Need help converting to all belt drive.

Keeponkeepnon · Mar 12, 2013

I built my motorbike about 4 years ago. Went with a 4 stroke and modified the intake as well as exhaust with the top priority being to make it quiet. When I fired it up for the first time I was stoked on the stealthiness... then I took it out for a ride and the gear box screamed like a banshee. I tried greasing it all up, filled it with 90 wt, even built a closed cell foam cover for it but it was way too loud. So I threw it in the corner of the garage and it has sat ever since.
Recently my interest in motor biking has been renewed and I tore off the gear box, breaking the outer cover in the process. The clutch shoe had a deep gouge in one and a lesser gouge in another, the third had a tall lip on it. Factory direct crapola. I'm not sure if it was the clutch or the gears making all that noise but either way, I'm done with that set up.
Since then the 4g and the EZM have come out. Some cheap Chinese 18" rear wheel sheaves have come on the market as well. I want to go all belts to make it as quiet as possible but still gas powered.
Question #1. Will the 4G bolt right up where my old gear box was? The motor is a Hua Sheng 49cc, the only identifying stamp I could find was on the block under the clutch "142F". The shaft is keyed and I measure it as machined down to 9/16 on most of the exposed area and 11/16 closer to the engine... do we call that a "5/8 keyed shaft"? Its definitely not tapered, is there just the two types, tapered and keyed?
Question #2 Any recommendations on what size and where to get the pulley to replace the 11t sprocket and belt I will need to join the tranny to the rear wheel sheave?

Thanks for the help

ocho ninja · Mar 12, 2013

Answer to question 1 is that it will bolt up, to your engine. The newer 4g transmissions work with the keyed straight shafts, look at bicycle-engines.com they have em in stock.

My 4g transmission to chain secondary drive was one of the quietest bike i ever had, even pedaling the noise was quieter than most derailleur equipped mountain bike.

Keeponkeepnon · Mar 12, 2013

That's music to my ears... and my wallet. I suppose if I wasn't satisfied I could always switch to rear sheave later.

ocho ninja · Mar 12, 2013

Its always money with these things. My funds are desperately low with my current build, I swore not build another until i successfully get out of debt lol

only thing im not sure is the size of the shaft were the 11t sprocket goes... if its a 5/8 shaft than there is plenty of options as far as front pulleys go.

If you do get the the 5:1 4g, i recommend to weld up the 11t freewheel or find a solid out put sprocket... they seem to go out pretty easily.
There's a couple of other mods to the 4g to make the bomb proof like replacing some of the bushings for bearings, but i can't find the thread were a member did a how to on

BigBlue · Mar 12, 2013

Keepon, sounds like you have a stepped shaft or it is worn down. 5/8" is .625 inches - 9/16 is .5625 inches and 11/16 is .6875 inches. It definitely is not a 5/8" straight shaft. You can order a new crankshaft from Bicycle-engines.com

CobraFreak has done a bearing mod on the HS 49cc engines for the 4G grubee transmissions that might help. You use 13mm bearings: http://motorbicycling.com/showthread.php?t=37410&highlight=4g+bearing+mod

Just measure the diameter of the 11 tooth spocket and buy from McMaster-Carr or any other place that sells pulleys.

Good Luck,

Chris
AKA: BigBlue

The_Aleman · Mar 12, 2013

The bearing mod does wonders for your idle. The stock 4G clutch bushing is crap and even with an Oilite replacement, will wear the bushing out kinda quick.

Also, the 11T freewheel isn't bad - when you have a SBP shift kit anyway! I've had mine since 2010 and it has 6K miles on it, never an issue.
The 12T is supposed to be much better for non-shifting setups.

BigBlue · Mar 12, 2013

I think the OP wants to replace the 11t freewheel sprocket with a pulley since he wants to have a sheave belt drive system. I don't think quality is the reason for replacement, but stealthiness.

Chris
AKA: BigBlue

Keeponkeepnon · Mar 12, 2013

Yes replacing the sprocket with a pulley is part of the goal. I just want to make sure I don't order a transmission that won't fit my motor and I figure somebody here has replaced the sprocket with a pulley already and could tell what to get with no guess work. I will check out Mcmaster-Carr
Keeping it quiet is a top priority but reliability is a right there in second place so any recommended modifications like the cllutch bearing are welcome information. Tweaking and modifying are part of the fun with these projects.
The cobra freak bearing modification sounds great and with my abnormally small crank shaft the bearings may fit right on or only a small amount need be removed from the shaft. It sounds like I could build the shaft up a little too if needed for the rest of the clutch.
McMaster-Carr is awesome. It has pulleys, belts, bearings... i could spend hours looking at the stuff.

