Manco Streaker Mini Bike

So I aquired this old mini bike a few days ago for $150 in pretty nice, running, and driving condition:





Nice little bike. Good running 3.5hp Tecumseh 4 stroke engine, the usual centrifugal clutch and chain setup, twist throttle, rear scrub brake with foot pedal, etc.  

Been driving it around alot and man is it ever a blast to cruise around on!

Dropped the oil while it was nice and warm a couple days ago and filled it with sime nice fresh 10w30.





So far all I've done to it is modify the throttle butterfly plate on the carb for some more RPMs, add a return spring for the brake, and change the rear fender setup and add a little mud flap:



Noticed some muck was getting on the engine before, so I figured I'd add some more protection, haha.

Plans for it aren't too crazy, probably gonna have a custom intake and exhaust, maybe make a neat looking chain guard, add a tach between the bars, maybe a headlight, stuff like that. Also if the Teccy ever proves to be insufficient power wise, my Honda G200 flat head might take its place. That'd be a nice upgrade, haha.

Anyways I thought I'd share my new little toy, haha. Let me know what ya think!

Nice little bike. My kid's friends are always asking me to mod the frames of those for bigger motors and fix the forks because they always hit stuff with them. My mini bike has a 3.5 hp Briggs on it and hit 34 eventually tweeking the gov. Strong little motors on the top end of rpm, just sucks starting off.

Nice mini bike man!  Don't forget the crew while you have fun on it. 

Thanks fellas! Yeah the nice thing about swapping that G200 in would be that it would actually bolt right up to the mounting plate and should also fit nice under the upper frame tubing (according to my measurments) , so luckily I wouldn't have to do any frame modifications. I'll probably keep the little Teccy in for a while though as it runs quite well.

I like the mud flap idea a lot to protect the motor.

Those are interesting grips on the footpegs.  I see what I think are finger grooves in them.

HAHA, I saw those grips too. Man I missed the mudflap the first time around.

Thanks fellas, the mud flap thing has proven quite effective since I put it on.

I guess I never payed attention, but I guess the foot peg grips do have little bumps on the bottom sorta like finger grips:



Haha. Not sure what the deal is there, who knows.

Also forgot to mention I'd like to try and make a cooler looking brake pedal possibly, like weld a piece of steel checker plate on it or something. Just another little decorative touch, haha.

When I got this little guy I noticed the clutch liked to slip pretty bad in the tougher terrain, I assumed it was just wore out from use over the years so I took the clutch apart to see:





If you look closely you can see the wear.

Yeah she needs a new centrifugal clutch for sure, but I just sanded it up a bit, oiled the bushing, and it back together for the time being. It'll stand up until I get a new one. It's one of the "Max Torque" clutches too, so I'd like to get one of those same ones, they're a bit under $100 I think which isn't too bad.
I'll see if I can get myself one of those so I can do some trail riding! Haha.

Well the little mini bike made it down to the farm a couple weeks ago, gonna be nice having all the land to drive it around on now! Haha.

First minor mod I decide to try was a nice simple exhaust pipe.

The muffler bolts actually broke loose real nice and I was able to remove the muffler quite simply:



Had a screen between the outlet and the little bolt on cap.



Pretty plugged up as you can see. That'll never do!





Much better!!

Nothing special obviously, I'm gonna give it some paint tomorrow as well, so it should look pretty neat after that. I used a washer as a flange (mr.mod's idea) and used some thin stuff that I found for the pipe.
It sounds great! Nice and snappy, but not obnoxious. Used to bog pretty bad too, but it doesn't seem to do it at all now, so I bet that plugged up screen was causing some issues.

I also put a different fuel tank on it because the old one leaked pretty bad and I couldn't seem to be able to fix it.

It's actually the old fuel tank from the rat rod, pretty much the same tank so it bolted right up.



I did have to cut a bit off the mount though due to the different fuel filler cap location:



Perfect!



The offset fuel filler is actually a lot easier to get to than the old tank, which is nice.



Nice to have that done. No more leaks! Haha.

So yeah just a couple small things, but I thought I'd share nonetheless. Let me know what ya think!

So when I had the mini bikes.  I bought a $30 clutch for one and a $100 clutch for the other since it had just the amount of teeth I was looking for.  I didn't really see any huge difference in quality or performance  between the two.  I would get two cheap clutches so you have a new spare on hand.

Does that engine have a 4 bolt flange pattern on the case cover? You could ditch the CC for a fancy CVT. That would be cool.

Yeah we'll have to see what kinda clutch I end up getting.

Also I'm not sure about the bolt holes for a CVT, but I'll probably keep the ol' centrifugal clutch on this rig, haha.

I think a cvt would be nice if you wanna go fast. That engine fits like a glove, lol.

The CVT wouldn't make it any faster really, I could simply swap the rear sprocket for a smaller one to go faster, which I'd like to  maybe try sometime. The CVT would allow for much quicker takeoffs and be better suited for trail riding, but I like the current setup and it works quite well.

