My first experiment with a built hs50

joshua. c.

Well-Known Member
The bike I recently finished some mods to is the second mini bike I ever owned. I gave it to my cousens daughter a while ago and recently she gave it back to me not wanting it anymore. so I added it back to my growing collection and made some mods.

I took the motor and ported the intake and exhaust mostly just rounding all the sharp edges and removing flow restrictions. I added a billet rod made for the ohh55, completly removed the governor parts, added a mild 275 lift cam, added 24lbs springs made for a predator (less coils in them so they fit quite well). added the h50 hot coil and installed a header. I has it geared way to high at first and it had issues with climbing hills but I fixed that recently when I installed a comet 30 with a juggernaught driver. Its geard near perfect now and it takes off just shy of pulling a wheely. It still could if your not cairfull. I'm pritty happy with the results so far it starts easy and this thing rips! I didn't shave the head because my other bike, a built raptor kicks back on me allot and Im trying to avoid that with this build.

The only mod the motor is missing is a mikuni carb but as soon as I get a manifold made up for it I'll fix that. I will have to relocate the tank higher for that mod.

This is an older pick before the torque converter was added and I had to re work the way the handlebars were mounted. (this way of mounting made them weak) I'll get an updated one this weekend.

This bike feels like no other. The seat hight and firmness/ softness ratio as well as the footpeg position and handlebar shape are just perfect making this bike the most comfterble bike I own. Everything just feels right in a way no other bike I have dose. I know that seat looks weard but its so comfterble. I may fix that soon I know somone who can make a great cover for relitively cheep.


joshua. c.

Well-Known Member
New photo as prommised


I fixed the handlebar mount and added the torque converter since the last picture.

Adding a mikuni is going to be hard but not imposible with this setup due to a lack of space where it needs to go.

As far as other future mods the kick stand is to short the forks are a bit to wide (aftermarket) and the front brake hasn't been added yet. I need to swap that front tire to match the rear one for better traction and paint that front wheel to match the rear.

I was origenaly goint to put a rear swing arm on this bike but now im questioning that. Gomas mini bike massacre an even I attend every year has recently broken the event up into classes bassed on the bike. Without rear suspention this bike can fit into the stock class and my full suspention bike fit the unlimited class and if I bring my trike I can race in the more than 2 wheels class. If I keep this bike as is I can race in 3 separate classes thus increasing my fun!

This bike is one of six I have that run and I have just as many as un finised projects, not to mention 3 snowmobiles 2 go karts and 2 trikes. I have a fleet lol.

The blue on the exhaust is from tape. It was threatening to rain on uss at an event I went to last year so I taped up the air filter and exhaust to protect the motor, it never got removed untill today. It started to rain just minutes after the event finished up so we got lucky.
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It looks like you'd have plenty of room for a carb if you got a different exhaust pipe. Or modified your existing pipe.
Oh wait- now i see your motor is mounted flat and not at an angle.

joshua. c.

Well-Known Member
I think its a trail horse the only other frame It could be is a similar looking gilson frame. The handlebars are a modifted set fron the origenal frame bent back at a 45 degree angle for better comfort and cut off the origenal tripple trees. The forks are a universal set from go power sports. The wheels are rupp and I dont have a vidio cammera or youtube account.

I deleted my youtube acount when I was forced to have google search engine acount and it Kept messing with my ability find what I was searching for. The issue was never solved so I never went back. I find it hilarious how youtubers plead for subscribers when google murderd that community years ago and its never recoverd.

joshua. c.

Well-Known Member
Also I will fugure out how to mount the new carb when I have some free time so don't wory about that. Right now this bike runs good and I have other projects to get to that take priority so it might be a bit before I circle around to this one again.

joshua. c.

Well-Known Member
I got looking at this bike a little sooner than I first thought. I got a set of honda ct70 fenders for this bike and they will look great but the carb right now is to close to the tire to fit the new fender so I looked at the issue. I think I can adapt a briggs animal intake and carb to fit right next to the exhaust straight back. It will be a bit close to the exhaust to I'll have to heat tape the exhaust. I will still need to source the parts then jet the carb so I dont know yet when I'll get to this but the wheather will have to be quite a bit wormer to get the jetting right.
I have one with almost the same mods as yours, Isky cam, billet rod, Hot coil and vm22! it is a atlas tt5000 and has the original tc88 converter. It has a wheelie issue that makes it dangerous to drive. When starting up till the driver starts upshifting (about 5mph, it will just flip over throwing the rider I think because of the short wheelbase, not because it has any more low end.


joshua. c.

Well-Known Member
Good looking bike.

My bike did have a wheeling issue but I solved it by exchanging some of the ridiculous bottom end for a bit of top end by increasing the teeth on the jackshaft sprocket. Its much more ridable now and still has loads of grunt. Have you thought about dooing the same?
Yes but when it shifts to top it's like Bonneville gearing. But thinking about it I could limit the driven unit and add a tooth or two to the jackshaft sprocket. Good suggestion!