2 motorized bicycles With GT2 Frames

[massdrive]

I'm building two custom motorized bicycles with GT2 aluminum frames, Worksman 26 x 2.125 alloy wheels, coil spring suspension forks, alloy stems and bars. I recently finished mocking up one bike, I plan on painting it royal blue so I'm calling it the "Royal". It has a front drum brake and the engine has some minor mods, like a cut piston and drilled wrist pin. I replaced the wrist pin bushing with a roller bearing, and that's it. I'm running a 44T aluminum sprocket with a 415 drive chain. I haven't done any carb jetting and I'm using the stock pipe and air filter. I had trouble starting it until I switched the choke to the off position and she fired up. At first it barely ran and I was fearful that I had a 66cc lemon. After tightening the carb clamp and carb cap it ran much better. I've burned less than a quart of fuel at an 18 to 1 break-in premix ratio. The more I ride it the better it runs. I weigh 230 lbs. and yesterday I was clocked at 32mph on level blacktop with no tail wind!!! This fare exceeds my expectations for this almost stock china engine. Kudos' to Motovelo from whom I purchased the engine.

The second bike is still on the rack about 85% complete. I call it the "Sprint". The engine and all the components except the wheels are blacked out and I installed a front disc brake. The frame will be brushed and clear coated. The engine came with a cut piston and drilled wrist pin and I replaced the wrist pin bushing with a bearing the same as I did to the Royal. I replaced the entire top end with performance parts; 6.0 - 1 high compression billet aluminum head and a ported jug. Unfortunately the porting job I paid for looked like it was done with a hammer and chisel so I had to rework the intake, exhaust, and transfer ports myself (Jake Bike SUCKS). I also had to match the plenum intake to the cylinder intake port because it was a full 2mm smaller (Jake Bike SUCKS), I matched the intake gasket too. Before I installed the expansion chamber I welded up the deficits on the inside of the chamber manifold and matched and polished it to the cylinder exhaust port, and of course matched the exhaust gasket too. I installed a Mikuni VM 18 dual stage carb, and a 90 degree free flow air filter. I'm running a 40T aluminum sprocket with a 415 drive chain. After being so very impressed with the Royal I can't wait to see how the Sprint runs!!! Check out the pics. I'll keep you all updated. By the way both bikes are for sale...

 

[Huffydavidson]

Reallllllyyyyyy, well you won't make many Freinds around here BASHING the sponsors .
Jake is a freind of mine and excellent machinist .

 

[massdrive]

Hi huffydavidson,

Reallllllyyyyyy. Nobody can please everyone, not you, not me, not jake. I had a very bad experience that formulated my negative opinion of jake bike. Do you really want me to post the details? On the other hand I had a very good experience with Motovelo that formulated a positive opinion, and I gave Motovelo kudos for there good work and customer service in the same post. Does anyone have a problem with that? I didn't think so. I can only call it the way I see it friend. I hold no ill will towards you for being friends with jake. Please don't hold any ill will towards me for not being friends with him. We are all entitled to our opinions. No doubt jake is an excellent machinist, but as a journeyman toolmaker I can tell you that even the best make mistakes. What commands respect is how we handle ourselves in these situations. I'm sure that you have had personal experiences that left you twisting in the wind and lacking respect for someone. Good for you for being a loyal friend. We all need more friends like you. Since you have not had any personal experience with me please don't judge me.

KInd Regards To All...

 

[KCvale]

I like the GT2 frames, but I couldn't read through your post, try some paragraph breaks as you go bud so it's readable.
Just a tip.

 

[boocher13]

I'm planning on using one of these sweet frames for my next build. Can you tell me where you bought yours? The only site I've found that sells them is custom motored bicycles. Are there other vendors and if so is a steel frame of the same type available anywhere ?

 

[massdrive]

hey boocher

I purchased my frames from kingmotorbikes.com for $169 each plus shipping, $182 total. zone8 also has them for the same price. I bought the gt2a and the gt2a-s and recommend the gt2a-s frame, because the engine sits lower in the frame, and personally I think it looks better. I found out after the fact that I could have purchased the frames with a 66cc Grubee engine kit for $289. I've seen it several times while browsing the net, but can't find it now... So shop around my friend.

You will need to buy larger front and rear motor mounts and clamp because the front down tube is 1.5 in. dia. and the rear down tube is 1.25 in. dia. You can buy them or make them. I choose to modify the engine case by securing the entire engine in a power lock vise, squaring up the mount surface to a vertical mill table and plunging a 1.5 in. dia. end mill into the 1.25 in. dia. front mount. Don't cut any deeper into the case, just walk the end mill in while plunging it up and down until you dust the inside edge leaving a witness and maintaining the original depth. Machine a new clamp from aluminum pipe with a 1 1/2 in. inside dia. I'll included some pics.

The rear engine mount needs the same treatment, enlarged to 1.25 in. dia. Custom Motor Bicycles sells rear 1 1/4 in. clamps that work well.

If you have never done anything like this do not attempt to do it yourself, find someone who has the skills. Simply grinding out a larger diameter will cause you problems during installation and operation. Correctly mounting the engine is critical. Keep in mind that building from the frame up (component build) is time consuming, every thing needs to be fit and tested. Also I trashed the stock mounting studs and replaced them with M6x1 cap head socket screws. Don't forget to use lock tight...

 

[boocher13]

Wow for $169 that's a great deal . Custom Motored bicycles is selling them for $100 more. I wonder what the difference is? I know the Custom frame comes with a welded in lower mount plate which is nice. I wonder if there are any other differences.

