Nothing runs like a Honda that is for sure. I paid $75 for 79cc and $140 for the 99cc. I can't justify buying another engine for $500. I'll put the $500 into the 99cc Predator and I'm sure I will be satisfied. I'll try a GX on another future build. Thanks for the tip.
99cc Predator Build
- Thread starter agk
- Start date
Yes I see that too. What about a CVT to a jackshaft to a shift kit. Again I realize the CVT makes a shift kit mute, but I can't stop thinking about it. The only way to stop this chain of thought is to try it.
The 79 and 99 will not make the cvt work right, not enough hp. You going to spend 500 on upgrades to that motor? What's the plan?
My "semi-build"--am taking over a more or less assembled project that needs to be reworked--has a centrifugal clutch run via belt through a jackshaft arrangement and ends up driving a chain leading to the five-gear hub and original derailleur. The former owner said it would not go above third gear. When I test rode it I never got it that high but it did shift under power just as a conventional bike does while pedaling. It was so unsteady that I was afraid to try to run it out. It balances quite well, but was riding on 26 x 1.25" touring wheels which were completely out of true (most of the spokes are actually loose). I changed the wheels out today for a set from a mountain bike I've had laying around for a while--those are 26 x 2.5". NOW it feels like it'll hold onto the road.
I am planning on building the engine also. Right now it is completely stock--indeed, it's been run less than an hour. But, first things first: the brake pads are shot (probably 40 year old original pads) and I may replace the calipers with those from the aforementioned mountain bike (considering a disk for the rear but strongly suspect that there's no way to mount a caliper on the 1970s frame). And I discovered today that there's not a single lock washer on anything added during the conversion (owner told me that bolts kept coming loose and seems to have had no idea why). Will be tapping the hardware store's stock heavily tomorrow, I guess. Once I know it won't shake itself to pieces I'll be able to give it a proper workout.
It's very weird--the guy started with an abandoned tandem bicycle and did a remarkable, if somewhat complicated, build (hope to have pictures up soon). But he appears to have given up before taking on the details that will convert it from something to putz with in the garage to, I suspect, a decent motorized bicycle. He bought a brand new set of tires for those skinny wheels which I suspect are not original to the bike (VERY lightweight for a tandem bike), then never trued them or even checked to see if the spokes were tight. Then he bought a brand new engine which he didn't bolt on correctly.
Must say that the jackshaft assembly, etc. is very solid and certainly more than was needed (there's even a spare pulley--looks as if you could hook a saw rig or some such onto it). I got the whole thing for less than he claims to have spent on parts (and should be able to sell the wheels and tires that came with it for something) and I'm a detail person, so....brakes, lights/horn, etc. and then....the joys of convincing the DMV to register it!
I am planning on building the engine also. Right now it is completely stock--indeed, it's been run less than an hour. But, first things first: the brake pads are shot (probably 40 year old original pads) and I may replace the calipers with those from the aforementioned mountain bike (considering a disk for the rear but strongly suspect that there's no way to mount a caliper on the 1970s frame). And I discovered today that there's not a single lock washer on anything added during the conversion (owner told me that bolts kept coming loose and seems to have had no idea why). Will be tapping the hardware store's stock heavily tomorrow, I guess. Once I know it won't shake itself to pieces I'll be able to give it a proper workout.
It's very weird--the guy started with an abandoned tandem bicycle and did a remarkable, if somewhat complicated, build (hope to have pictures up soon). But he appears to have given up before taking on the details that will convert it from something to putz with in the garage to, I suspect, a decent motorized bicycle. He bought a brand new set of tires for those skinny wheels which I suspect are not original to the bike (VERY lightweight for a tandem bike), then never trued them or even checked to see if the spokes were tight. Then he bought a brand new engine which he didn't bolt on correctly.
Must say that the jackshaft assembly, etc. is very solid and certainly more than was needed (there's even a spare pulley--looks as if you could hook a saw rig or some such onto it). I got the whole thing for less than he claims to have spent on parts (and should be able to sell the wheels and tires that came with it for something) and I'm a detail person, so....brakes, lights/horn, etc. and then....the joys of convincing the DMV to register it!
