Topping out at 40 MPH, 6hp, TAV, 10:72, 20" wheel

socal_machinist · Jul 9, 2012

http://motorbicycling.com/showthread.php?t=40267

I've got a 6 hp 196CC tecumseh with a TAV, and a 10:72 sprocket set to a 20" wheel I cant go ANY faster than 40 MPH I tried removing the muffler and the air filter I got a half a mile faster. What can I do to hit 50?

professor · Jul 9, 2012

Find a hill!
Just fooling.
Change the gear ratio, your motor is probably screaming.

But my question is "Do you really want to go that fast?"
Observe the pavement flying underneath you, then imagine some malfunction causing you to depart the bike at that speed, and contemplate what it would feel like sliding down the road.
Maybe my age is showing- had enough pain for one life.

wayne z · Jul 9, 2012

Do you still have the govenor disconnected? If not, that's holding back the rpm's. 50 is way too fast for safety with standard bike tires and wheels. At least wear a helmet safety gear.

Venice Motor Bikes · Jul 10, 2012

40 MPH is a very respectable speed for a motorized bicycle!
You should upgrade the brakes NOW!

socal_machinist · Jul 10, 2012

Venice Motor Bikes said:
40 MPH is a very respectable speed for a motorized bicycle!
You should upgrade the brakes NOW!

Oh I'm running motorcycle brakes right now, front and rear disks WITH brake lights. Stopping from 40 MPH is NO issue
http://www.youtube.com/watch?v=nX8Cs5FDTnE

I just need another 10 MPH, how the fudge are people doing 50 MPH w/a 2hp 2 cycle engine? is everyone getting "creative" with numbers or something?

EDIT I am running a 12:72 ratio

I've got two sprockets in the mail one 16 and one 18

40x (16/12)=53.34MPH
40X (18/12)=60MPH

I REALLY doubt that math is a direct correlation to actual speed if I had to guess the 16 is going to put me at 45 and the 18 is going to put me at 50.

Just an FYI sprockets for $3-4 each !!!!!!!
https://www.surpluscenter.com/ bookmark that guys!!

wayne z · Jul 10, 2012

socal_machinist said:
Oh I'm running motorcycle brakes right now, front and rear disks WITH brake lights. Stopping from 40 MPH is NO issue
http://www.youtube.com/watch?v=nX8Cs5FDTnE

I just need another 10 MPH, how the fudge are people doing 50 MPH w/a 2hp 2 cycle engine? is everyone getting "creative" with numbers or something?

EDIT I am running a 12:72 ratio

I've got two sprockets in the mail one 16 and one 18

40x (16/12)=53.34MPH
40X (18/12)=60MPH

I REALLY doubt that math is a direct correlation to actual speed if I had to guess the 16 is going to put me at 45 and the 18 is going to put me at 50.

Just an FYI sprockets for $3-4 each !!!!!!!
https://www.surpluscenter.com/ bookmark that guys!!

LOL no way do I believe the chinagirls will do 50 mph.

I have a 99cc Preddy on my 2 speed tranny build. I have a 10.75:1 final drive ratio, and I can get 46 mph out of it.

579326_475107762505328_100000183244892_2036434_1363544906_n.jpg

Yo need to get your drive ratio to around 10:1 to get to 50 mph without over revving your engine.

The_Aleman · Jul 10, 2012

I agree with Wayne about the governor, sounds like OP still has it hooked up.

wayne z said:
LOL no way do I believe the chinagirls will do 50 mph.

Oh, it's definitely possible. I've personally seen Baird duck his way to 54MPH on GPS. Twice. I've heard he's gone faster since then.

But his engine had a few mods and he's not a large guy.

locell · Jul 16, 2012

Run the engine as lean as possible (less oil in the gas), get a 36 took sprocket on the rear, don't run a chain tensioner on the drive side, put it on the pedal side. make sure everything is well lubed and moves smooth, I got my cranbrook to 59 mph with this in mind.

The_Aleman · Jul 16, 2012

locell said:
Run the engine as lean as possible (less oil in the gas), get a 36 took sprocket on the rear, don't run a chain tensioner on the drive side, put it on the pedal side. make sure everything is well lubed and moves smooth, I got my cranbrook to 59 mph with this in mind.

Doubt it. Not that your post has anything to do with this thread, but I truly doubt you spun your engine to 11,200RPM on your Cranbrook.

That's with a 26" wheel. If your Cranbrook has a 24" wheel that's about 12,000. Sorry, not going to believe that. rotfl

locell · Jul 16, 2012

The_Aleman said:
Doubt it. Not that your post has anything to do with this thread, but I truly doubt you spun your engine to 11,200RPM on your Cranbrook.

