Switch From 4 Back to 2-stroke?

[showtime586]

Ditto,,,,,,,,, ;)

I have seen broken rods in 4 strokes and I have seen broken rods on 2 strokes. The comparisons on maintenance costs are very subjective.
I do not like checking valves, but I don't like premixing either.
The 4 stroke is loud and the 2 stroke has spooge.
The 4 stroke is heavier, but has a controlled throttle response.
The 2 stroke is lighter, but is twitchy.
Bottom line, I would rather ride either one than not be able to ride. It is my only source of stress relief.

 

[marcusgunby]

Ditto,,,,,,,,, ;)

I have seen broken rods in 4 strokes and I have seen broken rods on 2 strokes. The comparisons on maintenance costs are very subjective.
I do not like checking valves, but I don't like premixing either.
The 4 stroke is loud and the 2 stroke has spooge.
The 4 stroke is heavier, but has a controlled throttle response.
The 2 stroke is lighter, but is twitchy.
Bottom line, I would rather ride either one than not be able to ride. It is my only source of stress relief.

The 4 stroke is loud but the 2 stroke doesnt need to spooge.

You have no other form of stress relief?? hmmm use the internet much? :laugh:

 

[john3_16]

I really don't think premixing is an accurate comparison to checking valves...


I don't know if the CRF's tranny oil and motor oil are seperate or not but that would be a more accurate comparison to pre mix...

But checking valves ? Seems a bit more difficult and time consuming to me... How hard can it be to pour a bottle of oil into 4 gallons of gas ?


And facts are facts....There are less steps to rebuilding a 2 stroke motor....There are less moving parts and fewer parts to be the potential cause of a major engine failure...

Yeah rod's have broken in both...But one of them doesn't have valves, cams, cam chains, cam chain tensioners ect ect...

If you have to do a top end, it'll be much easier on the two stroke...

 

[steve125]

But checking valves ? Seems a bit more difficult and time consuming to me... How hard can it be to pour a bottle of oil into 4 gallons of gas ?

Not to mention the horror, to check those valves and they measure tight. Can you say time for a valve job and the panic of no riding on that weekend? The dealers must love 4 strokes:)

Id rather mix oil and gas

 

[Casper250]

Not to mention the horror, to check those valves and they measure tight.

Checking valves takes 10 minutes tops. Take seat off(I do it any way to clean the airbox), Take gas tank off, then off with the valve cover and it's right there. You should be checking them regularly so you will know when it's time to shim.

Its the equivalent of taking a compression check on a 125 and finding that you have a low reading. If you are as strict with keeping up on maintenace with a 125, you would probably be re-ringing your motor as much as a 4 stroke needs to be shimed.

I switched from a cr125 to a crf250 this winter and the increase in power off sets the slight annoyance of checking valves and such. But, I would have to admit, I have been thinking about 2 strokes again with all the talk about the aluminum framed YZ125 and YZ250.

If and when I move to the 250 2s/450 4s racing class, I think I might go back to a 250 2s. In the 125 class though, I don't think the CR125 was as competitive for me at my riding level.

 

[DougRoost]

Casper, you're comparing Hondas only. Some of the other brands of 4 strokes require draining coolant, removing radiators, etc. just to CHECK the valves. If they require shimming it's a whole 'nother thing of removing cams, chains, etc.

Sorry, when I hear people talking about premixing as maintenance it's just ridiculous. I switched back from thumpers to 2 strokes 2 years ago and you just can't beat the smiles/$$.

 

[Chris_S]

10 minutes...wow, it takes me a lot longer than that!

 

[showtime586]

Casper, you're comparing Hondas only. Some of the other brands of 4 strokes require draining coolant, removing radiators, etc. just to CHECK the valves. If they require shimming it's a whole 'nother thing of removing cams, chains, etc.

Sorry, when I hear people talking about premixing as maintenance it's just ridiculous. I switched back from thumpers to 2 strokes 2 years ago and you just can't beat the smiles/$$.

