4T Fiasco

240 hours out of a 4t top end? That would be cool. I was getting around 80 hrs on my '06 KX250. If I was a faster rider I probably would get less though. I imagine I'll get 40-60 hours out of my 144. I also have yet to smash a pipe (a guard goes a long way to prevent that.)

If your compression is 12:1 or greater the min. octane should be in the 96 or above range. You can get away with less if it's jetted a little rich, at a higher altitude, the timing is backed off a little or you ride it easier like trail riding compared to competition. If it's on the edge tuned for max horsepower in good air and a 12:1 engine you won't get away with using pump for long.

I'm not saying 2ts last longer than 4ts only that when they both break, and they will both break, there is a long list of expensive parts that the 2t guy won't be buying.

I should have added that just because the advertised compression is 12:1 doesn't mean that it is. Most factory production engines are built with a safety margin so unless you blueprint the engine you're probably quite a bit below that. A true 12:1 engine with a reasonable camshaft ground for some mid-range power will have a cranking compression in the 225psi range.

Lot's of guys getting a lot more than 240 hrs on the stock top end. I have 336 ish on my 07 TE, which is gonna get looked at due to a severe watering out last summer.
Many guys out there with 4&500 hrs on competition 4ts.

It really really depends on the motor, combustion chamber shape, size, and how it's set up, machined and a whole bunch of other factors;
1967 Small block chev 302 Trans Am race motor 12:1 - definitely need race gas.
2007 Stock husky TE250 - 87-91 octane is fine in almost all conditions.
Some cars are coming out in the next couple years that will have 14:1 comp on regular pump gas.

Some bikes will break, some won't; both 2ts and 4ts. Read the entire thread and there is enough evidence shown that narrows the overall ownership cost differential to almost a wash.

It looks like I better run out and rebuild my 2003 GASGAS twice and repack the muffler 150 times so that it will be a "wash" when you rebuild your 4t. LOL

Interesting topic, 2t-4t. I have seven bikes, most are 2t, 1994 and up. If I was a dealer I would be pushing the 4t to sell, but I'm a buyer of used bikes and I wouldn't buy a used 4t.
except one that is extremely cheap. When ktm or husky or anyone else makes a fuel injected 400cc 2t, sales of the 4t will fall big time. Because the only one that will buy
a 4t will be someone that doesn't know much about bikes. Better fuel millage, use very little oil in the mix, lighter, faster, and less polluting. Look at mercury outboards and evinrude.
That's the future dirt bike engine. A plain ole 2t fuel injected 400 engine, will stomp all the 4t high performance 450's out there.

When you buy a 4t Motocross type bike now, you are getting a real race engine with all the headache's that go with a race engine.

Sorry 2t's dirt bikes are the future, sound strange, but all it takes is a bike manufacture to bring out an engine like mercury's. pass the epa and carb with flying colors and its green sticker time,
something the high performance 4t's can't do now.

I like my KLX300, but it aint a kx250 or my 250 wxc by far.

Ohhh if you switch over to a 2t and never owned one, you have to shift alot more
Mike

Well you are a dealer, right? People will buy what is raced, what is raced is what wins. Because there is a ban to race major races with two stroke's, and it's not because of a little puff of smoke
that comes out of the exhaust, it's because a 250 two stroke will beat a 250 four stroke and on and on. The mercury and evinrude outboards weigh way less than the four strokes
that have the same hp rating. Direct injection to a two stroke bike, I would think, would weigh less than a carbon fibered, exotic metals, made to the limits four stroke, and the two stroke
wouldn't need all that weight saving expensive stuff. Plus you can toss a piston and rings in it for 150 bucks, and you have a new motor (clean up your power valves too)

So my thinking is when its built, when its approved, (by carb,epa,AMA), what choice would they have if the bikes pass easy.
any one hoping that the 2T will stay banned, just to keep the 4t alive, should check into lake Tahoe boat police on the most restricted lake in the country.
two strokes have been banned on lake Tahoe for a long, long time, except the DI injected two stroke, and guess what the water cops on that lake run on their boats?
DI injected two strokes, why? because they don't pollute as much as the 4t counterpart.

the DI two stroke will win races, lots of races. Then the pro's (that get their bikes free anyway) will have to
ride the better 2t to compete. Which means Honda and the rest will have to make DI bikes to stay in the dirt bike biz, and of course they will have their riders ride them in races.

What choice do they have? most get a free bike to race don't have to maintain them, and don't get offered many 2t, so yeah they ride 4t.
Taddy is one of the few that rides a 2t, that I know of. He's almost untouchable on the track.

But any way, big diff. between a guy who spends nine thousand dollars to buy a bike he has to pay to maintain, just to race once in awhile and play on the rest of the time
Than a pro rider who does it for a living. Given a choice I think the bike buying bunch, would buy a bike that is a few thousand cheaper, its faster, lighter, it's cheaper to maintain
and would last as long if not longer for him/her, and be way fun to ride.

People buy what the pro's use and win on, that's what racing is really about, selling bikes. Malcolm Smith was part of a new world when he started racing and selling
That little beast called a husky, it made all four strokes that raced at the time go away, the 2t was a better faster lighter bike at the time.
If the four stroke came out later as it did, and was way better than the 2t, then replaced it. I wouldn't have anything to say about it. The four stroke didn't
replace the 2t because it was a better bike, it was political. The exotic four strokes we have now have gone almost too far, the cost, the racing engines just to make a decent trail bike
and still an older design, basic (chain saw motor) 2t can be competitive against them. If there were any big bore 2t around to race them.....soon, I'll bet.

