at a loss.... because the more I type the less you heed. Seems that rather than making you rethink the errors of your inspiration, the more its encouraging you to carry on.... you are just NOT getting the idea...
There are many motors that might fit in your frame bolt for bolt. Even more that would probably be persuaded to with a little adaptation, BUT rather than heed the advice that its NOT a great idea to start trying to hack your bike about, to fit an engine it was never intended to take... you seem to have just taken the bit that making another engine of a different type fit, might actually be easier than you thought!!!!
NOOOOOOOOO
That is the easy bit!
Takes more than just getting the engine to sit in the frame... the chain needs to line up with a spocket on the engine and another on the back wheel. You need exhausts and brackets to habe them; you need carburettors and they need to fit up and drag air through the chokes, and cables that work the throttle slides or butterflys and another for the chokes.... Generator needs to make electric to charge the battery and make sparks to light the fire in the pot, at the right time.
And STILL I dont think you get it, and have erroneous ideas that what you say you want to do will some-how achieve what you hope.
Denting even further the complete lack of confidence I have that you can pull off a project of the sort you suggest!
I mentioned hot-rodding a CB125TD-C with a CD200 Benley engine.... that engine makes 15bhp a whole 3bhp more than the 125. The CB250 nighthawk you have mentioned, makes as standard a whole 19bhp... neither in their native frames make enough power to top much over a genuine 70mph, if that. You are not going to turn your 65mph commuter single into a 100+mph road burner with one even if all goes to plan....
The CB-D12-00 was exactly as 'slow' as the standard 125. Had a bit more bottom end grunt, but that was about it. It was no 'faster', nor did it noticeably alter the MPG. The 200engine actually had a lower rev cieling than the 125 and would have actually been slower,but for the fact it was geared upo by the CB125's 18" back wheel over the 17" wheel the motor would drive on a CD200..... see where the little niggles start to creep in? And we have that matter of electrics, which needed more than a little mix and matching... and the know-how to do so.
Its NOT simply a case of finding engine that will bolt into the frame, like for like. That is pretty easy. Making the whle thing work, let alone work how you hope, is the hard part, and utterly missing the point when beaten around the head with it.... AHRG!!!!!!
Maybe the only way you'll learn, is to o try.... just don't come back and start moaning when it don't go quite the way you hope!!!!
I really am at a loss here.
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| wr6133 |
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wr6133
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| Easy-X |
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Easy-X
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| Posted: 11:27 - 12 Mar 2020 Post subject: |
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I'm reminded of the (now classic) Grom 300cc engine swap tactic. The MSX only comes as a 125 and the bike is unique so jamming in some other Honda engine is about your only option. Go watch some of the videos and see how "easy" the job is 
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| terrytibbs |
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terrytibbs
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Old Thread Alert!
The last post was made 4 years, 32 days ago. Instead of replying here, would creating a new thread be more useful? |
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