Road master BTR tribute: gc160 or Preddy 212?

[KeithSeymour]

Hey guys,
I'm new here and have made my introduction in the intro part of the forum. I actually joined this forum to learn how to build a BTR tribute bike. I've poked around enough to learn a little but wanted to get some feedback from you guys as I plan out my build. I have a 1952 road master frame and fork I was able to get a decent price for on eBay to use for my BTR tribute. I'm a pretty big guy (6'4" and 280lbs) so I've been looking to use a bigger 4 stroke engine such as a predator 212 or gc160 to push my weight. My goal for this bike is to have a fun, torquey, good looking motorized bicycle to ride around the neighborhood and maybe commute 7miles to work occasionally. I live in va where the only limitation of motorized bicycles are they have to stay under 35mph but I'd like a bigger motor to get me there fast. My hesitation in doing so is that it may involve a bit of fabrication over my head for my first build to do the 212 or gc160. I do have a general mechanical knowledge as I've worked on cars and bicycles almost my whole life but my time is very valuable as I have to small kids and work quite a bit. I just don't want to get in over my head with this project since I've never built a motorized bicycle. Here are my questions:
1. As far as ease for my first build but still accomplishing my goal of having some torque, would the gc160 or preddy 212 be better (or maybe another option in a kit form I'm missing?)

2. I wanted to do an inframe tank but am not at the skill level to fab one myself and not sure if the sportsman flyer hornet one will fit my road master (the cost is quite an issue as well). I've considered making a PVC tank or using another canister and just making a tank cover to save money and welding skills. Thoughts on this?

3. I've seen the preddys and gc160s all use jack shaft set ups. Im new to and very unfamiliar with what a jack shaft does. Is this a necessity for these motors and are there any resources you guys can point me to to understand how they work?

Sorry for the long post but wanted to get your feedback. Everyone has been helpful so far and I appreciate your patience in the future as I may have stupid newbie questions. Thanks!

Keith

 

[itchybird]

Hey Keith,

Welcome to forum, it's a good place to hang out. The 212 Predator is a big powerful motor, the GC less so, but is still a powerful little motor. These are great motors and as a big guy, it's nice to have a powerful motor, but mounting the motors properly takes some skill, but it can be done. Even the little China dolls will haul a big guy around, but they'll never compare to a nice 4 stroke motor. As to you specific questions:

1. I'm a big fan of the Honda GX motors and their clones, be it Predator or whatever. After market part network is excellent.
2. A Sportsman tank for a Schwinn Hornet style is probably not going to fit right. But the straightbar frames are easy to come by.
3. The 4 strokes (GC, Predator, or whatever) typically don't have any gear reduction and you want to be around 10:1 to 12:1 overall ratio for a street bike.

Have fun and do your homework before you start shopping.

Rich

 

[jazz2561]

Howdy Keith,
Like itchy said, welcome. I can attest to the 212cc because I've had them on my bike, and they are really good engines. 212s are torque monsters(it pulled a welded and reinforced jackshaft of my bike twice.) As fun as they are, be careful because these engine can really fly when geared low enough.

 

[SlowBalt]

Hi Kieth. I actually have several roadmaster bikes. You will need a custom mount for any engine you decide to install. My last build was with a predator 79cc . The bike can get up to 40 with a 200 lb rider. You can just get a bolt on jackshaft from Agk.
As for the Gc 160 . It is too talk for the frame. The 212 will fit but I would hold off until you have some more experience.

Also the roadmaster forks look the best in my opinion but, they are very unstable in corners.

 

[atombikes]

Also the roadmaster forks look the best in my opinion but, they are very unstable in corners.

SlowBalt- is that a kit tank covering your clutch and jackshaft? Brilliant and looks good! Also, I thought the Roadmaster springer fork was the "best engineered" springer fork design??? Think I read that on the CABE. The Roadmaster springer design does seem like it would alter the trail value as the springs compress, but so does the Schwinn design.

 

[SlowBalt]

The fork floats like an old Caddy .Any bump or throttle into a corner will change steering angle mid corner. they are fine on a pedal bike, but scary on a motor bike.
I'm using them on one of my two stroke bikes, but I know what not to do.

 

[KeithSeymour]

Hi Kieth. I actually have several roadmaster bikes. You will need a custom mount for any engine you decide to install. My last build was with a predator 79cc . The bike can get up to 40 with a 200 lb rider. You can just get a bolt on jackshaft from Agk.
As for the Gc 160 . It is too talk for the frame. The 212 will fit but I would hold off until you have some more experience.

Also the roadmaster forks look the best in my opinion but, they are very unstable in corners.

Thanks for the input! I love the look of your bike. I'm planning on stripping the frame/fork down and painting it black like yours. It's red and white now and it pretty rough condition paint wise.
Did you fab your own in frame tank? You're not willing to part with one of them for my build are you?

I was planning on going with a springer fork but now with your input, I think I may stick with the stock and add some truss rods for the looks.

You said the GC160 won't fin but CCC mentioned in one of his posts that it was 12.5" tall. I measured the inside of my frame and came up with around 15 inches if I remember correctly. I figured id factor in a few inches for dead space under the mount. Am I missing something?

Also, I know you've done a 79cc preddy but I have heard that the size isn't too much different with the 99cc (same mount?). Maybe I could get going with a 79 or 99cc initially then upgrade using most of the same parts for a 212cc later. Let me know your thoughts on this as far as ease as a beginner with the 99cc. Thanks for you help!

