My first race bike build 212cc predator!

[dmb]

one of my whizzers has a belt drive manual clutch and its a slip and slide to get it to grab. you could use a lock up like the early motorcycles. but i think the load on the crank would kill the bearings in short order. a speedway jackshaft style clutch would work great but they cost $1000+. but good luck and i hope it works out for you. dennis

 

[young grease monkey]

wayne has done a few builds with belt primary drive as the clutch. i think i will burn belts because of the way i like to ride. and these engine are made to handle side loads, i think it will be ok. it's the same setup earth tillers use.

 

[bajaracer1]

ok i got all the parts i need from agk.
i'm looking for a wider pedal system with a pretty small front sprocket. i can't find out where to get one. does anyone have any suggestions?

 

[young grease monkey]

You could have a machine shop make you a crank for a 3 piece setup, give them a regular one and have them cut off the tapered part and extend it. Idk if they would charge too much to make it worthwhile. I think a couple of vendors that sponsor this site sell a one piece wide crank. Ask a bike shop where to find a really wide crank, don't mention that it will go on a motor bike.

 

[Old Reliable]

had to remove my pic to post on other thread

 

[bajaracer1]

yesterday i ordered a 25t sprocket so i would have more room to mount the engine. i also bend my stock 1 piece crank to make room for the engine. used a torch and bent them in a vise. i did a pretty good job. don't think it will wobble at all. maybe 1 side...
thanks for your advise Jeff.
also decided to just buy a jack shaft setup. diden't like my original idea.
before:

and after:

 

[bajaracer1]

i'm almost done. just have to figure out a gas tank, cut my chains to size, do some final welding, make an exhaust, and solve all the problems that i'll have in the future.

 

[bajaracer1]

got a temporary gas tank on the bike. i'm planning on something that's better looking but i just want to ride this bike now. let me know if you have any suggestions on a gas tank.

also welded the frame support back. i made it a bit higher so i can remove the valve cover without having to remove the engine.

all the chains line up.
look at the engine mount i made for the front of the engine. those mounting tabs use to hold the gas tank. this engine is not moving anywhere unless the frame goes with it!

i got it started and rode it around the block a few times. it rides really nice, and feels like it can take some fast turns.

i'm still waiting for my 22mm mikuni carb and adapter, and for my 1 inch exhaust. either than that the bike is done!
i'm hoping to make it to the race on the 15th. well see...

this temporary exhaust burnt my leg yesterday. if you look closley you can see the philips screw imprinted on my leg.

 

[bajaracer1]

 

[scotto-]

Are you ready to race? The bike is looking just about ready......hang on, you're in for a fast ride....er....race!

Hope to see you at Adam's.......it will be fun.

 

[bajaracer1]

the bike is all ready and assembled, but i'm still waiting on the carb adapter from AGK. they say it's out of stock.
i'm starting to get the feeling that i might not make the race because of this. i'm hoping for the best.

 

[bajaracer1]

ok i finished the bike today! took it for a test drive. WOW it's fast. very stable and predicable handling. no vibrations at all. it is a blast to ride.

i do have one pretty big problem with the 22mm mikuni carburetor i got from agk. i installed it and it started perfectly on the first try. but it idles at way to high rpm. the clutch engages as soon as the engine starts. i have tried adjusting the two screws on the carb but they don't change the idle at all.
i know scotto and ccc have these carbs on their bikes. what do you think i need to do to get the idle much lower?
pleas help. i really want to make it to the race this weekend.

pics

 

[culvercityclassic]

The problem is the slide is not seating all the way due to the outer cable sleeve. You are going to have to trim 1/8 to 3/16 off of it. This will make the cable longer to close the slide. You can do this with a dremal and small cut off wheel.

 

[scotto-]

The idle adjustment screw is the one on the right hand side of the carb.....turn it counter clockwise. You might check your throttle cable as it could be hung up on the ferrule at the grip

See you in the pits......

ok i finished the bike today! took it for a test drive. WOW it's fast. very stable and predicable handling. no vibrations at all. it is a blast to ride.

i do have one pretty big problem with the 22mm mikuni carburetor i got from agk. i installed it and it started perfectly on the first try. but it idles at way to high rpm. the clutch engages as soon as the engine starts. i have tried adjusting the two screws on the carb but they don't change the idle at all.
i know scotto and ccc have these carbs on their bikes. what do you think i need to do to get the idle much lower?
pleas help. i really want to make it to the race this weekend.

 

[bajaracer1]

thanks guys! i found out the problem. the lead piece of metal on the end of my throttle cable was to big. it protruded out past the end of the slide. so it wouldn't go down all the way down, but felt like it did. fixed that by grinding the lead piece smaller.
i rode the bike and kinda tried to tune the carb, but i don't really know what i'm doing. it feels fast but i feel like it has a lot more potential. it is not a smooth acceleration.

well see if i can do some research tomorrow and fix it.

any suggestions?

 

[bajaracer1]

my engine has the following modifications. let me know what pilot and main jet you think is right:

212cc harbor freight engine
governor removed
18lb. valve springs
straight pipe exhaust
air intake
22mm mikuni carb

what pilot jet and main jet do you think i should have?

 

[agk]

We would use a 12.5 pilot jet and a 125 main jet in that combination. You can put the needle clip in the center position and leave the air screw in the factory position which is 2 1/2 turns out.

 

[scotto-]

I would go with AGK's suggestion.......my Mikuni 22mm came stock with a 90 main jet (which I had to drill to 125) and a 15 pilot jet.

 

[bajaracer1]

i don't know which pilot or main jet i have. AGK would you happen to remember which jets you put in the carburetor i have?

also will you be at the race in 2 days?

anyway today i got the bike tuned pretty good. acceleration is smooth and the top speed is smooth. still needs some work though.
i rode the bike for a while today and towards the end of my journey my exhaust broke off from the header. i think this is because the pipe was mounted metal to metal. i think i should have some rubber insulators holding the exhaust.

but i noticed a few guys here don't have any mounts for holding the pipe, except the header. is this a good option?

 

[buck0]

Check this out http://www.affordablegokarts.com/carburetor-tuning.php