GN 250 shed rebuild

[General-Lee 0]

Hey guys, thought I'd show you my current project. A 1996 Suzuki GN 250, It's the purple bike in my Avatar, or was.

So far it's all been sand blasted, powder coated. Nuts and Bolts all replaced with Stainless steel, Carbon steel and of course, nylocks.

Pistons been cleaned using paraffin and a sonic jewellery cleaner (real handy kit).

Hardest part so far was the petrol tank, the original tank was full of rust and dented, and I don't like making life easy so I decided I wanted a BIG tank, A GZ marauder tank. Took two brackets to do it.

Anyway heres some photos






So although GNs are renowned for being trollop I've tried to spruce it up a bit, what do you guys reckon?

[dick65 0]

always good to have a large tank,colour looks nicer

[RichardH 0]

Blimey, that's a bright frame

[General-Lee 0]

Cheers guys, hehe yeah a lot of folk have commented on the frame colour. To be honest I gave it to the powder coating guy and said "do it in the brightest red you have", to which it came back "s**t-box red" (That is it's actual name apparently)

[madsod 0]

ITCHY wrote:

Blimey, that's a bright frame

all most a bright as mine , nice work by the way

[trebor4460 0]

doing a great job buddy, looking good.

[lee1 1]

[Stue11 0]

Bright is good i like, keep us updated and plenty of pics, thanks for sharing em

[Chadatious 0]

oooh very bright, still looked good, and different. i like different

[General-Lee 0]

I'm glad you like it, I love different. I'm one of those sorts who prefer something other than standard.

Update: Today I've had a go at grinding an exhaust valve in. Now it has 4 Valves, 3 of which have ground in nicely bearing in mind I bought a new set of valves in the first place. This one I did today is a nuisance, this was the 5th attempt to grind it, each time it looks lovely, nice shiny ring and same with the seating. But when I do the weep test it's leaked quite badly by the next morning. I'm hoping tomorrow it hasn't leaked, Touch wood ey.

[BanditMike 0]

Good work so far. Keep at it, and keep the pics coming

[General-Lee 0]

Got the handlebars... they are bigger than I thought

AH well, selling them on gumtree. I've got my eye on a set of keystone style bars.

Meanwhile the new valves we're giving me a lot of trouble grinding in, discovered in the end it was just because the plunger had perished. So bought a new one, tried again and finally getting somewhere. Although the pitting on the exhaust valve seat is scary, hoping I can grind it all back

[dick65 0]

thems ape hangers

[madwilly 0]

cracking job so far

[Stue11 0]

@madwilly wrote:

cracking job so far

[streetfighter 0]

Nice one keep the pics coming

[General-Lee 0]

Hey guys, ain't been on for a while, been busy as hell with this build.

FINALLY got it running! Slight issues though that I could use some help pin-pointing with. First off, before I ran the engine there was a small oil leak coming from one of the crank case bolts, just above the clutch housing, I assumed the gasket had had it so I replaced it. Seemed fine after that, once the bike was running straight away it started coming out the same spot. (My assumption is there's a blockage in the oil channel behind this bolt causing it to push oil out that way)

Secondly, the bike is burning a ton of oil, like it filled the whole street with blue smoke, absolutely reeks. I thought it might just be getting used to running after all it's the first time it's run in two years, but it isn't getting any better and the oil level is slowly going down. I'm hoping it isn't the piston rings, I can't bare to take it all apart again. Could it be related to the leak/blockage?

Anyway here's a vid of it in action :/

[Oldfart 0]

Looks like oil entering the cylinders but there are a number of things that you would need to know to make a diagnosis.

1. Did you overhaul the engine?
2. If so was it rebored/honed. Were just new rings fitted?
3. If just rings, were the rings gapped in the bores?
4. Oil leak appears as you say to be at top of clutch housing. This is above the centre line of the crank. Some engines have a restrictor which limits the oil to the cam and rocker gear. Has this been lost (if fitted). Will then cause excessive oil supply to top of engine with the result that the excess will flood down the valve guides and into the cylinders or exhaust tract.

