JD Themed GT2A-S, 4 stroke

GoldenMotor.com

sportscarpat

Bonneville Bomber the Salt Flat record breaker
Jun 25, 2009
1,839
471
83
california
Nice looking bike. Good to hear the bars worked out. There is almost always untapped potential in any engine, at least any stock engine, but 50cc is a bit on the small side. Still, with the right upgrades that thing should pull like a tractor!
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Great bike. I bought the same fork after seeing yours. I hope to have it set up on Friday. I'm not familar with them. Can you adjust for ride? Make them hard / soft? Hows it riding btw? I can't wait to have a little give on the front end.
 

runnermike

Member
Nov 18, 2012
936
0
16
Sanford, FL
I have the same forks. They are great for motorized bicycles. They do have a bit of adjustment on them. Not so great for straight pedaling....bike tends to bounce up and down when you are standing up and pedaling.
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
Yup, I love the ride. I've hit a couple lumps in the road that I would have preferred to steer around, but it soaked them right up. I wouldn't want it on a straight up pedal bike, too much bob for out of the saddle pedaling, but it's awesome for motoring. I actually haven't had to adjust mine at all. I've been happy with it right off the shelf.
 

Toothy

New Member
Mar 25, 2014
181
1
0
San Diego
Cool! I have a 1" threaded set-up and its been a little tricky to get it to work. I may have to get a little inventive but I'm determined to get it to work. Next i'm going to buy a bmx style stem and set of bmx handlebars with 8-10" rise. Form and function!
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
Pretty much solved the air filter clearance issue with the fuel feed. Got a high flow banjo fitting like would be used for a custom oil cooler or something. Picked up a bolt to go with it that was a little on the restrictive side so I drilled out the hole to open it up. Inline filter and shut offs. I'll tidy it up a bit longer term with a right angle filter, for now I just looped it around the seat tube. Also checked valve clearances as per Aleman's excellent write up, intake was very loose and exhaust was tight. Gained some power but hardly any top end. On a 15 mile run that I was previously averaging 17mph, avg went up to 20mph, but top speed on the flats is still about 22-23.

 

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
Knight, have you thought of sending a picture to JD?

Not sure it is a great idea but bet they would love it. She really is a beautiful build and a great homage.
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
Knight, have you thought of sending a picture to JD?

Not sure it is a great idea but bet they would love it. She really is a beautiful build and a great homage.
Thanks for the compliment! I haven't sent any pics in, I may when it's "done". I still want to add some aesthetics to the project. Like bobbed/shorty fenders, rack with ammo can pannier, brown or yellow seat, and some lights.
 

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
Oh man! Gonna look suweet!

Purty work, Knight. Don't let me interrupt. Carry on and post lots of pics!
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Look'n really excellent...



... but I have to ask about the saddle.
Are the two absorbent patches on it for just in case you literally 'scare the crap out' of yourself? Kinda like depends for your seat?

Just kidding man, you built a fine machine, bravo!
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
LOL, that seat is pretty comfy, but it has got to go. It's a Bell that came off a bike a I pulled from the dump. The two weird looking patches are a rubbery air/gel pad. Whatever it all is, it sure does dampen the vibrations but aesthetically, it's ugly as sin.
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
Alright, finally got a couple more tweaks done. I moved over the front chainring, that took a little grinding/filing of the kit crank spindle, but now it lines right up with a sweet chainline. I still don't like the crank, but it'll do for now.



Next up I swapped out the CDI.
Here are the two I had, on the left is the Honda version I swapped for the bad one in my kit. This is the one I believe to be rev limited. On the right is the new one from SpookyTooth, which hopefully tomorrow will carry me a touch faster on the flats. Fingers crossed.
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
...with the right upgrades that thing should pull like a tractor!
HOLY CRAP! Now I know what you guys were talking about! Swapped that CDI and it's not even like riding the same machine! I just did a quick shakedown run, but it takes off with no need for pedaling at all, I can actually feel the throttle response, climbs hills without dogging down, and now hits 27mph pretty quickly (former top speed 22mph). At WOT and top speed, it's starting to wish for a little more fuel but if I back the throttle down to cruise at about 26.5, it's buttery. This is hilarious, with no frame of reference for the motor, I had no idea how much more pick up it should have had. I'm feeling like a kid that just had the training wheels removed. :D dance1

Nooooow I'll get on to the rest of the cosmetics...
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Just FYI, the new generation coil you removed is paired up with a new flywheel that has the key slot cut in a different position to alter the timing in an effort to regulate the new engines. Changing the flywheel out to an old style one to match your new-to-you old style coil should net even more performance.

This information was shared with us by worksuxx in his thread.
http://motorbicycling.com/showpost.php?p=517915&postcount=60
 

knightscape

Member
Jul 29, 2013
340
1
16
Maine
Interesting, I'll have to pull the flywheel and measure. I have the Gasbike.net/Kings kit version with the taper shaft and 20t x 80t pulleys, so maybe it is one of the older ones anyway? I never got to try the initial CDI, it fired once, then died before I could mount up and ride. Been riding with the Honda replacement ever since, till this weekend. It does have the non-tunable carb though, so I guess I can't be sure without measuring.

Had an awesome ride to work this morning, first time commuting on the bike. 15 miles along the river. 7 miles of it with a paved breakdown lane all to myself. Just need to mount up a coffee cup holder...
 

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
That sounds so awesome, Knight. There is just some thing about ridding these things to work that makes for a great day.

Years back I had a regular job and was ridding past the Travelers BLDG. in Hartford. I was on a point beach with a HF79. Ugly, thrown together MB that I loved.
2 woman at a bus stop were laughing hysterically at me. (not in any way with me) All's I could do was smile back. From ear to ear. They stopped laughing and looked at me with confused expressions. Was a cool moment. Met disdain with happy. Didn't even understand their dismissal until later. Was having to much fun. .....and they were waiting for a bus. snork.

If it rained, I had a car and if it snowed, had a truck.