homemade rat racer
- Thread starter harlyhermansson
- Start date
thanks
well since i started school i haven't had that much time to build and i am studying for a motorcycle driving license and that has taken allot of time as well. but i will try to do some bushings for the valve lifters before the snow comes. since turning a vertical briggs horesontally makes the lubrication a bit worse teemed with a bigger and more adjustable carb has led to problems with the valve lifters wearing out the aluminum guide holes... but i will make some new brass busshings in school
well since i started school i haven't had that much time to build and i am studying for a motorcycle driving license and that has taken allot of time as well. but i will try to do some bushings for the valve lifters before the snow comes. since turning a vertical briggs horesontally makes the lubrication a bit worse teemed with a bigger and more adjustable carb has led to problems with the valve lifters wearing out the aluminum guide holes... but i will make some new brass busshings in school
I love your old-school ingenuity! Keep up the great work! I look forward to more bikes and eventually, motorcycles too!
it was a while ago i built something on the board rat, but today i started checking what i would like to do with it, took some measurements for a new clutch setup and such.
i am planing to use a centrifugal clutch and chain threw the whole drivetrain, instead of the belt tension setup. i'm also lowering the gear reduction a bit, so i don't have to rev the nuts out of the engine all the time...
i will try to take some pics of it tomorrow
i am planing to use a centrifugal clutch and chain threw the whole drivetrain, instead of the belt tension setup. i'm also lowering the gear reduction a bit, so i don't have to rev the nuts out of the engine all the time...
i will try to take some pics of it tomorrow
For 1 rotation of the wheel (an what size wheel?) how many revs of the engine crankshaft does it turn?
I'm looking to be able to do parade and slow moving under 5mph with my build and hill climbing and I have a 3hp Briggs that has 8.3 to 1 with 26 inch wheel. I near getting finished with it and have still to see about a larger sprocket on the jack shaft to make temporary gear down for these events, but am having some trouble with getting them at a price I would be comfortable with. Also I have seen ones with a plastic or something for all but the teeth (teeth are metal) and would not think it would hold up. Looking at McMaster-Car and will be calling them to see if they can find what I need.
Since you have already test rode your bike and it is similar HP maybe, just like to know what kind of slow speed you can go without stalling and the ratio you have now.
Thanks
MT
I'm looking to be able to do parade and slow moving under 5mph with my build and hill climbing and I have a 3hp Briggs that has 8.3 to 1 with 26 inch wheel. I near getting finished with it and have still to see about a larger sprocket on the jack shaft to make temporary gear down for these events, but am having some trouble with getting them at a price I would be comfortable with. Also I have seen ones with a plastic or something for all but the teeth (teeth are metal) and would not think it would hold up. Looking at McMaster-Car and will be calling them to see if they can find what I need.
Since you have already test rode your bike and it is similar HP maybe, just like to know what kind of slow speed you can go without stalling and the ratio you have now.
Thanks
MT
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i also running a 26inch tire. and i'm planing to run a 9:1 ratio now, before i began rebuilding it i ran a 13:1 and with that ratio it went like 6mph on idle. i think my engine has a bit more torqe since it's 148cc and not 128cc like the normal 3.5hp horizontal shaft. for slow riding it should work great with a 13:1 ratio maybe even a bit higher reduction, like 15:1. but then it wold be very painful for your ears to ride at normal speeds...
when i ran a fresh belt and recently lapped valves, it would go of the line spinning the rear wheel, although that was on gravel. but it still scares the crap out of me...
when i ran a fresh belt and recently lapped valves, it would go of the line spinning the rear wheel, although that was on gravel. but it still scares the crap out of me...
