Bike of the Month October 2021

This is my First time out writing the blurb for BOTM, not as easy as you might think, but thankfully this month’s bike of choice doesn’t need too much of an introduction. I volunteered to write this because I knew the builder and the bike well, having spent some time with them both at a recent OSS dyno day as well as various other OSS events.


Paul Morris’s and his gorgeous looking GS750 pretty much sums up what OSS is all about for me. For those of you who don’t know Paul, Paul is one of the OSS events team and over the years has organised many events from dyno days to OSS stands at shows, always there to lend a hand, eat ice cream and take the piss. 100% OSS material, just like his GS750.


Like many of us here at OSS, Paul did what a lot of us do (okay, what I would like to be able to do, but I lack the talent to do), take your all-time favourite bike/first big bike and give it a massive boot into the 21st century with radial brakes, better suspension, better tyres, add a trip to FBM for some turbocharged tomfoolery, a fancy LCD dash, a very sublime paint job and then finished to whole build to a standard that Suzuki San himself could only have dreamt about, when this bike first rolled off the line.

The standard of finish on this build really has to be seen to be appreciated, read the build thread to see what I mean. Oh, it also goes rather well on the road too, as I witnessed first-hand when Paul demonstrated with some high speed low level sorties over some of North Yorkshires finest roads on our way back from the last OSS dyno day.

I must admit, I was quite gutted when Paul broke his last Turbo GSX creation (also a former BOTM) and I thought, at the time, he must have had brain freeze from too much ice cream, but seeing what he has built to replace it, I now fully understand why it had to go.

Congratulations Paul your GS is BOTM, mines a 99 with a flake, thanks.

Members discuss this here.

Bike of the Month January 2020

It’s early January. You could be feeling full of cheese, confused about which day of the week it is, have back-to-work blues or you may even be doing one of those ‘dry January’ or ‘veganuary’ fads. Not me, I like beer and cheese too much. I also like really clean, tastefully modified naked bikes, especially if they are blue and white and have clip-ons. Anyway, enough of that, look at this…

January is a great time to look back on the last year and consider what you’ve acheived. OSS member Allspeeds can do that with great pride, having transformed this humble 750K into a stunning 7/12 turbo in (just over) a year.

The bike was completely stripped and a 1200 engine was sourced. Apparently they are ideal for turbocharging and continue to remind us what a great donor bike the humble Blandit is.

The attention to detail on every component is amazing. Polished / coated / modified or upgraded everywhere you look. I looked at it a lot, you should too.

The turbo route was chosen and looks fantastic. 380BHP anyone? On carbs too. Mmm… carbs. Oh sorry, I got back to beer and food again. Anyway, just look at it…

So, what are you going to look back at in January 2021 and say you acheived in the past year? Get planning (beer optional, however recommended). Get building. Get it documented in the OSS projects section of our forum.

What a transformation in that time. Congratulations Allspeeds, your stunning, brutal 7/12 turbo is our January 2020 Bike of the Month.

You can find out more about this bike and discuss it here.

Bike of the Month December 2019

Some bikes are built because you can, some because you want and sometimes because you need to. A sense of urgency before you miss that window of socially accepted ownership, so to speak. Such is the tale of Kraptanaman’s turbo GS1000.

Excuses at the ready to justify the actual turbo to the good lady, parts were gathered from inside OSS-land and the build commenced swiftly. This very bike will be the first awarded BOTM twice, because the frame is YoshiJohnny’s old GS1000 Yoshimura-rep, previously earning BOTM way back on the old page.

Playing around with the hacksaw to make the engine fit properly without having to re-do the headers, all fell into place after some persuasion and focus was shifted to the frame itself. Deciding on a slightly shorted seat, the backend was lopped off and the seat shortened to suit.

Making use of the talents and knowhow of several OldSkoolSuzuki heavy-hitters and also a few local tradesmen, the project neared the end of the journey and after the obligatory MOT, it was out on the road, all nice and legal.

