just ordered everything i need. i decided to build my own jack shaft. i have a really good idea for it.
My first race bike build 212cc predator!
- Thread starter bajaracer1
- Start date
in my opinion it's a pretty low performance motor. 212cc only makes 7hp. 12hp if you spend $400-$500 in performance parts. that's pretty bad.
a 2 stoke 80cc motor can make 20hp stock!
but the harbor fright engine is really cheap so i can't complain.
a 2 stoke 80cc motor can make 20hp stock!
but the harbor fright engine is really cheap so i can't complain.
i ordered some parts from AGK and now no eta. didn't even know they did not have the parts in stock. i just payed them the money expecting they would have them[didn't say back ordered] until they took payment. now who know's when they will come. i don't. they don't? it's only been 9 day's so i'm not mad but it would be nice to know whats going on that's all. customer service i think thats what they used to call it. it make's people want to give you money more than one time. dennis bell oh and i like the AGK guy's at the race's too!
that sucks! i placed my order today and got a tracking number 2 hours later. 1 part was on back order so they will ship it separately when they get it in stock. i'm pretty satisfied. i spoke to Shane and he seems really swamped right now. he is constantly building go kart engines. i think that's why things might be slow right now.
I'm gonna make a j shaft with a go cart front wheel hub, get them for $20 on eBay and lotsa colors to choose from. All it needs is to be bolted up to a plate. Gaaahhh, off with the covers! We wanna see your nude engine! Lol. I took the pull start off my 99, I will make a low-profile pulley to put on the flywheel so I can use a string to start it, even though I am making a manual clutch so I can bump start. You don't need the blower with a bike as long as you're moving. The pull starts make motor bikes look like goofy mini-bikes, not like a motorcycle. You can mod the engine while waiting for parts, start with a thin copper head gasket. Anneal the copper sheet first by bringing it up to red heat, it relieves stresses from rolling and makes for a better seal. That will bring up compression.
The copper head gasket will anneal itself after the first run with initial torque down, then re-torque it for proper seal. Re-check the valve lash while you're at it, the valve cover is already removed 
G/M i too am interested in a manual clutch for my 212. but it seem's that none are being produced unless you buy a $1,200 speedway type.
Thanks scotto! I am using a v belt and tensioner, good for lots of power but doesn't have the feel of a real motorcycle clutch. I also have an idea for a manual variable transmission, but parts would be around 300 total. I would use two self-tightening pulleys and have the drive one set up with an offset bearing cup to allow a lever to pull it open. You would use the clutch as a ratio controller and as a clutch. If you don't know what self -tightening pulleys are, they are pulleys that have springs to pull the halves together so they automatically tighten the belt. Hmmm just thinking out loud, you could use a regular pulley on the drive and just have an idler pulley as the clutch! That would bring price way down! It wouldn't have as wide of ratios as with 2 auto tensioners, but would bring the price into reach for many people. Those pulleys are $100+ each depending on size. I am going to do this once I get some dough, for now I just need to finish my build with fixed ratios. This will solve the problem that cvts are almost impossible to make them behave exactly how you want and that they do funny stuff that limits top speed. This is the solution for a racer looking for the best option. I think I will call it an MVT, manually variable transmission. I should manufacturer them, I can make the jackshaft plate from cast aluminum and the rest would be bought. Holy mother this is a great idea!
young grease monkey, i really like your ingenuity, you have some interesting ideas! i wonder how much power loss there would be with all those extra parts and the friction associated with them. you might end up losing more power that the amount of efficiency you make.
scotto what do you think? you have the torque converter that probably takes a lot of power away from your engine.
can't i buy a copper head gasket for higher compression? or do i have to make one?
i haven't though about the pull starter yet but i guess i would like to loose the extra plastic stuff. have other people cancelled their pull starters? any pics?
ok here is my jack shaft idea!!!! i ordered this motor mount /jack shaft.
http://motorbicycling.com/attachment.php?attachmentid=50409&stc=1&d=1343663529
i plan on cutting off the whole motor mount part and using the jack shaft part for my bike. but i'm going to leave one side of the motor mount so i can bolt it up to the side bolt holes next to the output shaft of my engine. then it should look and work the same way as $135 jack shaft works from AGK .once i get it i'll post some pics. total cost was $85. and i think it would be pretty heavy duty and look great in red.
