Welcome back to me - first bike problem :)

[crashalots]

Hi all - old member here. Just bought another bike after about 11 years with no road bike :eek:

I'm an engineer so I do enjoy the maintenance slightly more than the riding... so I've picked up a clapped out GSX400E to convert to a cafe style.

My question is generic about engine troubleshooting:

The engine isn't running and the seller said, quote: "it started getting harder to start, until finally i could only get it running via crash-start rolling down a hill, then eventually nothing. I did a compression test and was low compression. Pulled head off to investigate and nothing obvious. Gave up."

So the head and everything was on finger tight and I've re-disassembled and confirmed so far nothing obvious is wrong. I'm also going to remove the cylinder today and check piston rings, and do a water tightness test on the valves.

My challenge is, I want to get the engine assembled first and get her running so I can isolate all faults and price up the project (for all I know he tested compression wrong and has disassembled the engine for no reason. Might actually be a fuel or ignition issue?!)

What I don't want is to pay for an entire gasket kit and use it for 5 minutes to reveal noisy gearbox bearings etc, only to disassemble it again.

1: Would it run OK with the old head gasket for testing?
2: Should I maybe just gasket-glue the old gaskets for testing?
3: Should I bite the bullet and pay for a set, knowing I'll disassemble it soon to paint the motor anyway?

Im leaning towards 2... $20 tube of CRC gasket...

[Bonez]

These and especially the GSX250s can be prone cracking between the valves. Yeal just for a quick test I see no reason not to use the old head gasket if it isn;t damaged. Did that on my GSX750EX. Don't use gasket material on it's own.

Stale laquered fuel in the carbs is one thing to watch for on a bike that's been out of commision for a while.

Reg/Rect units are notorious for going on this era Suzuki and as well alternator windings in some cases.

What you describe happening to the previous owner could well be just the battery getting so flat it couldn't provide enough spark. This happened twice to me on my cb550 until I replace the rectifirer then later reg and rect with an after market solid state set up.

[crashalots]

These and especially the GSX250s can be prone cracking between the valves. Yeal just for a quick test I see no reason not to use the old head gasket if it isn;t damaged. Did that on my GSX750EX. Don't use gasket material on it's own.

Stale laquered fuel in the carbs is one thing to watch for on a bike that's been out of commision for a while.

Reg/Rect units are notorious for going on this era Suzuki and as well alternator windings in some cases.

What you describe happening to the previous owner could well be just the battery getting so flat it couldn't provide enough spark. This happened twice to me on my cb550 until I replace the rectifirer then later reg and rect with an after market solid state set up.Oh thanks thats interesting.

Scary thought that his compression test might've been low for the same sluggish battery issue ... that'll mean I got a free bike with nothing wrong with it (except it's in pieces [emoji23])

I'll be sure to check out the cracking around the valves. Cheers!

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[Blackbird]

Have you got a manual? I've got an soft copy (pdf) manual for a GSX 400 F. There will obviously be differences but a lot of common stuff too. You're welcome to a copy if it's any good to you.

Cheers,

Geoff

[F5 Dave]

Petrol test not water.

Reread Bonez post 3 more times, it is very likely. They killed battery, stator rectifier and then eventually cdi.

[jellywrestler]

Petrol test not water.

Reread Bonez post 3 more times, it is very likely. They killed battery, stator rectifier and then eventually cdi.

methlyated spirits is less smelly

[Bonez]

methlyated spirits is less smellyAlways wondered what was in that hip flask.

[crashalots]

Have you got a manual? I've got an soft copy (pdf) manual for a GSX 400 F. There will obviously be differences but a lot of common stuff too. You're welcome to a copy if it's any good to you.

Cheers,

Geoff

Thanks for the offer. I picked up a free Manual online for this model very easy.


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[FJRider]

Push starts and hill starts use no electrical power to get the engine spinning fast enough to light the fire in the cylinder.

Having said that ... low compression will not help either.

If you seriously want a reliable runner ... pull the Barrel off and hone the bore ... and put new rings in.

Top end rebuilds aren't that cheap, but reliability seldom is.

Get it starting and running before any other work gets done.

[F5 Dave]

Old GSXR400 ex gf bought wouldn't start. Been sitting ages. Towed it (dangerous if not careful) that got it going. A long thrash using low gears seemingly ungummed the rings .

Ran fine after that starting good, even dynod better than her other one.

[Bonez]

Old GSXR400 ex gf bought wouldn't start. Been sitting ages. Towed it (dangerous if not careful) that got it going. A long thrash using low gears seemingly ungummed the rings .
..Sounds more like off fuel/low speed jet bockage. Generally jappers can sit at least a decade without rings seizing.

[F5 Dave]

Thrashing it wouldn't have cleared blocked jets. But yes have played that game, actually worst case was choke ccts on a similar bike. Needed a 0.4mm drill bit from chole cct down tube and a further one in the float bowls. Very odd carbs.