The cvts are more for torque than speeds, as the pulley setup on them gives steady power in any rpm range, but gives a fairly good speed but still has a good performing off road capability. whereas a clutch would overheat from slippage. the clutches give faster response and do not have an rpm limit like the cvts do.

Hmm I dunno for certain, but I believe a CVT will give you a higher top speed along with the low end power.

All this talking in here and not one comment about my super slick high-tech exhaust.

But yeah, probably not going for a CVT on this little guy. Just gonna buy a new clutch for it someday.

I think the next thing I'd like to do is build a little stand for it so I don't have to use a lawn tractor rim:



Hahaha. Probably just try and make something simple out of lumber, that'd probably work pretty good.

Had a little bit of snow to bomb around in with the mini bike, nothing too crazy but it's kinda fun to slide it around. Haha.



One small thing I did was add a choke control that can be operated from the seat. Usually you gotta drive it for a short distance on half choke when the engine's cold so I figured it'd be nicer to be able to not have to reach under the seat, haha.





Pretty simple obviously, works great though. The mount for the knob looks pretty weird but oh well, haha. Should work pretty good!

I like the remote choke knob. I hate reaching under the seat on my trike to fumble with the choke.

Thanks! Haha, yeah it's a lot nicer having a "dash" control.

Well boys since the nice weather is here, the little Manco Streaker chick magnet is back to cruisin' the means streets!
Well more like gravel roads, but still.

But yeah, I've been bombing this little thing around on a regular basis for the last little while. It sure is a blast!! One thing I finally got around to doing today was giving the exhaust a shot of paint, meant to do it right after I made it, but if course that didn't happen. Haha.

Got it cleaned up with the ol' wire wheel:



Then the paint!





Oh yeeeeaah!! She looks even more like a hot rod now than before! Hahaha.

All joking aside though I think it looks pretty neat, much better than before.



Fun little bike, haha. Let me know what ya think!

How fast will it go? Ever gps it? My mini bike goes about 34 now. Been over a year since I rode mine though.

It's nothing crazy, tops out at 23mph after I tweaked the governor a little bit to get a few more RPM's. Feels plenty fast on that tiny thing though, hahaha.

Well me and my cousin have been doing some serious mini bike wheelin' in the last little while, been super fun! Unfortunately the fun was cut short today though when the ol' scrub brake finally caught up with the poor back tire:





Yep, got me a flat. Haha. Been wearing on it for quite some time as you can see!

Got it all tore apart and ready for a new tire though:



Cleaned and re-lubed the bearings too while it was apart, as they were pretty dry sounding.

Gonna buy a new tire for it tomorrow provided I can find one, then it might be time for a brake upgrade! Stay tuned!

Well it would appear this turned into more than a new rear tire....





Haha, yepper! I figured it was time the ol' Teccy got some love, so I yanked it out and tore it down on the bench.

Got the cylinder head off, doesn't look too bad for the age of the engine:



Next I pulled the valves, since I figured on lapping them and doing some port work:



Then I got myself a mirror and some sandpaper and sanded the head down nice and flat:



I know I won't be taking enough off for much of a performance gain, but it'll help a little.

After sanding it 'til the high spots were gone I set it on the block to test the flatness. I found that was able to rock it maybe 0.001" with my finger so then I used the valve grinding compound to sand the head and the block together:



Turned out nice! Should be good and flat now.

Next came the port work. The stock ports were actually not too bad, so I just did some minor cleaning and made the inner bend a lot wider and smoother to free up some flow.

Before:



After:






Got the valves lapped and got a nice finish on them and the seats on the block:



I also figured on giving the cylinder a good hone, since there was no cross-hatching left and a little bit of scarring.

Before:



After:



Turned out pretty nice! Still just a hair of scarring left, but it shouldn't hurt anything. It's much better than before.

When I had the piston out I also noticed that the top compression ring was siezed:



I'm sure that wasn't helping performance, haha. But I ended up useing some penetrant and a screwdriver to get it freed up and springing nicely again. Then after some cleaning the piston went back in:



Didn't really check clearances like I should have, but the bearing surfaces looked onto be in beautiful shape so I didn't worry about it too much. After I torqued the rod bolts I got the block ready to go back together and put the cover back on:



Looking pretty freshed up!



Put the valves in next. Both springs got shimmed up with some washers:



Shouldn't be too much, I checked them at full lift and the springs aren't being compressed past their limit, so I don't think it will hurt anything.

Here's how she sits as of tonight:



Pretty happy with how things went! Gonna be cool to get it back on the bike and see how it does, haha. Tomorrow I'll get the head put back on with the new gasket, then I'm gonna try a bit of a timing advance to see if I get get a bit of a top end power boost. I'll most likely port the intake manifold a bit too before I put the carb back on.

Gonna be good I'm thinking! Got a new clutch coming for 'er too so hopefully I can put some power to the ground a bit better, haha. Let me know what ya think!