CRF70 starts and REVS TO THE SKY

Alright heres my story. I got a crf70 a little bit ago to learn how to wheelie on (instead of my 650r) and i got this bike and it starts right up everytime. I wanted some more power and went to re-jet it. Put it all back together (im familiar with this stuff) and went to a 13t front sprocket. Put it all back together and kicked it over on full choke and it fired right up. Took it off choke and that thing reved to the moon and back. on choke its rough but not sky high. if i take it off and crank the throttle it dies...this is stumping me pretty good. Ive taken the slide out a million times and its all the way down in there and i can watch it open and close. Ive tried turning the idle all the way down, no changes. There is one thing i noticed and the alignment nub inside the carb for the slide is gone. The guy that had it before me musta messed that one up but the slide is on the screw on the bottom...what could it be? ive worked on numerous 3 wheelers, quads, dirtbikes and what not and never have ran into this problem. Hope ya guys can help me cuz google isnt doing much for me.

anyone know whats going on? do i just need a new carb because that nub is gone? id go aftermarket because 30$ is alot better than 150$. if so what size should i go? Nothing special to the bike no baffle, uni filter, new highspeed jet

First thought was the slide, but sounds like you know not to put it in backwards. Next thought would be, pull the bowl and make sure your main jet didn't fall off; I've had this happen and it raced off with my son on it.

A 24mm china carb like this should work should work, you may need to rejet it though.

Yea i thought it was the slide aswell but im pretty sure it isnt lining up right with the nub not being in there to guide the slide all the way down, so then i took the carb off and took out the jet i put in and put back in the old one (bike ran like a top before i took it apart) and nope didnt do it, checked the idle screw and eventually went to my best friend (ebay) and i ordered a new carb for it. Im just going to stick with a near stock sized one for now. I plan on upgrading to a 125cc engine in the future...my reason? to show my girlfriends little brother and all his friends that my little bike can go faster than theirs even with my fat ass on it. They basically have a little motorcycle gang

First thought was the slide, but sounds like you know not to put it in backwards. Next thought would be, pull the bowl and make sure your main jet didn't fall off; I've had this happen and it raced off with my son on it.

A 24mm china carb like this should work should work, you may need to rejet it though.

If you're going to use one of the Chinese carbs, make sure you get one with the choke lever on the left side of the carb. The right side mounted levers are hard to reach with the exhaust pipe in the way.

Hot point dirtybkr! Here is a carb that's more suitable.

I wish i woulda let you guys tell me before hand, i belive the one i bought has the choke on the exhaust side. but ill deal with it because i really wanna ride her around in this snow :lol:. I apriciate you guys help with this one. it confused the hell outta me but in the end money always fixes stuff

Hot point dirtybkr! Here is a carb that's more suitable.

so i got my china carb in the mail today, so excited to ride BUT the holes to mount it are different than the stock one, so i send the guy on ebay a message and i hope to hear back from em tommorow. i guess i need an adapter or a new intake pipe..guess you could call it the intake manafold. unless you guys have found somthing quick and easy. it has the choke set up on the exhaust side but its set up for a cable so ill put a a handle bar choke set up. and then i was going to switch the cable over and being so excited i just wanted to pull it right outta the cap cuz the carb came with a new one and then i figured out that didnt work and i couldnt get the cable back threw...but luckily me and my friend are lazy and happened to have a thumb throttle for a 3 wheeler hidden under the snow in the truck. so figured that one out. just need to find a way to mount it

What's different about the mount? Are the hole spacings off?

What's different about the mount? Are the hole spacings off?

Yea, the new one is alot wider, i belive the holes are 50mm spaced. Im not sure f the factory ones spacing

That's a real bummer, it sounds like a carb for a 200cc, they have 47mm spacing (I think). I am not familiar with an intake manifold to adapt the different size carb. Good louck and keep us posted.

That's a real bummer, it sounds like a carb for a 200cc, they have 47mm spacing (I think). I am not familiar with an intake manifold to adapt the different size carb. Good louck and keep us posted.

I ended up calling the people up and they told me which one to buy. its a whole new intake manifold. I really want to rip around. I live on a college campus and i romp around on it. They havent yelled at me yet but ya know a big guy on a little bike crusin up the driveway isnt anything to mess with :lol:. thanks for your help. its nice to have a forum that people actually post on lol. So this 10$ part should have me fixed up

can you post a link to the manifold?

ill make sure i tell ya how it works

So i got my part the other day and put it together that night, i dont like this intake manafold because its made for larger carbs so now i need to buy a pod filter on her. but anyways got it together and it doesnt want to start. sat around on it for a little while and remembered the ground wire on the bolt for the air filter :lol: so it runs and i can ride it but im pretty sure i have an air leak on the new manafold because the crappy china thing is just metal, no o ring. so ill make a gasket outta it tommorow im my shop class. the RPMs just hunt up and down and i know thats usually what makes em do that. other than that it was pretty fun in the snow. after the air leak i iwll have to tune the carb in right.

The o-ring isn't on the manifold, it goes on the isolator that you should have order in addition, because it appears one was not included. You need to be running this to be sure you get a good seal. There is also a gasket between the head and manifold.

The o-ring isn't on the manifold, it goes on the isolator that you should have order in addition, because it appears one was not included. You need to be running this to be sure you get a good seal. There is also a gasket between the head and manifold.

I made a gasket today, goes on real nice and tuned in the carb. good throttle response and everything, what is the purpose of the isolator? (plastic thing inbetween carb and manafold

I made a gasket today, goes on real nice and tuned in the carb. good throttle response and everything, what is the purpose of the isolator? (plastic thing inbetween carb and manafold

To keep the transfer of engine heat from the head to a minimum. The insulator (or heatstop) can also be mounted between the head and the base of the manifold to achieve the same purpose, as shown in the pic below.

000_0596-800.jpg

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