However, as normal with pretty much any bike built in any shed, trouble rears its head when you think you’ve done everything properly. This was no different and work was needed to the tank because it sprung a leak under the new paintwork, which ended up needing a different tank and another complete paintjob again.

Over time a trip to Blair’s dyno to get the best out of the old oilboiler, Andrew ended up with a 200+ Bhp machine, having scratched his mid-life itch of building and owning a turbocharged motorcycle.

Long overdue since it has been finished for some time; congratulations Kraptanaman, your GS Turbo is this months Bike of the Month.

Buildthread here

Discuss here

Bike of the month August 2018

Having something like BOTM on Oldskool is a big deal. It carries a certain weight, which makes OSS stand out from all the other websites and facebookpages that scatter the internet and, to me anyway, just water things down. Good bikes are good bikes, but having to visit 10+ websites and filter through the bolt-on brigade to find a few bikes worth reading about, gets old really quick. We’re different, we know it, others know it, and it will only get better.

One could argue that choosing BOTM for the next month, should be for a newly finished project, largely built on the forum, with its own thread and many, MANY pictures. However, due to the sheer amount of bikes being built over the years, sometimes a bike more than worthy of being chosen as BOTM has to wait for a bit.


This bike is such an installment. Its owner/builder Arttu has been a OSS-household name for many years. While many of us modernise our bikes with newer suspension, wheels and brakes, Arttu takes it up a notch. You see, the bike you see here is basically a rolling test bed for all sorts of EFI-trickery, which really shouldn’t have any place on one of our air- or oilcooled motors. Now, he didn’t just get it to work properly on his turbo EFE-powered EZ, he now helps many others out to convert their bikes to fuel injection as well.


I personally have been up close with 2 projects Arttu has been involved with and I can tell you the quality is beyond what you’d expect from a factory, let alone someone working from a little shed in Finland. It’s all pretty impressive and with the build reaching a next stage, it will only get better.


Arttu, congratulations on BOTM for August 2018.

Read about the project here

Discuss here

Bike of the month February 2018

Oh no, here he goes again, twittering on about “evolution , not revolution” and “genetic engineering of an extinct species”

Well, nearly but not quite. I’m going to mix it up a bit this time and tell you a tale of evolution AND revolution.

Back in the Dino days of the old site there were many lovely bikes built but because they were scattered around the world you didn’t always get to see them in the flesh. I travelled a lot for OSS and I was lucky enough to see quite a few, close up. Some lived up to the hype and some didn’t. (I include my own creations in the latter category)

As luck would have it though, I didn’t have to travel far to see a bike, where the opposite was true. The pictures I had seen of this bike online, before I stumbled across it at a local bike meet, had not done it justice. That bike belonged to Gregg Campbell AKA Wee Man.

Looking around Gregg’s GSXR1100M Slingshot you could just tell his had been a long and intense love affair. It had the look of a bike that had been tastefully, and carefully evolved to meet its owners exacting tastes and requirements. All of which, were very tidy and meticulously well executed. If our FBOB had been there, he would have been forced to say “bugger me that’s shiny”. It instantly got my “bike you’d most like to take home” vote.

“But KM you promised us a revolution as well as an evolution!”. Easy tiger, I’ll get to that bit.

Fast forward a few years and I’m loafing around at the Fast by Me workshops drinking coffee and listening to Dave telling me about how he took an angle grinder to his modem, while on the phone to his internet provider’s customer support line. Out of the corner of my eye a familiar bike caught my attention. It was none other than Gregg’s Slingshot. “I know that bike” I said. Now we all know what happens to anything that goes to uncle Dave’s. That’s right, it gets the boost.( unless it’s a faulty modem)

The boost is pretty much Dave’s solution for everything ( I think he’s onto something). Gregg’s Slingshot was in for one of Uncle Dave’s rock solid turbo kits. Even Dave paused his internet tirade for a moment to chip in how tidy the bike was.

