Predyno 99cc......the ultimate daily cruiser!

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MotorBicycleRacing

Well-Known Member
Jul 28, 2010
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SoCal Baby!!!
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One is quite obvious in these pics I took today and the rest hiding beneath the plain exterior. Heavier valve springs, a billet rod, a billet flywheel and ???

The little Dyno cruiser is ready to battle the big, bad race bikes at Grange in a couple weeks. In the meantime, I'll be riding it to work everyday......

pushing 5hp........maybe? see you in da pits
Huge thanks to Richard at Joker Machine for the trophy for your bikes class if there are more than four 99 cc / 79 cc HF bikes in the Midrange class race.


 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Please answer my PM
Billet flywheels are high on the safety issue agenda for ungoverned motors.
I know I don't want to be anywhere near fragmenting flywheels.
The billet flywheel was an experimental prototype made by a friend and was not balanced or timed properly for the set-up I'm running.

So now for safety's sake I'll be wearing chainmaille chaps and a titanium cup.....stand back! laff
 

Master-shake

New Member
Feb 24, 2013
315
0
0
texas
Hey scotto just wanna say nice bike. I've admired it for some time now. Anyway I wanted to know about that disc brake you have in the middle of your bike I think it looks really cool. Is it functional for stopping? What's going on with that thing? Parts list or is it all fabricated? Is it a modified jack shaft or is that what a jack shaft is
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Hey scotto just wanna say nice bike. I've admired it for some time now. Anyway I wanted to know about that disc brake you have in the middle of your bike I think it looks really cool. Is it functional for stopping? What's going on with that thing? Parts list or is it all fabricated? Is it a modified jack shaft or is that what a jack shaft is
Why thanks Master-shake, the disc brake mounted on the jack shaft is a very powerful stopper. I don't really have a parts list as most things on this bike were fabbed up and thrown together. The jack shaft is just two pillow block bearings and a 5/8" keyed shaft bolted to 1/4" aluminum plate. A very simple set-up.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
I took a little ride yesterday running some errands and just getting some fresh air before going to work. Got the 99cc up to 48mph and it was turning a whopping 7,680rpm with it's 12:1 gear ratio.

Pretty crazy I know, but the engine was just purring and the valves were not floating at all. It's been a great little engine so far.......

 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
I think I am selling my bike this Monday. It too slow for me... Lol

I picked up a new bike project today so that's my focus.

What do you think our bikes are worth?
I'd say $1,200 and wouldn't settle for a penny under a grand. Which one are you selling, the tan or the blue? Too slow?

You should ask at least $1,400 for heavens sake......seriously.
 

culvercityclassic

Well-Known Member
Sep 27, 2009
3,115
177
63
Culver City, Ca
The blue one that I took to the race, it runs real good at home now. I will gag you if I get what I want. It's a solid bike and I do have some cash and labor in it.

The other one stays in the living room... Lol
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
The blue one that I took to the race, it runs real good at home now. I will gag you if I get what I want. It's a solid bike and I do have some cash and labor in it.

The other one stays in the living room... Lol
Two grand wouldn't be asking too much, your bikes are damn near priceless knowing what goes into them. You are one of the best builders on the planet.....charge accordingly!

On a side note.....took the bike up to 7,680rpm again today......wish quality billet parts were made for this engine (so I don't blow it).
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Here is the bike put back to it's everyday tasks of commuting and just running around town......











This little 99cc powered beach cruiser has proven itself on the track and on the streets of San Diego......what more could I want from a build?
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
That bike is awesome, scotto!
Due to the success of your 99cc build, I am torn now between saving up for a HF79cc build or an electric build. I know the 79cc will have a longer range, but I like the stealth of an electric. I might even go hybrid over time...
But anyways, that bike of yours seems to work perfectly and is really swaying me away from the lower powered HS142 I have sitting in my garage.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Here is a little upgrade today on the 99. Made a new intake manifold for the 19mm carb I won at the races from AGK. The manifold is a kit, also from AGK, and I brazed it rather than welding it. Here's how it looks....





Here's the old carb and manifold....





Only took it for a short test ride around the block this eve......pulls a bit stronger than before in the low to mid rpm range....
 

atombikes

New Member
Feb 14, 2010
525
2
0
Northern VA
Scotto-
New intake manifold looks great. On the AGK kit, are the holes large enough in the flanges that the tubing is a press fit into them, or do you have to butt the tubing against the flange? For brazing, I would hope it's a slip fit.

I really wanted to buy one of the AGK intake kits, but their shipping rates are a deal killer for me on the east coast.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Scotto-
New intake manifold looks great. On the AGK kit, are the holes large enough in the flanges that the tubing is a press fit into them, or do you have to butt the tubing against the flange? For brazing, I would hope it's a slip fit.

I really wanted to buy one of the AGK intake kits, but their shipping rates are a deal killer for me on the east coast.
Yes, they are a nice tight slip fit 1" OD tubing.
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
I like the new manifold. There really did not seem to be anything bad with your old one, but if you got a performance gain with the new one, that says something there. It probably has something to do with a smoother, laminar flow due to the smooth bend of the new one rather than the sharp angled bend of the old one. Do both carbs have the same throat size?
Now that you are running a slide type carb I bet you could get even more performance out of it by using a device like the Boyesen X wing.
How tight is the bend on the new one? Does it hug the cylinder tight or does it stick out a bit?
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
I like the new manifold.
How tight is the bend on the new one? Does it hug the cylinder tight or does it stick out a bit?
To answer your question I took a few more pics.......







It sticks out a little ways, yet tucks in nicely. I used a different 90 degree 1" tube than the one that came with the kit as it was a tighter 90 bend. It was also from AGK and it put the carb where I wanted it.