Doodlebug Fork Vibrates!

[Frank Bullitt]

When cruising down the smoothest of roads the fork legs and wheel vibrate back and forth. It seems the fork isnt sturdy enough or something. The thing shakes towardss the frame and then away.
Anyone reinforce their fork? Or is this normal?
I don't want to end up at the bottom of a ditch with a concussion because my fork broke.

 

[jim fallon]

if you have the right size bolt hold the fork into the frame tube there shouldn`t be any movement in the forks other then maybe a 1/16th of an inch at most,

 

[zipseattle]

There was a thread a few weeks ago regarding neck bushings/washers on the Doodle Bugs. Maybe those were installed incorrectly...

 

[Frank Bullitt]

even though I was sure mine was good and tight I double checked it after reading that thread when it was first posted. everything is bolted all nice and cozy.
I should have explained it better but the vibrations I am talking about are from the fork flexing. Maybe I should have my front tire balanced? I could only imagine the reaction from the guys at Les Schwab when I want to balance a mini-bike tire.

 

[Strigoi]

i highly doubt they'll be able to balance a mini bike tire on one of their machines. they aren't calibrated to do something that small.

 

[delray]

Frank Bullitt,i think it maybe coming from your engine mount plate. with the engine mount plate being welded only on the ends only and the way it is made on the ends. it lets the engine rock back and forth. making the whole bike shake and the front forks seam to absorb most of that energy. my bike did the same thing until i regeared it. now the clutch locks up better and the motor and clutch and bike are not fighting against each other. it still vibrates little. the best thing you could do is box(weld) in the engine mount plate and if you are running a 2.5hp motor, i would regear it.:thumbsup:
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[hayden]

make sure the engine is tightly bolted to the frame when i put my clone on the db i didnt tighten it all the way and it vibrated the forks .

 

[Frank Bullitt]

Frank Bullitt,i think it maybe coming from your engine mount plate. with the engine mount plate being welded only on the ends only and the way it is made on the ends. it lets the engine rock back and forth. making the whole bike shake and the front forks seam to absorb most of that energy. my bike did the same thing until i regeared it. now the clutch locks up better and the motor and clutch and bike are not fighting against each other. it still vibrates little. the best thing you could do is box(weld) in the engine mount plate and if you are running a 2.5hp motor, i would regear it.:thumbsup:
.....................

Thanks for the tips guys I would never have thought the engine plate would cause it.
I thought it wasnt possible to re gear these things due to the odd bolt pattern on the rear sprocket?

 

[delray]

Frank Bullitt,i got a blank 80tt sprocket for $14 and had it machine out for free:thumbsup:
the other option you have is to by a bolt on jackshaft. ebay for about $20-$30 and then you will have to buy couple new small sprockets for it. total cost in setup $35-$45?
thats still not to bad ,when only probable paid $220-240 for the bike,less then $300 in it:thumbsup:

i would use this setup if you can't get anyone to machine out a sprocket cheap and it would be a bolt on with just little work on the cover for the chain to come out and you could still keep the rear chain cover on.

 

[Frank Bullitt]

I got a torque-a-verter from a go-kart lying around I might see if it will work.

 

[delray]

Frank Bullitt,if you are still using the 2.5hp motor you will have to make a sleeve for the crankshaft or something. crankshaft is 5/8 and most converters are 3/4 or 1inch.
if you can make the converter work? it will give you that extra lowend and still have good top end and your virbration will probable go away. you won't have the clutch fighting with the low hp engine and small rear 65tt sprocket:thumbsup:

 

[~JM~]

The lower fork legs on my DB30 flex fore & aft when the bike is brought up to speed on asphalt.

I believe that the tread pattern has the lugs spaced to far apart & too tall. I also think the tubing used for the forks may not have enough wall thickness.

I would like to hear more about this subject. I bought this bike to be the girlfriends starter bike & don't want to be concerned about frame failure.

 

[minibug]

My doodlebug always goes up and down for some reason on smooth roads. I think it is because my back wheel is messed up or something...