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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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 Posted: Wed Aug 22, 2012 6:27 am Post subject: |
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| Chris Reinhardt wrote: | | Toned that down a bit aye? |
Yes Chris, you know me when I go off on one, so backtracking was in order!!  
Larry,
Each to their own. Enjoy your chosen sport.
Alex
I don't think that the CR500 would be any quicker than a CR250 and that heavy piston would certainly reduce reliable rpms. It might even be seen flying through the air on an early downchange.
You don't need a slipper clutch with a 2-stroke as there is a much lower level of engine braking. With the 4-strokes it's easy to lock the rear wheels and cause damage to the motor on an early downchange. Nobody in the UK is running a slipper clutch with CR250. In the US some run the Hegar Sprague (hopefully I spelt that right), which is a bit like a freewheel on a pedal cycle. The advantage of that is that if you stick the motor, you just coast to a stop without dragging the motor round and further damage (we learn to be quick on the clutch!!). The disadvantage is that you loose some control if you are on/off the throttle through a bend (although I have never actually tried one).
The electric start is perhaps the greatest attraction, but to be fair, the guy who used to be the pusher can be seen running around the pits with a battery pack. If you spin, especially with a hot engine and stall the motor, the battery can be flattened before the motor will restart.
The Rekluse is a good quality piece of kit.
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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paul rees
Joined: 06 May 2007
Posts: 264
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| Posted: Wed Aug 22, 2012 9:45 am Post subject: |
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| Ian Harrison wrote: | Hi Paul
I think the shale used on our Speedway tracks might be a bit painful  and the barrier rails are very close to the track. But your right, it would be wicked 
Best Regards
Ian |
Hi Ian the track our club runs on is Decomposed Granite. The catch barriers on a lot of US tracks are wooden wall bull rings. |
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paul rees
Joined: 06 May 2007
Posts: 264
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| Posted: Wed Aug 22, 2012 10:13 am Post subject: Clutch |
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| The Rekluse is a good quality piece of kit. What would be the gain with this on a Dirtkart |
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Alex Granelli
Joined: 04 Aug 2006
Posts: 15
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| Posted: Wed Aug 22, 2012 2:30 pm Post subject: |
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| The rekluse takes away the traditional clutch on a dirtbike for example. You still shift up and down through the gears as normal, it also adds some centrifugal mass. They tame dirtbikes and prevent stalling if adjusted properly. The attraction for me, in a kart, would be that you press an e start button, drop it in to gear and never worry about stalling or needing a push. In my eyes, it would turn a superkart into a much more user friendly, headache free ride. |
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Racer Johnson
Joined: 08 Feb 2009
Posts: 116
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| Posted: Wed Aug 22, 2012 9:52 pm Post subject: |
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heres the difference, and I see this all the time..... two stroke siezes....I call customer.....it stuck -got the piston and cylinder... (customer ok fix it) then a 450 comes in siezed......I call customer- ok it dropped a valve, started to tie up, took out valves, piston, cylinder, cylinder head and rod.......price to fix it is about value of engine...(customer.....nah ...Ill part it out)
-Eric Johnson |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2918
Location: United States, New York, Ossining
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| Posted: Thu Aug 23, 2012 4:21 am Post subject: |
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| Racer Johnson wrote: | heres the difference, and I see this all the time..... two stroke siezes....I call customer.....it stuck -got the piston and cylinder... (customer ok fix it) then a 450 comes in siezed......I call customer- ok it dropped a valve, started to tie up, took out valves, piston, cylinder, cylinder head and rod.......price to fix it is about value of engine...(customer.....nah ...Ill part it out)
-Eric Johnson |
You're on the right track but it's not quite that bad....
We've seen pictures here of CR250 crank blown up and took out the cases also, not cheap.... I dropped a valve on Darcey CRF450 head, that's a $2500 head!!!! It cost me $500 to have the head welded up and new seats and valves put in, add a new cylinder, piston, and cam holder, back in business. I don't have the receipts for the parts, but far from a total loss.
The most expensive failures I have seen and that's with 4 CRF450's that were some of the top karts at that time, was rod failures like I stated before. That basically took out the cases, cylinder, top end and crank, if the head was messed up also, that would be a total loss.... Put in a Falicon, or Carillo rod, problem solved....
CR
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Roger Miller
Site Admin
Joined: 19 Jul 2001
Posts: 2923
Location: United States, California, San Jose
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| Posted: Thu Aug 23, 2012 9:19 am Post subject: |
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Been here and done this before and been shouted down before, but here goes again - the Honda CRF450 will starve the bottom end rod bearing and it will fail due to the setup of it feeding oil from the long end of the crank back into the middle and in long sweeping turns, the oil is pulled away from the bottom end. Happened with a stock rod, and with a Falicon rod, thank you.
