GN250 Engine Swap / Help

[Trader]

Hi,
I have a 1984 GN250, making bad engine noises, sounds like piston slap but no smoke and it still runs, so I think the valves etc are OK, the guy I got it from changed the camchain but that didn't help so I am looking at the rockers and top end, it might be the crank or big end but don't know how to tell without pulling it apart, plus I will check to make sure he did the chain right. In case the engine is knackered (46,000kms) I was looking for a way to revive it with a different engine, so anybody know what fits in the frame? I read DR350 or NZ250 might plus the GN400 barrels and new head might fit on the 250 bottom end, but I am not too sure. Has anyone changed the engine before or have any advice. (none of the blah blah blah buy another bike GNs are crap stick a turbo on it buy an R1 instead comments please, I have an FJ1200 and a Sportster too but need a cheap to run bike for work so this is it...hopefully!)
Thanks
Chris

[Squiggles]

had same thing, mine spat the dummy... its either siezed or i blew the bottom end... is yours burnin a bit of oil?

early dr250 motors are the same as gn's i believe.... or at least parts of them are (such as the head)

[Deviant Esq]

Pretty sure no NZ250 parts are the same as GNs, so I don't think the NZ motor would bolt straight up. It'd prob fit in the frame easily enough as it's a compact enough motor... but I know from trying (and failing) to source parts for my NZ that they don't share components with anything else. Pain in the arse. Good little motor though, bit more revvy and better geared than the GN with a few more hp too, and impossible to overheat them. Great for commuting. LOL.

Sounds like it's running okay, just a bit noisy. I'd ride it until it goes bang (might last a while yet), then slap a new motor in it. Good luck!

[Trader]

Hi,
Pulled it apart today, the bottom bearing has gone, looks easy to fix but no real experience with GNs. The rest is luckilly looking good, head OK and cylinder only slightly scored (very lucky I think!)
Anyway the saga continues.
Any advice?

[Trader]

Where's the cheapest place to get spare parts from? My local Suzy dealer wants $300 for crank pin, bearing & con rod, $200 for piston & rings & $200 for a gasket kit, seems expensive to me but surely there is a kit you can buy?

[Steam]

Where's the cheapest place to get spare parts from? My local Suzy dealer wants $300 for crank pin, bearing & con rod, $200 for piston & rings & $200 for a gasket kit, seems expensive to me but surely there is a kit you can buy?

Wow expensive. Suppose it's all new Suzuki bits though. Sounds like you need a crashed bike to cannibalise for parts. You see them often enough on Trademe.

[xwhatsit]

Wow that is seriously expensive. My CB250RS is a similarly simple design, and was nowhere near as bad as that. When I blew mine and wasn't sure what was wrong, this man http://www.kiwibiker.co.nz/forums/member.php?u=1522 named TonyB said to send him a PM, as he said

I can do piston kits, conrods, big and small end bearings and crank pins. All seriously cheap.

. Might be worth asking him? Maybe it was just Hondas he was talking about, or XR250s. Seems more likely now I think about it.

Pity there's no Econosuzuki, like there is an Econohonda.

[jeremysprite]

You could try putting volty engine in

[Bonez]

A 350 Goose engine could be the go too.

[Trader]

Thanks for the suggestions, the poor old GN is looking a bit sad in the bottom end, all the race bearings have gone too, so there must be a pretty bad oil supply problem somewhere. The LHS crank case has had some epoxy-metal plugged into a suspect looking oil feed so I'll grind that out and have a look at getting it welded. Anyone know how to get the bloody crank apart ?!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I've knocked six bells out of it and it won't shift!

Just a word of advice... never trust anyone you are buying anything off!

The bastard I got this from swore nothing had ever happened to this bike and it was probably just a tappet / cam chain tensioner problem. ha ha ! Luckily I pulled it apart before it seized eh?

Thanks again, I have a lead on another engine from a wrecker in Sydney, so if this one is a gonner I'll part it out on e-bay and stick the new one in.

Cheers

Chris