I’m sure Gregg will agree with me that the arrival of “the boost” has been anything but evolutionary and every bit Revolutionary! (made it, see)

This tells you all you need to know about limitless possibilities offered by 80s and 90’s Suzukis. The best part of breaking up, is making up, especially when the making up bit includes a extra-large bucket full of lairy charged up horses.

Gregg, congratulations you’re our bike of the month.

Members discuss this here.

Bike of the Month August 2017

Bandits, they crop up for discussion from time to time on OSS. Are they interesting? Are they not? They get referred to as ‘blandits’ unless they’re decent and have always been seen as a good source of parts, particularly the engine for our beloved OSS bikes.

So, when we set about rebooting OSS into what it is today we had a think about how to word which bandits we’d like to see on here… specifically no blandits! However that needed a tad more definition so we ended up with the following as part of the rules: “Standard bandits just aren’t that interesting. Trick ones are another thing though, there are indeed some out there and we’re not talking bolt-on tat. GSXR running gear, 1216, flatslides, turbos etc, that makes them interesting!”

When it was time to choose this month’s BOTM, I saw Colinworth79’s Bandit Evo thread and re-read that definition. My thought was that maybe it’s time for a ‘non-blandit bandit that’s still somehow a bandit’ BOTM. I also like well-executed tasteful trick details and I like shiny… so here we are.

Trick frame? Tick. Upgraded running gear? Tick. Turbo? Fucking tick! There are so many upgrades and details on this bike. GIA frame (11kgs lighter than the stock), Ohlins suspension, Harris/custom yokes, that swingarm, lightweight wheels, big bore, turbo, the list goes on with some amazing details and one-off parts along the way. Recognisable as a bandit however very trick and lacking in renthal bars and twin dominator headlights too!

The bike has competed at the Brighton Speed Trials and has since been seriously crashed and rebuilt along with further upgrades. It doesn’t stop there though, a 1340 motor is now being prepared for it too.

So, here we have it – we’ve got a bandit as BOTM. Yet it’s not a blandit. It’s the opposite of bland yet it’s still got the recognisable silhouette of a bandit. Is it still a bandit? Who cares, it’s our BOTM.

Colinworth79, your Bandit Evo is this months BOTM.

Read the project thread here.

Discuss this article here.

If it ain’t broke, it doesn’t have enough power yet – The quest for speed.

This year we’ve had the pleasure of following one of our youngest members on his crusade to build a winning 300bhp turbo wheelie bike based on a GSXR1100 Slingshot from the 1990’s. We all watched in amazement as the master plan took shape and we rode the roller coaster with him throughout the year.His determination and focus was such that  it soon became clear he was either going to break a record, break his engine or break himself.

Fortunately he managed the first 2 and not the 3rd. Here’s Kev Kearsley’s round up of  his 2016 campaign. He went into this  year as the Kid Kearsley but nobody can deny that he came out the the other side Da Man!

The Quest for Speed

Kev Kearsley

Ever wake up and think I’m going to do 200mph today? Tuesday was one of those days.

The Top Speed Tuesday put on by Straightliners at Elvington marked the last event of the year for myself, and what a year.

With numerous top speed days for tuning the bike for the Wheelie Comp, seeing a failed 194mph kilometre wheelie for dropping it a few metres short of the required distance.

A trip to Pendine sands in South Wales where I set two land speed records reaching 174mph on sand.

Hundreds of miles on the road two up

A track day at Oulton Park in the soaking wet, 300bhp on summer race tyres in the wet is not advisable Kid.

A few static displays at various motorcycle shows to fly the OSS banner including Donnington where my alter ego Rene took the old girl for a few laps of the track.

Many visits to RTR motorcycles for dyno runs, one off which was for the OSS dyno day where the bike made 300bhp.

So all in all a good year! Just think of the stress that engine has had doing all that, the only fault I got all year really was a leaky block so I’d say quite a reliable one.

Lets go out with a bang! I had that shit or bust attitude on.

