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

Mini Bike & Go-Kart Parts

Magnaflux? Man I check stuff like that with WD40...... If it has a pin hole it will show it. But if your Tig welding its not any fun to fix then..... My old neighbor in Charleston had a Magnaflux machine. He was old as dirt and it was older I think. I wish I had his.... They are very useful and I would never have thought to use it for checking a weld...... Cracks yes, welds no.

Looking good!

Doug
 
Magnaflux? Man I check stuff like that with WD40...... If it has a pin hole it will show it. But if your Tig welding its not any fun to fix then..... My old neighbor in Charleston had a Magnaflux machine. He was old as dirt and it was older I think. I wish I had his.... They are very useful and I would never have thought to use it for checking a weld...... Cracks yes, welds no.

Looking good!

Doug
Its easy.
Spray the red penetrant on the inside.
Spray the white developer on the outside.
Wait 3 mins.





Weld the red, check again.
 
Do you bend your own pipe or buy pre-bent sections?
I need to make some adapters like that.
Danford1
Sorry man, didn't see your post from 3-1/2 hours ago!!

I work in a shop that has 5 or 6 benders ... they bend up all kinds of tube ... I just find a piece and work with that.

It will come in handy when I make the exhaust.
 
Its easy.
Spray the red penetrant on the inside.
Spray the white developer on the outside.
Wait 3 mins.





Weld the red, check again.
The one my neighbor had used metal particles to find a crack. It looked like an electric magnet and the particles were almost a powder. He didn't have any liquids to use.... But boy would those particles stand up and show a crack.
 
Swapped out the 130 jet for the 125, mounted her up with the new intake, hit the "choke" ... 2nd pull .. VAROOOOM!



Wouldn't go above 5000 RPM without stumbling ... likely its the air cleaner again ... no time to look into it ... off to work!!
 
For securing the driver I didn't want the bolt sticking out making it wider ... the driver was chamfered for a 3/8-24 x 2-1/2" flat head cap screw.



The driven was too big and would hit the mounting plate when mounted to the jackshaft.
Also the driven needed to go in .550 ...
To fix this the jackshaft bracket was cut in half and .550 removed from the center, the sprocket side remains in its stock position while the driven side was moved in.
To eliminate the driven hitting the mounting plate a 1" riser was added to the bracket. This worked well as it made a good base to mount the now cut bracket to.
It was all welded up.
The 1" riser is tapped, the mounting holes are 5/16-18, it is bolted in from the bottom and still using the original mounting holes that were in the mounting plate.

 
OK! Been awhile since we have made and forward strides ..
The motor issue has been resolved, it was a bent valve.

I got the everything tightened down, brake is working, made keys for the TAV driver and driven .. the driven support will need a bit of work so I didn't put it on for this test.
Motor started hard, but starting fluid got her going, good enough for now.

Here is a pic just after testing ..


The TAV works great but the gearing is way to low for this bike, its exactly like my VT-1040 was, no surprise there. I will see what I can do to get a bigger sprocket on the back ...
I never got the motor above 3200 rpm as it was just too fast for comfort.

Awhile back when I had the clutch on I popped it and dumped the bike in the road bending the forks so the steering is askew.
I don't like how the handlebars wiggle where they bolt into the lower.
So there is some front end work to do.
Just feels too loosey goosey ...

to be continued ...

Kevin
 
Kevin,
Maybe it is too early to ask this yet as you may not be done tweaking the engine, but I (and I would bet others) are curious...
How does the overall performance of this Tecumseh Motorsports engine compare with that on your stock Super Bronc with a 8 or 10 Hp engine? (e.g., acceleration, torque, top speed, etc.)
Michael
 
Kevin,
Maybe it is too early to ask this yet as you may not be done tweaking the engine, but I (and I would bet others) are curious...
How does the overall performance of this Tecumseh Motorsports engine compare with that on your stock Super Bronc with a 8 or 10 Hp engine? (e.g., acceleration, torque, top speed, etc.)
Michael
I only spent 10 mins tops but I do have a sandy hill on my street to ride up so I do get an all around feel with hills and street ...

