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Matthew Walker
Joined: 12 Nov 2006
Posts: 67
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 Posted: Thu Aug 23, 2012 8:08 pm Post subject: 4 stroke Superkarts |
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There seems to be a good number of 4Strokes running long course in Japan. Wonder what they've found that we have't...
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Fri Aug 24, 2012 1:18 am Post subject: |
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Hi Chris
We've probably done the subject to death, and I'm more into sharing the debate, so that others can contribute and hopefully benefit.
I think your summation is probably pretty accurate. It appears that either in a class on it's own right or in direct competition with 250's, that the ex-motocross 4-stroke isn't an attractive proposition for a Superkart. Which I think answers the question at the head of this topic. 
Chassis is looking good, but only 2 pedals  Do you produce different versions to suit twin and single? What are the main tube specs and wheelbase for each?
I don't know anything about the Japanese "scene", Matt, but it would be interesting to know a bit more detail of what they do.
Best Regards
Ian:D
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Ian Harrison
Viper Racing UK
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+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012 |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2919
Location: United States, New York, Ossining
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| Posted: Fri Aug 24, 2012 4:07 am Post subject: |
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[quote="Ian Harrison"]Chassis is looking good, but only 2 pedals Do you produce different versions to suit twin and single? What are the main tube specs and wheelbase for each?/quote]
Right now the chassis is an ICE single, the perimeter of the chassis is 1-1/4" x .083" wall, mild DOM tube. The prototype chassis had an adjustable wheel base, that chassis is fixed to what was determined as the "sweet spot", I would have to get back to you on that measurement, it's not committed to memory just yet...
Yes 2 pedals, we use a hand clutch....
I'm looking for a European agent...... 
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Greg Lindahl
Joined: 13 Jan 2011
Posts: 264
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| Posted: Fri Aug 24, 2012 9:29 am Post subject: |
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Gents;
Some experiences I've had from building/racing a four stroke motorcycle powered formula car.
For these engines to survive side loading g-forces, they are using baffled crankcases to keep the oil at the pump pickup and/or dry sumped.
Over-reving is attempted to be controlled by slipper clutch, quickshift control strategies and driver training (he pays for damages!).
With these two strategies, engines survive quite a long time and costs are contained. |
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shaun everard
Joined: 28 Feb 2009
Posts: 111
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| Posted: Fri Aug 24, 2012 2:05 pm Post subject: 450f |
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We do race karts on shale ovals but only at Norfolk arena 5 round winter series if you fancy ago Ian. We have a class for250 4 strokes they are quick not c
Another thing guy who I no raced motor cross bikes he used to blank off the oil filters on faster tracks his belief was the filter was slowing the oil to much. |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2919
Location: United States, New York, Ossining
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| Posted: Fri Aug 24, 2012 2:28 pm Post subject: |
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| Greg Lindahl wrote: | Gents;
Some experiences I've had from building/racing a four stroke motorcycle powered formula car.
For these engines to survive side loading g-forces, they are using baffled crankcases to keep the oil at the pump pickup and/or dry sumped.
Over-reving is attempted to be controlled by slipper clutch, quickshift control strategies and driver training (he pays for damages!).
With these two strategies, engines survive quite a long time and costs are contained. |
Greg, I built a F600 car with a CBR600rr fuelie motor, very different from a motocross type engine. The motocross engines have a crankcase similar to the 2 strokes in that it's separate from the rest of the motor, and the gearbox has it's own oil supply like the 2 strokes. It really doesn't have the tradition sump, it has basically a oil reservoir in the left side case cover, it's more narrow top to bottom, and not very wide side to side, so there really isn't any place for the oil to go with a side load. It's not like an open crankcase like a modern 4 cylinder sport bike....
Here's a little history for you guys...
This is THE head off Kyle Martin's Laguna Seca winning CRF450... Rob Morris had it in his kart, he dropped a valve and bought a new head, I had it welded up and used it.
As promised, this is a stock rod that came out of my motor, after a season of running...
The Cobalt chassis in my other post, is the sister kart to the PSR shop kart, so basically I could build a complete and accurate replica of that winning kart....
