Motorbike not climbing steep hills

I really like your double belt drive setup!
As far as the belt slipping, All I can come up with is....
Adding a tensioner or running 2 belts instead of one.
Or both?

You're going to have to get a bigger sheave on the rear wheel or change the secondary pulley size to climb hills, but you're going to loose top end speed. Search the forum to see what others have done. Sorry, I can point you to a direct post.

Chris
AKA: BigBlue

if the 3" pulley is 5/8 shaft it will be easy to go get smaller ones...dont go much below 2" or it'll wanna slip there.
Is it not climbing because of the power or the slpping though? you said it bogs. either way Id try a 2.1 or 2.3 pulley

btw...you could also increase the size of that spoked pulley there and achieve the same goal

Maybe try a wider B belt, you didn't say what pulley is slipping i take it the rear one. They have to be tight. .................Curt

Looks like by guessing at your pulley sizes you are close to a 10:1 ratio. That's great for flats but above 12:1 is better for hilly riding. I have run basically this same set up on a Lifan 98cc@ around 14:1 it was an excellent hill climber and still made 30+ mph.

I have a Briggs 3hp and have a 14:1 ratio, but my wheel is 26". I have yet to test it climbing hills, but when I do I'll let you know. Your bike looks like 24" or 20" wheel which has to be added into the equation along with the pulleys. What I mean is if my 14:1 works on hills then if you use the same 14:1 but with smaller wheel than my 26" you would likely do even better climbing hills.

I want to also be able to go slow under 5mph for when my motor bike becomes an art parade vehicle, so I am going to have a ratio I can adjust between 14:1 , 21:1 and 30:1.
I had a 1.7 inch pulley and I found it slipped and decided to go with gear and chain for one of three connections. I use two belts, one chain and two jackshafts.

What you mention is a 15 inch rim, I guess it is considered a pulley or sheave like on Whizzers. If you can tell if it is slipping on the 15 inch rim I wonder if it suffices to be used as a pulley with the width of the belt you are using. If it is the adjustable pulley that is set at about 3 inches, then maybe go to a cogged belt the AX type v-belt.

MT

http://motorbicycling.com/showthread.php?t=29678&page=15

I just wanted to say that I think you have a great looking bike.

You could try lining the inside of the rim you're using as a sheave with either rubber or leather to improve the grip.

Here is a link to my build which is similar but different. Maybe it will shed some light on what you are trying to do. http://motorbicycling.com/showpost.php?p=271027&postcount=55.

I can see right away that the belt will slip less with the idaler pulley were it is. A hole lot more coverage, awesome bike cannonball.............Curt

Hey beginner01, I forgot to mention that motor bike has got style!

An idler pulley I use on one of two belts that I use on my build, it is a back idler type. I don't use a spring on it, I just set the tension with a pry bar and lock it in place. If you can get a spring loaded one that could be installed that would be best.

I was not finding one of these spring loaded idlers that I could install already made to fit easily on my bikes second rear wheel belt drive. I got the adjustable diameter pulley instead. You mentioned using one of those adjustable diameter pulleys. You can look at how I tension the belt using it on my bike but it is no where near as neat as a spring loaded idler.

Without the spring loaded idler I used to just pop the belt on the rear wheel sheave, but one time it had cracked it. I actually for my rear wheel sheave use a large cast white metal washing machine pulley attached to the spokes.

On a previous motor bike I built they had washing machine pulleys made of steel a lot stronger, they did not crack doing the same method. The belt goes on the small pulley first then pop the belt onto the large pulley by rotation it slowly. Watch to not get fingers in between, for bad blood blisters or worse can happen!

I got smart and decided after setting up a spare washing machine pulley on the spokes again, I would have a new method for putting belt on.

First I set the adjustable diameter pulley to nearer its smallest diameter. Next I move the rear axle in the dropouts just far enough that it won't fall out, but I can put the belt one with out any tension. Then I pull the axle back in the dropouts to tension the belt with a device I made. It hooks onto both left and right side of the axle with additional hardware. Turn buckles make it easy to pull fully into the drop outs.

If it is too tight or loose, then repeating the process after adjusting the adjustable diameter pulley for a second go around. (see not very easy, but it works)

MT

Post #90 on bottom page #9 and post #91 on top page #10 deal with my tensioning tool I made for use with adjustable diameter pulley.

http://motorbicycling.com/showthread.php?t=29678&page=9

http://motorbicycling.com/showthread.php?t=29678&page=10

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My dirt bike pics post #129 on page #13

http://motorbicycling.com/showthread.php?t=29678&page=13

beginner01 said:

Thanks for the replies. I tightened up the rear belt and there is no slip now... Now the engine just bogs. The overall ratio is about 9.5:1 (front 3.5 to 7 rear 3 to 14.25) and it does feel steep. Not to mention, the rear belt seems to introduce a ton of drag into the system. I think I might go with a chain to the back. For now I will keep the front belt but I'd like to go with a minibike 2-speed auto if it will be all chains anyway. CB I'm lovin your rear brake setup.

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Thanks for the kind comments on the build yall. That was a great riding bike.

Beginner01: The little Lifan was 98cc and rated at 2.5hp and it had plenty of power for the set up. I wouldnt ditch the double belt drive yet, its clean and quiet and pretty trouble free once set right. I believe the ratio was really 12:1 3"/6" on the primary and 2.5"/15" on the secondary. The idler forced about 180 degrees of belt into the small pulley for a positive drive. This bike was loosely built on the Popular Mechanics motorbike of the 50s, the brake is my rendition as I remember.

For sure the Wizzer and and old Monarch twin had that setup for years. Just keep trying and it will workout. I had a Monarch twin 50+ years ago and run it to death,was a awesome bike. .................Curt

curtisfox said:

For sure the Wizzer and and old Monarch twin had that setup for years. Just keep trying and it will workout. I had a Monarch twin 50+ years ago and run it to death,was a awesome bike. .................Curt

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Wow Curt a Monarch! Bet you wish you had it now, what a rare piece.

Sure do,knocked a rod out of it and pieced it out. I think the rod bolts came lose on one end. Had a big crome tank was a super delux model. The only thing left is the motor mount that my son has.
Never botherd me much untill i joind this fourm and now wiched i had it back,oh well what is gone is gone...............Curt

beginner01 said:

Well I'm flat broke, so I didn't go with changing the rear belt ratio... I found the old 2" pulley from when I first started building the bike and wanted to go with a manual clutch, and set up the manual clutch to make it work. It ran OK, I'm having some mixture problems... feels like the engine blew a gasket somewhere now.. it loses power after idle unless I get on the gas, let it rev, then let out the clutch. Weird. I will test it on big hills tomorrow. Is it normal to work on bikes till 2am after a dozen beers?

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Cant tell exactly from the pic but is that a Tecumseh carb? If so do you know what it came off of. I have used them for years on different engines and it real important to get one with a proper venture size for the displacement or it will bog in the mid range.

Yeah beers and bike building kinda go together, but at my age im in the rack by 10.