GN 400

[alice]

Hi all, new here. Thought I'd look in having been given the GN, a bike not much featured on this forum
This example has lived in a hedge for the last two years and will need plenty of tlc. I wonder if  it will be worth the effort or should I pass it on as a boat anchor

[SteveC#222]

You don't see many GN400's on the road these days. Nice bike, good strong engine and no major problems other than the ' Suzuki Disease' - crap regulators and occasionally generators and the fact they are 6 volt electric so lights tend to be a bit crap.  These problems can be fixed fairly easily. Otherwise a nice little bike. Not sure if anyone else in the club has one now but there are a couple of folks here who have owned them in the recent past.  If it's in good nick it's worth keeping. I had a GN250 and an SP370 ( The GN's dad) and enjoyed them both.

MANUAL

[alice]

Well that's encouraging, after the thaw I shall take a proper look. If the motor is fit, then the rest will follow.
Thanks for the info'

[tommy]

hi alice that gn might make a nice cafe racer with a bit of work check out ,custom bikes and cafe racers site ,there was one or two gn,s on there last time i looked .......tommy

[tommy]

sorry that web site is classic bikes and cafe racers

[alice]

Thank you Tommy, I shall take a peek

[guest7]

One of the club members made a lovely little GN-based mini custom a few years back, I'm sure Pat (Squirrel) will be along soon to tell all.



There's a bloke here in Cardiff who rags a rat GN everywhere. He specialises in backroad adventures, getting as far off the beaten track as he can get. He's been using the bike for years and I've seen him many times belting back from the Dragon Rally in February.

GC

[SteveC#222]

Or......




..now that is NICE!!

[alice]

Both those pic's are inspirational, along with a few others I have unearthed. Right now the GN is under one of three mounds of snow. BUT come the thaw!

[alice]

OK the snow has gone and I have started to walk around the GN and point and stare. It seems basicaly sound but will need a lot of time and effort'
Here's the next question :- Does anyone know if this motor needs a battery to excite the ignition? I'm guessing not since the loom has been hacked. So I'm pointing at the coil, anyone know a ballpark figure for resistance values?

Thanks

[cloggy]

 The DR400 and the SP400 are pretty much identical to the GN. There's a possibility of some gearbox parts not interchanging but that's about it
 The SP and GN vacuum carbs have very slight differences in jetting. If you run either without the airbox you'll have to drill out the main. About 1mm is the size as I recall. I've got a carb with the correct alteration going spare, though the diaphragm may be knackered by now.
 The electrics don't use the battery for the ignition, there are completely different circuits
 You can run 12 volts AC or DC with stuff from electrex world without changing the generator, but beware their website has some incorrect info.
 The DR400 slide carb won't work without it's airbox [single taper needle] but the SP370 carb will [double taper].
The GN uses a modded SP frame.
 Manuals for the SP400 are almost always on ebay and have a GN section
 Back in the very late 70's Vic Camp ran a racing school using modded SP370s. The bikes handle

[Dick Scratcher]

I hope that 'Take your litter home' sign was not in response to parking your bikes there. As an aside the wheel alignment of the bike on the left in the picture looks a little odd, not more-or-less central to the bike which tends to be the usual.
                                               Regards to all........Dick Scratcher.

[johnr]

The DR400 and the SP400 are pretty much identical to the GN. There's a possibility of some gearbox parts not interchanging but that's about it
 The SP and GN vacuum carbs have very slight differences in jetting. If you run either without the airbox you'll have to drill out the main. About 1mm is the size as I recall. I've got a carb with the correct alteration going spare, though the diaphragm may be knackered by now.
 The electrics don't use the battery for the ignition, there are completely different circuits
 You can run 12 volts AC or DC with stuff from electrex world without changing the generator, but beware their website has some incorrect info.
 The DR400 slide carb won't work without it's airbox [single taper needle] but the SP370 carb will [double taper].
The GN uses a modded SP frame.
 Manuals for the SP400 are almost always on ebay and have a GN section
 Back in the very late 70's Vic Camp ran a racing school using modded SP370s. The bikes handle

not quite accurate. the sp370/400 has points ignition with the points on the head, the gn has cdi type ignition which is self generating from a pickup on the flywheel. the gn will run without a battery, the sp wont.
i had an xl250 honda fitted with a gn400 motor running a straight through pipe and a kawasaki klr650 flatslide cv carb, it went like the clappers.

[alice]

Thanks fellas, great information. just a couple of degrees warmer and I'll get stuck in. The bikes previous owner gave me a  a wiring diagram, but if I can work with just the ignition circuit whilst I prove the motor it will save a lot of time short term.

[cloggy]

  I've owned an SP 400 since the 80s
The SP/DR370 has points. All the 400 motors run cdi. At the last count I had 5 assorted DR and SPs in bits, all 400 s and all interchangeable. Both of my MOTd DR's are running  SP400 engines; need I go on? For accurate info try

http://suzuki-thumpers.com/technical/

and then enter the discussion board There's loads of info on wiring, some of it even helpful.