When the bearing lets go, the rod end crashes into the low clearance cases and also the head. Both times lost the following:
Head
Valves
Cylinder - when the piston hits the head/valve, the skirtless piston wedges into the cylinder and the rings make a mess of the walls - both times
Piston and what goes with it
Rod
Cases
and one time the cam was twisted
and one time a gear in the tranny was busted
And yes, we had a bottom end fail on a CR250, and also lost those cases, but we were able to keep the cylinder and all other internal parts so it just cost a set of cases and a much cheaper head, and new crank/rod and piston assy.
And I pick up CRs off ebay for $800, and do a port job and freshen and ready to race....
YMMV |
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Greg Lindahl
Joined: 13 Jan 2011
Posts: 264
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| Posted: Thu Aug 23, 2012 10:32 am Post subject: |
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I wonder how long the CRF450 would live if it was rev limited and oiling mod's were done to the rod oiling system?
As long as CR 250's are available at low prices, it seems to be a pretty clear choice for cost vs. performance. |
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Roger Miller
Site Admin
Joined: 19 Jul 2001
Posts: 2923
Location: United States, California, San Jose
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| Posted: Thu Aug 23, 2012 10:49 am Post subject: |
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I should have included - my driver, Ryen, was very, very mindful of the RPMs, and I have the mychron files to prove, that our CRFs were held to 10K max. Upshifts, downshifts, whatever. Never cracked 10K.
And we carried this over to the start of our CR250 program as we started with the OEM ignition package, and were able to avoid the rev limiter advance spike at the end of the ignition curve. And finished 2nd at Laguna in 2006 with that configuration. |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2918
Location: United States, New York, Ossining
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| Posted: Thu Aug 23, 2012 3:30 pm Post subject: |
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Roger, I'm very sorry to hear that you had those issues, and I'm sure that it left a sour taste, but that is not typical of those motors at all. If it were typical, you wouldn't see hundreds of flat trackers and motards that run every weekend...
My experience is with 4 different karts, more than 4 different drivers, all front runner's, nobody lost a Falicon crank, a couple ran stock cranks without issues. If anybody wishes, I can give you the names and you can follow up.
Kyle Martin in a Cobalt with an 02 CRF450 won the ICE class at Laguna, 02 or 03 I believe, that was a Phil Darcey head, and a STOCK crank, I have personal experience with this motor, I rebuilt it.
PS As a matter of fact, I ran a stock crank in my motor in 03, Falicon returned the old rod to me when they did a Supercrank. I still have it on the parts shelf, I'll shoot a picture tomorrow, it looks brand new.
CR
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East Coast Super Kart Series
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Roger Miller
Site Admin
Joined: 19 Jul 2001
Posts: 2923
Location: United States, California, San Jose
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| Posted: Thu Aug 23, 2012 3:37 pm Post subject: |
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I hear what you are saying Chris, the thing I would say about anything in a 2 wheel chassis is that they are leaned over in a turn so the oil is forced downward, not sidewise as in a kart.
As I said - YMMV |
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Thu Aug 23, 2012 4:31 pm Post subject: |
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Hi Guys
I have seen exactly what Roger describes with the CRF and he is spot on with the lateral force explanation. They were never designed with 3G in mind.
In the UK they are only allowed limited tuning. The crankcases, crank, rod and cylinder and head casting must be standard O/E. No variation in bore and stroke. Original carburettor (or fuel injection). Ignition is open.
The head can be worked but valve sizes and valves must be O/E. Standard cams must be used although cam timimg can be varied. A slipper clutch may be added.
In this spec it seems that only the KTM is up to the job. It's just the overheating issue that really let's it down and we have seen transmission failures as well.
To allow what is basicaly free tuning causes costs to run away (as Chris has indicated with his head and crank costs) and when the inevitable blow-up happens the cost of replacement is just too high.
If they were super fast or handled and braked as well as a 250 2-stroke then there might be a saving grace. But in the end competitors get p*ssed off and throw in the towel. In the worst case they leave the sport.
This has to be true, otherwise there would now be grids of F450 Superkarts, which is patently not the case. In effect some competitors (like Ryen and Roger) have chosen by (expensive) experience. Others have learned the more economical way by observation.
That is the big area in which the 2-stroke scores. Yes they can and do break, but repair and race preparation is quick, easy and economical.
In the end, it becomes a no-brainer.
