NC21 Wont start after 1 year of staying

[demerdzhiev]

Hello, I'm new in the forum, my english can be bad but I am from bulgaria, sorry for that. So recently i bought this nc21 and the previous owner haven't ridden it for an year, so when i went to buy it, the bike was left without gas in it, when we filled it with gas somewhere from the carbs it started to leak, which was not unexpected, so we left it that way and he lowered the price for that reason. Last week i charged the battery made more thorough look at the bike and tried to start it, at first it didnt started at all, then it sputtered couple of times and fired up on 2 or 3 cylinders, but at one moment it started to leak gas from the exhaust and a loot of smoke came out and there was this booom bom , Ofcourse i stopped the engine immediately, stripped down the carbs, some of the float valves didnt hold up so i had to clean them and change the float height. Either way i had already stripped them down so i cleaned the jets and mounted them again. Now it wont start at all. The plugs give a spark, the cylinders have compresion i checked each of them. The strange thing is that if i pour a small amount of gas directly in the carbs after i removed the air box the bike starts immediately when i twist the trottle and in 2 seconds when it consumes the poured gas it dies. tried with choke on, with choke off, with trottle , without trottle

[Neosophist]

if you open the float bowl drain screw at the bottom one each carb does gasoline come out?

did you connect the vaccumn pipe from the fuel tap to the vaccum pipe again? withotu it fuel wont flow to the carburettor..

also when they are dry they take some times to fill up.. you have to crank it for about 5 seconds and wait a minute or two and try again

full choke / no throttle

[demerdzhiev]

Yes the float bowls are full, I have disconnected the tank and use alternative one, so no vaccum pipe.
And wait for them to fill.
The idle screws are at 2 turns out.
Is it possible the choke line to be blocked by junk from not working for a long time and leaving with gas?
+ I cant understand why, even when i fire it up by sipping gas through the air box it dies immediately after that, which leads me to the teory that the diaphragms are blocked too because the main jet is clean. They are moving when i lift them by hand but I dont know how light they should move.

[Neosophist]

i think you mean cv slide (diaphram) they only move up when the engine is revving.

if could have stale gas blokcing up the carb

i think you need to remove the carbs from engien and clean and service them.

there is a thread in the workshop section at the top called vfr carb guide.. there is some info and pcitures in there how to clean the nc30 carbs.. most of thsi applies to the nc21 carbs too.

[demerdzhiev]

I came to a similar conclusion so today i already removed the carbs from the engine, disassembled them completely which includes parting them four, removed all the rubber parts and plastics and sinked them in kerosene, i will leave them like that for couple of days, then clean them with new kerosene and hope for the best :D .

I came to another problem while disassembling them, one of the diaphrams had a hole, I guess it was stuck to the carb cover and when it moved it got ripped because there was a small amount of rubber on the cover. Any suggestions for repairing it because it is hard for me in bulgaria to find a new one.

[Neosophist]

you mean the CV diaphrams?

i dont think you can repair it but replace it. you can now get cheaper copy diaphrams online.

i wouldnt have adviced to spilt the carbs into separate pieces.. taking the float bowls off is enough.. if you split them into 4 pieces then you disturb all the o-rings between the carbs and they often leak when put back together so you may need to replace the o-rings on the pipes that link the fuel and air between carbs.

[demerdzhiev]

I watched a video where this dude repaired it with some kind of high temperature and oil resistant rubber sealer, its kind of glue/silicone and it looked quite good after that, still flexible.

I have said it wrong in the last post it is not kerosene but coresilin, i am not sure if its called that way in english or if it even exist in your country, its sort of a paint thinner but it is very strong.
I had to split them because there are some little parts from plastic/rubber that i am not sure are resistable to that thinner and was afraid they could decompose, after i clean them i will wet the o-rings with gasoline. Usually they leak until they get soaked in gas so i will do it before putting them and hope they wont leak.

[micpec]

one remark: paint thinner may be a too agressive fluid to use.

[demerdzhiev]

I have that in mind, but i have already done it with other carbs. Thats why i disassembled and separeted everything and removed the rubber and plastic parts before sinking them. When i find a new cv diaphram and assembly the carbs i will tell what was the result.

[Neosophist]

ok !

usually kerosene / parrafin is plenty strong enoguh to clean carbs, just use a high pressure airline to blow out the small passages