Vintage Grumble Posted February 15, 2010 Share Posted February 15, 2010 I have been slowly collecting parts for this wee project for about a year, and after seeing CDL's Brigg'sMX project it kinda motovated me to make a start on it. I plan on making a half assed 1900/1920's style motorcycle out of bike parts, powered by a basic home made parallel twin engine, which is going to be a pair of modified 2hp B&S horizontal shaft motors side by side and joined at the crank. I will most likely make the frame from scratch, from some tiny exhaust tube I have laying about. It will be hard tail, and I hope to make some sort of cantilever suspension for the front. I will post up some pics tonight of what I have/plan to do. The style im going for is kinda a mix of these: Quote Link to comment Share on other sites More sharing options...
tortron Posted February 15, 2010 Share Posted February 15, 2010 god speed good sir Quote Link to comment Share on other sites More sharing options...
tortron Posted February 15, 2010 Share Posted February 15, 2010 also this Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted February 16, 2010 Author Share Posted February 16, 2010 Heres some of the crap ive amassed to make this bad boy outta, First up, my lawn mower "Colonel Brigg's" kindly donated his engine: I have two other motors, ones a runner, found it at the dump on a hoe, the others out of a scrap bin, was full of water, and had a few bits missing. The two motors I plan to link, I hope to get them this close together: Drilled out the spot welds on one of the starters, so I can leave the cooling shroud on, and have a hole to link the cranks: The rims I plan to use: Belt drive tensioner: The steel frame I may use parts of/mud guards/sprung seat: Wanna get the motor going and then make the bike frame to fit. Have to do a bit of research on the motors as I want to make up a manifold and run one carb for both motors, off a motorbike or summin, if anyone out there is a B&S motor expert, any info or advice would be great. Quote Link to comment Share on other sites More sharing options...
Goat Posted February 17, 2010 Share Posted February 17, 2010 Unless you specifically want to run only 1 carb. There wouldnt be a problem with each cylinder having its own carb. Because they are both linked, that tiny difference in power caused buy unbalanced carbs will be taken up by the other engine, so the carbs dont have to be exactly tuned, just close enough. And because its no GP racer, it can be haggard cos you don't need optimum performance. Hah Cos finding a carb and jetting it will be fiddly.. Looking wicked though, like the twin/joined engine idea. This is going to be choice. Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted February 17, 2010 Author Share Posted February 17, 2010 Unless you specifically want to run only 1 carb. There wouldnt be a problem with each cylinder having its own carb. Because they are both linked, that tiny difference in power caused buy unbalanced carbs will be taken up by the other engine, so the carbs dont have to be exactly tuned, just close enough. And because its no GP racer, it can be haggard cos you don't need optimum performance. HahCos finding a carb and jetting it will be fiddly.. Looking wicked though, like the twin/joined engine idea. This is going to be choice. The main reason I was going to go to one carb was so I can make a lush tank, and have it above the motor on the frame, and do away with the two std tanks. The std briggs carbs suck from the tank, so dont think you can just slap a fuel line on the pick up? would flood seeing as it has no float bowl wouldnt it? But like you say, getting the rite sized carb, and then jetting it will be a bit of a cunt. Mate of mine reckons/kinda makes sence that unless you have them firing at the same time you dont need a carb thats twice the size of one std one (I was going to add the two engines CC's together and then try find a carb from an engine of that cc?) as they wont both be sucking shit in at the same time? Is that true, OR do you still need twice the air/fuel to run them no matter when they are firing? Am keen to get motor running, will play with firing set up for optimum chur soundingness, im thinking while ones on the exhaust stroke, have the other on the compression stroke/firing for max lumpyness? Quote Link to comment Share on other sites More sharing options...
Goat Posted February 17, 2010 Share Posted February 17, 2010 True. They do suck from the tank. So an overhead tank will be the floodster. Have a look at villiers carbs. They are super SUPER simple. And have a float bowl. Plus, theyd probably be sweet as for 2 brigs motors. It probably just has to be in the general vacinity of size/fueling efficiency. Because, its not as if the brigs will be pulling 12083649rpm under high load. Rich is safe Its not going to be a competitive machine, so just experiment with the cheapest/free shit you can get. hah Get one running, get both running, see if they both run on one brigs carb. then grab a villiers carb or something and it will be wicked. Quote Link to comment Share on other sites More sharing options...
thegreatestben Posted February 17, 2010 Share Posted February 17, 2010 When you join both motors how will you have them in terms of position of each crank? Like say 90deg apart, Would it make much difference? Quote Link to comment Share on other sites More sharing options...
peteretep Posted February 17, 2010 Share Posted February 17, 2010 i saw the other day scootling sells brand new slide carbs fro around $100, probably too expensive for whta your looking for though Quote Link to comment Share on other sites More sharing options...
sentra Posted February 17, 2010 Share Posted February 17, 2010 When you join both motors how will you have them in terms of position of each crank?Like say 90deg apart, Would it make much difference? make them some obscure angle and reduce idle speed to barely moving for maximum points Quote Link to comment Share on other sites More sharing options...
thegreatestben Posted February 17, 2010 Share Posted February 17, 2010 Was pretty much what I was thinking/hoping for. Obscure Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted February 17, 2010 Author Share Posted February 17, 2010 When you join both motors how will you have them in terms of position of each crank?Like say 90deg apart, Would it make much difference? make them some obscure angle and reduce idle speed to barely moving for maximum points Thats the plan, if you take off the kill switch, these things will go down to like 3rpm (or so it sounds) so with two of them doing 3rpm, with straight pipes, I think they will sound pretty good. I will make the crank link thing adjustable, and then play around with them till they sound the best, like I said up there ^ "will play with firing set up for optimum chur soundingness, im thinking while ones on the exhaust stroke, have the other on the compression stroke/firing for max lumpyness?" = BANG BANG ..................... BANG BANG .................... BANG BANG ............... and so on. Anyone know if theres some kind of calculation on how to work out carb/jet size for a certain displacement of engine? like a general rule or anything? Aint gonna be no race motor, but I dont want it to be a total cunt. Have found cheap new ones on trademe but dude says they are for "50/70/100/125cc motors" seems like a wide range for the same carb to do? Have to wait a few weeks till I can get my hands on a lathe, so have got frame and wheels at work, so I can start on that. Quote Link to comment Share on other sites More sharing options...
