Project Corner: Turbo’d Bandit 400

Who doesn’t love a project bike? We speak to the owner of this turbo’d Suzuki Bandit 400, Chris Jennings, and quiz him on the process, the problems and whether it’s a keeper…

Why this bike?

I’ve always favoured smaller capacity bikes, having had various 400s over the years; an NC23, which I’ve still got, and a Moriwaki themed Z400J, along with the various Suzuki 400s. I always try to build odd stuff that’s a bit off the wall and have previously built a GSX-R400 Turbo, that’s currently taken about 9 years and still doesn’t run right, so I figured what’s better than one non-running turbo’d Suzuki 400 than two?!

Many moons ago I had built another Bandit 400 with some additions to the frame rails to make it look like a mini Harris Magnum 4. The original plan was to put a turbo on it, but I didn’t get round to doing it, and ended up selling it, so there was a certain amount of unfinished business with the idea.

I had bought a Bandit 400 engine and some parts from a chap on the PB Evo forum a good few years back as a spare, just in case the first turbo grenaded itself, but over the years it just sat under the work bench gathering dust. Eventually, during a big tidy up, I decided it either needed to go or be put in something. Initially, it was destined for a 70s Bultaco trials frame but fortunately it wouldn’t fit without a daft amount of work. It was at this point that I decided to revisit the Bandit 400 turbo idea, armed with a lot more knowledge than when I started the GSX-R attempt and the suspicion that the Bandit might be a bit more user friendly when it came to getting it to work.

I’d also been in touch with Ian and Jim Cross, of Cross Customs, over the past few years. They specialise in Suzuki 400s and currently run the most epic GSX-R400 based drag bikes which are beautifully engineered and properly fast. They had a white Bandit 400 featured in Streetfighters way back in the day, which was always a big inspiration as well.

What’s the end goal and why?

With the original GSX-R turbo project the end goal was to see if we could get 100bhp out a 400, even if it was just for a few minutes before meltdown. As to why? Everyone puts turbos on 1100 and 1200 Suzukis, but there aren’t many in lower capacities, so it seemed like a good start for a daft idea (I now know why…) . A chance conversation with Jim Cross about their drag bikes and some leftover parts, including some machined pistons and a modified engine cover, was enough to kick the first turbo project off, which has now snowballed into Mk2.

The other main reason was to use up as many of the random bits from previous projects I’d got kicking around in the workshop to make a bit of space. It’s been relatively successful from that perspective.

I always try and do something I’ve not done before so I’d also challenged myself to build my own aluminum fuel tank for this one, mainly because it’s built out of bits and I couldn’t find a decent Bandit 400 tank anywhere.

How long has it been since you started, and how’s it going?

I started this project around the middle of June 2024, so it’s taken about 15 months to get to a fully dry built state, running ready to test, which is pretty good for me. Going into it with the info gained from the first turbo project has really helped streamline the process, mainly with what not to do. I’ve been able to refine most areas of the turbo kit, the headers on this version are stainless rather than mild steel and have (I hope) a much better flow design over the first ones I made. The Bandit 400 carbs are also much more like a “normal” GSX-R11 or Bandit 12, where the GSX-R 400 carbs are quite different, which I’m hoping should make running and tuning an easier prospect.

Biggest problem encountered so far, and how did you get round it?

So far, the biggest headache has been getting the bike started; I’ve spent about 8 weeks going round and round in circles checking wiring and killing spark plugs. Again, going into it pre-armed with all the issues from the first go I thought I’d pre-empted them by changing all the electrical components, pick-up coil, CDI unit, plugs, coils etc. before I started. As it turned out, it was the simple two pin plug from the pick-up coil that had had the wires reversed previously, causing the CDI to get confused. It ended up being a two-minute fix and resulted in the bike starting perfectly. Operator error rather than component issue.

Suzuki 400s are notoriously terrible for starting, so in addition to replacing all the electrical bits, I’d also stripped and ultrasonically cleaned the carbs before rebuilding them with fresh seals to give it the best possible chance.

What have you learned about this bike?

So far, I’ve learned once again, do not assume just because you think you’ve done everything correctly that you have. Check, check and triple check your wiring because a single reversed wire that you don’t know has been reversed can cause you all manner of problems and sleepless nights.

Also, be logical in your fault finding; don’t change more than one thing at once and make notes as to the results. It makes identifying issues a more streamlined process. That said, 8 weeks solving this problem is way better than the 9 years the other bike has taken so far.

Best tool in the box?

For this project I treated myself to an AC/DC tig set to learn how to weld aluminum, as not being able to has always delayed projects in the past. Even being able to tack bits together has really sped the process up although I still take any safety critical bits to a grown up to finish.

Best Product/Service?

Got to be Paul at Black and White bikes in Spilsby; he was really helpful scouring the YSS technical data books to find a shock short enough to match the Bros swingarm to the Bandit frame with a correctly rated custom spring for the odd combination of parts and maintaining a suitable amount of damping. Ended up being a top line YSS MSX125 GROM shock which is really nice quality whilst being sensibly priced.

Also, Jim and Ian at Cross Customs for always taking the time to answer my daft questions and for the fancy lock-up clutch which is still waiting to be fitted. They started doing some really tasty billet bits for more modern bikes too.

Budget V’s Actual?

I swore to myself that I would never build another project out of parts again, it always ends up being vastly more expensive than you plan but here we are once more. As with all these things, it started off small and snowballed rapidly. Originally this started as a project to use up a load of spares from the loft with minimal outlay but with the addition of a fancy shock, one off ally tank and a lockup clutch, it’s gotten out of hand – as it usually does.

What’s after this project?

I think this one will be an ongoing one for a bit. Once it’s been dyno’d as is to get a baseline, I’ve got some FZR600 pistons to go in which take the capacity up to 442cc, which should help a bit and also the lockup clutch to fit as the stock one is liable to give up at anything over 80hp. It’s also going to need to come apart to have the frame rails fully welded and everything powder coated and painted, but that’ll be a way off I suspect, probably over the winter.

Next on the list, once this one is up and running completely, is a refresh on my NC23 over the winter. I should also revisit the first 400 turbo eventually and see if I can get it to run properly. I’m officially out of garage space now so something is going to have to go before I start a new full bike project

Keep or sell?

This will be yet another keeper I suspect. I don’t think anyone would be daft enough to buy it, pretty much like all the other bikes I’ve ever built. I’ve ended up with a garage full of keepers.