 

[massdrive]

The g2ta frame has a slight "s" curve in the front down tube and requires the frame welded engine mount. The "a" frame also requires a vibration isolator mounted between the engine mount and the engine. You can buy it on line, but it looks home made so I made one. With out it there is a chance the engine case will crack.
The g2ta-s front down tube is almost straight and the engine can be securely mounted directly to the frame. Take a look at the pic I uploaded and compare it to the others.
As fare as I can tell that is the only difference between the two frames. Be sure to clean out the fuel tank before you do anything else.

 

[boocher13]

I checked King's, says the gta is not available until november 15th . I think my biggest obstacle is going to be the bike part of the build cuz i dont know crap about cranks,bars,forks etc. and what will work with what. As far as fabrication and mounting the engine goes I've got that covered.

 

[massdrive]

Personally I like the gt2a-s frame better. Both frames use a standard American cup bottom set, and a 1 1/8 in. head post. I choose to go threadless. I purchased Worksman HD 2.125 in. double wall alloy rims. They are more than twice the price of the competition, but come with 11 gage stainless steel spokes, front and / or rear drum brakes, or rear coaster brake, or free wheel. As no one seems to be able to find this size wheel any ware else it seemed like the only choice at the time. I am very satisfied with them. I highly recommend that you order the wheels as soon as possible because it will take Worksman about a month to get them to you... Worth the wait... If you have any other questions or problems I'm happy to help.

 

[boocher13]

You ordered your wheels directly thru Worksman? Ideally I would like rear coaster and front drum. Do they offer that option?

 

[massdrive]

Dude... I went over that... Yes, drum brakes and coaster brakes. There web site is difficult to navigate so just call them and tell them what you want. Be specific... 718-322-2000 Dive into the deep end of the pool.

 

[rock out]

Wicked looking bikes man. I just finished building my gta-s. Gave me so many headaches probably cause I've never put a bike together before Lol but its looking good now.
Oh and what did you make that rubber for the front mount? They never shipped one with my frame
Here's a pic not most recent I changed a couple things but you get the idea

 

[Ronzworld]

http://motorbicycling.com/showthread.php?t=54134
Check it out just completed my 1st Grubee GT2-A frame build and have already ordered another frame the same too start on a "old school" cruiser version with a springer front end , ape bars , etc. I had a nice old school bike motorized and sold it lasty week and am missing it so gotta replace the void ... but hey .. isn't that why we do this ? for the build ?? I know I get as much enjoyment from the building as I do from the ride !! (well almost ...)
Thanks for looking and let me know what you think.
Ron.
** ride with pride**

 

[massdrive]

The bike looks good. I have the components you need and want for GT2A and GT2A-S bikes. Check out BikeBobber.com and Bike Bobber on Facebook. You won't be disappointed. Again the bike looks good.

 

[Ronzworld]

Hey thanks for the compliment on my build ...means a lot coming from a fellow builder !
I went for a surf through your site and was very impressed with what I saw. You have an eye for detail and an artistic ability in your work ... looks good I suspect that you will do well with your custom components and builds.
I'm pretty much into the same things up here in Canada , only thing is that our summer is just way too short ! I have to run studded tires and ride in a snow suit for about 4 1/2 months of the year ! I do it tho ... ride EVERYday of the year ... at least the distance it takes to get me to work (or to classes the last few months) Finding new people who are into, or wanting to get into , the motorized bicycle world ..... it's been really good to me to say the least ! Hopefully it will keep growing and I will be able to continue to support myself (and my on-going need to play w/my bikes) for a long time to come.
Been putting alot of thought into making a trip South for a few of the colder months of winter... I would like too haul a couple of my bikes along and maybe even do some racing ??
** ronzworldmotorizedcycle.ca **

** Ride with Pride **

 

[wheelbender6]

I think using the GT2 frame can make a low-skill builder like me look like a better builder. I think they also make a home built motorbike look like more of a factory built item.

 

[massdrive]

I think using the GT2 frame can make a low-skill builder like me look like a better builder. I think they also make a home built motorbike look like more of a factory built item.

I disagree. It is no different than using any other bare frame. You still have to make things fit and work together. Depending on what you want there is still cutting welding and grinding to be done. Although aluminum is easier to work with than steel, it is also easier to mess up than steel. These frame's are no more difficult than any other frame. However they do have a significant "cool factor" going for them. Everywhere I go people stop and ask questions about my bikes. I've had motorist's flag me over so they can look at my bike's. It was kind of scary the first time it happened...???

 

[Ronzworld]

Hey there wheelbender .. how's it goin ? have you built a Grubee GT2 framed bike ?
They are a very nice , workable frame that is a great base ta base a build on for sure. I really like mine , no complaints and have ordered another to get started on as I have had a lot of interest locally from my customers ( actually from pretty much everyone who has seen it !)and a couple that are waiting to purchase it obnce it's finished. That's always a good sign that your building in the right direction !!
OPh yeah ... thanks for checking it out and showing the interest it's always nice ta hear from fellow builder/motorized bike luvers ...

**Ride with Pride**

 

[Ronzworld]

Hah !! lol !! Like you said ... people everywhere ask questions and have comments and go to all lenghts ta talk to you on one .. I just about got ran over by a guy a couple of days ago that was tryin to get my attention ... seen two cars crash into each otgher trying to get to me too !! People are strange animals at times !!
But in agreance w/you on the building one is no diferrent than any other ... just cause the tank is there dosen't make the rest of it "magically" appear !