So as it is today with the exact same driveline as a VT-10 .. (different motor of course) ... so that is my benchmark as I remember how the VT-10 felt.

Top speed wise I would guess if it would hit 7000 RPM with the correct valves the bike would do 60 to 70 ... WAYYYY to fast for this bike.
Acceleration was better as the RPMs came up but on start to 20 mph I think the VT-10 has the edge.
Torque is the same way ... The VT-10 has the edge ...
The 5HP is no slouch but its just not a 10hp motor ...
I think if I could get the RPMs up at a lower speed I think this motor will come into its own.
I need to change gearing ...
 
I only spent 10 mins tops but I do have a sandy hill on my street to ride up so I do get an all around feel with hills and street ...

So as it is today with the exact same driveline as a VT-10 .. (different motor of course) ... so that is my benchmark as I remember how the VT-10 felt.

Top speed wise I would guess if it would hit 7000 RPM with the correct valves the bike would do 60 to 70 ... WAYYYY to fast for this bike.
Acceleration was better as the RPMs came up but on start to 20 mph I think the VT-10 has the edge.
Torque is the same way ... The VT-10 has the edge ...
The 5HP is no slouch but its just not a 10hp motor ...
I think if I could get the RPMs up at a lower speed I think this motor will come into its own.
I need to change gearing ...
OK- Thank you. That's some good (and interesting) information there. I believe that you are the first to try to adapt a "race" engine into a Super Bronc, at least on this forum. You are 100% correct about the (potential) top speed with the Motorsports engine with the gearing you currently have. NO WAY that I would want any part of anything over about 40MPH on our VT-8! As you and others already know, these bikes, especially on pavement, steer like trying to drive a big bus down a winding mountain road. It sounds like if you lower your gearing some more with the Motorsports engine that the low end performance would be similar to what you get with the stock 10 HP engine, which is pretty good considering the much smaller displacement.
Michael
 
OK- Thank you. That's some good (and interesting) information there. I believe that you are the first to try to adapt a "race" engine into a Super Bronc, at least on this forum. You are 100% correct about the (potential) top speed with the Motorsports engine with the gearing you currently have. NO WAY that I would want any part of anything over about 40MPH on our VT-8! As you and others already know, these bikes, especially on pavement, steer like trying to drive a big bus down a winding mountain road. It sounds like if you lower your gearing some more with the Motorsports engine that the low end performance would be similar to what you get with the stock 10 HP engine, which is pretty good considering the much smaller displacement.
Michael
Pretty much 10hp but at a much higher RPM ... good for sandy hills!!
 
Spent some time with my girl this morning.

The front forks were bent from me dumping it in the road a while ago ... also the handle bars bolt to the lowers leaving them sloppy.
The angle of the bars was to much For me as well.
I brought it into work and straightened everything using the level on my iPhone ... worked great.
Then I found a position I liked the bars, not straight but not so much angle.



You can see how much I rotated them in this pic.
I put a #6 screw in the hole and turned them till they hit the screw then welded the bars in place.



Took her for a spin and the steering felt heavy, the pressure was at 5lbs, brought the front up to 25lbs and the back to 10lbs ... felt better but still a bit heavy. Took her off road on the sand hill by the house and it was much better ... we will have to get her off road for some trail riding soon and see what's what.

The gearing is still too tall ... a OldMiniBikes member is sending me a 72 tooth sprocket, that will help.
I see eBay has an 84 tooth sprocket, I will keep that in mind.

The TAV's driver and driven engage too soon and they need to do that at higher RPMs ..
I will take them to work, make a tool to disassemble the driven, take out 3 of the pucks.
The driven will get its spring wound a little tighter.
That should force the driven and driver to start working at higher RPM's.
I wont know what I want till I feel it.