 

[SlowBalt]

The 99 and the 79 are the same size. The 212 is quite a bit bigger. It would require a different mount than the 99 or 79cc. you could use the agk jackshaft with all these engines but it would require a 3/4 shaft clutch with a 212 , and a 5/8 clutch with a99 79cc.

 

[KeithSeymour]

So I just realized the 99cc is no longer available through hf so that might be out. Forgive me if it is somewhere else but is there a complete parts list for a 212, gc160, or 79cc setups? And maybe someone's build thread you guys would recommend I check out to see everything involved?

 

[truckd]

Here is a link through the swap & shop section of this forum that might help your dilemma with engines, predator is gone the Honda is still available.

http://motorbicycling.com/showthread.php?t=44239

 

[KeithSeymour]

Here is a link through the swap & shop section of this forum that might help your dilemma with engines, predator is gone the Honda is still available.

http://motorbicycling.com/showthread.php?t=44239

Thanks for the info but I'm not quite ready to pull the trigger on any motor until I do more research. I have seen some gc160s on my local craigslist for pretty cheap so if I decide to go that route I'll be on the lookout.

 

[silverbear]

http://motorbicycling.com/showthread.php?t=51172

The above link to a current thread addresses some of your concerns.

Regarding a Panther tank fitting your frame... it would be a miracle if it did. to the casual eye a lot of frames look so similar that you imagine the space available for a tank is really close or the same. Not. Even with the same make, for example a Schwinn cantilever... the 51 frame I have is different from the 53. One of the tanks would fit one but was too big for the other. So I had to make a smaller tank. And neither would fit a 1970 or so Schwinn cantilever. Be prepared to pay dearly for a hand made in frame gas tank. They require a lot of time and skill to do them well.

BareleyAWake did a nice sticky on how to make an inframe tank without welding... he shows you how to do everything up to the welding which you then take to a welder to have done. You can save a lot of money that way.

If Slowbalt will make you one, go for it. He's a good guy and knows what he's doing. He also gave you good advice regarding the 79cc. That would be my suggestion, too. They have more grunt than one would imagine and there are upgrades which will goose them some more. You can have a lot of fun with that one. Later on when you know what's what you can think about the 212. 35 or 40 mph on a motor bicycle seems pretty darn fast... woohoo!
SB

 

[KeithSeymour]

http://motorbicycling.com/showthread.php?t=51172

The above link to a current thread addresses some of your concerns.

Regarding a Panther tank fitting your frame... it would be a miracle if it did. to the casual eye a lot of frames look so similar that you imagine the space available for a tank is really close or the same. Not. Even with the same make, for example a Schwinn cantilever... the 51 frame I have is different from the 53. One of the tanks would fit one but was too big for the other. So I had to make a smaller tank. And neither would fit a 1970 or so Schwinn cantilever. Be prepared to pay dearly for a hand made in frame gas tank. They require a lot of time and skill to do them well.

BareleyAWake did a nice sticky on how to make an inframe tank without welding... he shows you how to do everything up to the welding which you then take to a welder to have done. You can save a lot of money that way.

If Slowbalt will make you one, go for it. He's a good guy and knows what he's doing. He also gave you good advice regarding the 79cc. That would be my suggestion, too. They have more grunt than one would imagine and there are upgrades which will goose them some more. You can have a lot of fun with that one. Later on when you know what's what you can think about the 212. 35 or 40 mph on a motor bicycle seems pretty darn fast... woohoo!
SB

After checking out the linked thread, I may have been talked off the ledge of the 212 and gc160 and may just go with th hs 49cc grupee kit for $360 to start off then upgrade to a 79cc preddy once I get my feet wet. The major downside to this for me is the look of the 49cc on a BTR. Do you guys know of any btr pictures that have the grupee 49cc looking vintage?

 

[silverbear]

Keith,
I'm not that familiar with the Grubbee kit as I started my 4 stroke adventures with the EZ Motors kit, but it uses the same engine, I believe. I don't know that removing the plastic shroud makes it look vintage exactly, but it does make it look lots better in my opinion.

http://motorbicycling.com/showthread.php?t=24275

The above link will show you how to make an alternate shroud that is easy and actually looks good!

Glad you stepped back from the precipice. You're going to have a lot of fun with that smaller engine. After I did my upgrade to first a 79 and then a 99 I sold my perfectly good 49 to a forum member who was glad to get it.

Good luck to you and please do a build thread. Someone else out there is reading this thread and is also deciding to start out more modestly... so you will be breaking ground for that person and your experiences will be a real help.
SB

 

[FMB42]

After checking out the linked thread, I may have been talked off the ledge of the 212 and gc160 and may just go with th hs 49cc grupee kit for $360 to start off

Hi Keith, and welcome aboard,

I just want to say that $360 seems to be a very steep price for a Chinese bicycle engine kit. Unless I'm mistaken, more than a few retailers offer good or better Chinese kits for well under that price (That's Dax, Custom Motored Bikes, etc, etc). You might also consider the 66cc version over the 49cc units just for the sake of having more power.

HTH

Edit: Sorry, I thought you were talking about the 2 cycle kits...

 

[KeithSeymour]

Hi Keith, and welcome aboard,

I just want to say that $360 seems to be a very steep price for a Chinese bicycle engine kit. Unless I'm mistaken, more than a few retailers offer good or better Chinese kits for well under that price (That's Dax, Custom Motored Bikes, etc, etc). You might also consider the 66cc version over the 49cc units just for the sake of having more power.

HTH

Edit: Sorry, I thought you were talking about the 2 cycle kits...

Yep, I'm thinking of going with a four stroke for ease and reliability. Are there any good quality 4 stroke kits with higher displacement than 49cc?