I've been working with my maxtorque centrifugal clutch on my 98cc flathead, and have it to the point where it doesn't chatter on takeoff at all. I pedal assist a little to help get up to speed, but that's about it. The clutch is powering an agk jackshaft. What I did with my clutch was replace the bushing, used a heavier spring, installed a thick fiber washer between the clutch shaft and the bushing to take up the space between them, and instead of oiling the bushing, I take the clutch apart once every week or two and grease the bushing and the shaft. No problems with chatter or slippage since going this route. I soon plan to install heavier shoes to test a theory about clutch tuning, but I just wanted to share this info for anyone who is using a maxtorque clutch. They can be made to run reliably if you work with them. The thick fiber washer is from home depot and cost about 60 cents. I took the old thin fiber washer that was in the clutch originally to match up the diameter. The maxtorque clutch I have is for a 5/8 shaft, but the clutch shaft was bored for a 16mm shaft, because that's what my engine has. I also grease the crankshaft before putting the clutch on, and this helps keep it from getting stuck on the crankshaft. It used to get stuck so bad I'd need a hammer and an equalizer to get it off. But since I started greasing it, it slides right off.
Well seeing as how the engines are still in the boxes and the build is still in the concept phase, I'd have to say the plan is still in the planning stage too. I know some go kart racers that use the HF 99's very successfully thought I would also consult with them when the time comes. This is my first 4 stroke build and although I have the needed skills I am moving slow and exploring all avenue's before I come up with a concrete plan. I am certainly taking your advise seriously, but when someone tells me it can't be done....... you can guess what is probably going to happen.
Mine doesn't chatter at all, though I think it slips somewhat starting off. Once the bike is rolling, it's very smooth--no chattering, jerking, or anything of the sort and throttle response is quite good. It's just when a bit more oomph is needed to get rolling that it seems to lag a bit
The former owner claimed it would hit 40 mph. With the modifications I am doing and at least a partial engine build, I expect to get more torque out of it, though I don't really need more speed.
Does anyone have any ideas on the efficiency of the average centrifugal clutch? My hope is to turn mine into an ultra-efficient "utility vehicle" that will haul a large bicycle trailer and be used more for errands than running around (I have two motorcycles for the latter). Hoping to get near-moped gas mileage and solid reliability. With no suspension, I don't think high speeds are going to be a good idea.
The former owner claimed it would hit 40 mph. With the modifications I am doing and at least a partial engine build, I expect to get more torque out of it, though I don't really need more speed.
Does anyone have any ideas on the efficiency of the average centrifugal clutch? My hope is to turn mine into an ultra-efficient "utility vehicle" that will haul a large bicycle trailer and be used more for errands than running around (I have two motorcycles for the latter). Hoping to get near-moped gas mileage and solid reliability. With no suspension, I don't think high speeds are going to be a good idea.
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The theory I am planning to test with clutch tuning is this. I read somewhere that the best way to get smooth engagement across the powerband is to use a heavy spring and heavy shoes. Now I know a lot of people are going to dispute that, because it goes against popular theory. But after having heard it from probably 25 people, I still plan to test it. I'm currently running the black spring, which with the stock shoes raises the engagement to about 3100 rpms. With the heavier shoes, I'm expecting (guessing) the engagement to drop to about 27 or 2800. The shoes can also be mixed, as long as it is done evenly. It's a six shoe clutch, so you can have every other shoe light/heavy (3 light and 3 heavy alternating), or two light, one heavy, or two heavy, one light. I'm going to try running all 6 heavy first and see how that does, if I don't like it that way I'll play around with the arrangement. I'll share my findings on here. It is my belief that with the proper shoes and spring, a maxtorque clutch could be used for towing, although you might need to replace the bushing a little more often depending on how much weight you're hauling. But I will let everyone know what I find when I start playing around with the shoes.
They will change the rpm engagement of the clutch. The black spring is the heaviest I know of for these clutches, the green is medium and the silver is lightest. My clutch slipped badly with the silver spring, never tried the green. Went straight to black. Green engages around 2550 and silver around 2200.