It had been raining all Monday night making it look like the event would be cancelled, that gut wrenching feeling driving to the track in the rain for 2 hours thinking this ain’t gunna happen today. The rain stopped thankfully and after waiting a few hours to allow the track to dry we were given the all clear to attack the track.

The bike is, as a few of you know, made for wheelies, this means a short 55″ wheel base and big horsepower, not an ideal combo for Land Speed Racing.

Time to do the job. I was waved off by the starting Marshall after sat staring down a 3km runway. Short shifting 1st, 2nd, 3rd into 4th with a little wheel spin as the track was cold and still damp, into top gear and the bike is now naturally wanting to wheelie up in the air, feathering the throttle on and off to try keep the front wheel planted was an impossible task.

kk-speed-1I felt gravity some what take over just shy of the line and I managed to pin the the throttle open all tucked in with my chin on the tank as I had no fairing to hide behind.

kk-speed

Made it. Still alive. Slowly throttle off as not to upset the bike, heart beating, did it do 200?? That drive back to the pits and the timing office seems to take forever.

203.8mph! On an unfaired 30 year old motorcycle with a well and truly abused engine.

kk-times

Thank you to all involved over the past year for parts, advise and food.

Use the link below to view the onboard action.

https://drive.google.com/file/d/0B0QcmiqJi-rISzdsMzdYTkJscU0/view

 

Setting up CV carbs for a turbo

See below all I know about blowthrough CV carbs. This is worth several hundred hours of sorting out and at least €1000,- worth of dyno time, so feel free to thank me! (and/or make a paypal donation)

Bowl pressure
If pressure in venturi of carbs is raising due to boost, so should the pressure in bowl raise. Because if pressure in bowls is lower as it is in venturi, no fuel can be taken into the engine.
In my experience dynamic boost is absolutely nessecary, and it’s best to give each connection on the carbs it’s own spot on the tube going to the plenum: not in the plenum itself as there is to much pulsing. Make sure they are “angelcut” and in the middle of the airstream. (also known as pitot tubes)

On the GSXR1100 model 92 with the 40mm carbs you need to fasten the rubber T’s for instance with steel wire to prevent leakage and pressure drop.

Membrane pressure (CV carbs only)
Pressure above slidemembrane is not needed: it got it’s signal/pressure through the hole in the slide. Don’t enlarge the holes because the slides go up too fast and cause stuttering. (beware of dynojet kit modifications: larger holes and softer springs are a real pain in the butt for the midrange!)

Pressure below the membrane is needed. On the GSXR1100 model 92 with the 40mm carbs you have a seperate “venting” system with external hoses. Those are not suitable to pressurize. I removed that system, plugged the holes and drilled holes from the bellmouth towards under the diafram. When you drill you cross a not used hole. You have to plug that up also to prevent leakage and pressure drop. So it is made like the earlier models: the 36 and 38 mm CV carbs do not have this system.

Fuel pressure
The pressure of the fuel going to the bowls should be higher than the pressure in the bowl. If not, not any fuel is flowing into the carbs causing starvation as soon as boost starts to build.
Therefore you need a pump capable of making enough pressure to overcome boost + 2-3 psi at sufficient amount of fuel. The standard membrane pump on some carb bikes is definitely not up to the job: don’t even try it. An automotive EFI pump coming out of a car with the same amount of horsepower you are aiming for should work allright.

If you don’t use a regulator: you will have the maximum pressure on the bowls the pump can handle, and that will be around 90 psi and the end of your carbs.
A regulator is used (I use a malpassi and highly recommend it) to give the carbs a 2-3 psi above boost, so difference in pressure between pump and carbs is always the same independent of boost. Make sure you use a bypass type, not a deadend type as it is less accurate. If you can get away with 5 psi on the carbs without leaking, you can use static pressure and don’t need to modify the malpassi. It you have trouble with it, as I have, you need to shorten the spring in the malpassi a bit to achieve 2-3 psi. I also needed a bigger 8mm return line to be less restrictive. Than you definately need the dynamic pressure to prevent starvation under boost!

