Built an absolute screamer

[theguy2024]

So I been building these motorized bikes for some time now and had this engine kit laying around in parts in my garage for months. Decided to go out and buy a cheap bicycle and throw it together took a couple hours. (First time I did this it took me nearly 1 week!)

Every one of these I’ve built with the standard 66cc china motor and NT carb + 26 inch wheels 44 T sprocket has done about 45km/h to 60km/h. I was expecting this one to do about 35/40km max as I didn’t really mod **** on it. But WOAH I was ripping down the street doing nearly 85km/h and I weigh 220lbs! I wasn’t even full throttle as well.

Is this a fluke engine or what cause man I didn’t expect that. One thing I did do was port the cylinder intake and exhaust it’s also a G4 open transfer cylinder. Gonna check the durations and see what kinda numbers I got running on this. Also I got the squish down to like .7mm which is important. Oh also I just remembered I either advanced or retarded the timing a little I can’t remember. I guess I did do some mods now that I realize it lol. I use 94 Octane ethanol free and 40:1 ratio

 

[Mossy]

I'd be interested in knowing the timing on that what crank etc... I'm guessing it's a zeda triple 40 ?

 

[theguy2024]

I'd be interested in knowing the timing on that what crank etc... I'm guessing it's a zeda triple 40 ?

i’ll get the numbers

 

[Venice Motor Bikes]

85 kph = 52.8 mph... That's extremely fast for a mildly modded stock engine & 44t sprocket!

I'm curious how you measured the speed?

 

[Tom from Rubicon]

km/h, Dude is in Vancouver BC living in a park if you can believe the member map. Engine powered bicycles are not legal North of the border. Fast or slow.

Tom

 

[Mossy]

km/h, Dude is in Vancouver BC living in a park if you can believe the member map. Engine powered bicycles are not legal North of the border. Fast or slow.

Tom

Not legal south of the border in almost every state... 49cc or smaller some of them...

 

[theguy2024]

Not legal south of the border in almost every state... 49cc or smaller some of them...

Here in Vancouver I have never been stopped once by a cop. They simple do not care

 

[Mossy]

Here in Vancouver I have never been stopped once by a cop. They simple do not care

They don't care everywhere... Or they don't know what it is and what to write it up for... It's not worth their time...
It's comical that these legal beagles will scold you for breaking the law and then in the next reply tell you how to break the law even louder and faster...

A shout out to those that came before and made it illegal with all the fun and hard work they put into that... Because it's fun to break the law...

 

[Sidewinder Jerry]

So I been building these motorized bikes for some time now and had this engine kit laying around in parts in my garage for months. Decided to go out and buy a cheap bicycle and throw it together took a couple hours. (First time I did this it took me nearly 1 week!)

Every one of these I’ve built with the standard 66cc china motor and NT carb + 26 inch wheels 44 T sprocket has done about 45km/h to 60km/h. I was expecting this one to do about 35/40km max as I didn’t really mod **** on it. But WOAH I was ripping down the street doing nearly 85km/h and I weigh 220lbs! I wasn’t even full throttle as well.

Is this a fluke engine or what cause man I didn’t expect that. One thing I did do was port the cylinder intake and exhaust it’s also a G4 open transfer cylinder. Gonna check the durations and see what kinda numbers I got running on this. Also I got the squish down to like .7mm which is important. Oh also I just remembered I either advanced or retarded the timing a little I can’t remember. I guess I did do some mods now that I realize it lol. I use 94 Octane ethanol free and 40:1 ratio

I've done 50 mph (80 kph) on my 4 stroke 33cc RS35. Oh I live in the mountains and was going down hill.

At 85 kph on a level road using 26" wheels with a 10\44, your minimal modified engine would have to be turning 12,318 rpm. All of this from an engine you were only expecting 5000-6000 rpm at best. Because in the past the best you were able to get (I'm assuming with engine mods on 26" tires using a 10\44) was around 8700 rpm.

 

[Mossy]

The GT5 Skyhawk out of the box did 39mph that was from a guy following me on a moped... After a kx85 pipe and some tune it went faster than that but wanted to vibrate everything to much... Like the gas cap would fall off and the mounting studs would break.... A guy with a zeda 40 could fly past me every time... And a guy with a pk80 could barely keep up with me... This was in 2016 and we all had 44t sprockets and beach cruisers the other guys were lighter than me by 50# and ran stock kits no expansion chamber...

 

[Mossy]

The long rod hi hole cranks with the open transfer is the gt5b (only available in Canada) or the zeda... The closed transfer cylinders were the gt5 and original zeda... The 40mm stroke gave the zeda the advantage 69cc over the 66 Gruber... The open transfer is where the extra top end comes from but I like the closed transfer cylinder better for bottom end.... Those guys I rode with couldn't keep up from 10-30 mph the 38mm stroke had the advantage there... But that's my understanding of the difference between the 3...

 

[Sidewinder Jerry]

Hope you plan to market what you've discovered and can replicate it with another basic kit engine.. The Phantom 85 is producing 10,000 rpm from the factory. You're saying you did some minor mods to a basic kit engine. And that the there must be some undiscovered special aspect with it along with your mods, enabling you to get over 12,000 rpm.

 

[Mossy]

12k isn't unrealistic with some basic prep on the right parts... I've done that before... No big secret... And he's going to share the port map after he's had his fun...

