Hi all, just want to put the feelers out there.
Now Australia doesn't adopt the CIK rules in there entirety which not only would it make all of the purchasers of my crankcases ineligible to race in Australia but in my view it’s a very good thing we don't as many of their rules are made up purely to line there pockets with manufacturers money which inturn is then passed down to us, the racers.
With top 250 twin engine packages now days costing in the high teens to low 20's in thousands of dollars, where are we going?
I just really want to know if someone could and should start 4 stroke developments for this class in Australia which if successful could lead the world into it. How good would that be? I'm not necessarily talking of being eligible for winning a Championship while competing with it, just running with the rest of the class.
A few years ago, there was a UK based engine development called the Maxsym GP500 and GP600 of which the company made 10 units. The GP500 was to compete in the 250 International class and they had incredible potential but for a few reasons, (A large one of them being the CIK hand brake) the company went into receivership.
Now the GP 500 had the correct torque characteristics, HP and the lack of weight to do the job and started at around 8000 pounds. I think and they were taking pre orders and spent money like big companies do. They spend heaps of money on marketing strategies, tooling and other expensive assets which are liabilities, without really knowing the market they are dealing with.
I think it can be done and I think with the correct manufacturing, design and component selection, this could be done via a very small prototype run combined with being able to be bolted onto a 250 chassis without modification and most importantly without upsetting the balance of the kart.
Comments please!! :-\ :-\
Regards Scott
Comments11
Re: 250 International Engines
As you know, if you blow up or have engine bugs in a 4T for whatever reason, (not maintained properly/over reving/etc etc) you need to be carrying a spare engine to swap at the track. You cannot rebuild a 4T at the track between races like we all currently do with 2T.
The other problem is rules/control of engine mods. If you make a "No modification" rule, the reliablity will remain high on the engine, but try police against engine mods in 4T inspection would take a day per engine....valves, valve springs, cams etc etc etc. There is so much to be gained with internal engine mods with 4T.
So my recommendation/comments on this is;
1) the cost of the engine has to be such that we can afford to purchase 2 units each, not just 1 unit
2) an open mods engine policy (to make engine inspection easy) but have a controlled intake resitictor plate to give back some reliability.
3) The need to be able to swap engines is paramount to continue racing at the track.
The final and upmost issue is that it has to be proven to be accepted.....accepted by the people racing and accepted by the governing body.
Re: 250 International Engines
Mate Bill Wilson and Owen Davies are already on the case and already have CRF450 bolted to a chassie up here in NSW. Its fuel injected and is at the back of the 250 national field. But with a bit more tinkering ( and these boys dont mind a bit of tinkering in the shed ) it has the potential to do big things not to mention it sounds nice going past as well. they run it on pump fuel the only thing with that specific kart is it doesnt have the starter motor onboard so they carry a seperate starter motor around.
It is very reliable and the engine is straight out of a 09 CRF 450 no special ignitions or power jet carbies just a box stock engine.
Basically they bought the whole bike removed all the engine and wiring harness etc. sold the bike frame and mounted the engine on the chassie and starter plumbing and wiring.
It looks good and from what i have spoken to them about eits totally different to drive. Bill even thinks its more enjoyable
Re: 250 International Engines
I'm talking about building and using a prototype engine in the class at race meetings not building, selling and using customers to do the durability testing for me first up like most of the inline manufacturers.
My design will not require the purchase of 2 units because there would be proven durability first and no need for mods unless the top 5 runners all have them. Also no valve train to fail!!
A restrictor plate (if necessary) would be fine to try to discourage modifications.
If it can't be used in the class as a one off testing unit, who would build one? Its pretty hard to prove anything without using it first.
Thanks Jay,
Unfortunately modifying a bike engine is not what I'm talking about. They just don't cut it, for the 250 International class anyway. If successful they will be the first ones to modify a 4 stroke bike engine and get it to do everything that is required on a kart and be up the front of the 250 National fields.
