Dorothy, Heald VT-7 (anything goes) project ...

Mini Bike & Go-Kart Parts

With YOU sitting on the bike, what is the measurement from the bottom of the chain on the rear sprocket to the ground? I ask, because it is getting siginificantly closer with this larger sprocket. While not a concern on pavement, what about off road, especially sand? You do not want that chain dragging in the dirt/sand. Going to a 84 tooth rear sprocket will only have it get closer. Just something to think about...
Michael
 
With YOU sitting on the bike, what is the measurement from the bottom of the chain on the rear sprocket to the ground? I ask, because it is getting siginificantly closer with this larger sprocket. While not a concern on pavement, what about off road, especially sand? You do not want that chain dragging in the dirt/sand. Going to a 84 tooth rear sprocket will only have it get closer. Just something to think about...
Michael
I had considered that and thoughts of a few minis I have seen that touch down on pavement came to mind when I was thinking about going bigger.
You can see in the current pic that it will take a lot to hit down .. Ratio wise I'm sure my Hilltopper Sprocket is closer ...



Its about 3-1/2" from the ground now.
I keep 10lbs in the tire ...

I wont be going to an 84 tooth ... I don't think that will give me what I want .. a second jackshaft might be needed to get there.
 
What about limiting the travel on the driver?.............Maybe a small spacer to keep the shieves from closing completely, that would knock down your top end, by the sounds of it your already geared too low as it is.........................Tom.
 
What about limiting the travel on the driver?.............Maybe a small spacer to keep the shieves from closing completely, that would knock down your top end, by the sounds of it your already geared too low as it is.........................Tom.
I like that idea ... I will look at how the driven works and see if there isn't a place to put a stop ...

For now I've lightened up the pucks a little.
All 9 weighed about 500 grams.
I ran with 3 in the previous review and that was 165 grams.
The pucks had a .200 hole in the center of the steel insert ... I opened it to .375 ..
Here is what they weigh now ...



So I shaved about 75 grams or about 15% of the puck weight ...

I want it to wind up a bit higher before engaging ...
 
DOROTHY ... Come out the PLAYEEYEE!! (Warriors)

3-27-17 I picked up a Heald VT-7 with a vague idea about what I wanted ... I am still a far cry from where ever that is!

Sunday 8-6-19 was the day she was ready to hit the streets and trails!!

The Hour/RMP meter says Dorothy was run for over 2-1/2 hours Sunday.

A few days before the carb was cleaned, replaced the pilot jet (17.5) with the one that came in it (15.). Blew air through it.
I remounted the motor mounted gas tank and made sure there was a filter inline.
My brother was over and was buzzing up and down my street, got it to about 5000 and I could hear that "marbles in a can" sound ... I assume its the valve tapping the head ... we wont be running high RPM for this outing, its mostly a shake down to see what I've got.
89 octane was drained and 93 was put in the tank. fresh oil was added to the crank.

We buckled her down to the mini bike trailer and were off!


We met up with some friends at a school, drove around a bit on the surface streets and alleys ...


Then rode back to our cars for a second ...




As expected the gearing isn't even close to what I want, it performs much like a VT-10 ... I won't harp on gearing or getting the motor into the 7000 RPM range .... today is just to shake her down ...
She started easily and ran what I would call flawless.
The Mikuni is very nice, smooth idle, responsive, better than a stock carb to be sure!
Nothing went wrong and in the last hour I was beating the shit out of her!
Others in the group tried her and proclaimed her a beast ...
My wife rode her and found she was well behaved!
I was wondering if I would like the handlebar position ... no worries, I liked the bars being slightly bent back.

We are fortunate enough to have a couple places we can ride that are heavily wooded in the city ...



One of our favorite places is the now defunct Grand Rapids BMX Track.
Its a place where BMX bicycle racers used to come and compete.
Hell of a fun place to ride/beat on/test out a mini ... and so I did ...



One section is about 1/8 mile of Whoops ... small hills evenly spaced in a row ... 2 friends were ahead of me, I wound her up and let her rip ... I flew past them jumping from hill to hill ... I weigh damn near 300lbs, the bike must be 80 to 100lbs ... that's at least 350lbs jumping, landing over and over ... for the 1st time ever I lost my phone out of my pocket .. (found it) ..

We found some mud ....



I chose not to put the fenders on ... that's was not a good idea!

After 2-1/2 hrs the spark plug looked like this ..



She got up to 4200 RPM but was mostly maxed out at 3800 RPM.
The belt felt like it was slipping a bit at the end .. could be heat or it could be a bit wet?
Drilling the Driven pucks made next to no difference. Engagement was about 1900/2000 RPM.
Out of the hole I was about the same as other minis in our group with the exception of the Baja with a warmed over 212 Predator ... he was faster out of the hole and had better acceleration ... but while the Baja topped out Dorothy kept pulling like a freight train ... still seems like RMP and MPH are about the same ... (4000 RPM = 40 MPH)
The front tire still feels a bit heavy even in the trails ...

As she is now she is a well behaved and excellent running bike.

