Help gsx400 flywheel on gsxr250r gj73a and other problems Now Running with Video :)

Possibly get away with your old exhaust gaskets and re use..but for their cost I'd go new..part no is 14181-35600..if you've not removed your existing exhaust then I'd use the time wisely and spray all the studs with penetrant - will hopefully mean they come undone fine when you come to do it. Also loosen the cam cover as it'll likely be stuck on at the junction of the two water pipes - same again and use heat if you encounter problems. Cam cover gasket is rubber and reuseable. Head gasket is the same on 73a/74a/75a etc - part no 11141-06C00 or 11141-06C01. On closer inspection that engine (the new one) has a few broken exhaust studs but if its genuine 5K miles then I wouldn't be to concerned over wear and the bottom end so long as there's not been any water ingress. Check obviously for wear in the bores when the head is off before reassembly. On closer inspection that engine is actually from a very rare in the UK GSF 250V (GJ77a)..not sure why the description says 74a (?) but its basically the same but uses VVT for the cams - suzuki's version of variable valve timing and is 1995- I've only done the standard swop with 74a onto 73a and vice versa - not a VVT (77a one) but its likely you'll need to block off the oil actuator pump supply feed (the hole in the crankcase that supplies the oil actuator in the head) and look at transfering over your signal generator in addition. Not too much work but definitely an easier swop would be a 74a crankcase as suggested..here's another picture of the exact engine you need again warranted - its doesnt look as good as the 5K mile one and is a bit batttered and bruised but it does say warranted and they do refund exchange - 16000 miles or so the ad says. I cant see as it makes heaps of difference lol but just thought I'd make you aware as you dont need any more headaches by the sounds of things!!!! Link is Suzuki GSF250L GSF250 L Bandit GJ74A 1989-97 Engine Motor J705-125015 & Warranty | eBay. Dont be afraid of the work as its not hard you just need to be methodical - if you've done a 2T rebuild then I wouldnt worry - just a few more parts

 

Its not a thread but this is about where your at..

-remove tank
-disconnect battery
-remove plastics
-remove airbox
-remove carbs
-drain coolant
-remove radiator (required for access)
-remove coils(access)
-remove signal generator cover (timing)
-remove exhaust..
-loosen cam cover, remove.
-mark timing, loosen cam caps
-remove cams
-remove head (dont forget there is one bolt externally that goes upwards from the block to the head)
-remove block if needed

It should now look something like this...

 

I'd go for the one thats less worn if it was me buddy..whichever one it was..but I can see the merits of the easier swap if you've not done one before - wouldnt worry about any issues with the seller as that's a 77a engine and not a 74a so its misadvertised if you want to change..the other one is it comes with the starter motor and the other doesn't..the starter splines are different but I'm just thinking along the lines that you've not done anything like this before and easier may be better That sounds bad but its not meant to be..I know you just want it up and running!!!!!

 

A full engine rebuild is pretty expensive..liners are £550 a set but I know a company who can now do them to order, piston set OEM std bore (4x pistons,pins,ring sets) £390 delivered, £70 gaskets but you'll still need the bottom end to put them on due to the flywheel..that's without the head/carbs..if that engines good and compression is as it should be I'd hit the buy it now!!!! days work and your away you seen this fzr FZR 250 PURE SPORTS - JUST 6,500 MILES FROM NEW LAST OWNER 20 YEARS - SUPERB | eBay ..thats about 10K AUS..prices are on the up again..me thinks you'll get your money back whatever you spend providing it runs as it should

 

Hiya pal - a few questions there - but good to do the research now instead of later Yep the engines are slightly different - I've only ever worked on one 77a engine - there that rare in the UK that I've never been able to cannibalise one for parts!!! I believe you'll be able to use the crank/flywheel/stator/generator casing/barrels and pistons (all the unknown elements or broken bits on yours). I know the starters are different/sump/flywheel/carbs/engine mounts - but looking at it it could be done - fairly easily I think.
I've always looked at the early bandit engine as being the one to go for as its literally bolt on - I've done the 73a top end onto a 74a bottom several times and a 74a head onto a 73a bottom end -not likely you'll do that now as there's no 250GSXR 73a bottom ends left now due to the flywheel issues lol parts list you'll need is the one I listed earlier.
As to which to go for engine wise I'm unsure - the 77a one at those low miles should be a peach inside, but alarm bells ring as its had the engine number ground off, almost certainly why its misdescribed as a 74a and not a 77a engine. Makes you think if the mileage is really as quoted. Not trying to put you off but there things I'd look at. The other one is higher miles but you will literally be able to bolt it in as is if need be (check the sump and starter motor differences quoted earlier). I'd still pull the head and check whats inside as per the bore issue but you could just take a chance and bolt it straight on..likely at 16000 miles (again if thats correct as half of what you buy isn't whats described) it'll benefit from new rings but there's a chance it could just go from the off!

Used engine buying guide in an ideal world if you want to bolt it on and go (parts engines are another matter....):

Hear it running
Hear it start hot/cold
Hear it idle
See it hold temperature
Check compression
Check engine number
Check its the owners to sell

If the above checks out you have a good serviceable unit. Not sure if any of the sellers have compression readings but i'd ask. Midway through another rebuild too..delays with parts due to covid slowing things down but patience is a virtue

 

Dimples on the clutch cover are the giveaway of an early 74a engine..that part came over from the 73a direct lol..suzuki knew the issue with the flywheel and modified it but your 'new' (?) engine has one in situ..check it before you buy as although I know there easier to get hold of..there not that easy in the UK (more cost). What I'm pointing out is you have a problem and need a best fix - make sure you have the fix in what you purchase.. Also its not as bad a problem but it wasn't actually fixed until the magnets were replaced with one piece magnetic rings about six years later in the suzuki model range..check the magnets for a white line in the middle..I'll see if i can get a photo up..that's the precursor before they snap in two and go astray. The 'new' 74a engine will go straight in, head bolts will line up and the mounting points. Sumps may or may not be different based on engine number. Swap yours over if the new is different. Cranks are slightly different but will work the same (73a is lighter)- basically keep the whole bottom end. Block/pistons are the same, head gasket too. The previous 77a engine is slightly lower compression (11.7 or 11.8:1 as opposed to 12.5:1) if memory serves me right..the difference is in the gasket thickness (head/base)..it was to reduce the peak down to 40hp and fatten out the torque curve..just check the starter motor splines if you need to swap over..this caught me out once as the early and later variants are different..me thinks suzuki were using up surplus stock..same part number though!!