Can I get advise for a powerful 4-stroke setup?

B

BeaverRat

New Member
Hello,
I have recently became competent in the art of the 2 cycle engine, so I do have a decent amount of standard engine knowledge. Anyway, I have been enlisted by my friend to build him a nice 4 stroke motorbicycle.

On first thought, I was just going to get this kit:

SkyHawk 49cc 4 Stroke Motor Kit

...and mount it on a mountain bike (with ample room in the triangle).

But, he and I are worried that it will not be powerful enough to carry him (roughly 190 pounds). He wants to be able to travel at around 30-35 mph on flat ground, and it also must be able to carry him at 25 mph up a decently steep hill. Does this engine have enough power to achieve that goal?

If not, are there any suggestions of a relatively easy method of mounting a more powerful engine onto a bike frame? It doesnt need to be a kit, I can assemble parts, but I cannot fabricate anything. I must be able to buy all the required parts to make it work online.

Thanks in advance!
 
I have a bunch of pictures on my profile. I weight 230 and the bike goes about 50mph and will climb straight up steep incline hills. I've since taking it apart for further mods its just a hobby now that its winter again.
Anyway I went with the beach cruiser frame, SBP 4 stroke shift kit and Honda GXH50 motor. Its quite expensive as some look at it that way but I am vary vary happy with it. I also use the stage 3 tranny.
Your friend would love it I'm sure of it.
Hope this helps
 
Thanks
That does look like a pretty good setup... I would probably order one of the HT 4 stroke kits with the 4G T setup, and then use the SBP shift kit.

Question: SBP's website says that the 4 stroke shift kit is designed for the stage II or III transmission, would it still work with the new 4G T clutch setup, because I would prefer the lower noise levels of the belt drive?

Also, if I was to just go a direct drive route and not get a shift kit, are there any easy methods of using say the 99cc harbor freight Predator engine? What parts would I need to make the predator work?
 
also interested in the predator question,,, looks like agreat deal


also on a side note, do ppl have problems with not having 99c engines? i mean of course Id take stickers off but if the cops eyin me down it sure is bigger than a weed wacker 20cc,,, but then again smaller than those scooter 50cc
 
BeaverRat said:
Thanks
That does look like a pretty good setup... I would probably order one of the HT 4 stroke kits with the 4G T setup, and then use the SBP shift kit.

Question: SBP's website says that the 4 stroke shift kit is designed for the stage II or III transmission, would it still work with the new 4G T clutch setup, because I would prefer the lower noise levels of the belt drive?

Also, if I was to just go a direct drive route and not get a shift kit, are there any easy methods of using say the 99cc harbor freight Predator engine? What parts would I need to make the predator work?
Click to expand...

There is no problem with combining the 4G and the Sbp shift kit.As long as it is the Honda/Hs motor with the 4G.Not the Hs with the clutch pack build into the engine.
 
I just finished putting a 4g and SBP shift kit combo with an HS on a mountain bike. It is a great set up for speed and/or hills. I'm 235 and I can pull my two daughter in a bike trailor up some pretty good size grades
 

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Ok,
Thanks for all the replies guys!

I think I am going to go with the 99cc Predator engine route, because my friend is not mechanically inclined at all. And I am thinking he will not be able to fix all the complicated shifting parts if it breaks.

With that being said...

Question: Can someone help me make a list of all the different components I need to adapt the harbor freight 99cc predator to a bicycle?

Thanks
 
BeaverRat said:
Ok,

Question: Can someone help me make a list of all the different components I need to adapt the harbor freight 99cc predator to a bicycle?

Thanks
Click to expand...

I second, went to HF and almost bought the engine... going to hold out until next paycheck to grab it,, but Im doin same build..

Have bike, sort of, picked out, and engine size, now how do I make it run :Pzpt
 
Add AGK's "Jackshaft Assembly" for $135 and you have a transmission. $45 for the aluminum cover.

Then you just need a motor mount, ~56T rear sprocket and #41 chain, a fuel tank (or re-purpose the HF one), accelerator, and fuel!
 
The_Aleman said:
Add AGK's "Jackshaft Assembly" for $135 and you have a transmission. $45 for the aluminum cover.

Then you just need a motor mount, ~56T rear sprocket and #41 chain, a fuel tank (or re-purpose the HF one), accelerator, and fuel!
Click to expand...

Which side of the bike does AGK's jackshaft assembly put the output sprocket on?
 
The_Aleman said:
Left side, here's an example of the finished product, no cover. Also, a MaxTorque clutch is needed.
Click to expand...

Thanks,
Will that thing fit in a biycycle triangle with the cyllinder head oriented backwards that way? It seems as if it would fit better with the slanted head facing towards the front of the bike.

Anyway, how does this parts list look?

affordablegokarts: Jackshaft Assembly for 79cc HF Engine

affordablegokarts: Max Torque Clutch

affordablegokarts: Output Shaft Bolt Kit

affordablegokarts: Motor Plate for 79cc HF Engine

Ball Bearing Chain Tensioner [4S-CDS-BBCI] - $12.99

Standard 9 Hole Sprocket - $19.99

Standard Sprocket Install Kit - $12.99

Standard Twist Throttle Kit w/ Matching Left Grip - $15.99

1/2 Gallon Gas Tank (black) [4S-FS-GTB] - $29.99

Black V-Frame Mounting Plate Kit [4S-ACC-VMKB] - $29.99

Predator 99 cc OHV Horizontal Shaft Gas Engine - Certified for All States Except California

Is there anything I am forgetting?

Thanks again
 
Looks like you have everything covered, but I wouldn't use a ragjoint system for the sprocket.

Go with a hubmount system like ManicMechanic's or Sportscarpat's. It'll save you a lot of headache for an extra $25-$30 or so.
 
Thanks for all the help guys... I finally feel like I can do this!

Are there any known bikes that this engine will fit in? I am trying to decide on a good bike for this large engine.
 
Why not go cvt? Not that much more and will be faster.. Not sure if I have seen one that fits 5/8 .. But I've heard of adapters.

I'm doing the same build.. Maybe the gx200 clone though
 
The engine turns the wrong way to mount cylinder foreward and use chain drive. You would have to use a fricton drive to reverse rotation like this.

-a.JPG
 
wayne z said:
The engine turns the wrong way to mount cylinder foreward and use chain drive. You would have to use a fricton drive to reverse rotation like this.
Click to expand...

Ok
Since that's the case, are there any specific bicycles that will for sure fit this engine with the cylinder backwords (for a chain driven setup using the parts listed above)?

Thanks
 
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