I assume you're fitting up that large gear because you're putting it on the back wheel. Before you get too far with that lemme warn you that it's never going to generate enough friction going wheel speed. You can lighten up the springs all you want but with the wheel spinning that slow, the pads aren't going to build up enough centrifugal force.
yes i know that would not work, that's why in not putting it on the rear wheel
i am going to extend the axle and that's going to be the jack shaft. i'm running a chain sprocket on the engine axle down to the clutch shaft, threw the jack shaft and chain drive to the rear wheel.
i am going to extend the axle and that's going to be the jack shaft. i'm running a chain sprocket on the engine axle down to the clutch shaft, threw the jack shaft and chain drive to the rear wheel.
today i brought the axle to school so that i could lathe it down from 17mm to 16.1 for it to fit into the jackshaft tube... i got it a bit to big so i't doesn't fit... ill guess ill have to bring it tomorrow as well
here are some pics of my clutch and jackshaft setup. it's just a mock-up i still need to make a clutch bearing holder and a sprocket pully on the engine
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while i wait on getting material to do the clutch bearing holder i figured that i should try to do some break improvements, so i removed the hub from a old moped tire and now i try to find some spokes in the right length. sat for five hours last night trying to fit the original spokes in a different pattern, but no luck with that...
yesterday i found a old moped clutch a proper manual one. might try to build it with it instead of the centrifugal... hers some pics of the new wheels. 26inch with drum breaks
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You got some good parts and drum brakes too! I'll like to see how you get the new clutch set up!
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What diameter was that yellow colored pulley that you had used before your making changes for a non-manual clutch?
Also was the diameter of the pulley that was the idler pulley for where you have the cable attached to pivot the idler pulley taking up slack and engaging the engine to the drive wheel?
The reason I ask is that I have got a hold of a second 10inch pulley and it is going to be on my jack shaft to get overall about 25 to 1 ratio and it drives a 26 inch wheel. This was the trying to get 5 mph with my centrifugal clutch.
The problem that might not really be a problem; is that when I have a 10 inch pulley just clear from scraping against a 2 inch pulley that a v-belt goes around the both of then, the 2 inch pulley does not really get wrapped around much by the v-belt.
I am afraid that there might not be enough friction to have the smaller 2 inch pulley from slipping. Further the use of the Link-Belt although easy to adjust may even have less friction to hold to the 2 inch pulley. I can revert back to a standard v-belt if necessary.
Just I would like to get an idea of I understand was working for you when you rode a manual clutch like you made to give me an idea what is acceptable.
Thinking if two of the same size pulleys are attached with a v-belt, then you would have about half the pulley circumference about 180 degrees of the round on the belt and that would be the maximum amount of contact surface of the v-belt. Just wonder is there a rule of thumb how much that amount can be made smaller before the v-belt would not serve a useful purpose as the amount it would hold before slipping was not worth it? When the angle the belt approaches the smaller pulley gets too wide.
I have pictures of the 10 inch pulley near where it would be placed. I can possibly return it for refund, or get maybe a slightly smaller one. The clutch I have not purchase yet.
The clutch I found costing about $60 and the pulley about $25, whereas getting a large gear as much as 7 inch is like $150 or more, so I have parts I think I can work with and am hope I can have it work. I know a chain has no slippage if I find that I find a supplier that has them at a lesser cost as I've found so far, I’ll go with that as I already have a gear clutch.
The rear wheel pulley and the one it connects to on the jackshaft will not be change. I will have to move the jackshaft up about 2 inches and 1 inch back, which I already have in mind how that will be done.
I found this http://en.wikipedia.org/wiki/Belt_friction
but just knowing in reality what worked for you should tell me if I can get by with the angle of the belt I'll have with the smaller pulley.
Thanks
MT
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What diameter was that yellow colored pulley that you had used before your making changes for a non-manual clutch?
Also was the diameter of the pulley that was the idler pulley for where you have the cable attached to pivot the idler pulley taking up slack and engaging the engine to the drive wheel?
The reason I ask is that I have got a hold of a second 10inch pulley and it is going to be on my jack shaft to get overall about 25 to 1 ratio and it drives a 26 inch wheel. This was the trying to get 5 mph with my centrifugal clutch.
