gn400 revs

[spooky]

Right, gn400 that i just got starts easily, but when i ride it, it runs ok ish to 4000rpm then everything happens and it goes like billyo, before i look at anything, is it likely to be fuel or ignition,  ?  any  suggestions

[themoudie]

Aye Rufus,

IMHO have a look at the air filter and then the carb, sounds as though either the air filter and or the pilot jet and maybe the needle jet are gummed up or partially obstructed. A new iridium spark plug wouldn't do any harm either, if you can stretch to it. All the best and good health.
My regards, Bill

[spooky]

thanks bill, cleaned air filter, it was a bit dirty, think it`s time to take carb of and give it a bath, plug looks ok, maybe santa can afford an iridium plug when he gets paid.. the bike hadn`t run since 1996 so carb probably is the culprit.

[johnr]

gn400 ignition is fixed with no mechanical advance retard unit, so it either runs or it doesnt. the sp engine of which this is a derivative has points on the head with a mechanical adv ret unit, but the gn doesnt, meaning that youre looking at the carb. assuming the fuel is fresh and its got a decent spark plug, id give the carb a strip and clean first before altering anything.
i had a gn engine in a little trail bike frame once, and i fitted the flatslide cv carb off a klr600 to it. the bloody thing went likee a scalded cat afterwards!

[johnr]

just thought id mention. theres a gn400 just come up for sale on ebay, its listed as a barn find and looks pretty grotty, but its all thre. at thee moment its at 250 quid and is in clitheroe.

[spooky]

Thanks John spotted that and Bill sent me a link as well..

[johnr]

well its not a million miles from me so if you need someone to pick it up and store it whilst you sort transport, im only a few miles away.