GT_Escortina Posted February 18, 2010 Share Posted February 18, 2010 i like it and have some carbs that im not using ill have a look to nite and post pic or so B&S engines have different cam profiles for Lawnmowers, Rotary Hoes etc Quote Link to comment Share on other sites More sharing options...
Hemi Posted February 18, 2010 Share Posted February 18, 2010 When you join both motors how will you have them in terms of position of each crank?Like say 90deg apart, Would it make much difference? make them some obscure angle and reduce idle speed to barely moving for maximum points Thats the plan, if you take off the kill switch, these things will go down to like 3rpm (or so it sounds) so with two of them doing 3rpm, with straight pipes, I think they will sound pretty good. I will make the crank link thing adjustable, and then play around with them till they sound the best, like I said up there ^ "will play with firing set up for optimum chur soundingness, im thinking while ones on the exhaust stroke, have the other on the compression stroke/firing for max lumpyness?" = BANG BANG ..................... BANG BANG .................... BANG BANG ............... and so on. Anyone know if theres some kind of calculation on how to work out carb/jet size for a certain displacement of engine? like a general rule or anything? Aint gonna be no race motor, but I dont want it to be a total cunt. Have found cheap new ones on trademe but dude says they are for "50/70/100/125cc motors" seems like a wide range for the same carb to do? Have to wait a few weeks till I can get my hands on a lathe, so have got frame and wheels at work, so I can start on that. omg that would sound amazingly horrible lol . go for it though Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted February 18, 2010 Author Share Posted February 18, 2010 i like it and have some carbs that im not using ill have a look to nite and post pic or so B&S engines have different cam profiles for Lawnmowers, Rotary Hoes etc I was a bit worried about the cam thing, as 2x motors are off rotary hoes (the 2 shitter ones) and the other off a lawn mower. I only just noticed the other night, that the lawn mower engine has a much smaller out put shaft, I'm guessing because it fed into a clutch, and didnt have a pulley/belt driving straight off it like the others? I pulled the shittest motor apart, and if needs be can slap that cam/crank into the other motor. Is really hard finding any info on these motors, found listings for all the engine codes, but nothing saying what the difference between them is? And yes, it will sound horrible, horrible like a FOX! Quote Link to comment Share on other sites More sharing options...
GT_Escortina Posted February 19, 2010 Share Posted February 19, 2010 hell theres some cool shit for the old B & S engine like .... billet 7075-T6 alloy aluminum rods http://www.horstmanclutches.com/pages/b ... ngine.html 50 hp From 34 ci(12hp) B & S http://www.hotrod.com/newsletter/hrdp_0308_racing_engine_jr_drag_racing_league/index.html ^^i do got some what side tracked at time^^ http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=00Al4s http://www.oldminibikes.com/forum/briggs-stratton-engines/ i cant find anything on 2 engine together ill keep looking as its a very cool idea Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted July 8, 2010 Author Share Posted July 8, 2010 Soooooooooo, been pissing around with this now and then, mostly at work, as my shed is full of crap. Aint done a lot, but that will change, should get a lot of things done very soon, some stuff I have done is, Sorted the basic shape of the frame Added a few pipes and taped it together Got the smallest Jaw coupling we sell in (its in that blurry ass pic some where) to join the motors. Father in law will be doing a bit of machining on this and a few other parts for me in the next few days. Also sorted out the seat today. Will have the frame spotted together very soon. Will pop down to the local mower shop tomorrow for a chat about carbs. Quote Link to comment Share on other sites More sharing options...
Toucan Posted July 8, 2010 Share Posted July 8, 2010 Hell yes Quote Link to comment Share on other sites More sharing options...
elevenhundred Posted July 9, 2010 Share Posted July 9, 2010 Similar to a big bang setup on a multi cylinder engine, will sound mint I reckon. Leave those wheels how they are too, rusty stz Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted July 15, 2010 Author Share Posted July 15, 2010 Got a little bit more done, machined up spacers for the seat springs, cut up the original seat frame and bent it round a bit, Also bored the coupling halfs, cut the cranks down, and machined the front off the one way clutch, so its now just a funny looking nut to hold the flywheel on. Also bolted the motors down to some 30x10 flat bar, will be reinforced once attached to the frame. Will make up some sort of shroud to go between the two motors, to cover the coupling and make it look more like one motor, Slapped it into the frame for a nose, its sticking out one side a fair way because the bikes to close to the wall. The motor will sit a fair bit further forword than this, as the frame is a little slumped, the front uprite will be more vertical/closer to the front wheel. Will take the pull starter off and make up a crank handle, to make it look less mower like, Next thing to do is get carb, make manifold, and see how it runs. Will tac the frame togeather soon too. Quote Link to comment Share on other sites More sharing options...
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