1987 Suzuki Impulse GSX 400 X GK71E Restoration

[James Deuce]

Yeah, I know what the Impulse looks like Jim but wondered if the motor was the same. Don't have any knowledge at all about those small Suzuki motors. Never mind

The one you posted is a twin.

[T.W.R]

Yeah, I know what the Impulse looks like Jim but wondered if the motor was the same.

Impulse is a baby oil-boiler

[Blackbird]

The one you posted is a twin.

Have a closer look......

[James Deuce]

Have a closer look......

Can't won't let me expand the pics on KB anymore.

I take it that that's the air-cooled four then? Repulse is a SACS engine. Oil cooler and under piston oil jets.

[T.W.R]

Repulse is a SACS engine. Oil cooler and under piston oil jets.

So is a XN85 and it's air cooled

[James Deuce]

So is a XN85 and it's air cooled

Yeah, yeah.

[Blackbird]

Can't won't let me expand the pics on KB anymore.

I take it that that's the air-cooled four then? Repulse is a SACS engine. Oil cooler and under piston oil jets.

Yep, it's a 4 and sounded really sweet.

[T.W.R]

Yeah, yeah.

the XN85 is the grand daddy of the whole SACS family they had to do it because the 1st incarnations kept melting the pistons of the standard GS650 motor so they thickened the piston crowns & started the under piston oiling jets

[Grumph]

Yeah, I know what the Impulse looks like Jim but wondered if the motor was the same. Don't have any knowledge at all about those small Suzuki motors. Never mind

The GSX400 aircooled four was - along with the GSX750 - Suzuki's first family of 16V plain bearing motors. All that family suffer from lubrication faults - as in not enough and poor oilway design. When the GSXR came along they'd obviously found a man who knew how to lay out oil galleries properly and a source of big enough pumps...
Other than being a four and 400cc 16V, there's sfa in common with the later engines AFAIK. The Impulse followed the GSXR400 and both were as has been mentioned partially oil cooled. If someone who knows how, bleeds the cooling system they don't overheat.

[Blackbird]

The GSX400 aircooled four was - along with the GSX750 - Suzuki's first family of 16V plain bearing motors. All that family suffer from lubrication faults - as in not enough and poor oilway design. When the GSXR came along they'd obviously found a man who knew how to lay out oil galleries properly and a source of big enough pumps...
Other than being a four and 400cc 16V, there's sfa in common with the later engines AFAIK. The Impulse followed the GSXR400 and both were as has been mentioned partially oil cooled. If someone who knows how, bleeds the cooling system they don't overheat.

Always something to learn - thanks for that!

[OddDuck]

No sir this is my first restoration but I have some help. My brother is a panel beater and I have just started some part time work at a garage so have a couple of people that can help. Any advice would be appreciated as this is all new to me. I owned a repulse back in the day so this is purely a memory lane deal. Not so concerned about getting it perfect. I really would just like to ride one of these again.

OK, advice to follow, here's what you'll need:

1) Space, both working and storage for the bits that'll come off. 1 single car garage working space, 1 garage worth of shelving for bits. Stacking storage bins will do in a pinch. It's amazing how much the volume expands once the bike comes completely to bits.

2) Cash. You'll be buying tools, supplies etc... watch those dollars. Buy stuff after it's clear that you'll need it, not by guesswork in advance. My rule of thumb was first time, borrow or improvise, second time, just go get the right tool.

3) Lines of supply. Scout the local shops. What's there? When are they open? What can you get on-line and what are delivery times like? Can you buy a solution to a problem, instead of putting in crazy amounts of work? You will also need a reliable source for replacement parts. Some components will be stuffed and will need replacement.

4) Light. Lots and lots of working light. For some unknown reason Kiwis seem to like working in grungy caves... save yourself the eye strain, paint the workspace white, seal the floor if you can (wish I'd done mine), put lights in everywhere, take a weekend out from the resto and work on the workspace. White surroundings will bounce light into corners and keep contrast levels under control. Keeping things visible really reduces the fatigue.

5) Ziplock plastic bags (all sizes, lots of), marker pens and masking tape for labelling the bags too. Mechanical components that should be kept in oil (like engine innards) should be in the ziplocks. Oil-soaked rags will dry out after a while (six months to a year) and you'll come back to rusty camshafts.

6) A digital camera that you can use. I can't stress this enough: A camera which you can drive, that does what you want it to. You'll want to choose where it focuses, and what values it selects for exposure so that you can actually see what it's a picture of. I tend to avoid using flash (tried; too many problems with bounce off metal) and use a tripod and long exposures instead.

7) Internet, public library, people with experience.

8) A car. It pains me to say it but you'll need a car. There will be quite a few times you'll have to move something heavy or big.

9) A bike lift isn't essential but is very, very nice to have. Unless you have trick knees or a bad back. Then it's essential.

10) Accurate measurements. This is a pain in the arse at first but good measurements mean good decisions. No measurements means guesswork and probably having to do stuff twice, or wasting money doing things you didn't have to do.

11) Get PPE in advance and wear it. Bikes come and go, but you only get one set of eyes, ears, nervous system, lungs etc.. exposure or risk will add up after a while.

And some quick basics...

Keep the place tidy, it's faster and easier.
Use six point sockets wherever possible (twelves rip things up).
CRC 5.56 or PB Blaster work best when allowed to soak in overnight.
Spray paint drifts like crazy, expect spray droplets to mark things ten feet away from whatever you're painting. Take it outside and close the door. Seriously.

*** wrecker's or secondhand parts are a pretty serious crapshoot in this country, there are a lot of cowboys out there selling 90% stuffed at 50% of new price. ***

That's probably way more than enough for now, good luck and keep us posted.