Hope you plan to market what you've discovered and can replicate it with another basic kit engine.. The Phantom 85 is producing 10,000 rpm from the factory. You're saying you did some minor mods to a basic kit engine. And that the there must be some undiscovered special aspect with it along with your mods, enabling you to get over 12,000 rpm.

This is why we can't have nice things

 

[Mossy]

So the phantom has a 4k handicap over the original saw it's designed from... And why I'm only using their cylinder...

 

[theguy2024]

Okay folks well I have unfortunate news.

I decided to go for another top speed run after applying a lot of threadlocker to those exhaust and intake bolts. Those bastards vibrate loose like crazy at high RPM’s.

I use a Speedometer app on my iphone that has been extremely accurate in my endeavours. For some reason, that night I clocked nearly 85km must have been a glitch because I hooked up my amazon RPM tachometer and gave it my all just now and I clocked 61km, absolute max it would go and I tried to glance down at my tach and I saw roughly 7,500RPM. The max speed I was going tonight feels about what I was doing that other night so there’s no way I was going another 20+km. It definitely glitched.

61km is still really good in my opinion for 26” wheels 44t sprocket. Now i’m wondering, what speed I would hit if I went lower on the sprocket.. Going 60+km on a bicycle is kinda terrifying it feels like the engine is gonna explode lmao

 

[Sidewinder Jerry]

Okay folks well I have unfortunate news.

I decided to go for another top speed run after applying a lot of threadlocker to those exhaust and intake bolts. Those bastards vibrate loose like crazy at high RPM’s.

I use a Speedometer app on my iphone that has been extremely accurate in my endeavours. For some reason, that night I clocked nearly 85km must have been a glitch because I hooked up my amazon RPM tachometer and gave it my all just now and I clocked 61km, absolute max it would go and I tried to glance down at my tach and I saw roughly 7,500RPM. The max speed I was going tonight feels about what I was doing that other night so there’s no way I was going another 20+km. It definitely glitched.

61km is still really good in my opinion for 26” wheels 44t sprocket. Now i’m wondering, what speed I would hit if I went lower on the sprocket.. Going 60+km on a bicycle is kinda terrifying it feels like the engine is gonna explode lmao

Those GPS apps are notoriously inaccurate. At 7500 rpm using a 44t rear sprocket on 26" tires your speed would've been 51.7526887359 kph.

The 61 kph could've been a down hill reading. There comes a point when your engine is no longer contributing to a down hill speed and gravity has taken over. To do that speed with your setup on level ground would require your engine to do 8841 rpm. Get an actual speedometer.

 

[Venice Motor Bikes]

Okay folks well I have unfortunate news.

I decided to go for another top speed run after applying a lot of threadlocker to those exhaust and intake bolts. Those bastards vibrate loose like crazy at high RPM’s.

I use a Speedometer app on my iphone that has been extremely accurate in my endeavours. For some reason, that night I clocked nearly 85km must have been a glitch because I hooked up my amazon RPM tachometer and gave it my all just now and I clocked 61km, absolute max it would go and I tried to glance down at my tach and I saw roughly 7,500RPM. The max speed I was going tonight feels about what I was doing that other night so there’s no way I was going another 20+km. It definitely glitched.

61km is still really good in my opinion for 26” wheels 44t sprocket. Now i’m wondering, what speed I would hit if I went lower on the sprocket.. Going 60+km on a bicycle is kinda terrifying it feels like the engine is gonna explode lmao

I'm glad you figured it out & posted it.... There have been a lot of heated arguments on here over the years because of outrageous claims of top speed.

61km is still considered a total screamer for a mostly stock engine with a 44t!!
With a few more simple mods, (gut the pipe & jet the carb), that bike should hit 65km.

It's very unfortunate that we still have delusional members here who stick to their outrageous claims of 12k RPMs on a mostly stock engine.

 

[Sidewinder Jerry]

Here's how ratios work. My RS35 can do around 9000 rpm no load. It's max hp is at 7000 rpm. I have a shifter bike. If I'm in a gear and am doing 7000 rpm at full throttle on level ground; shifting to a higher gear won't make the bike go any faster. What it'll do is cause the engine to be under more of a strain; thus making the rpm drop lower. Yet the speed will remain the same. The only way to get more speed then is to do engine mods for more power.

So if you're getting 7500 rpm at full throttle on level ground using the 44t switching to a 36t won't make you go any faster; it'll simple cause the engine rpm to drop. The bike will certainly accelerate much slower as well doing this.

 

[Mossy]

For $40 you can be the fastest kid on the block... Mixed with a long rod hi hole...
But we're still waiting on the 0P #'s
Zane smith has been busy...

 

[Mossy]

Something new... I shouldn't be posting this until I get a few to look at... But anyway California motorbike has a CNC clutch... Cafemotoracer has the spring... So you don't have to wait for years for RDM to complete a transaction... not having to deal with RDM is great...
The other forum has black listed California motorbikes so they can promote bicycle engine.****... RDM did the bushing fix for the original phantom and there all linked with the Zedamafia crew who ripped off people for years... Anyone remember the pre pay program where you never got you mz65 in 2015? The original CNC engine cases were designed by Burt Rod...
I'm just glad there finally getting some competition... What's the point of something great if only a handful of people can get it... I know it's going off topic... But how many people have been around for decades to know how these companies and parts have evolved? Who's legit and who's just taking your money... Making claims that aren't realistic...