Two Stroke Mini Bike

[Desertduler]

the spark is going to shoot Through the seat and shock your gonads!!! lol jk nice build.

Yes indeed, that is why I will be wearing an insulator!

 

[Desertduler]

Short day today, I will resume tomorrow, I was starting to lay out the jack shaft location so that I can weld the bearing mounts to the frame.

 

[NewbCarter]

Hmm ... are you going to put on a wheelie bar ?

Just looking at the size of the engine compare to the frame ...

 

[Desertduler]

Hmm ... are you going to put on a wheelie bar ?

Just looking at the size of the engine compare to the frame ...

Don't worry son I can handle it, if I can hang on to my 540 KTM desert racing bike for a 140 miles during a desert race then I am sure that I can hang on to this little squirt.

 

[Desertduler]

Here is the material that I am using on this build to make the axle spacers and bearing retainers for the jack shaft, the material is T6 aluminium.The 5/8 jack shaft and axles which are dead on at .625 are from a tracked machine that I had repaired and these were track link pins which are hardened material, just a benefit of being a pack rat of sorts I thought that I might could use these one day and now this is the case! Here are some photos of the "Little Evil" along with some shots of a possible but not set in stone fuel tank location. The mini has 6:5:1 gearing which I will try first to see how I like it. These are the widest tires that will fit on this frame, I had to space the rear sprocket out in order to get the chain to not rub on the rear tire but all is good!

 

[landuse]

Man that looks good.....

 

[Desertduler]

Man that looks good.....

Thanks, she is coming together one step at a time.

 

[itsid]

thank you thank you thank you...
I bothered you too much already with all that "no paint" stuff and "centerline wheels" and engine tilting shirt;
so I didn't dare to ask for that exact tank you mounted
I'm sooo glad I don't have to *imagine me grinning ear to ear*
The moment I saw one like it in Kelly's thread I thought it'd be the right one for exactly this occasion
needs to get a tad darker to match though... but time is on your side here

Oh divine power of the flying spaghetti monster I love this build.

'sid

 

[Desertduler]

thank you thank you thank you...
I bothered you too much already with all that "no paint" stuff and "centerline wheels" and engine tilting shirt;
so I didn't dare to ask for that exact tank you mounted
I'm sooo glad I don't have to *imagine me grinning ear to ear*
The moment I saw one like it in Kelly's thread I thought it'd be the right one for exactly this occasion
needs to get a tad darker to match though... but time is on your side here

Oh divine power of the flying spaghetti monster I love this build.

'sid

Lol, you like that tank huh? That is a spare spun aluminum one that I had kicking around. I have a seat coming that is a retro Bonanza seat that I bought off of eBay. I am scraping the expansion chamber, I have tried out every direction that I could and the pipe would be too gigantic and ugly so I will go with plan "B" remove the cylinder and piston and phase the exhaust port facing the rear and use a aluminum muffler off of one of my KTM 300's which I will modify. The engine will not make as much power but in it's stock form it is rated at 19.5 (DIN) with a stock Sachs muffler which if I remember correctly (DIN) is about 98 percent of SAE hp. figures. I will use a 30 mm Mikuni on this engine which will give good low end punch.

 

[Poboy kartman]

Man that looks good.....

What he ^ said!!!!!

 

[Desertduler]

So I flipped the piston and cylinder around on this Sachs engine and I installed the carburetor and I took an extra silencer that I have that came stock on one of my KTM 300's which I could not use because it is mandatory in desert racing in my location that your bike must have a spark arrestor in order to pass tech and be able to race (BLM) which is good so I took this silencer and cut it down and I installed a stainless steel section of an exhaust pipe which I had for as an extra for one of my Rotary engines and it fit perfectly! I will modify this silencer further so that it has an open chamber leading into the silencer packing toward the exit opening, I have no idea how this engine will run with this set up but it ought to be better than the stock snowmobile muffler I hope. The silencer is just mocked up in the location to where I will install it. I will use rubber isolation mounts to mount the silencer.

 

[chancer]

That looks good. Too bad there will not be room for your expansion chamber. I know how much performance technology goes into the design of those. Almost seems a shame to go through that much engine work with an expansion chamber in mind, and then have to scrap it.