Keeponkeepnon · Mar 22, 2013

I ordered a 4 g transmission, 5:1. It bolted on no problem but my drive shaft had serious issues. It actually has 2 steps in it. The first step was more than 5/8 which did not allow the clutch to sit as close to the block as it should so I ground it back. The next step was less than 5/8 which meant the clutch was not a tight fit so I had to build it up with JB weld then sand it back.
The clutch bell housing was a bit out of round which caused to barely scrape on the main transmission plate so that got ground back.
While doing all this ginding I figured I might as well do the cobra freak conversion and ground the crank to 13mm. It wasn't easy, not a project I would recommend to a newbie in the mechanical world.
The build of the 4G is such that my final drive sprocket sits much closer to my frame than the old one did, about 1/2". It is too big of a difference to make up for by shifting the motor mounting, so it is not useable as a chain drive at present. I plan on going all belt drive anyway and I will be able to mount my v-belt pulley much closer to the transmission. I have ordered a 15" rear wheel sheave and need to order my front pulley. From the reading I have been doing it looks like a 16:1 ratio would be about right.
Am I correct in going for 16:1 final ration on a 49cc HS and a 26" wheel?

The_Aleman · Mar 22, 2013

Keeponkeepnon said:
...From the reading I have been doing it looks like a 16:1 ratio would be about right.
Am I correct in going for 16:1 final ration on a 49cc HS and a 26" wheel?

You can answer that yourself best if you take a look at it with a decent Gear Calculator, like this very popular one:

Dave31 said:
Index of /ratiocalc

Using that you can vary the RPM and everything to get an idea what speed you'll be going at what RPM.
You may be more advanced than it, but many members here use it successfully in their endeavors.
Think of what you'll be doing, where you're riding, and adjust the ratio as needed. Enter ratios instead of sprocket teeth

My opinion: 16:1 with a Huasheng is that it's not up to for climbing hills or fighting wind, but it's a great flatland ratio.
Figure ~10MPH @ 2000RPM (roughly idle) and ~29,30MPH @ 6000RPM (nice cruise).
Downhill and/or an aftermarket carb, cam, nice exhaust and you'll be ~40MPH @ 8000 (safe redline)
Stockish, it's hard to exceed 36MPH with a Huasheng on the flats and 16:1 gets you ~34, 35MPH at 7000RPM (hp peak).
With a mean headwind, you can get pushed down to ~4500RPM (torque peak), though, but hills will get you worse.

Of course, if you're willing to pedal and you have decently thought-out pedal gearing, high ratios don't suffer as bad!

Keeponkeepnon · Mar 22, 2013

Thanks for all that Aleman. I was wondering where the torque peak was too.

It appears the largest pulley I will be able to fit on the 4g is about 4". A 4" pulley to a 15" wheel sheave gives a 3.75 ratio. That makes my final, and minimum possible ratio 18.75. Wow, I thought if anything I would have to worry about my ratio being too low. I would have been better off with a 4:1 transmission.

From the calculator above I will get 18.6 mph at 4500 rpm and 28.9 mph at 7000 rpm. I should be able to go up some pretty steep hills.

After measuring in the daylight I may only be able to get a 3.5" pulley in there, which makes me even slower.

I know pictures are always appreciated so here is the bike. I put a lot of work into the original build. Converted the top tube into a tank. Bar end brake lever to a drum brake with the cable hidden in the bars/forks. Stock exhaust with a 80cc 2 stroke silencer mounted in series aimed at the ground/tire to try to quiet it down. How bout that lightened racing timing wheel on the 4g (Haha just for cosmetics). I hate cables, gas tanks, wires, anything that clutters a bike up. Don't pay attention to the date, my camera is not set right.

The_Aleman · Mar 22, 2013

Keep in mind, a Huasheng only has about 2 lb/ft of torque. It takes a lot of reduction to climb steep hills without any pedal power!

My 4G runs through a Sturmey Archer 3-speed, my current ratios are such:

1 - 29.44:1
2 - 23.55:1
3 - 17.67:1

There aren't many hills where I live, but 10 miles away there's a really steep hill I use for testing. I can't pull that hill in 2nd gear, but I can in 1st - with pedaling lol
I could barely pull that hill with a stockish chinagirl 66 @ 18:1 while pedaling hard, but that engine made about twice the torque @ 4500.

Anyway, you can replace the 4G's 100T pulley with an 80T to get the 4:1. B-E has one for $35, you'll need the belt for 80T, too.
This is assuming you have the solid pulley model and not the infamous freewheel pulley 4G.

Keeponkeepnon · Mar 22, 2013

Thank you again Aleman. That is great news that I can switch to 4:1 in the transmission, I was getting ready to throw the bike back in the corner of the garage. The area I plan to ride doesn't have anything very steep. I would have thought the 29:1 would be a stump puller. Maybe I'll be OK with 21.4:1 afterall. Its good to know that it is possible to get lower, makes me want to procede with the build.
I could get down to 17.15:1 with a 4:1 in the 4g and a 3.5" pulley on the output. All that drilling to make my 100 tooth wheel pretty would have been for nada.

The_Aleman · Mar 22, 2013

I put over 5K miles on mine with a 15.5:1 ratio in 3rd gear. While it didn't climb hills very well and could get pushed down to 20-23 with mean headwinds, it cruised really nice at 30 most the time. I rarely go over 28-29, so it worked for me. Then I started riding to visit family in Auburn and realized I need more reduction for those Auburn hills!

