WE can't get her going & are at the end of our rope, need a pair of carbies to buy or try to rule them out. She's going to the scrap yard if we can't find the problem, shame cause she's a nice bike.
Since you're after a pair this would be a T or N model then? If it were an RS I'd have a carb to spare!
Nope. Looks like the CB250NA has VB30B carbs - http://www.cmsnl.com/honda-cb250na-1980-australia_model15819/partslist/E19.html#results Can't find anything on the 1980 CB250T carbs yet. I bought 3 carb kits that were for the wrong model while looking for the RS carb kit - probably for a CB250N or CB250T. I have two left - they might do for a rebuild?
Yes it's an 'n' model, they actually are a 'na' The only dodgy thing i've found in the carbies was that the washer & 'O' ring onone of the mixture screws was missing but I fitted another one & filed down a washer to fit. The problem is affecting both cylinders, thats why we went after an electrical fault but it all checked out so now we are back in the carbies but it's a problem common to both carbies. I keep thinking we are rebuilding them back the same way we found them, which all looks right & compares to all the diagrams. The bikes for my brother, he got his 'L's yesterday so you can imagine how excited he is to get on the road. Here's a possible scenario, it's like the bowl's are only filling partially & when revved it sucks them dry, but they should re fill & allow some fuel to get sucked up but once she starts dying it just stays like it, pull out the choke & up she goes. I'd love to try another set of carbs.
Have you done a flow test? Take bowls off the carbs and with a dish to catch the fuel, turn on the fuel tap and let run for 60 seconds. Then take fuel hose off and put into dish and run for same time. Compare the amounts of fuel and if vastly different then you have a blockage/restriction somewhere in the carb bodies. Try this also with any filters you may have in the line to carbs. Have you cleaned the fuel tap and the filter inside the tank? They could also be blocked.
I'm running fuel straight out of an old go kart tank/container, no restrictions there, fuel free flows out of the line, no taps or filters etc. I'll try a couple of clear fuel lines from the bowl drain thingoes, wind out the screws & see where the fuel in the bowls fills to, I'll see if I can work out a mark on the outside of the bowls. The floats aren't adjustable, theyre all moulded plastic & nothing to bend, I've had thoughts that the needles might be wrong if someones replaced them, maybe theyre too long & shutting off too early. As you can tell I'm stretching the imagination but that's where I am with it. It'll be something simple when it's found, just an adventure trying to find it. Thanks for the interest, keep on thinking, It's helpful. I'm building a new office & some serious sheds so I can let my hair down with these bikes, probably give me somewhere to sleep too when I'm in trouble & thats often. Got TV & Internet & maybe FOX too.
I get what you mean, I might try that, there could be a bit of crap still in the inlet maybe, I spent a lot of energy on the jets & all the other tiny little galleries in the carb body but never really concentrate on the inlet cause they are so large & they always seem clear.
Maybe useful to someone down the line, I figured out what was wrong, no air filter ! I got to the end of my rope & went to see the mechanics & he was straight onto it, bloody air filter. It crossed my mind but being more a car bush mechanic I didn't think it was so critical. I've spent hours & day's checking everything 10 times & it was so simple all the time. Too much air flow, too lean & upsets the lift of the slides. I tried a smart trick to check the CV carbies are lifting properly, good test if you suspect your rubbers are leaking, Hook them up to a vacuum cleaner, off the bike of course, & you can see it all before your eyes. Blue slip now & she's on the road. Happy days.