That's with a 26" wheel. If your Cranbrook has a 24" wheel that's about 12,000. Sorry, not going to believe that.

I don't have a tach, just a gps, so i'm not really sure what my RPMs run. You didn't even ask if I was going downhill.....

Ibedayank · Jul 16, 2012

locell said:
Run the engine as lean as possible (less oil in the gas), get a 36 took sprocket on the rear, don't run a chain tensioner on the drive side, put it on the pedal side. make sure everything is well lubed and moves smooth, I got my cranbrook to 59 mph with this in mind.

this bike has gone 55+ a few times

31cc friction drive 7/8s roller and 26 inch tires
so anything is possible

when its tied down on a trailer or in the back of the truck

The_Aleman · Jul 16, 2012

locell said:
I don't have a tach, just a gps, so i'm not really sure what my RPMs run. You didn't even ask if I was going downhill.....

Wouldn't change the fact I don't believe you. The math is easy to calculate, your ratio as you claim is ~14.76:1
I've seen HTs destroy the upper conrod bearing at 7K RPM, no way am I going to believe 11+K.

When Baird hit 54, his professionally tweaked engine wasn't even doing 9K, he had a 27 or 28T sprocket.

You'll be hard-pressed to find anyone who will believe your speed claim. Anyway, that's all I've got to say on the matter. This aint the thread for it.

locell · Jul 16, 2012

The_Aleman said:
Wouldn't change the fact I don't believe you. The math is easy to calculate, your ratio as you claim is ~14.76:1
I've seen HTs destroy the upper conrod bearing at 7K RPM, no way am I going to believe 11+K.

When Baird hit 54, his professionally tweaked engine wasn't even doing 9K, he had a 27 or 28T sprocket.

You'll be hard-pressed to find anyone who will believe your speed claim. Anyway, that's all I've got to say on the matter. This aint the thread for it.

cool story bro. .wee.

socal_machinist · Jul 16, 2012

Ibedayank said:
http://motorbicycling.com/attachment.php?attachmentid=49256&d=1340506966[/IMG]

this bike has gone 55+ a few times

31cc friction drive 7/8s roller and 26 inch tires
so anything is possible

when its tied down on a trailer or in the back of the truck

I was about to post spiderman questioning till I saw the last line lol.

Well I put on that 16T gear and got like another 4-5 MPH so big whoop I might try another speed run later tonight

http://www.youtube.com/watch?v=GLk-JMOo2-8

wayne z · Jul 16, 2012

locell said:
Run the engine as lean as possible (less oil in the gas), get a 36 took sprocket on the rear, don't run a chain tensioner on the drive side, put it on the pedal side. make sure everything is well lubed and moves smooth, I got my cranbrook to 59 mph with this in mind.

Running an engine lean normaly means less fuel not oil. The oil mix is referred to as ratio, not rich/lean .
The amount of oil on the fuel does have a very small effect on fuel mix, but our engines are tuned to fuel/air mix, not oil/fuel.
Referring to oil fuel as rich/lean just confuses matters for the inexperienced.

locell · Jul 16, 2012

thanks, ya, it does sound like an air/fuel thing. I should of phrased it differently. "run the ratio on the fuel mix with as little oil as possible"

Ibedayank · Jul 18, 2012

locell said:
Run the engine as lean as possible (less oil in the gas), get a 36 took sprocket on the rear, don't run a chain tensioner on the drive side, put it on the pedal side. make sure everything is well lubed and moves smooth, I got my cranbrook to 59 mph with this in mind.

being that he is using a FOURSTROKE there is no oil in the gas to start with
......

locell · Jul 18, 2012

Ibedayank said:
being that he is using a FOURSTROKE there is no oil in the gas to start with
......

LOL thanks for pointing that so promptly, the community appreciates it.

martinjstn · Jul 21, 2012

on a side note... where did you get those keepers for your rear?

mat_man · Jul 21, 2012

Hi Socal_machinist

The EPA has these motors running lean. If you take off the muffler and air filter
it makes it even worse. You have to open the jets
http://www.affordablegokarts.com/Drilling Main Jets.php

Also set the valve lash (at bottom of page):
http://www.affordablegokarts.com/govenor-removal.php
I am not sure if your motor is a true Honda clone,
so find the numbers for your motor.

Best of luck

Topping out at 40 MPH, 6hp, TAV, 10:72, 20" wheel

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