CR
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Greg Lindahl
Joined: 13 Jan 2011
Posts: 264
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| Posted: Fri Aug 24, 2012 4:49 pm Post subject: |
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Hi Chris,
Can you explain why the rod is a different color from mid point to large end? Looks like heat, but if so it would have failed.
The red coating is applied for a purpose that I don't recall (surface oxidation protection?).
Thanks;
Greg |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2919
Location: United States, New York, Ossining
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| Posted: Fri Aug 24, 2012 8:10 pm Post subject: |
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| Greg Lindahl wrote: | Hi Chris,
Can you explain why the rod is a different color from mid point to large end? Looks like heat, but if so it would have failed.
The red coating is applied for a purpose that I don't recall (surface oxidation protection?).
Thanks;
Greg |
That's a factory finish, they look like that new. I believe it's a heat treatment called carburization.
Another thought I had is that Honda makes essentially the same motor in their quad, if the system had oil supply issues, it would show up there....
CR
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East Coast Super Kart Series
"This is how we roll!"
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CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com |
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Fri Aug 24, 2012 8:28 pm Post subject: |
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| Chris Reinhardt wrote: | | Another thought I had is that Honda makes essentially the same motor in their quad, if the system had oil supply issues, it would show up there.... CR |
Chris
Your obsessing now
3G on a quad . . . . . it would have long been on it's back like a turned turtle!!
It's the sustained high lateral G that you find in a Superkart and nowhere else.
In the end it dosen't really matter, how fast, how reliable, variety of useable engines . . . . . . etc., the fact that for any combination of reasons it's a failure as a Superkart racing class is the crux of the matter.
Best regards
Ian
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Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
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+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012 |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2919
Location: United States, New York, Ossining
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| Posted: Fri Aug 24, 2012 9:32 pm Post subject: |
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[quote="Ian Harrison"] | Chris Reinhardt wrote: |
3G on a quad . . . . . it would have long been on it's back like a turned turtle!!
Ian |
You're not pulling 3 G's on 2 wheels either!!!
Ian, if it were or never succeeds, I'm ok with that, I just want to get the record straight, there are some bad experiences I'm sure with these motors, and that can be said about ANY motor. These motors can be made fast, and are reliable if built and treated correctly....
CR
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East Coast Super Kart Series
"This is how we roll!"
www.eastcoastsuperkart.webs.com
CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com |
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Riley Will
Joined: 03 Sep 2001
Posts: 1361
Location: Canada, not USA state,
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| Posted: Fri Aug 24, 2012 10:28 pm Post subject: |
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After installing and developing an Aprilia SXV550 engine in a superkart, I came to some conclusions that I believe are relevant here. The most significant is the lack of oil volume in the engine. Due to our sustained rpm, the minimal oil would break down almost immediately. There is a good reason why RoadRace bikes carry 5+L of oil and use oil coolers! The second is the simple (cheap) valve trains used in mx. For the proper bikes you have direct cam actuation on the valve bucket. The bucket is also usually coated with a DLC or similar technology.
The 550 Aprilia made 74 HP in stock trim. It would be maybe GasGas fast, but certainly not on par with a Div1 kart. Even with upgrading the lubrication system with volume and a cooler, it would be more along the lines of a 2 stroke twin cost wise to compete with. The time factor to maintain it would also be exponential!
Here s a link to some testing video:
http://www.youtube.com/watch?v=ZPdWAZIlwQA&feature=youtube_gdata_player
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Alex Granelli
Joined: 04 Aug 2006
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Sat Aug 25, 2012 3:22 am Post subject: |
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| Chris Reinhardt wrote: | | You're not pulling 3 G's on 2 wheels either!!! |
Mmmmmmmmmmmmmmmm, I don't understand what your getting at here, Chris. Isn't that part of my point.
It's only in a Superkart that you pull 3G lateral and at 90 degrees (ish) to the motor vertical axis and may experience the oil starvation problem.
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Interesting comments from Riley ref the Aprilia SXV and valve actuation systems in particular.
