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  #6711  
Old 12-31-2013, 09:53 AM
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Default Re: what did you do to your motorized bicycle today?

Quote:
Originally Posted by rogergendron1 View Post
stock main jet was real tiny.....say .69 or .70mm

i squeezed a .74mm saftey pin through it and it was real tight so i slowly worked it in twisting it around untill it slid in easy and snug.

main jet is now .74mm or .0285

edit.... it squeezes in snugly so i know its actually a size smaller... .73mm or .028 in
Order you these two items and you can drill the jet to exactly where you need it, and if it ends up being to big just put a small piece of solid wire solder in the jet heat it with propane torch and re-drill it, this is the best way I have found to jet the carbs correctly, cheap easy and it works perfectly, been doing it to mine since I started playing with these engine in 2009, Tom/2door and other taught me that little trick early on and it is best way to go in my opinion.

Links:

http://www.widgetsupply.com/product/WB05.html ($3.97 wire gauge bit set)

http://www.widgetsupply.com/product/SHG3-840.html ($2.97 Pin Vise for bit)


Map
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  #6712  
Old 12-31-2013, 10:24 AM
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Default Re: what did you do to your motorized bicycle today?

I have a drill set with a pen type drill handle, the solder and drill method is what I do also. The one thing I have learned is everyone of these engines are different, what works on one may not on the next. On my 48cc with the cns2 I'm at a 66 drill size, that's where the plug color got right. On other bikes I've tuned the stock jet (71 I believe) was OK. These things are very simple, that's why they drive us crazy!
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  #6713  
Old 12-31-2013, 10:45 AM
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Smile Re: what did you do to your motorized bicycle today?

Quote:
Originally Posted by Greg58 View Post
I have a drill set with a pen type drill handle, the solder and drill method is what I do also. The one thing I have learned is everyone of these engines are different, what works on one may not on the next. On my 48cc with the cns2 I'm at a 66 drill size, that's where the plug color got right. On other bikes I've tuned the stock jet (71 I believe) was OK. These things are very simple, that's why they drive us crazy!
DITTO..!

So far all of my 66cc engines with NT carbs have liked a jet drilled with either a #72 or #73 wire bit, my RT carbs have both run perfectly with the #70 jet that came with them, only slight low rpm 4 stroking and zero under throttle or at cruise speeds and a nice medium brown spark plug electrode, climate and altitude play a part in all this jetting stuff also, so yes it is not universal when tuning the carbs, it's a matter of running the engine and figuring out what it needs and like the best based on how it is set up and with what exhaust it has which has a lot to do with the amount of air that can flow through the engine.

Map
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  #6714  
Old 12-31-2013, 11:08 AM
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Default Re: what did you do to your motorized bicycle today?

i have pleanty of micro drills .......................... they are in new hampshire 75 miles away at my fathers machine shop though ! i took my vernier caliper and went around the house measuring a bunch of paper clips and saftey pins til i found a pin that was exactly .74mm just about 2 jet sizes larger, right where i wanted it to be, so i reamed it out with that and its around a .72 or .73mm jet now as the pin still fits a little snug so its a lil smaller. if i need more i will go back and ream it out some more with the same pin till it slides through easyer

something to think of if your in a pinch and are running lean and you dont have any micro bits around, just use a small saftey pin ! be shure to measure it with a micrometer or vernier first !

here are the other 2 filters i used,
the large white brigs and straton one ran the best it flowed quite well and there was only minor 4 stroking when not under any load top end was good but plug showed a little lean at high rpms
the orange brigs and straton one caused a lot of 4 stroking, especialy at the midrange and off idle but was useable in a pinch and the top end was perfect
the new SBP 90 deg filter flows with no restriction i can feel by blowing through it in and out unlike the other 2 where i can feel the restriction with my breath.

i didnt think changing to a high flow filter could warrent sutch a major change in jetting like this but but hey when i cleanned out the carb i found nothing blocking anything and the whole inside was spotless that i could tell. also removed the gasket and though it is over compressed and sort of flat from use, it does not seem to be leaking and i forgot that i used gell lock tight type super glue to seal all around the carb flange and plastic spacer ring so there was no leak there. if there are no leaks and there was nothing in the carb than the main jet must be too small right ?

just incase it was leaking, i am making a new intake gasket anyway out of thick 1.6mm gasket paper, this one will be a lot better port matched to the jug and manifold
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http://motorbicycling.com/showthread...485#post528485

Last edited by rogergendron1; 12-31-2013 at 11:12 AM.
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  #6715  
Old 12-31-2013, 01:20 PM
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Default Re: what did you do to your motorized bicycle today?

"i have pleanty of micro drills .......................... they are in new hampshire 75 miles away at my fathers machine shop though!"

And for $10 you can have the right tools for the job where your at now so that you can fix the problem you're having since you are 75 miles from Dads shop .........

If the safety pin does the trick for ya thats great and it served the purpose you needed it for, just trying to help out with the links.

Map
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  #6716  
Old 12-31-2013, 03:12 PM
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Default Re: what did you do to your motorized bicycle today?

Just finished my remade 'Frankenstein II' exhaust. Haven't run it yet, but should sound the same as 'Frankenstein I'............it should......



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  #6717  
Old 12-31-2013, 03:20 PM
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Default Re: what did you do to your motorized bicycle today?

now i am realy confused.....

so the carb is perfectly clean and the main jet is 2 sizes bigger 70 to a 74mm and there are no air leaks what so ever !

yet i am still having the problem ! only now its at around 3/4 to WOT i bog right out and sputter as if there is no enough fuel or i am loosing spark or something.

i forgot to mention that i am running nearly 13:1 comp and i fuelled up my bike before i set it for the weekend ..... soo i suspect i got ripped off and given 87 oct instead of 93 ! that would explain the tottal change of tone in the motor to the sharper tone like its being forced harder and also detonation gets worse the higher up the rpm range you go soo..... i am going to drain my gas and put new gas in that i know is 93 oct and see whats up. i suspect 87 oct run at 13:1 comp can not be good at all !!! lol

another thing it could be is my plug.... i am running a brand new plug but its a (R) resistor type nkg br6hs i am not shure if that could be the problem but i am going to swap back to a non resistor instead to see if it helps.

before i set it for the weekend it ran perfect ! i am stumped but since the last thing i did before leaving it was fuel it up, i am leanning heavivly torwds the fuel ! i think i got ripped off at the pump ....AGAIN ! this has happend before !
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http://motorbicycling.com/showthread...485#post528485

Last edited by rogergendron1; 12-31-2013 at 03:24 PM.
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  #6718  
Old 12-31-2013, 03:52 PM
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Default Re: what did you do to your motorized bicycle today?

I hope that will cure your problem, wow 13/1 is getting up there on these engines. Mine is so low I think it would run just fine on kerosene!,

P.s. I went out to ride the cranbrook that I seldom ride only to find a flat front tire, at least it wasn't the back again. Patched the tube till I can replace it with a good one and off I went, met the new neighbors walking their dogs and found out they ride bikes as well. He told me he picked up two worksmans at a deal , I espressed intrest so he may sell me one for my next project.
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Last edited by Greg58; 12-31-2013 at 04:02 PM.
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  #6719  
Old 12-31-2013, 09:09 PM
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Default Re: what did you do to your motorized bicycle today?

Guess I just wimped out on soldering and drilling the jets.....just ordered an assortment from Pablo. It's time to start getting every bit of performance that my bike has to offer.
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  #6720  
Old 12-31-2013, 10:47 PM
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Default Re: what did you do to your motorized bicycle today?

Today I rode my motorbike to the Autoparts store to buy parts to fix my car!
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