up jeting my 83 nu 50

i have a 1983 honda nu50, i bought a DR 70cc kit, i havent put it on because i dont know about getting it enough fuel, i orderd a new main jet,an 85, i beleave the factory one is a 75, has anyone else done this before ? any help ill take, im wondering about oil too

Re: up jeting my 83 nu 50

best way is to just replace the stock carb and get rid of the oil injection and auto choke systems.

you should at least ditche the oil injection with a kitted bike because it will draw air and cavitate and sieze the bike, this means you'll be running premix from now on. most hobbits with with a DR and a proma run a 90-92 jet

Re: up jeting my 83 nu 50

stock is 85, ebay some micro drill bits, like .9mm & .95mm. try .9 if running just the kit, .95 with pipe & kit, assuming you're still using stock airbox. hobbit stock size is 78, so the sizes above are a bit small.

Re: up jeting my 83 nu 50

Welcome to the internet, I am in for some videos of you putting on your shoes or eating some dinner.

Re: up jeting my 83 nu 50

The thing you can't compare is that the hobbit and express carbs are of a completely different type. One is a slide carb and the other uses a butterfly. Aside from that they are both Keihin and use the same jet sizing designations and so you can use as a rough guideline the size increase based on fuel need.

Say a 78 to a 92 would be the same increase (fuel delivery amount) as an 85 to a ~98. The difference again is that the air boxes are different and the carb is more or less efficient at delivering fuel. They really can't accurately be compared.

If the stock is 85 I would start at a 95 if they are available and work from there.

Also the ignorant remark about the oil pump having cavitation is ridiculous when you realize that it is pumping oil that does not contain air, the pump does not use an impeller of any sort to create cavitation and unless the tank were to run empty or the lines removed and not properly bled after install it is impossible to draw air. The stock oil injection does pump rich but is well made and uses quality hardened parts. The only thing dangerous about it is the mechanic screwing with it. The autochoke works pretty well when clean and properly connected also.

Re: up jeting my 83 nu 50

yea for keeping the stock carb, use jet drills (or welding tip files) to slowly jet higher until you find the right size. agreed tho much better and easier to get a whole new carb/intake setup and jet properly

Re: up jeting my 83 nu 50

weakends intake and vm20. set up was EZ

Re: up jeting my 83 nu 50

I read somewhere.... that the stock was an 85 on the 83 nu50. I put in a 90 and I feel good. It gave my nu a way more consistent acceleration but didn't add much top end.

Re: up jeting my 83 nu 50

Stock is an 85. If you simply stuck a 90 in a stock bike you are an idiot. The bike was rich off the factory floor but more importantly was tuned well within a safety margin. "More consistent" is likely a soggier response. If you put a cylinder on and stuck a bigger jet in without doing even a plug chop, still idiot.

You are also pulling up a completely dead thread.

Re: up jeting my 83 nu 50

from my experience using the stock carb with the DR70cc; a 90-95 jet is some where in the ballpark. remove the oils injection pump and block off the port with a freeze plug or something similar. the oil injection pump is actually good quality , the failure point IN MOST CASES (on Honda) is not the pump at all, it is having sludge or junk from the oil tank restricting flow to the pump or jamming it up. if you choose to keep the oil pump installed you will have to mix some supplemental oil to the gas due to the increase in surface area of the piston and cylinder at this point im just spitting back info i have read in the past but from my experience i had sized my stock top end due to inandaqit lubrication due to some fault in the lubrication system so no i run 32:1 and i have removed and blocked off the oil pump hole/ port with a freeze plug.

short answer: run a 95 jet if you are not 100% sure what you are doing, its best to be on the safe side. remove oil pump and run 32:1

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