[crashalots]

These and especially the GSX250s can be prone cracking between the valves. Yeal just for a quick test I see no reason not to use the old head gasket if it isn;t damaged. Did that on my GSX750EX. Don't use gasket material on it's own.

Stale laquered fuel in the carbs is one thing to watch for on a bike that's been out of commision for a while.

Reg/Rect units are notorious for going on this era Suzuki and as well alternator windings in some cases.

What you describe happening to the previous owner could well be just the battery getting so flat it couldn't provide enough spark. This happened twice to me on my cb550 until I replace the rectifirer then later reg and rect with an after market solid state set up.

Turns out the head is cracked...

Just got a quote for $1000 to weld up the head and reinsert the valve seats. Steep.

Any ideas for remedying this cracking other than a full weld and machining?
Any repair shops who would specialise in this?


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[F5 Dave]

Wrecker for engine or parts. At some point very quickly you could over capitalise a GSX400. Keep that in mind. How much can I sell a good one for? How much will I actually spend? At some point even working for free it might be sell it on as spares and save for something else. It's what the last guy did, just more dishonest in description by the sounds.

[Bonez]

As above. Wrecker. That's what I did when I reconditioned the CB550s donk. The rocker box was worn and the engineer I took it said I wasn't worth welding it up.

A grand is way over the top though.

[Laava]

Turns out the head is cracked...

Just got a quote for $1000 to weld up the head and reinsert the valve seats. Steep.

Any ideas for remedying this cracking other than a full weld and machining?
Any repair shops who would specialise in this?


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Cobble it back together and sell as a parts bike.
use this money and what you would have to spend on repairs to buy something decent.
Something you can test ride before you buy.
that is, unless you really want a project?

[F5 Dave]

On reflection it would be hard to find at a wrecker, they likely would have weighed it in if it hadn't sold by now.

[crashalots]

Cobble it back together and sell as a parts bike.
use this money and what you would have to spend on repairs to buy something decent.
Something you can test ride before you buy.
that is, unless you really want a project?

Yeah im strangely captured by these old GSX’s

It’s definitely intended to be a project, but I’m being careful not to spend too much on it.
Got the bike for the cost of the registration outstanding and keen to fix it up for under $1000


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[Bonez]

An optoin might be a GS400 head and pistons. Or bore out the sleeves out and fit a GS450 head and pistons.

[F5 Dave]

They were 2 valvers and even older. That would be a hybrid of uncertainty.

[Bonez]

The GS450 is AFTER the GSX400. They ALL share the SAME bottem end.The GSX400 share the same frame etc as the GS450'

[F5 Dave]

The 450 was an over bored 425 I believe, not sure if I've seen one here, itself derived from the 400. Yes the 500, both 400s and 450 and 425 all look like the same bottom end. Maybe you can swap them, are you sure this has been done or could you run foul of some innocuous change like a tensioner runner change, oiling hole etc? You'd want to be sure people have done it.

You're getting very preachy Bones. Do you need a coffee?

[Bonez]

No sleep last night. Insomnia damnit. I'll take a little blue bill tonight. Better mood tomorrow hopefully.

[crashalots]

Bottom line is... While I’d love a GS450 mod which would make it a cool and one-of-a-kind build, I just want to get the GSX running with minimal effort and cruise on her on the weekends.

I’ve found 2 replacement heads so far and both of those were cracked too.

I’m going to pursue getting my cracks TIG’d up by a friend for some beers (he’s a certified welder but not a machinist), and then go to the reconditioning shop only to reset the 4 valve seats. That should save some money.


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[husaberg]

Bottom line is... While I’d love a GS450 mod which would make it a cool and one-of-a-kind build, I just want to get the GSX running with minimal effort and cruise on her on the weekends.

I’ve found 2 replacement heads so far and both of those were cracked too.

I’m going to pursue getting my cracks TIG’d up by a friend for some beers (he’s a certified welder but not a machinist), and then go to the reconditioning shop only to reset the 4 valve seats. That should save some money.


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Talk to Grumph hes played with a few.
https://www.kiwibiker.co.nz/forums/member.php/29978-Grumph

[F5 Dave]

No sleep last night. Insomnia damnit. I'll take a little blue bill tonight. Better mood tomorrow hopefully.

Have you tried podcasts? If they don't send you to sleep at least you get entertained.

[crashalots]

Talk to Grumph hes played with a few.
https://www.kiwibiker.co.nz/forums/member.php/29978-Grumph

Yeah I messaged him on Grumphv2
He knew exactly what I was faced with. He guessed - correctly - that I’d struggle to find an uncracked head.

He also felt there was little value in spending too much time or money on a GSX, hence why I’m keen to remedy it as cheaply as possible [emoji58]


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[Bonez]

Have you tried podcasts? If they don't send you to sleep at least you get entertained.Good idea. Thanks.