Edit: by the way, love your bike, very clean build. Looking forward to seeing how it comes out with the sheave

Velodrome · Mar 24, 2013

!! WOOF!! That is one good looking ride! Do I see the petcock behind the seat tube? How did you seal up behind that ? VERY CLEAN bike!

Keeponkeepnon · Mar 25, 2013

Thanks man. I found a steel nut that the petcock screwed into, drilled a hole in the frame bigger than the inside diameter of the nut but smaller than the outside, then welded the nut to the frame. The fill neck was a steel pipe end welded on, with a universal (rubber bore) oil filler cap from the car parts store.

I just realized you probably were not asking how I stopped up the petcock but rather the rest of the frame. It was a pain in the rear. There are several holes that have to be addressed. There is a hole inside the head tube going into the top tube. I smeared some bondo on the hole from the head tube side to temproarily plug it and then poured liquid epoxy in (surfboard resin) through my filler neck on the top tube side to create a more permanent seal. There is a hole in the seat tube into the top tube which required similar treatment but much more difficult. I did a couple epoxy applications here because you can't tell if it is well coated. The inside of the seat tube then had to be filed flush so the seat post could slide in. The stanchions are pretty much solid epoxy. I then used Red-Kote to line the inside, a lot of guys use Cream.

MEASURE TWICE · Mar 26, 2013

Your work on that tank and the paint is great!

I have a from scratch 3 v-belt with centrifugal clutch, just so I can parade speed under 5 mph at a 40:1 ratio. For off roading and no pedals (swapped for pegs) I intend to get a shorter belt between the twin jack shafts. Then I will remove a 4 inch pulley for a 2 inch pulley replacement. With the belts on adjacent pulleys the same size I will cancel out 1/2 the reduction when I need more speed and end up with a 20:1 ratio.

I have a need to use something and probably Bondo and Epoxy or Polyester (glass) Resin with fiber glass cloth or tape to put on a cover that is for safety. I made it quite strong I can stand on it, but the metal is still just a bit too thin to weld up nice and smooth and I want it covered over.

If you used the Bondo and Glass Resin on any of the exterior metal and it is steel metal, I would like to know if you roughed it up some how? You know any special things so it adheres well.

The tension on the belts I have adjustment that I got them quite tight, but I guess even a hill 30 foot length up about a 15% grade gives the 4 stroke 3hp some work, but the motor does not stall. One belt still slips, maybe it has oil residue left over from when the oil breather needed a new gasket and was leaking. It have it sealed very well now and the hose to the carb from the breather is not leaking.

So I have still a problem with the belt slipping up a steep hill, but I may try as I have heard another had done by sanding the inside of the pulley groove to make more friction by smoothing it out. Then also with some thinner remove the metal dust and see if the belts grabs better.

MT

http://motorbicycling.com/showthread.php?p=467456#post467456

The_Aleman · Mar 26, 2013

Measure Twice, have you tried a good belt dressing? Dielectric grease will do wonders on belts!

Keeponkeepnon · Mar 26, 2013

Bondo is a polyester resin and sticks pretty darn well to steel sheet metal on cars if you rough the surface with 100 grit sand paper and clean it real well with degreaser/acetone. Epoxy sticks even better. I haven't used either for anything that needs to be strongly adhered to the bike. It is just plugging holes that will have no more force on them than gas sloshing around. For a belt cover I would want to screw it on so it could easily be removed for maintenance.

For slipping Vbelts I would definitely try sanding the inside of the pulleys. I just got my rear sheave and it is polished shiny, I foresee roughing it up. I would try degreaser/acetone to clean the contact area of the belts as well, I have done it on my truck when the belt adjustment was maxed out and the belt stopped slipping.

Aleman, I have read about people using dielectric grease on belts before but I just assumed it was to keep them from drying out and cracking. It seems anything with "grease" in its name would promote slippage.

Keeponkeepnon · Mar 28, 2013

I pulled the motor off today so I could really measure my clearance. It looks like 3.5" is the max size output pulley I can use on the 4G and that will require a little grinding. Can anybody tell me if the screw in the center of the picture is? Will I need it later or can I grind it down to a nub?

I received my wheel sheave and mounted it. I got in on Ebay from Whizzerpaul. He answered my questions very quickly and sent it out immediately. My first impression of the sheave was that it is cheap Chinese sheet metal keyrap...and it is. But after handling it for a while I realized its actually very strong and any more thickness would just be unnecessary weight. They are really easy to mount and basically center themselves, way easier than the rag mount sprockets. Is it just me or is it amazing to find something that just fits right on a motor bike with no modification? The welded seam actually did need some help, it was not ground down with much care and had sharp edges, that only took 10 minutes to solve though.

And this is just a little hot rod bling. Gotta have steel braided hose for these high pressure fuel systems right?

Need help converting to all belt drive.

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