If I was a dirt bike dealer, I would be so up on this stuff, cause in that biz, the wind can change so fast. I wouldnt want to be holding 15 or so 10000 dolar bikes for a few years.

I dont get it??
Mike

I'm going to get crap over what I wrote above
Anyone interested, should check out the Evinrude site and learn about DI injected 2t motors. You know the outboard industry
went through the same changes as our bike industry, political pressure and (who was that manufacture?) Honda that's right. forced the industry to
get out of the 2t biz.

Well a hero came from that battle, and it's a well known little company called Evinrude, who not only refused to put their meager
funds into high tech expensive 4t racing engines for their outboards, they came out with a 2t DI engine that weighs less, out powers,
gets better gas millage, and beat all the 4t outboards out there in the pollution dept (the 2t was cleaner).

The tech. is here, has been for a while, its proven itself. I'm not a two stroke four stroke whatever guy, I just want the best for my money.
whatever I found out, I don't mind sharing.
Mike

Mike-
You must be new around here.....
Pretty much everyone has been talking about the DI 2t holy grail for years now -on this board and every other one. Riders want it, mfr's are rumored to be building one, but each year the carrot is still hanging out there. I'd probably buy one if it showed up in a ~200cc size.
Skidoo has had it for a few years, but there's been some grumbling about short engine life on snowmobiles with it, and it does add at least $1000.00 to the cost of the engine.
I'm not sure why you feel that a 4t rider has to pay to maintain their bikes, I've owned both types and do all my own work (except suspension rebuilds/revalves), not that the modern 4ts require all that much;
gas and go for 5-15 hours(depending on bike), change oil(10minutes), gas & go 5-15 hrs, change oil, gas & go,, repeat, repeat, check valves around 40-50 hrs (1/2 hr or so on a Husky - big deal......) gas & go.
Yep - a whole lot of time and money.
I spend waaay more time washing my bikes than anything else.

Ride what you like

I was referring to the guy that buys his own bike as opposed to a pro that gets his free, and all the maintenance gets done for him/her. That would be for a two stroke too.

I actually like the four stroke bikes, but really think it's a stretch to say a 4t costs less or the same to maintain or repair than a 2t. In the short term the maintenance is
about the same, but when you get into valve adjustments, top ends or worse, a blown engine, there's no comparison. On most 4t's you can't even adjust the valves
the old fashion way, you need to use shims.

I like my klx300, by far not a full blown racing engine, since 2002 when I bought it, no top end yet, but a 300 dollar valve adjustment at the dealer.

My 99 kx250 has had one top end and runs like new, for sure this bike has been babied and taken care of, its whole life. I can do all the repairs on the two stroke short of cracking the case But the klx is too complex for some things, I could probably do a rebuild on it, but it isn't going to be a two hour job for me, and I can't do a valve job at home. If I went to the trouble of popping the cyl. off to do a top end, I would for sure have a valve job done to it.

I spend more time washing the bikes too.....

ohh anyone want to see video's of DI 2T V High performance 4t check this out from 2005....http://www.evinrude.com/en-US/Videos/Etec-challenges/Hole-shot

Mike

Direct injection is not just for 2ts, Hyundai already has DI 4t automobiles. I drove one and they have linear feeling power like an electric motor. Once DI 2ts come out on motorcycles the 4ts will probably have to go to DI to try to keep up.

Lets face it, if 2ts weren't handicapped there would still be no 4ts in the smaller engine classes. Once the engine produces more power than you can use cc is not the determining factor and weight savings is the only advantage gained. A bigger 2t like a 300cc would still be able to make more midrange power to compete with the 450 4ts

I'll bet there will be a DI 2t motorcycle in production before the production of slowpoke's 14:1 car of the future that runs on 87 octane. lol

I would like to see an open class (run what you brung) format in racing that allows anything including superchargers, DI, nitrous, electronics with the only constant being fuel. That would bring new ideas to the forefront and show what really works rather than the change the rules until the big manufacturers have what they want to sell winning. Hill climbing is about as close as it gets but with no factory involvement not much money is spent in the R&D dept.

Nobody here said, or tried to say, they cost the same to repair, the issue is the OVERALL ownership cost and that the cost to repair the modern 4ts has come waaaaay down from the 2003 era when spending $2500.00 on a top end wasn't uncommon & it had to be done every 40-80hrs or so.
Now they cost much less to repair & last a lot longer than they used to, bring the OVERALL ownership costs closer in line with a 2t. OVERALL OWNERSHIP COSTS, I repeat; OVERALL OWNERSHIP COSTS....
I'm not sure what conspiracy theories you've been reading about valve adjustment on a 4t, but it doesn't take that long(espec. on a husky), shims are only a few dollars each, last forever & can be traded around.
I just sand mine down a bit when they need it which is only every couple hundred hours or so, on one or two valves. Big deal......
I've seen too many guys stuck in the past about these issues and having trouble seeing what the present reality is.

Ride what you like.

Back to 2011......

Kelly,

Most people aren't as educated as you when it comes to choosing their next bike. They walk in to a dealer and the salesman sells them what they have or want to sell. I think Husky and GASGAS and KTM owners are probably a little more independent in their thinking and don't follow the mainstream marketing.