[Grumph]

Yeah I messaged him on Grumphv2
He knew exactly what I was faced with. He guessed - correctly - that I’d struggle to find an uncracked head.

He also felt there was little value in spending too much time or money on a GSX, hence why I’m keen to remedy it as cheaply as possible [emoji58]


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Lotta bullshit being taken as gospel on this thread.

Motors - the GS400 and 425 have roller bearing cranks - not interchangeable with 450/GSX400. The GS450 and GSX400 have plain bearing cranks - dimensionally identical and interchangeable.
The GR650 has pretty much the same plain bearing crank and it can be swapped in - or the 650 top end put on a plain bearing bettom end.
the GR does use a morse camchain which involves swapping cam sprockets to suit whichever crank you use.
The 450 top end - or the GR650 top end can be put on your GSX400 cases. Machining required. GSX750 pistons can be used in a GSX400 with a 1.25mm barrel spacer.
Simply having your mate weld the head is likely to produce more problems. As I've told you, the right way is machine all the ex seats out, weld up EVERYTHING remachine and fit new seats. Retap plugs smaller - usually 10mm.
Welding the visible cracks is likely to loosen the inserts. Wasted time IMO

Heads from overseas are possible. Aussie and Canada got them new. Some did get to the UK.

[Grumph]

Site won't let me edit a post.

What i forgot to mention is that a GS500 top end will go on your cases. They're a big bore slightly restyled 450 and use the same bottom end - but again a morse camchain.
Whole 500 engine would drop in I think.

[crashalots]

Lotta bullshit being taken as gospel on this thread.

Motors - the GS400 and 425 have roller bearing cranks - not interchangeable with 450/GSX400. The GS450 and GSX400 have plain bearing cranks - dimensionally identical and interchangeable.
The GR650 has pretty much the same plain bearing crank and it can be swapped in - or the 650 top end put on a plain bearing bettom end.
the GR does use a morse camchain which involves swapping cam sprockets to suit whichever crank you use.
The 450 top end - or the GR650 top end can be put on your GSX400 cases. Machining required. GSX750 pistons can be used in a GSX400 with a 1.25mm barrel spacer.
Simply having your mate weld the head is likely to produce more problems. As I've told you, the right way is machine all the ex seats out, weld up EVERYTHING remachine and fit new seats. Retap plugs smaller - usually 10mm.
Welding the visible cracks is likely to loosen the inserts. Wasted time IMO

Heads from overseas are possible. Aussie and Canada got them new. Some did get to the UK.

Im not in a position to argue against bullshit when we’re talking engine and head combos. I’m not experienced nor am I interested in making a Frankenstein GSX at this stage.

To clarify on your assumption, I’m not talking about doing a half-measure weld job ... my friend is a certified aeronautical TIG welder and would do a full depth reconstruction of the cracked areas.
His workshop is just not set up to redo the machining and re-inserting the valve seats. For that, I’ll take the welded head into the machinist. Pretty sure that’ll reduce the cost significantly.

Ive searched and inquired around NZ and Europe for a replacement head. Only 2 hits so far:
1 in Chc looks like it’s been home-welded with a MIG.
1 in Germany has same cracks.

I’ll inquire across the ditch just in case...


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[Laava]

That crack issue, on every machine, would be enough to put me off altogether. The best welding job you can get will not restore the head to as new condition, and then, well, they tend to crack by the sound of things. Do what Grumph suggested and put a whole new 500 motor in there or get shot of it IMO.

[crashalots]

That crack issue, on every machine, would be enough to put me off altogether. The best welding job you can get will not restore the head to as new condition, and then, well, they tend to crack by the sound of things. Do what Grumph suggested and put a whole new 500 motor in there or get shot of it IMO.

Yeah I’ve got “giving up” firmly tucked up my sleeve depending on a resolution of this head issue. It might be a wise direction to take...

I might make an observation though - and @grumph might say this is a BS theory - but my bike was running a Yoshimira 2into1 shorty pipe and I bet she wasn’t jetted. Thus, I might question if leaning the engine can add to/cause the issue?

I’m not sure if you can apply this theory to every cracked head though...

My colleague has my identical bike (a 1986 GSX400E) and he’s done 190k on it since buying new.
Never had a single issue on it.




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[Bonez]

Mum had a high km GSX250 which I understand were more prone than the 400. Which the 400 being more ore less half a GSX750 which
I owned two of over the years. First an EZ from new then an EX I bought off my brother who was short of cash. I had a burnt out exhaust valve on one at about 50,000kms and that was the only engine issue I had.

[crashalots]

Found a mint head out of Aussie for $150.

She’s going to be a beauty [emoji3526][emoji3526][emoji3526]


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[Bonez]

Well done.