Next up on the list will be gearing and getting the stainless steel valves in the motor.
 
Outstanding!!!

Glad to see you out enjoying it after all the work. You mentioned taking the low octane gas out and adding high octane gas. Now you have me wondering if you are hearing spark knock when you hear the "Marbles in a can" sound..... I have no clue what kind of compression these motors have but that is a possibility. Adding Octane booster might help that. Another thing that come to mind is Ignition Timing. It would cause spark knock if it was advanced....

How do you like the rear tire? Is it smooth or does it have a little bump to it? How about the exhaust? How did it sound? So many questions.....

Doug
 
Outstanding!!!

Glad to see you out enjoying it after all the work. You mentioned taking the low octane gas out and adding high octane gas. Now you have me wondering if you are hearing spark knock when you hear the "Marbles in a can" sound..... I have no clue what kind of compression these motors have but that is a possibility. Adding Octane booster might help that. Another thing that come to mind is Ignition Timing. It would cause spark knock if it was advanced....

How do you like the rear tire? Is it smooth or does it have a little bump to it? How about the exhaust? How did it sound? So many questions.....

Doug
The marbles in the can is valves ... when I first fired this motor I had 103 octane race gas in it and marbles sound was there ...

I thought I heard rattling that might have been pre ignition but it was the exhaust threads loose in the block but to avoid potential problems I switched her out to 93 for the ride anyway.
It is a very high compression motor and will rip the pull start handle out of your hand so I will likely keep her fed with 93.

There is no ignition timing adjustment .. it is what it is ... however it came with a hi performance magneto that was replaced with another hi performance magneto (both were made for this motor) when we were shaking down what turned out to be bent valves.

The back tire was smooth on the road, at least I didn't notice bumps but I wasn't paying attention, but I would have noticed if it was bad. The front tire was very noticeable tho on dirt and street.

I ran with and without the spring ... my friend Ryan thought there was a performance gain with out it ... felt the same to me ...
I have hearing aids so it sounded good but guys that could hear said they heard the spring making a *tinging* noise.
I think I could shorten the spring and secure it at both ends, maybe wrap is in something then put it in the pipe .. something to play with but all in all I would call it a success.

Had a great time, learned a lot and its helped me plan my next move ..
Gearing wise the driven needs to engage at a higher RPM ... the 44C Driven is very adjustable in that respect ... a 2nd jackshaft will be needed to get the gearing lower ... and that's got me thinking about a swing arm instead of a sprung seat ...

Valves in the motor should be easy ...

Got a vacation coming up to your neck of the woods as discussed to ride the "Tail of the Dragon" so Dorothy will likely sit for a bit ....
 
Got a vacation coming up to your neck of the woods as discussed to ride the "Tail of the Dragon" so Dorothy will likely sit for a bit ....
I was wondering the other day if you had hit the Dragon yet. That will be fun I am sure. I know lots of guys that ride it every year as a group. They always have a ball. Be safe on the road and watch out for the lost Truck drivers on the Dragon. 318 curves in 11 miles is going to keep you busy.....

Doug

Some of you may not be familiar with the Tail of the Dragon so here is a link for those that are curios. Make sure you scroll down and check out the picture of the 18wheeler taking up the whole road.....

Tail of the Dragon at Deals Gap – Motorcycle and sport car tourism serving Tail of the Dragon at Deals Gap, Cherohala Skyway, Moonshiner28, Devils Triangle, Diamondback, Blue Ridge Parkway, and more.
 
Brought the 30 degree carbide valve seat cutter into work and made an arbor for it.

The cutter came with 1/2-20 threads so I got a 1/2-20 hex cap, threaded the cutter on and removed any threads that would hit the bottom of the valve bowl.
The hex cap was put in the lathe and 5-1/6 threads were cut into the threaded end for a 5-1/6 screw body to fit in the valve guide.
BUT ... the threads were not on center ... SOOO .... I put in a shoulder bolt and spun it down in a whirly gig ...
Looks like this ...



Dorothy's original block (smoked) was used to fit the arbor.
I tested the cutters abilities on the block ...



After 10 or so turns by hand the seat looked smooth and even. I am confident it will work on the Tecumseh Motorsports Motor.
 
4 Years and 2-1/2 months later here is an update on Dorothy!
We started moving about 3-1/2 years ago. We are out in the country 3 miles from any paved roads. It was time to revisit Dorothy.
In that time I have come to appreciate the Predator motor so the Tec got swapped out with a 212, air filter, exhaust and jet but stock otherwise.
My wife has a hopped up Predator 212 pushing 15hp that simply laid waste to Dorothys 10hp Tecumseh, the writing was on the wall.

Today was the 1st day Dorothy ran with her new motor.
WOW, she is one snappy bike! The front wheel comes up but not as well as my wifes 15hp bike.
I could go on but as this is a old thread it likely wont get much attention.
Here are some pics of Dorothy (white) and my wifes 15hp monster (red).

IMG_7194.JPG IMG_7190.JPG IMG_7193.JPG IMG_7175.JPG IMG_7192.JPG
 

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