# Bump start



## sirwalter (Aug 20, 2006)

I put a rear tire mouted Weedeater 1700 motor on a bicycle.
It starts fine on the bench but won't start when bumped.
The motor turns over several times while the friction wheel is in contact with the tire but it won't fire.
Could it be because the RPM's aren't there while attempting to bump start?


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## madmanmoose (Aug 26, 2006)

*clutch*

did you bypass the centrificial clutch


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## sirwalter (Aug 20, 2006)

No I didn't.
Do you mean completely remove it?

I have the friction wheel on the "flywheel" end.
The clutch on the other side is free wheeling.


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## sirwalter (Aug 20, 2006)

I just posted a photo of the motor mounted on the bike.
In thr tool bar above, Go to : "Photo Album"
Then scroll down, on the left you will see "Motor1".

I never have posted photos here before so I'm not sure I did it right...!


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## peppy (Jul 19, 2006)

If the flywheel is always turning, how do you intend to stop? Why do you not have the wheel to the side with the clutch?


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## sirwalter (Aug 20, 2006)

Then how wlould I start it?
The clutch is free wheeling until the motor starts.


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## madmanmoose (Aug 26, 2006)

I seen your pic. turn your motor around and attach the friction wheel to the clutch. you need the cluch for free wheelin while peddaling so you dont kill the engine while out of gas. put a pull start on the engine that you can reach while sitting on the seat add a thumb grip throttle to your handlebars for motor speed and after you get your rig goin build a metal frame for the motor cause that wood wont last 
and if you need to see some other bike motors
http://www.mopedarmy.com/photos/catagory/5/


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## sirwalter (Aug 20, 2006)

Thanks Madmanmoose,
Thanks for the advise, however, the object is, is to "Bump Start" not pull start.
Maybe I'm going at it wrong???
Objectives:
* Use the 1700 Weedeater motor.
* Mount the motor so as to "Bump Start".
* Once motor is running, use body pressure to engage or disengage friction wheel on tire.
However, my problem is::: The motor won't start when "bumped".

1- Is it due to lack of rpm's?
2- Is it due to the fact the friction wheel is on the flywheel side and not the clutch side?


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## 30yearTech (Sep 14, 2006)

possibly lack of rpm, check with a spark tester to see if your generating a spark at whatever speed your trying to "bump start", most CDI's need about 600 rpm to generate a spark that will jump the gap on a spark plug. I don't see any reason why your engine should not start this way as compared to pulling with a rope starter, however I am not sure if it has enough power to carry much of a load. Are you trying to start it with the bicycle wheel suspended and no load or are you trying to start it while riding?


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## sirwalter (Aug 20, 2006)

I tried to start while riding, then I tried it on a stand with the rear wheel spinning and still couldn't start.
I again removed the motor from my mounting rig, mounted it on the test stand, attached the recoil starter and on the second pull it started...!

I'm thinking maybe it's the motor that dosn't have the rpm or the jolt to start.
You know how a stuborn lawn mower is, when you give it a big jerk, bam...! it starts...!
Well, this seems to be the same way.
This afternoon I attached the friction wheel to the clutch side and will proceed to mount it with the ability to pull start it.
As far as the wooden motor mounts go, I really don't see why they wouldn't hold up,
we'll see...!
Thanks again.
I still would like to get it to bump start, now only because it won't...!


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## madmanmoose (Aug 26, 2006)

you might have to flip your motor to the other side of you bike you dont want to goin backwards when you start it
now you got me lookin for an old bmx bike at yard sales or throw out to do the same


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## sirwalter (Aug 20, 2006)

Yes, I had to do that.
I have the motor mounted but I havn't figured out yet how to make it adjustable to release the clutch pressure when I want to idle or stop.
Well, that's what makes this stuff fun...!


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## sirwalter (Aug 20, 2006)

I just posted a finished photo of the bike.
I tried to post a short clip however they are having technical problems so I'll try later.
Check back.


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## peppy (Jul 19, 2006)

sirwalter said:


> Yes, I had to do that.
> I have the motor mounted but I havn't figured out yet how to make it adjustable to release the clutch pressure when I want to idle or stop.
> Well, that's what makes this stuff fun...!


Does it not have a throttle?


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## jgj6331 (Aug 9, 2006)

Sirwalter - dang man, that thing is really coming along :thumbsup: - you were serious in your earlier posts. I'm still scratching my head on how'll I'll start mine. I've been out of town and really can't add much to what's already been said. I didn't read the entire thread before I looked at the pix - so the swap in the engine from one side to the other between pix was really throwing me off. I'm glad madmanmoose picked that up too. Is the friction wheel slipping on the tire? Maybe you need to add more weight, springs or some other tension adjustment to get more transfer from the bike wheel to the friction wheel..... I really can't tell how you have the friction wheel attached - if it is attached to the bell housing of the clutch, it won't start even if you get it to *100 mph* :freak: . In a centrifugal clutch, the motor itself has to reach a certain rpm for it to engage. Spinning the bell housing won't do *anything* on its own. You could connect the friction wheel directly to the crankshaft - then it should bump start - but you'd have to stop the engine to stop the bike and it would be hell pedaling against the engine compression with the engine off. You'd likely need to devise some way to easily raise and lower the engine on the fly to counter these problems. Good luck...


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## kbalona (Apr 27, 2006)

yeah is the engine turning over when you're trying to start it?


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## kbalona (Apr 27, 2006)

is the engine turning in the correct direction?


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## sirwalter (Aug 20, 2006)

*Motor bike*

JGJ6331,MADMANMOOSE,PEPPY,30YEARTESH AND ALL THE OTHERS
I just posted a short clip of the bike running.
Check MY GALLERY :wave:


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## sirwalter (Aug 20, 2006)

*Motor Bike*

jgj6331
I changed from a Bump Start to a Pull Start.
And also changed the friction wheel to the clutch side, yes it is attached to the clutch bell housing.
The firction wheel is actually a nozel from a commerical sprayer of some kind I found in the scrap heap in a local junk yard.
All I had to do is bore it out to fit the shaft and locked it in with a set screw.
I have the motor balanced with spring tention from the motor bracket to the under seat.
In a non operating mode, the friction wheel is about 3/4 of an inch off the tire.
When I sit on the seat with my weight forawd it won't make contact.
To make contact all I do is move my weight slightly backwards on the seat, that puts a counter action on the spring.
Same goes for stoping or going down hill. When I don't need or don't want power, I just move my weight forwad.
Easypesyjapaneezy...!
Simple but fun to build.
I'll be glad to supply free details to anyone who wants them.


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## madmanmoose (Aug 26, 2006)

*I like it*

now that setup look like fun whats your top end speed and how miles to the tank


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## kbalona (Apr 27, 2006)

sirwalter, that is awesome.


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## sirwalter (Aug 20, 2006)

Milage per tank...! Don't know yet. So far I ran it about 1 mile.


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## sirwalter (Aug 20, 2006)

Don't know speed either. 20 ???


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## jgj6331 (Aug 9, 2006)

sirwalter :dude: - you are a cool tool!!! That is way out and I like the way you've worked out the seat to engage / disengage the friction wheel. My motored bike isn't even on the drawing board yet - but I may need to compare notes in the future. Now you'll need to buy a black leather outfit to ride that hog... :thumbsup:


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