Good luck with that max torque clutch... Not worth the time or effort when we have other options. By the time your done you could have purchased something that works.
The maxtorque clutch was free, it cost me $10 to have it bored, the fiber washer cost 60 cents, and the shoes cost $25. Oh and the spring cost like $10, so let's see, $45? I know some people aren't a fan of spending time to get something working when they can just throw money at it instead, but I don't have a lot of money to throw at it, so I'm doing what I can. I've already got it to where it doesn't slip on takeoff, now I'm into tuning it so it doesn't slip going up hill, and despite what you may say, it can be done. There is no reason it can't, and snide comments aren't going to stop me.
When (not if, when) I get my clutch properly tuned, I will share what I've done with everyone, because a maxtorque clutch cost what, $50? The two next best clutches are hilliard and draggin skin, I'm not sure how well the hilliard clutch performs or how tuneable it is, but the draggin skin costs 3 times as much as the six shoe maxtorque, and even if I paid full price for my clutch, tuning it still wouldn't have cost me as much as a draggin skin. And a disc clutch is even more expensive, and I've heard takes work to mate to a 5/8 shaft. So I'll stick with tuning the cheaper clutch, thanks. Because I have more time than money, and I'm sure there are others who would like to know that this clutch can be tuned, so for my sake and theirs, please stop trying to shoot me down.
Oop, I forgot. The bushing cost me $10. 3.50 plus $7 flat rate shipping from OMB warehouse. So $55 altogether is what I've got in this clutch 
Actually that's minus the $25 for the clutch shoes, because I haven't ordered them yet, so I guess it's $30 so far. I'll be ordering the shoes on Friday if they're in stock.
I've no idea who made my clutch--will have to take a look at it and also the springs. No complaints with the way the clutch works. Open the throttle and it engages smoothly--perhaps a bit too soon to have as much torque as I'd like, but if I can change out the springs I can change that.
The jackshaft arrangement on my machine runs through two reductions by belt before connecting to a sprocket which connects to the original 5-gear hub. There are also two front sprockets, so, if I can get a bit more power out of it, I can switch to the larger of the two sprockets for speed and to the smaller when I want more pull. The dual reduction pulleys are large enough that they act as flywheels, making the power impulse very smooth. It's not at all what I am used to from a single cylinder engine.
The jackshaft arrangement on my machine runs through two reductions by belt before connecting to a sprocket which connects to the original 5-gear hub. There are also two front sprockets, so, if I can get a bit more power out of it, I can switch to the larger of the two sprockets for speed and to the smaller when I want more pull. The dual reduction pulleys are large enough that they act as flywheels, making the power impulse very smooth. It's not at all what I am used to from a single cylinder engine.
And SBP is "out of stock" on 3 of 4 of their shift kits.
And SBP does not recommend their kits on HF 79cc/99cc, so no sane builder
can take that liability on a sale.
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Some people like to throw money at things until they work the way they want without a lot of extra messing around. Other people are willing to experiment with one setup until they've either got it working how THEY like, or they've finally figured out that they just won't be able to. Culvercity, you go ahead and keep throwing money at things until you find the perfect bolt on and go solution. That's your choice. But as for me, I'll decide what my time is worth, not you, thanks.
Hey Monkey just trying help out some other members, you do what you got to do. I am sure people would be interested in your outcome, since most would rather pay for the max-torque. I know I would.
It was just a little over a month ago that Brandon introduced himself. No bike to show or no engine talk about. Just a big attitude and a plethora of useless information. Why are we even wasting time on this member. Should he even be a member since he's negative all the time??? I don't like it when new members start barking at elite members. No respect or forum etiquette at all! He'll probably start barking at me next .
I'm with CCC. Why polish a tird??? Save up for a plate clutch and exploit what you're putting so much time into! You'll be suprised and will slap yourself for your comments. That is if you even have a build going.
.I'm with CCC. Why polish a tird??? Save up for a plate clutch and exploit what you're putting so much time into! You'll be suprised and will slap yourself for your comments. That is if you even have a build going.