Re: 250 International Engines
Re: 250 International Engines
If it can't be used in the class as a one off testing unit, who would build one? Its pretty hard to prove anything without using it first.
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Scott,
If your keen to do it, build one and run it at AASA meetings. I'm sure VIC club would mod it's AASA 250 Int rules to allow it to be used as "experiemental class" for vision into the future of webmastering.
Same can be said for NSW Club as the CRF450 is running our AASA meetings, so you will have a place for it to run.
On the CAMS front, it would need to be first lobbied as "experiental for future growth". This is how Rotax Max started in webmastering to succeed over the 100cc Clubman as a non gearbox class.
The Big Dilema is...... someone first needs to drive the project and put their hands deep in pockets to get the first prototype engine out there for the testing...... that could eventually turn pear shaped.
Re: 250 International Engines
I fail to see what you mean by modified bike motor? The engine im refering to was surgically removed from the bike and mounted to the chassie the same way you would mount a 2t bike motor to a chassie. The engine has not been "SPLIT OPEN" at anytime to my knowledge. And from what i have perosnally seen from when it first came to the track to where the kart as a project is now, it wont be long before it will be at the pointy end of the National class.
Obvously when you ubdertake a project/ prototype of this nature there are gong tpo be teething problems but like i said it is agood thing. You dont worry about jetting, mixing fuel and oil, just change the engine oil each race meeting roll it out of the trailer and go skidding. I think its a great idea.
But what sort of engine are you considering constructing wouldnt happen to be a rotary would it?
Re: 250 International Engines
And from what i have perosnally seen from when it first came to the track to where the kart as a project is now, it wont be long before it will be at the pointy end of the National class.
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Jay,
Let's get one thing clear. A standard 450cc 4T dirt bike engine will NEVER be competitive to any 2T 250 single, be it Rotax 257, CR250, YZ250. This has been done to death in the USA with very smart people.
A full modded CRF450 may keep up to some good 250 2T singles but the really good 2T 250's are still way in front.
A full modded CRF450 will shite itself very quickly in a webmaster application for MANY reasons, not just one.
If they were a good thing, it would have taken off in the USA, instead on the West coast there are over 30x 250 singles - Rotax 257, CR250, YZ250.......and guess what....NOT ONE 4T 450cc anymore.
Re: 250 International Engines
You dont worry about jetting, mixing fuel and oil, just change the engine oil each race meeting roll it out of the trailer and go skidding. I think its a great idea.
[/quote]
WTF? Oh I get it now. That's when it drops it's guts all over the track.
Re: 250 International Engines
Re: 250 International Engines
To give an example a standard yhammy YZF 250 four stroke , puts out about 30-32 hp at the wheels modified maybe 34hp, your 250 CR HONDA or say 257 rotax are in the 60-64 , depends on whoes dyno as they can read quite different, but again its generally double or more capacity to get the same power. :)
Re: 250 International Engines
Scott,
I fail to see what you mean by modified bike motor? The engine I’m referring to was surgically removed from the bike and mounted to the chassis the same way you would mount a 2t bike motor to a chassis. The engine has not been "SPLIT OPEN" at anytime to my knowledge. And from what i have personally seen from when it first came to the track to where the kart as a project is now, it wont be long before it will be at the pointy end of the National class.
[/quote]
Hi Jay,
Below from one of your posts is what I’m referring to when I said "modified bike motor".
You said,
"Its fuel injected and is [u]at the back of the 250 national field. But with a bit more tinkering ( and these boys dont mind a bit of tinkering in the shed ) it has the potential to do big things [/u]not to mention it sounds nice going past as well. "
Feno
As Nat 22 suggested, that book is one of, if not the best for measuring clearances/tolerances and general theory for 2 strokes. However, as Sam said, a lot of practical trial and error and back to back testing needs to be done with literally hundreds of component types and modifications to get the very best out of any engine.
Paul, yes your general rule of thumb capacity for 4 stroke vs 2 stroke is correct.