running issue

[scubasteve]

hi,
looking for some advice with an issue im having on my 1993 nc30. Was out on the bike this weekend and all was well for the first 20 minutes or so when all of a sudden on a nice straight bit of road the bike cut out on me in top gear. I rolled to a stop and then tried starting it up again. No luck first few tries then all of a sudden it went. pulled away and by the time i changed into second it cut out again. Tried starting it, and again it took a few attempts but finally went and backfired. Went to pull away and as soon as it hit 3,000 revs just died. To cut a long story short i had to ride the bike home really slowly by putting the choke on and riding just using the clutch and the first 2 gears. As soon as i touch the throttle it just kills the engine. Had the fairings of today and checked for any loose connections on the battery e.t.c but nothing wrong there from what i can see. If anyone has suffered something similar or has any advice it would be much appreciated

[viper_biker]

First thing is to check the vacuum for the tank isn't either kinked or doved.

[Deviant400]

does the bike feel like its running out of fuel then die , if so then as viper said , i had similar experience once , once the bike was running for 20 mins or so it would just loose all power and struggle as if i was out of fuel, if the vac pipe is past it, by the time the engine has warmed up the vac pipe gets soft so any splits or holes will open up/become worse and could even collapse on itself hampering fuel flow to the carbs, also check the tank breather is not blocked this can cause flow problems , i bought a thick walled braided pipe and it fixed the prob , that would be the first thing id do if it was suspect fuel prob

[Neosophist]

As above.. Vaccum pipe or fuel tank breather.

[scubasteve]

Thanks guys, that's really helpful.

[scubasteve]

Bike doesn't feel like its running out of fuel then dying it just cuts out all of a sudden. At first I thought it might be electrical but when I took the fairings off the battery terminals feel tight and no obveous loose conections in the loom anywhere. As you've all stated I will check the vaccum pipe and breather first.

[VFRkieran]

TBH i think its worth replacing the fuel hoses anyway if you dont know how old they are. I had a similar problem looked at the vaccum hose and it seemed fine but thought id replace it anyway, problem sorted and it only cost about 6 quid from Rick o.

[Deviant400]

yep and at least you can rule them out and move on to the next thing ,carb strip clean (use cammo's guide for checking through the carbs) then you'll know the fueling side is in order , then possible electrics

guide here-----> viewtopic.php?f=24&t=14524

[scubasteve]

cheers guys, removed the fuel tank today and all looks ok with the vacuum pipe but like you say its probably best replacing it anyway. The breather pipe of the top of the tank is fine too, so looks ill have to take a look at the carbs. It was suggested to me that it could be the rectifier as these are a common fault but im not sure whether this would cause the problem im having as im a bit of a noobie with bikes

[Cammo]

It was suggested to me that it could be the rectifier as these are a common fault but im not sure whether this would cause the problem im having as im a bit of a noobie with bikes

Yes electrical faults are common on these bikes, all sorts of symptoms can show up with a dud system (some like you describe). The problems can be easily fixed for good though with the right parts.

You'll need to check over a few things with a multimeter, there's a guide on how to check the charging system here: http://www.400greybike.com/docs.htm