The problem that might not really be a problem; is that when I have a 10 inch pulley just clear from scraping against a 2 inch pulley that a v-belt goes around the both of then, the 2 inch pulley does not really get wrapped around much by the v-belt.
I am afraid that there might not be enough friction to have the smaller 2 inch pulley from slipping. Further the use of the Link-Belt although easy to adjust may even have less friction to hold to the 2 inch pulley. I can revert back to a standard v-belt if necessary.
Just I would like to get an idea of I understand was working for you when you rode a manual clutch like you made to give me an idea what is acceptable.
Thinking if two of the same size pulleys are attached with a v-belt, then you would have about half the pulley circumference about 180 degrees of the round on the belt and that would be the maximum amount of contact surface of the v-belt. Just wonder is there a rule of thumb how much that amount can be made smaller before the v-belt would not serve a useful purpose as the amount it would hold before slipping was not worth it? When the angle the belt approaches the smaller pulley gets too wide.
I have pictures of the 10 inch pulley near where it would be placed. I can possibly return it for refund, or get maybe a slightly smaller one. The clutch I have not purchase yet.
The clutch I found costing about $60 and the pulley about $25, whereas getting a large gear as much as 7 inch is like $150 or more, so I have parts I think I can work with and am hope I can have it work. I know a chain has no slippage if I find that I find a supplier that has them at a lesser cost as I've found so far, I’ll go with that as I already have a gear clutch.
The rear wheel pulley and the one it connects to on the jackshaft will not be change. I will have to move the jackshaft up about 2 inches and 1 inch back, which I already have in mind how that will be done.
I found this http://en.wikipedia.org/wiki/Belt_friction
but just knowing in reality what worked for you should tell me if I can get by with the angle of the belt I'll have with the smaller pulley.
Thanks
MT
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yes i'm thinking day and night about how i should do the clutch setup, now i have actually started thinking about running a belt tension clutch again but with a smaller rear pully.... i hate having to many choices
before i ran a 2.5inch pully on the engine and a 11.5inch pully on the jackshaft.
a 25/1 gear reduction will make it insane at low speeds. if you would run only chains you might risk tearing the spokes to pieces... about the pully friction problem, i don't think you would suffer to bad from some slippage. unless you are planing on running short drag-races if you have a decent tension on the belt it shouldn't be a problem.
before i ran a 2.5inch pully on the engine and a 11.5inch pully on the jackshaft.
a 25/1 gear reduction will make it insane at low speeds. if you would run only chains you might risk tearing the spokes to pieces... about the pully friction problem, i don't think you would suffer to bad from some slippage. unless you are planing on running short drag-races
if you have a decent tension on the belt it shouldn't be a problem.
Thanks for the info, I got ordering the belt clutch an to have by Saturday, but I have not been doing much as 5 days so far with a cold. I went to the hardware store to get some stuff to adapt to larger pulley on jackshaft and other stuff related to art covering for parade bike when I'll be doing that.
MT
http://motorbicycling.com/showthread.php?p=361136#post361136
MT
http://motorbicycling.com/showthread.php?p=361136#post361136
nice build MT
yesterday i started looking threw the engine and it seems that the clicking noise were coming from one of the valve springs hitting the valve and not the valve lifters, good news!
started building a new springer fork as well pics as soon as i find the camera
yesterday i started looking threw the engine and it seems that the clicking noise were coming from one of the valve springs hitting the valve and not the valve lifters, good news!
started building a new springer fork as well
pics as soon as i find the camera
here's the pics i promised. i have tried to ad some patina to the tank and started building the springer. i have also decided on the clutch, i'll run a belt setup as before but with a smaller secondary pully so i get the gear reduction a bit taller.
and i will try to build a belt cover that will force the belt to expand just around the motor pully.
and i will try to build a belt cover that will force the belt to expand just around the motor pully.