scotto what do you think? you have the torque converter that probably takes a lot of power away from your engine.
can't i buy a copper head gasket for higher compression? or do i have to make one?
i haven't though about the pull starter yet but i guess i would like to loose the extra plastic stuff. have other people cancelled their pull starters? any pics?
ok here is my jack shaft idea!!!! i ordered this motor mount /jack shaft.
http://motorbicycling.com/attachment.php?attachmentid=50409&stc=1&d=1343663529
i plan on cutting off the whole motor mount part and using the jack shaft part for my bike. but i'm going to leave one side of the motor mount so i can bolt it up to the side bolt holes next to the output shaft of my engine. then it should look and work the same way as $135 jack shaft works from AGK .once i get it i'll post some pics. total cost was $85. and i think it would be pretty heavy duty and look great in red.
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The reason cvts are not very efficient is that when they go into high rpms, the cones are trying to go into super-overdrive and the drive pulley can't open any farther so the driven tightens the h3ll out of the belt. An mvt is manually controlled and wouldn't have this problem, the only inefficiency would be if the springs in the pulley were too tight, and that can be fixed easily. If you try this, please give me credit. I wish I could produce them to sell, but I don't have enough time before summer ends to make a prototype and refine it. I am making engine mounts to sell, finishing the prototype today.
i probably won't try it since i already bought the jack shaft setup. i'll ride around on it for a while and then decide how i like it.
http://www.bmikarts.com/item/Motor-Mount-Plate-with-Jackshaft-and-Bearings-400361-6636
Not sure if this is going to work on his build.
Not sure if this is going to work on his build.
bmikarts.com has them for $28
i'm cutting the whole engine mounting part off except for the left side part. i will use the left side part to mount to the engine's side in back of the clutch. the whole piece is 12 inches long so it should easily move the jack shaft away from the engine. hopefully it will work. it's in the mail now.
i'm cutting the whole engine mounting part off except for the left side part. i will use the left side part to mount to the engine's side in back of the clutch. the whole piece is 12 inches long so it should easily move the jack shaft away from the engine. hopefully it will work. it's in the mail now.
dude, my idea uses a jack shaft. as long as you didn't already buy parts for a chain primary. a good clutch for this big of an engine will cost much more than $100 and it's fixed ratio.
so explain your idea in detail again pleas.
anyway i got some minor work done today. new thumb thrortle (i dont like twist thottle), new bear claw pedals, took the govenor out, installed air filter and made the engine naked!
Go to mcmaster Carr website. Find the constant tension pulleys. Use min/Max pitch diameter to calculate ratio, pitch diameter x 3.14. Only use type b belts, a belts are made for light applications. You will want a range of about 11-12 to as high as possible. Smaller pulleys will have more ratio range but you cant get super small pulleys on the engine so I suggest a very big sprocket. You will then need an idler pulley as the tensioner. Make a pivoting bar to put the idler on and have a long slot to move a cable mount on, you will want it to be very adjustable. Get a 1/4 aluminum or 3/16 steel plate and make a mount for the idler pulley, you will want to make slots in this too. It has to do with the curve of a circle and the progressive rate of travel with a fixed cable mount, you will want to be able to tinker with this. I will make my own probably a couple weeks after I finish my build. I sent it to get powder coated today, should be done in a week.
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OK i understand your idea and i guess it could work. i don't want to build it since i already spent $85 on all chain parts. but if i ride the bike in a race or two and fee like i want to try this out i might come back to it. right now i'm just trying to finish the bike and see if i like this sport of racing motorized bicycles.
another question. i found a .016 thick copper head gasket for my engine. is this thinner than stock? i should get higher compression right? is it safe to run this gasket in my engine if it's all stock except for intake, straight exhaust, 18lb valve springs, no governor, and #90 main jet.
with those engine modifications would it be safe to get the head gasket? and would it even make a noticeable difference in performance?
another question. i found a .016 thick copper head gasket for my engine. is this thinner than stock? i should get higher compression right? is it safe to run this gasket in my engine if it's all stock except for intake, straight exhaust, 18lb valve springs, no governor, and #90 main jet.
with those engine modifications would it be safe to get the head gasket? and would it even make a noticeable difference in performance?