Stock carb mod

real easy to do. step by step: take your carb off. remove float bowl (2 screws) with carb upside down remove pin holding needle holder(thin brass with tangs that hit float) now you should have the needle loose and in your hand. I used ultra-brite toothpaste on the sharp end of the needle. pencil eraser with knife cut down center. with needle and abrasive in place I stuck the eraser onto the needle and spun it pack and forth by hand. watched TV and did this for a while. removed needle and reapplied toothpaste several times. cleaned hole and needle with carb cleaner(and entire carb) cleaned hole needle goes into(seat) with Q-tip and blew out with carb cleaner again.(must be absolutly clean!) reassemble and set float level. CLEAR AS MUD RIGHT?
 
Good to hear that the idea still works after all these years, you never know when they will stop putting enough abrasive in the tooth past to use as a lapping compound. LOL One of the things I like about these machines is that they need us, my car just runs, BORING. I put up info on porting the makes the most difference in the power department, but it is the most difficult to do. Have fun, Dave
 
DanielMaia said:
This mod, increase the comsumption overall?
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If you mean the small hole in the carb, the answer is no. As a matter of fact if the engine runs better overall there is the best chance that you would get better Mileage. The stock carb is missing the slow speed circuit, this mod attempts to mimic the missing circuit. Have fun, Dave
 
.wee.
ken murphy said:
at the top of the page go to the first thread & egor explaine it well----------scroll to the top and lookon the right side--------go to #1
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check out the quench area on these slant heads they were made for the66cc but they have the 50 cc bore size they work good when u finish them out like the one in the pic see the differance?
 

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.wee.
Egor said:
What is happening with the piston you are getting? Dax has the long rod pistons and I got a short rod piston from Kings motorbikes Kmotorizedbikes.com But I can't insure that they have not changed vender's and now have something completely different.
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I think we got it Egor lenny says the motor will rev until it explodes port matching on the tranfers to the piston & the slant head,with modifacation to the quench area,were get'n em licensed,i'm already pullin my spokes out,goin heavy duty on that, bigger spokes,Ive got three bikes and a trike now,My next one is guna rock.
I still haven't replaced the piston I put the old one back in,it seems alright.
thx 4 ur help
murf
.shft.
 
+1 to the OP about the small idle circuit hole. I did the mod today but didn't see the need for slotting the slide, after all, it should be cracked open slightly for idle and my hole was very close to center. Runs and idles much better, more responsive to a throttle snap. I also soldered my main shut and re-drilled at the same time. This was to clear up my rich condition, I live at 4500 ft and WOT was too rich. I used a #74 drill BTW. I am happy to have found this thread, thanks.
 
r.ly.r.ly.r.ly.r.ly.
Just_Gassit said:
+1 to the OP about the small idle circuit hole. I did the mod today but didn't see the need for slotting the slide, after all, it should be cracked open slightly for idle and my hole was very close to center. Runs and idles much better, more responsive to a throttle snap. I also soldered my main shut and re-drilled at the same time. This was to clear up my rich condition, I live at 4500 ft and WOT was too rich. I used a #74 drill BTW. I am happy to have found this thread, thanks.
Click to expand...

sounds like u got it
happy trails
check ur plug!
 
I always wonder if the factory ever looks at the stuff we come up with. It would be simple for them to poke the hole in the carb and make there stuff work better, but then what would we do if they worked straight out of the box. I have two Yamaha carbs on two of the bikes and they work better but not enough to warrant the expense. I started this thread and some of the porting stuff I have done, if the group noticed and did all the mods I think the China Girl would be a bigger hit than it is. Have fun, Dave
 
Thx Egor for all your help----heat that plug wrench up w/the touch that Monkey will put er down
I'm tellen ya try the slant----I'm fabin some sprokets 4 spooky tooth now

I'm takin a lathe up to em next week------wait tell u see the new one#7ya 40+ from the start,I desinged new mounts ul c I'll post it Ps the lil girl is short lived
tell ya more later
murf
 
If I understand this mod. It's the notch in the carb slide that makes the diference. this leans out the idel mixture. Has any one notched the slide and not drilled the hole in the body of the carb. We notched the slides on larger bikes and also changed the slide cut-away. Vic
 
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Our little bike is running very rich. We had to drop the needle all the way to get it to run at 3/4 throttle. Will drop the main jet down 1 or 2 sizes as soon as we have some miles on it. Is this common to drop the needle all the way or is this just one of a kind. Vic
 
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I wish I could tell you one way or the other------Truth is that its hard to make any two engines the same,Ive built several and they all run differant, for the most part I think the key is carburation just look at the plug-------I like mine to run a light chocolate color.Check for leaks,Ive made my own specs and gaskets,Im try'n to find an economical carb,need to work on the intake manifold 2,Im going to fabricate my own. you will know when u get it because you will star pulling the spokes out of the rim.I've rebuilt my rear wheel twice. happy trails
 
Vic it sounds like you know what you are doing. If you have changed the cut in the slide then you know what it will do. On the little happy carb it is missing the slow circuit all together. In my mod I added the slot in the slide to increase the vacuum at the hole and get more fuel for the idle. One of the things I have found is that the float level from one carb to another is about as diverse and anything I ever seen. I would try and lower the float and see if that helps with the rich mix. See if that helps. Have fun, Dave
 
I am trying a new approach to the carb dilemma. I am trying out some Butterfly carbs. I will post some of the pic's of them. I still like the KeiHin carb's I have off of some old Yamaha's. But they are expensive and not easy to find. I have been looking for an easy carb to use in place of the Yamaha carb's. So far I like the second one it is the one that is easy to adjust. you can adjust it on the fly. I still need to put a new case gasket in this engine it is still leaking air and messing up the mixture. This is a complete tear down, that is always fun. LOL I will keep you posted on how things go with this one. Have fun, Dave
 

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