The KTM 450 has twin overhead cams, but still uses a type of rocker arms, although not in the usual sense of rocker arm operating either side of a fulcrum, it just sits between the valve and the cam, however they are DLC-coated. See Image:
The TM450F, Yamaha YZF and the Suzuki/Kawasaki F have twin overhead cams, with the cams operating directly on the DLC-coated buckets.
The Honda CRF has a single overhead cam, with the cam operating directly on buckets for the inlet valves and via conventional rocker arms for the exhaust valves
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Hi Alex
OK the discussion has widened a bit.
Going "outside of the square" with regard to engine selection has been tried many times and is probably a waste of time, if road racing (safely) in competitive form is what you are after (i.e lap times).
In the UK and Europe and I think Australia, there is a 250cc, maximum limit on 2-stroke Super Kart Engine size. (or the nominally 500cc 4-stroke).
In the US there have been some weird and wonderful Superkarts (like Santa's "sled" and Johnny West's "Can-Am" styled kart using 1,000cc Superbike engines and these have been allowed to race in an "unlimited" or "Run what ya Brung" class and usually alongside other Superkarts. These karts are great pieces of fun engineering but put the drivers in extreme danger because the power and weight is just too much for a Superkart type Chassis package. In fact I think Johnny is on record as saying such in this forum?
The 3 classes of engines generally fitted in Superkarts now are without doubt the optimum you can safely achieve and give a choice of power, speed and costs that can suit most budgets, although in common with all sports it isn't getting any cheaper, what with tyre costs, entries, fuel, etc, etc.
The 3 classes are:
1. 250 National/ICE: Motorcross based engines (mainly Honda) - 60-65Hp
2. Div 2/Super ICE: Primarily GasGas 250cc single - 68-72Hp
3. Div 1/FE: 250 Twin: TZ/RS/BRC/PVP/FPE/DEA - 85-95Hp
Real world top racetrack top speeds for the 3 classes are between just over 130mph for a National/ICE and around 145mph for a Div1/Twin.
The above figures are real and I see them on my dyno day-in and day-out and also on the race data.
Of course the driver is of paramount importance in a superkart (perhaps more so than other classes), so we still see a great driver in a single turning faster lap times than a mediocre driver in a twin. I don't want to dwell on that too much, as long as everyone has fun at their own level and working on improving their input, that's the aim.
With the pinnacle or the sport (FE/Div 1. Twins), the motors are now reaching power levels/spread of power that are arguably pushing the boundaries of the sport into undesireable territory, i.e. exceeding the capability of the chassis/tyres/brakes. I'll give 2 examples:
1. At a recent Australian Superkart National meeting at Queensland International raceway, some of the top competitors were having to fit new brake pads everytime out on track. such is the nature of the speeds and heavy braking of that track.
2. At top European level competitors are putting new slicks on the kart everytime the kart hits the tarmac (that may be as much as $2,000 - $3,000 worth of tyres per meeting).
The impressive performance of a Superkart comes from it's light weight, superb power (hence power-to-weight ratio), low centre of gravity and matched components that have evolved over many years. What I'm saying is that a Superkart package is a superbly integrated piece of kit, change one thing and you start an engineering paperchase that won't end until you arrive at the small bike engined formula type cars.
So, we have a distinct vehicle (Superkart) in 3 classes and if you want better this or better that, then the best way is to go race something else, but you will end up racing something that has more power, bigger brakes, bigger rubber, suspension and costs an absolute fortune. All this to go substantially slower in a lot of instances.
If you improve the brakes, they become heavier and the tyres can't take the extra braking load, so you fit bigger wheels and tyres, you go slower because of the extra weight, so you fit a bigger engine, then the unsprung weight is too much so you fit suspension . . . . etc., etc.
I'm sure that Riley would agree that even if he could have got a reliable 74Hp out of his Aprila SXV, that in a race situation it wouldn't even have been on the same racetrack as say a top GasGas powered outfit like JR Osbornes, especially if you start talking dry sump, oil tanks, piping, etc. etc.
Alex' specific question regarding the Banshee engine is perhaps a more interesting one. There are a number of tuners in the UK/US/Aus that are producing big bore/long stroke Banshee motors with massive power outputs.