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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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2918
Location: United States, New York, Ossining
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| Posted: Thu Aug 23, 2012 4:41 pm Post subject: |
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| Roger Miller wrote: | I hear what you are saying Chris, the thing I would say about anything in a 2 wheel chassis is that they are leaned over in a turn so the oil is forced downward, not sidewise as in a kart.
As I said - YMMV |
I knew you were going there, and consider this: Left turn flat track 1/4 milers, are wide open the full lap. The G-Force is pushing the oil where? To the outside right hand side of the motor. The motor is a dry sump essentially, using crankcase pressure to force the oil out of the crankcase through a reed valve, into the left case where the oil pump pickup is.
The motorcycle would have to be parallel to the ground for that argument to be valid...
I know what your saying Roger and I respect what you are saying, but like I said I have followed 4 other well built CRF450's, in Superkarts, all front runners that didn't have any oil issues, so I would have to say, your issues were rare.
Here's a link to the 2003 Laguna results that Kyle Martin won the ICE class in a Cobalt chassis with a CRF450: http://www.250superkarts.com/2003%20Laguna%20Results.pdf
Not only did he turn the fastest lap in the race of ANY ICE kart in the field he finished on the lead lap which would have put him about 6th overall against the FE's!!!
And....and... that motor was an 02 the first year of the CRF450, PSR ran it 02 to 04 I believe (with a stock crank), Rob Morris bought, Rob ran it a couple of years, then it Went to Gary Slayer, he ran it a couple more years, then Bill Schmidt bought the chassis, sold the motor off to a flat tracker...
Feel free to contact any them to ask about oil related failures,, there was none.
If they are restricting the motors to stock vales size, there's no way they will perform on par with the 250's.
CR
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East Coast Super Kart Series
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www.eastcoastsuperkart.webs.com
CR2 Motorsports
"Home of Cobalt Superkarts"
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Ian Harrison
Joined: 23 Nov 2006
Posts: 1670
Location: United Kingdom (Great Britain), Manchester
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| Posted: Thu Aug 23, 2012 5:57 pm Post subject: |
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| Chris Reinhardt wrote: | The G-Force is pushing the oil where? To the outside right hand side of the motor. The motor is a dry sump essentially, using crankcase pressure to force the oil out of the crankcase through a reed valve, into the left case where the oil pump pickup is.
The motorcycle would have to be parallel to the ground for that argument to be valid...
If they are restricting the motors to stock vales size, there's no way they will perform on par with the 250's.
CR |
Hi Chris
I think you exaggerate a little What you have to remember is that the difference between the lateral G experienced on a Superkart (regular 3G) and the lateral force on a (however slightly) banked flat-tracker is absolutely astronomical and plenty engough to cause oil starvation that can be a factor in an engine failure.
The whole idea of restricting valve size and the other restrictions in the UK, is to attempt to increase longevity. it's not about matching a 250, it's about attempting to create a viable class that might be attractive to some. Unfortunately it appears this is not enough, as the class is dying (well has died in reality) on it's feet in the UK.
I respect your experience, just as you have to respect Roger's own experience and my own observations. However rare (or common), the problem is extremly onerous when it wrecks an engine that was filled with hugely expensive tuning parts in the first place.
We can all quote individuals who have had incredible luck of either the good or bad variety. It's the general experience of the cognesenti that will in the end determine viability . . . . or not
The performance and lap times look good at Laguna, no doubt, as I would expect. A fully tuned 450 should easily match and exceed a 250 2-stroke in a straightline, even if it corners and brakes like a camel on steroids. And I've no doubt that the driver was probably one of the best around as well.
So, why, in your opinion, if it was so good, has the F450 class died the death in the US in the same way that it is doing (well has done really) in the UK?
As I said, my own personal view, but it appears that, for whatever reason, 4-stroke superkarts are just not attractive to the vast majority of potential/existing competitors.
Best Regards
Ian
_________________
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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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2918
Location: United States, New York, Ossining
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| Posted: Thu Aug 23, 2012 6:18 pm Post subject: |
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We never had a F450 class here, we had a 500cc max, no restriction 4 stroke that had to compete against a 2 stroke.
I believe it's the perceived cost advantage of the 2 strokes along with the perceived simplicity of the 2 strokes.
As Roger pointed out, you can buy a used CR250 off ebay, slap a ported jug and head on it, and go racing!!!
And if winning races was that easy, and if 2 strokes were that simple, there wouldn't be many tuners, and they wouldn't be making any money at it.
No doubt Kyle Martin is a great driver, but we're talking about an American built chassis and a 4 stroke motor that beat nearly everything on the track that day.. That's saying something.....
Ian, I would be happy to continue this conversation off line, you have my email...
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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