Jetting+tuning
Don’t make holes in the slides bigger, or use soft dynojet springs! They make things worse in the midrange area.
If you have your carbs and fuelsupply correctly setup: you don’t need to make big adjustments to needles and jets. Mine is actually on 125 mainjets (stock!) functioning just fine at 11.5:1 A/F
Don’t get an A/F any leaner then 12:1 A/F when you use some serious boost. You will burn up some pistons/valves. 11.5:1 is safe imho.
Use an A/F meter to see what’s going on. Looking at plugs is not saying too much, because if their getting hotter then normal on a turbocharged motorcycle they are white anyway.
Symptoms of lean and rich while driving can sometimes be very similar so in doubt always consult the A/F on a dyno!
Because of the lowered fuellevel it is nessecary to give more fuel for the idle, in my case 8 complete turns out for the mixture screws.

Extra tips:
Place a fuelfilter between pump and regulator. Not before pump because you restrict too much, and not after regulator because you messing with pressure which is critical on a carb/turbo setup. Make sure the fuelfilter can hold the pressure!
The return line of the regulator should be as less restrictive as possible: inside minimum 6mm returning into TOP of tank, not below fuellevel in tank. Otherwise fuel pressure cannot go as low as 2-3 psi. Don’t ever (I mean ever!) bend this line because fuel pressure can reach scary levels damaging your carbs seriously!!!!
Mount a fuelpressure gauge direcly next to the boost gauge so you can easy troubleshoot. Remove later if you want to.
Remove filter in your petcock, or better mount a less restrictive petcock without filter. Pingel makes these, but I machined a custom one with build in fuelreturn to the top of the tank so you don’t have to weld in a separate fitting in the tank
If it’s a vacuum operated petcock make sure you use the bypass mode: otherwise on boost the petcock will shut! This is a nice one, as you easily overlook it. On some models the petcock is really restricted in bypass mode so you have to modify that in some way.
If carbs overflow: put in new needles and valves. Make sure fuellevel is not too high: pressurized bowls have a slightly higher fuellevel so you maybe have to adjust it a few milimeters.
On very high horsepowerlevels there can’t flow enough fuel past the needles. Put in thinner/sharper dynojetneedles to solve this. Typical symptom is a sharp leaning out around peak torque, were you need the most fuel every stroke. This makes it harder to get the midrange ok.
At higher boost you can press out the choke plungers! This causes unwanted rich situations and stalling at closing the throttle. Put in stronger springs to solve.

Disclaimer
This info is true for my bike and my application. Some of this info is also true on other bikes/carbs but you have to check yourself. If it doesn’t work or you burn your engine up: I don’t accept any claims. If you crash due to an exploding engine: I’m really sorry and I will send flowers to your family but I am not responsible!

Good luck!

>> Check out the hints section of www.turbo-bike.com, site has an illustrated guide for “converting” CV’s for turbo use.
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The small 34mm gsxr750 carbs with alloy throttles and 4 screws on the caps and floats are actually the best you can use when going turbo. A friend (at is cranking out 420 rwhp at 2.2 Bar of boost.
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I’m also using 34mm carbs on my turbo GSX with alu caps. One more tip: Replace the o-rings in the T-s that go to the floatbowls; 9 times out of 10 they are old and brittle and will leak your precious dynamic boost so the motor runs like a pig at the transit from vaccuum to boost.
One important thing that I noticed during dyno-testing is that you (usually) start with std. mains, then lean it out a bit. If you go down-or upsize the mains, they have a bigger effect on fuelling than it would on an NA engine. So where you would normally say take it 3 sizes down at a time, you need to take one size at at time with this setup.

Marco.

for 38-40 mm carbs

vergaserdeckel-deckel

vergaserdeckel-gsx-r

http://www.gsg-mototechnik.de/