Here's a link to one of quite a few: http://www.twostrokeshop.com/
and another: http://www.trinityracing.com/yamaha-banshee4.html
and a picture:
and you guys certainly know how to bling them up!!
These engines could doubtless be easily engineered into a Superkart chassis (reverse cylinder as well perhaps?).
I had a Trinity motor on my dyno a while back (around 450cc I seem to remember), fitted into an Aprilia RS250 bike chassis. The reason for the session was to fit and tune a pair of Dellorto 39VHSB carburettors. I agreed with the owner that we would not exceed 10,000rpm (I was worried about piston weight). Once we got it all dialled in, it was producing in excess of 125Hp at 10,000rpm and the power was still climbing like the North face of the Eigar!! The sound was absolutely awesome
The engine is without doubt a fair bit heavier than the 32(ish)kg weight of a current Div 1/FE tandem twin (does anyone know?), so you are back to the power/weight argument.
The big question is could you "engineer" a capacity and power of a Banshee based motor to provide overall better lap times than a current twin cylinder superkart. My (educated?) guess would be no you can't, but you might get reasonably close for less money and perhaps with a less onerous maintainance scheddule/cost and better reliability, so it may be an attractive proposition to some. It would come down to a trade-off between straightline speed, cornering speed, brakes and tyre performace/life.
I'm sure these conversions have been done in the US and perhaps somebody will provide factual comments?
Of course your still looking outside of current "World Stage" capacity regs, so some (including myself), might see it as detracting from the superbly impressive status of the Superkart genre. Especially considering this Forum category title!!
Best Regards
Ian
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Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
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+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012 |
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Greg Lindahl
Joined: 13 Jan 2011
Posts: 264
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| Posted: Sat Aug 25, 2012 8:58 am Post subject: |
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Chris;
Thanks for the explanation on the color differences. Carburization IS common with cranks and rods.
Riley;
Interesting perspectives all. I used significant oil cooling and larger oil capacity and kept a close eye on oil temp's in the F1000 to keep it happy. Without cooling the oil would go over 300F, the absolute limit of race oil (many would say beyond it, except Formula V guys who have regularly run at this temp.).
Ian;
Those "rockers" are finger followers. They are at present (maybe arguably) the most advanced valve actuating technology. The BMW S1000RR uses them on their street bike and may be why they have the biggest power (larger valve openings possible with fingers is what I read). All F1 cars use them with DLC coating on cam and valve surfaces and they state that they can not reach above ~18,000 RPM without them (and, of course Pneumatic Valve Closing which will work up to 40,000 crank RPM). There's some debate about this since Honda had quite high RPM Indy engines without fingerr followers or PVC.
Unless there's a resurgence of two stroke engines in the general market place, we're probably all headed for a four stroke future (here come the howls!). |
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Sat Aug 25, 2012 9:57 am Post subject: |
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Hi Greg
Interesting info and perhaps it's becoming clear why the KTM was the most popular choice (in the UK at least) for a 450 4-stroke.
I think that we may eventually see the singles market go exactly the way of the twins (i.e. bespoke 2-stroke race engines). But whilst there are plenty of ex-motocross 250 engines about and a good supply of cheap O/E parts to keep them fresh (and I still have complete new CR250 engines on the shelf), that won't be a good few years yet.
Remember the TM250 and KTM250 motors are still in production. The TM is a great engine, which we will be racing in 2013 alongside our Hondas, we did have some early glitches and shelved it for 2012, but the problem is resolved now. A smaller more flexible company like TM would probably produce a batch of 10 or 20 engines a year forever if there was a demand.
It is a matter of getting the timing right and introducing them alongside the Honda as you have done in the US with GasGas. This will allow the ICE/Nat drivers to keep racing competitively so that numbers are not lost and equipment value is maintained.
In times of a harsh economic climate, it seem that the ICE/Nat numbers are maintained better.
ICE/Nat is the backbone of the sport in the UK and the US and just look at the confirmed entry list for Laguna, it would look pretty sick without those guys.
I'll lay a bet that we will still be building, re-building and selling Honda CR250 engines into the 2020's for Superkart use.
Best Regards
Ian
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Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012 |
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