 

[Desertduler]

That looks good. Too bad there will not be room for your expansion chamber. I know how much performance technology goes into the design of those. Almost seems a shame to go through that much engine work with an expansion chamber in mind, and then have to scrap it.

I know, I tried every way possible in my mind and it would have looked ridiculous Oh well I have more builds up coming that I will have room to build a pipe and hey will fit. I have another one of these engines too and others also, funny thing that I experienced one time was I was doing side work for a stand up scooter company and I was doing port work for people all over the country. They would send the scooter to the manufacture and then the company sent them to me to port them in different stages for the power delivery and level that the customer wanted and paid up front to the manufacture so that the company could get their cut of money and in turn the company paid me to do the porting, anyway the now bankrupt company had someone making expansion chambers for their scooters and they were not even close to being right the engines had no bottom end power and it would take forever for the engine to come up on the power band and get with it, I had many models of the companies scooters at my home and at the time they were power by 26cc Zenoah engines and I had other types of engines that I put on their scooters that flew compared to the ones that they were using and installing these so called performance pipes on which they were charging people 125.00 for that did not work. A man from Arizona sent them a competitors scooter which they agreed to have me do some port work to and install his new expansion chamber which he provided and have me test and tune his scooter and then send it back, I asked the scooter company if the gentleman wanted his old stock muffler that came on his scooter and he told them no to bother sending it back and just throw it away, so I kept this muffler which had a long header pipe that led into this little square muffler. I was messing around one day with one of the 26cc Zenoah engine powered scooters and I can't remember why exactly but I installed that little square muffler that was from the scooter from Arizona and gave the scooter a test run that little SOB flew and pulled hard from the bottom to the top rpm range! I could not believe what that muffler did for that scooter. Needless to say the owner of the bankrupt scooter company was floored, he tried to buy those mufflers from the other scooter company and they would not sell him any so the morale of the story is you just don't always know how things are going to work out until they are tested and proven no matter how much money you spend.

 

[rushking19]

Looking great so far

 

[NewbCarter]

Thinking of this , DD : http://www.helifreak.com/attachment.php?attachmentid=236682&d=1309142171 ? I have a few of these laying around ..

The exhaust looks ... fart cannon

 

[Desertduler]

Thinking of this , DD : http://www.helifreak.com/attachment.php?attachmentid=236682&d=1309142171 ? I have a few of these laying around ..

The exhaust looks ... fart cannon

Lol, maybe to you but I would rather use a KTM silencer than a tiny weedeater/chainsaw muffler like the one that you suggested. This engine is 293 cc's not 29 cc's.

 

[NewbCarter]

Lol, maybe to you but I would rather use a KTM silencer than a tiny weedeater/chainsaw muffler like the one that you suggested. This engine is 293 cc's not 29 cc's.

That was for the zenoah 26cc u mentioned on the scooter .. not the minibike engine ...

Tho , question : modifying the silencer , you are basically making it a sort of an expansion chamber / muffler ?

 

[Desertduler]

I would rather use a part from My 300 KTM than a donor like this little two stroke utility engine.

 

[Desertduler]

That was for the zenoah 26cc u mentioned on the scooter .. not the minibike engine ...

Tho , question : modifying the silencer , you are basically making it a sort of an expansion chamber / muffler ?

Half of the silencer will be an open chamber (hollow) the other half will work as a silencer which has sound deadening packing material with a perforated section of the silencer pipe going through it. it will not act like an expansion chamber, the one that I would need to build for this engine is 54 inches long or 1517.7 mm long which you think that my shortened KTM silencer looks goofy, well a expansion chamber 54 inches long on this mini bike would look more goofy than it already does to you.

 

[itsid]

You got me thinking...
I know it'd not be ideal, but couldn't you curl it up?
Say you tilt the engine forward a good amount (sorry, yes...hear me out )
then you'll be left with quite an amount of empty space under the seat..
that fully packed with a curled expansion chamber exhaust;
I bet it'd look super mean and maybe would still add enough power to be more than eye candy...
I bet it'd be a real PITA with all that nasty small bends, but I'm confident that you have both, the ability and patience to make it happen.

'sid