NC30 Wont start

[rabutcher]

Got my NC30 last April as a non runner for a project, got it running and had it running till last week.
Now when I go to start it to engine turns over but wont start, then it will blow a huge flame out the exhaust.

I’ve had the carbs of stripped cleaned with carb cleaner set float height. Spark plugs were replaced when I first got the bike. And it's not been ridden on the road yet.

Does anyone have any ideas to my problem?

Thanks for any info

Rob

[wullvfr]

the flame out the exhaust will be from unburnt fuel getting into the exhaust system.

check and see how well the spark plugs are sparking!!!!

the backfre would indicate that fuel is getting to the cylinders so that i don't think is the issue.

does the choke work correctly?

are you trying to start the bike using the proper technique,full choke no throttle?

you may have flloded the engine!!!!


william

[Cammo]

I would be betting also that it's flooded.

When the plugs get flooded there's diddley squat chance of them firing up. The plugs are very sensitive, you can flood them just by twisting the throttle a few times when the bike's not running.

Flooded plugs can sometimes be revived by putting them in a hot oven, but not always.

Otherwise stick in some new plugs and start it using the proper technique - Full choke, no throttle.

[mrfletch]

flooding an enigne isnt the end of the world, and i doubt it could even cause that much damage to a set of plugs. whip out the plugs and warm em up with either the oven when the leg iron aint watching or give em a quick blast with a blow torch. at the end of the day there sat in your engine getting pretty hot a tad more heat aint gonna do em harm

[rabutcher]

plug seem to spark fine, yeah i'm trying to start with choke and no throttle.

[mrfletch]

You say the spark is good and the back firing indicates your getting fuel, my only suggestion is to check over the components you have disturbed carbs plugs ht leads etc. Has the choke system been disturbed?

[Cammo]

plug seem to spark fine, yeah i'm trying to start with choke and no throttle.

Most of the time the flooded plugs will spark fine when out of the engine but don't have enough grunt under pressure to ignite the mix.

[matt_vfr]

Just had this exact problem on our cbr600f engine were using in a uni project... relatively new sparks which apppeared to work fine and it wouldnt start, then you take them out and they are covered in petrol and shit... clean em up and you get a great spark so put em back in and it wont start... repeat the cycle!!! Got a new set of sparks for it over the w/e and it fired up straight away!

When the cylinder is under pressure it takes more effort to get a spark, which wont happen if the plugs are at all shitty... after a few cranks the unburnt petrol builds up on the plugs and they become soggy and will never fire it up! Like has been said, get the plugs out, gently wire brush them to clean the crap off, stick em in a warm oven for 15 mins or so to evaporate off the shit inside them and try again, if that doesnt work get some new plugs!

Matt

[rabutcher]

well i took the plugs out yesterday cleaned them and adjusted the gap. put them back in today, it started as soon as i hit the starter, ran for a bit then died and didn't start again, so new plugs on order.

[mrfletch]

I wouldnt rush into buying a new set of plugs personaly. From a fault diagnosis point of veiw you have just proved that the spark plugs you have are fine. As you mentioned the bike was purchased as a none runner, any motorcycle will be tempremental when it comes to starting after being stood for a while. Id be patient and persevere with the plugs you have. If your engine is being flooded every time you will have the same result with the new set of plugs. How are the tappet gaps? If they are out the machine will be difficult to restart when hot