TANAKA 40cc on DH Mountain Bike

[lowracer]

Here is a pic of my latest project I'm always tweaking.
Its a 2007 Banshee Scream downhill MTB with a Dax 1.5" roller friction kit & Tanaka PF-4000.
I just added the Poo-Poo pipe (chrome pipe that comes with in-frame kits).
The pipe seriously quiets this engine down to very acceptable noise levels & has better performance than the loud, stock exhaust can. I had a pocket bike expansion chamber installed but the noise levels were way too high. I'll post more about top end performance with this pipe once I re-hookup the rpm meter. The expansion chamber allowed the engine to max out at 8640 rpm's @ 38.56 mph.
-Lowracer-

 

[Dave31]

Wow! Another awesome motorized bicycle by lowracer

 

[lowracer]

Thanks Dave.
Rode this bike today for a long way with the new pipe installed.
Only problem was the bolts holding on the pipe vibrated loose after about 20 miles & I had to pedal to my 1st stop to tighten them back up. Loctite would have been the smart move at this point but I didnt have any so after 15 more miles I had the same loosening problem & didnt have a tool to fit. Pedaled back home (approx 20 miles) & will conjure up a good way to solve this problem.
I'm thinking that because the muffler is hanging off the engine by it own weight by just those two bolts, it is prone to loosening.
-Maybe Loctite only?
-Loctite with a longer bolt to get a nut on the back end?
-Drill & wire the bolts tight (ala motorcycle racing)?
Any ideas or input would be appreciated.
Thanks
-Lowracer-

 

[boomarkert]

I think a longer stud and jam nut would be the way to go. If you have a lock washer, maybe you could simply do away with that and use two nuts; as long as the second nut has a full turn or so, it would probably put more pressure on it than the lock washer does.

 

[lowracer]

This morning went into the garage to work on the motorbike & while removing the exhaust bolts one of them snapped.
I ended up drilling it out & now have a nut behind the cylinder head to hold it all tight. I red loctited all the threads & allowed it to dry. I took it out for a test spin later today & this time I brought the necessary tools with me just in case it got loose again. Sure enough, it got loose again & I needed to re-tighten the bolts a few times throughout the ride (40 miles). I may go back to either the expansion chamber pipe or the stock exhaust canister even though they are both louder due to the low maintenance aspect...
-Lowracer-

 

[happycheapskate]

I wouldn't want to mount any muffler but a can, that hung by just the engine studs. That is a LOT of leverage, even just from vibration.

I am really interested in your mod with the grubee type pipe. What is inside the pipe? What kind of flange does it have? I'm interested in alternative mufflers for replacement later. The Tanaka ones are expensive, so if the same money could buy something better for a bike motor, that would serve well.

Perhaps you can get some flat stock, weld it to the pooper pipe, and bend it to fit so that you can bolt it to the gas-tank mounting screw, or bolt to the plastic guard under the fuel tank. Even the QR skewer on the drive system or the back of one or two of the engine mounting bolts (inside the channel) should give enough bracing to stop the pipe from wiggling/flexing.

 

[lowracer]

HCS,
The Tanaka 40cc has the same bolt pattern as the Happy Time engines so the std pipe flange bolts right up (but I did run a 1/4" drill bit thru the flange holes just to open it up slightly).
There is an engine block bolt hole that the stock can is supported by under the can. I think it can be used to somehow give a 3rd leg of support to this muffler. I think I'll experiment using your good idea...Thanks!
-Lowracer-

 

[happycheapskate]

Thanks for the info. I didn't want to pull it off to look since it's working, but I wondered if it had a square hole or a round hole.

 

[lowracer]

HCS,
The 32cc Tanaka & the 40cc Tanaka have different bolt patterns for the exhaust flange. The 32cc has its holes closer together and the poo-poo pipe wont fit without some kind of adaptor (homemade?)
Both engines have a rectangular exhaust port opening...
-Lowracer-

 

[happycheapskate]

Figures... I expected I'd have to get a friend to weld me a dual-flange adapter to change mufflers.

 

[lowracer]

Update:
I sold the Banshee Scream DH MTB w/Tanaka 40cc engine to a friend of mine.
I'm down to 1 motorized bicycle & 2 DIY Scooters, but have a brand new Mitsubishi 43cc engine w/5:1 pocketbike transmission waiting to go onto something real soon.
-Low-

 

[stephen1]

Ive got a tanaka 40 motor on a scooter been wanting to put it on a bicycle get a kit from dax see how fast i can go on that

 

[lowracer]

Get the 1.5" roller from DAX & a pipe...Should do around 38
-Lowracer-

 

[happycheapskate]

Can you post at Dax Friction Drive Fan Club on Facebook, when you have it complete? Are you riding it, now?

Ive got a tanaka 40 motor on a scooter been wanting to put it on a bicycle get a kit from dax see how fast i can go on that

 

[happycheapskate]

I'm about to pull off my stock muffler now. I think it's clogged. I can get the motor to run and rev, but it seems to lack power. Gaskets seem to be good all over. This happened before to me on a weedeater. The screen was clogged (spark arrestor). Removing it made it run great, but seemed out of tune. Putting a new screen in made it like new. I'll make note of the muffler shape and mounting dimensions when I have it off.

 

[KenX]

Cool bike.

 

[lowracer]

KenX,
Thanks.
I sold it to a friend of mine (for his son).
I'm always on the lookout for another Banshee Scream or Versus Weapon X for another build project.
I am really digging the twin engine setup of my recently converted Rocky Mountain RM7 mtb to scooter (see avatar pic)
-lowracer-

 

[happycheapskate]

I pulled my muffler off. Some clogging in the port, and the muffler's catalytic converter thing was plugged. The muffler has a 34 or 35mm spacing between the bolts, center to center, and a rectangular exhaust hole. The gasket was a very thick black fiber and very long like a heat shield.

 

[lowracer]

HCS,
There is alot more power available with a noise reduction simply switching to the normal sized poo-poo pipe (found on the china engine kits). I recommend wrapping the pipe completely with header tape & hose clamps (no leg burns).
-Low-

 

[happycheapskate]

Thanks, but I pull a trailer and don't want the long pipe. I found a cheap scooter muffler that had the same type flange pattern. It's not a direct fit (had to cut down the big gasket/dust shield, and knock off a little piece of casting about the size of a coat hanger, on the motor. It was broken anyway, so I just pulled it off. The muffler fit in the cage, too, and the exhaust tube is in a close enough location it still shoots out the same area through the plastic cage. Will post photos later. The scooter muffler was a little longer, and the box is flat in the back (why the gasket flap wouldn't fit around it).