First Baja Mini Bike (Help!)

[Shrek73]

New to the forum, can anyone help identify what Model this Baja Mini Bike is? I picked it up the other day and I believe it is a Dirt Bug, but do not know the model number or when it may have been manufactured. It has a Briggs & Stratton 3.5 hp motor model 91212-0189. I can see two different colors of yellow, which is why I believe it is a dirt bug.

I plan on restoring it and using it for some trail riding around my property in CO. I know I am missing the front fender, clutch cover, chain guard, and the throttle cable. I have the chain roller, but the chain appears to be very snug without out it. I am thinking of buying a replacement chain so that the roller will fit properly. Can someone provide a picture of what the roller assembly looks like installed?

The front end is pretty wobbly and it appears there are some bushings that are missing. Does anyone have a schematic for the fork assembly?

The engine runs, and my mechanic friend said it sounds like it has good compression. I will clean up the engine a little, replace the muffler and maybe tune up the carburetor. I also plan on getting new tires, but does it look like I am missing anything else.

Any help is appreciated, thanks!

 

[OND]

I've got one like it and its a Dirt Bug....but I put a 212 on mine.

 

[Shawnster]

The B&S is definitely not stock. But in my opinion, it is a major upgrade from the stock 97cc engine that came on it. As for the chain tensioner assy, here is a pic of the stock set up on a Doodle Bug (which is pretty much the same) minus the clutch cover and a link to a new Dirt Bug thread here on the forum.
http://www.oldminibikes.com/forum/baja-mini-bikes/4276-doodlebug-baja-97cc-power-8.html

Hope this helps,
Shawn

 

[jdogg]

There were some on here that swore to not needing a tensioner on those if the sprocket was true and the chain had proper tension so if its not hitting the engine plate or throwing a chain you may be ok without one!! Welcome to the forum!!

 

[Shrek73]

Thanks everyone for your replies and the photos.

I am new to the mini bike world, but not the mechanical aspects. When I bought it the seller pointed out that it needed a new throttle cable, which I promptly purchased. When I went to install it, I noticed the throttle linkage was also missing. The engine runs and I can manually push the throttle so it will run, but there is nothing there to connect the cable to. What do I need, and can somebody post of picture of how the throttle linkage is mounted? You can see the throttle in the picture, but I can take a better picture tonight if necessary. It looks like the previous owner had the linkage mounted on the long lug on the head, but I am not sure.

I am at a crossroads whether I will fix this engine up, or upgrade to the Predator 6.5 hp engine sold at harbor freight. I have heard all sorts of stories about the problems with the smaller 97cc engines but don’t know if the 3.5 hp will be much better.

I can probably dump $50+ in parts just to clean up the current engine, and would mind spending a little extra to get some more hp for the hills on my property. If I go the 6.5 hp route, what clutch to I need to by, or can I use the clutch that is on my 3.5? I know I need to buy a mounting plate, but is there anything else I would need for the conversion?