This is just for starters

[General-Lee 0]

Thanks for your help, but you'll never guess what it was. Gasket hadn't been cut out right, it had covered up half a channel! Had to get scissors out and cut it out, must have changed the engine design over the years or something. Since I've done that it's stopped the leak, although it is still burning a fair bit of oil.

I did over haul the engine, no rebore or owt just cleaned the piston, new rings, new valves, new rocker arms. As for a restrictor I haven't got a clue, everything I took out went back in, I have no idea what an oil restrictor would look like?

Sometimes it seems to stop burning oil, then 5 minutes later it will start again.

[Oldfart 0]

Does the oil burning (blue smoke) occur after its been idling for a bit. If so thats oil going down the valve guides. Sometimes even new valves wont take up the wear. Did you have any valve stem seals to fit when you put new valves in?



An oil restrictor is a small (usually brass) plug with a smaller hole than the oil gallery. It limits oil flow to the top of some engines to stop over lubrication. not all engines have them as it can be achieved by other methods. So dont worry if you didnt find one.

Hope this answers some of your concerns.

(Spent 50 yrs dealing with engines so I've got a few bits of knowledge lol)

[General-Lee 0]

One more thing I've noticed, normally I'm used to bikes when they're running you can't see the oil level, obviously because it's being pumped around. When this thing runs the oil level appears half way, perhaps I've over filled it? Although I measured out 1300ml as it says on the sump. Perhaps it doesn't want that much.

If that's the case it may solve the smoking issue

[General-Lee 0]

It does the opposite,as soon as its switched on it coughs a great cloud out, then after a minutes it will clear, then when I give it some it starts coughing it up again.

I think this engine might not have a restrictor, or if it does I don't think I've found it. I did replace the valve stem seals

[Oldfart 0]

I'm getting the impression you may have possibly overfilled it. On startup the oil is what has settled on the piston crown. This can be due to a faulty valve stem seal or excessive oil on the cylinder walls. If its overfull the oil scraper rings cannot clear the excessive amount thats splashed on the walls. (they clear it by removing excess from the wall of the cylinder passing thro' slots or holes in the ring and then via holes in the ring groove and into the sump. The oil also carries a small amount of heat away from the piston skirt helping to cool.) Did you check the ring gaps in the cylinder before assembly and the fit of the ring in the ring groove. On worn engines the rings wear the ring lands so the rings float up and down in the grooves as the engine runs. This action turns the rings into 'mini oil pumps' forcing oil into the combustion chamber, hence the blue smoke when you 'give it some'

[Davehutch-hutchs 0]

well explained Den

[BanditMike 0]

I have no idea what he said, but it sounded like English

Respect for the knowledge

[General-Lee 0]

Thanks man, I'll try dropping the oil out and put some fresh in, not as much this time, see where it goes from there. The rings should be fine to my knowledge, they we're new, the gaps we're at alternative sides of the piston.

I didn't check the ring gaps. I'm not that experienced lol

[dick65 0]

loosen the sump plug gently and let some of the oil out but not all then top up as neccessary,bit fiddly but saves forking out on more oil

[Oldfart 0]

@dick65 wrote:

loosen the sump plug gently and let some of the oil out but not all then top up as neccessary,bit fiddly but saves forking out on more oil

Thats the way to do it (heard that said before somewhere) also check the oil level with the bike on both wheels on level ground, not on the centre stand

[General-Lee 0]

Thanks man, I'll try dropping the oil out and put some fresh in, not as much this time, see where it goes from there. The rings should be fine to my knowledge, they we're new, the gaps we're at alternative sides of the piston.

I didn't check the ring gaps. I'm not that experienced lol

[Oldfart 0]

If youre still in the proverbial SH1 to the power of T. I'm not that far away.

[General-Lee 0]

cheers man , ill give it a go after the weekend