[Mikael]

Fucking moaners.

If I remember correctly they were $3999 brand spanking new. Suzuki sold heaps of them. Sportier and cheaper than a farty old 450 twin Suzuki, CB400 twin (fat, slow, boring) or old fashioned GB400 Honda. Can't remember Yamahas 400 of the day - old fashioned SR500 probably or XS400 twin. Kawasaki had the Z400/440 at the time (I owned a 440).

Yep the Suzuki was bright, fresh and screamed it's little guts off into many peoples hearts.

Restro? Questionable if it has any real value other than memory lane. But there are worse bikes to sink money into.

Memory lane value, I agree, for the money they were great little bikes.

[Mikael]

OK, advice to follow, here's what you'll need:

1) Space, both working and storage for the bits that'll come off. 1 single car garage working space, 1 garage worth of shelving for bits. Stacking storage bins will do in a pinch. It's amazing how much the volume expands once the bike comes completely to bits.

2) Cash. You'll be buying tools, supplies etc... watch those dollars. Buy stuff after it's clear that you'll need it, not by guesswork in advance. My rule of thumb was first time, borrow or improvise, second time, just go get the right tool.

3) Lines of supply. Scout the local shops. What's there? When are they open? What can you get on-line and what are delivery times like? Can you buy a solution to a problem, instead of putting in crazy amounts of work? You will also need a reliable source for replacement parts. Some components will be stuffed and will need replacement.

4) Light. Lots and lots of working light. For some unknown reason Kiwis seem to like working in grungy caves... save yourself the eye strain, paint the workspace white, seal the floor if you can (wish I'd done mine), put lights in everywhere, take a weekend out from the resto and work on the workspace. White surroundings will bounce light into corners and keep contrast levels under control. Keeping things visible really reduces the fatigue.

5) Ziplock plastic bags (all sizes, lots of), marker pens and masking tape for labelling the bags too. Mechanical components that should be kept in oil (like engine innards) should be in the ziplocks. Oil-soaked rags will dry out after a while (six months to a year) and you'll come back to rusty camshafts.

6) A digital camera that you can use. I can't stress this enough: A camera which you can drive, that does what you want it to. You'll want to choose where it focuses, and what values it selects for exposure so that you can actually see what it's a picture of. I tend to avoid using flash (tried; too many problems with bounce off metal) and use a tripod and long exposures instead.

7) Internet, public library, people with experience.

8) A car. It pains me to say it but you'll need a car. There will be quite a few times you'll have to move something heavy or big.

9) A bike lift isn't essential but is very, very nice to have. Unless you have trick knees or a bad back. Then it's essential.

10) Accurate measurements. This is a pain in the arse at first but good measurements mean good decisions. No measurements means guesswork and probably having to do stuff twice, or wasting money doing things you didn't have to do.

11) Get PPE in advance and wear it. Bikes come and go, but you only get one set of eyes, ears, nervous system, lungs etc.. exposure or risk will add up after a while.

And some quick basics...

Keep the place tidy, it's faster and easier.
Use six point sockets wherever possible (twelves rip things up).
CRC 5.56 or PB Blaster work best when allowed to soak in overnight.
Spray paint drifts like crazy, expect spray droplets to mark things ten feet away from whatever you're painting. Take it outside and close the door. Seriously.

*** wrecker's or secondhand parts are a pretty serious crapshoot in this country, there are a lot of cowboys out there selling 90% stuffed at 50% of new price. ***

That's probably way more than enough for now, good luck and keep us posted.

Thanks for all that, golden. Thats a lot of good info cheers. I have a mate willing to do a compression test for me and rebuild the breaks. It seems the more mates I show this thing the more people I have wanting to help (as long as they can have a ride on it!). A lot of guys in Taranaki have fond memories of these things, musta been a popular bike in the Naki.
Thank you for taking the time to share those nuggets of info OddDuck.

[Mikael]

I found these carb specs if anyone else needs this info...

Carbs

ITEM Specifications

type - AISAN AS27VW
I.D. No. - 04A10
Bore - 27 mm
Idle r/min - 1300+/-100 r/min.
Fuel level - 9.0+/-0.5 mm
Float height - 20.5+/-1.0 mm
Main jet - #94
Main air jet - 1.2 mm
Jet needle - 5B10-3rd
Needle jet - 2.60 mm
Throtlle valve - 11.0
Pilot jet - #34
By-pass - 0.8,0.8,0.8 mm
Pilot outlet - 10.8 mm
Valve seat - 2.5 mm
Starter jet - GS1 #60, GS2 #54
Pilot screw - PRE-SET (2 turn out)
Pilot air jet - 1.35 mm
Throttle cable play - 0.5 - 1.0 mm
Choke cable play - 0.5 - 1.0 mm

[Mikael]

The big find is that while browsing through a 1985 GSX 400 R workshop manual i have found that the carbs and break system is identical to the Impulse. This is great news as now I have a manual for those parts and many other systems that these two models share. The later model GSX 400 R used a different carb. This means parts availability has opened up a little wider now too.
Made some progress. Have cleaned a lot of grease off the bike and have discovered a lot of the parts are in reasonable condition. The chain and sprockets are completely rust free and in good order.
I have found the source of a couple of leaks (one of the cooling hoses is cracked and 2 fuel overflow hoses were hanging loose, so what I thought was an oil leak was just fuel peeing over the oily bike). Also found a broken air box hose connection from the top of the motor.
Will try and do a compression test this weekend so I know what Im looking at.
Need a new reg/rec as the system is overcharging at the battery.
CDI seems in order.
The lights and indicators all work (small blessing!).