The jackshaft support needed some re-engineering to fit under the driven. I used carriage bolts the keep the heads as low as possible and not tear up the belt. The support mounting holes were slotted so it can be slid in and secured.



The motor starts hard and wont idle very well ... I suspect the lack of fuel filter might be a problem ... I will go back to the motor mounted tank next time the motor comes out.
That will likely be when the 30 degree valve seat cutter gets here from India.
It will get the new SS valves that I thought came with it installed .. then I can work on cleaning the carb and jetting ...

On the plus side I put the UNI air filter on with out the outer cover and it ran ok ...

 
It looks like the gods have decreed that things will get done on this build ...

I brought the TAVs with me to work and as I was leaving I spotted the new 72t sprocket that [MENTION=45314]Ajf[/MENTION] sent ... I grabbed the stock 60t and jumped on the bike and off to work!

Made tools to get the driven apart ...



In the vice ..



I was expecting 6 pucks, I found 9 in there ...



But 3 is all I wanted so 6 are out!



I also wound the Driven 1/3 turn tighter.

Now on to the Sprocket ... the hole in the center was .725 .. I put a .750 dowel in the lathe and spun 1/3 of it down to fit the sprocket hole ... the dowel was mounted in a collet, sprocket was bolted to the table, I picked up the center of the sprocket, zeroed the readout and locked the table.
The biggest Silver and Deming I have is 1-1/2" so I put that through the center ... The hole will need to be 1.645 ...



A boring head was used to open the hole ...

[video=youtube;uW1KrWQPlZM]https://www.youtube.com/watch?v=uW1KrWQPlZM&feature=youtu.be[/video]

I made a plug on the lathe to fit the hole in the old sprocket then opened the new sprocket till the plug fit it.



The plug was used to align both sprockets and the 5/16" mounting holes were drilled using the old sprocket as a guide.



The finished product ...



I hope to put her together and see how she mis-behaves!!
 
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Got the bike back together ...



I'm noticing the chain is close to the frame ... this was after I moved the jackshaft sprocket in .250 ...
Making an 84 tooth sprocket work will take some thought.



Got her out on the road with the newly adjusted TAVs ...
I took off and the RPMs jumped to 3800 and quickly went to 4900 as power from the motor was applied. She then began to creep back down as the bike gained speed.
She stayed in the 4200/4500 RPM range or so till speed caught up and she was doing 40mph with the RPMs climbing.
I rode up the sand hill a couple times then buzzed up and down the street. I slowed down and found my belt wanted to lock onto the driver.
Put her up on the lift, pulled the TAVs, disassembled the driven, as I pulled it apart the 3 pucks and the spring came tumbling out.
They had fallen out of place and were jamming the driver together ...
You cant run the 44C Driver with 3 pucks, the spring will not go back into its groove after being at high RPM ...



It might work with 6 pucks but if lighter is the way to go then lightning the pucks would be a better solution.
1 puck weighs 55 grams ...



So 3 weighed 165 Grams ... 9 weigh 495 grams.

So where am I at?
With 3 pucks it stays in the upper RPM range but there is a lot of slip.
With 9 pucks I blip the throttle and she grabs and the front end jumps.
With 9 pucks in I can feel the tighter driven spring keeping the RPMs up more, maybe 500 RPM more or so ...

I think lightning up the pucks a little will give me a higher RPM but still maintain the Grab I want ... this will take some playing with.

The 72 tooth sprocket is an improvement but in the end the bike is still too damn fast and a 84 tooth wont improve it that much ... I think what's needed here is a 2nd jackshaft .. not sure how to stuff one in there, might take some frame alteration .... and if I do that do I just want to extend the back wheel out and add suspension while I'm back there?

Things to ponder ...
 
And while I was typing the previous post the 30 degree valve seat cutter from India came ...



I want to take Dorothy out on her maiden ride this weekend so I wont do any disassembling yet ...
 

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