The Yamaha manual says to drain the coolant and remove the radiators, but it is not necessary.Checking my valves may take 30 minutes or so. I don't consider mixing gas as maintenance, but it is a chore that is not required on a 4 stroke.

 

[steve125]

Checking valves takes 10 minutes tops.

I guess the word I ment to use was "adjust", Id say the time to do that is about the same as a 2 stroke top end. Thats if you have the proper shims needed and get it right the first time.

From everything Ive seen and read, once the valve clearance starts to tighten it doesn't stop, trouble is right around the corner. This means the valve face has lost it's coating and the valve seats are worn out of spec. The down time, the expense, the backordered parts, has lots of riders thinking 2 stroke for 05.

 

[gwcrim]

Yeah.... that mixing gas is a PITA! I'll tell you something else that is a MAJOR annoyance..... having to actually lift an aluminum can to my mouth so I can have a drink of beer. And don't get me started on breathing! :debil:

 

[Casper250]

Casper, you're comparing Hondas only. Some of the other brands of 4 strokes require draining coolant, removing radiators, etc. just to CHECK the valves.

Didn't know that.

I check my valves about once a month, every 3-4 races. I've actually gotten used to included checking the valves in my normal maitenance.

I'll agree that 2s maintenance is hands down alot easier to do. I just don't think that 4s maintenance is all that much worse though.

 

[DougRoost]

From an interview on RealMX with the CEO of KTM, Stefan Pierer:

Pierer: We are worldwide market leader in the 125 twostroke youth class. We also took the lead on the USA market. It was a mistake by the Japanese only to concentrate on the four strokes because they will only replace the purchase of product. Since that product is more expensive, it will reduce the market volume. Now they realise this and try hard to find solutions to keep the twostroke for the young riders alive. It is four times more expensive to race a 250 fourstroke than a 125. I don’t mean the riders salary, it is the engine technology. The chassis is almost the same but engine wise the costs are much higher. If you can afford to race at that level you should do it, but It comes close to formula one car engine technology. Even due to higher production quantity the costs won’t go down significant. The problem is that the sport regulations are done by people who don’t know what happens on the market. I have to admit, that the Japanese companies listen sometimes too much on their American fellows. Our strategic advantage is to be present global and to know what is happening to develop a long term strategy. At last we can only afford all this racing if we sell a lot of bikes to re- invest into the sport.

 

[steve125]

From an interview on RealMX with the CEO of KTM, Stefan Pierer:













It is four times more expensive to race a 250 fourstroke than a 125.

:yikes:

OK,, who are we helping out here, the racers or the manufacturers? It's all about the money :|

Is the racing now? four times better??? :bang:

 

[GhostRider32]

I love my KX. All I do is trail ride but it makes me happy. That said, I don't have any specific allegiance to a manufacturer. I've owned Honda's, Suzuki's, Yamaha's, and Kawa's and I will buy from any of them as long as they provide what I want. Head to head competition is what drives the manufacturers to build better bikes.

To me the article is saying that KTM is willing to give other options than just a four stroke. I'm all for options. If KTM makes the closest thing to what I want on my next bike, that's what I'll buy.

 

[Shig]

It's no surprise that a company who's bread and butter is two strokes is complaining about having to get with the 4-stroke program. The fact that they are preaching to consumers about corporate productivity is testimony to their desperation.

Clearly, the 250Fs need more R&D, but what about the 450s? Am I the only one getting 200+ hours out of a motor with less maintenance ($ and time) than a single top end job on a CR 250? Maybe I could be competitive on a CR 250, but only after spending an additional two or three grand to get it to run with a bone stock CRF 450. How about the reliability of a that heavily modified CR 250? With ports the size of a bay window, do you think a top end a month is saving me time and money? Since I'm much faster on a 450 than I ever was on a 250, and holeshots are no longer a fantasy, I sure would appreciate it if everyone I race against would please go back to a 250.

 

[steve125]

Remember your racing a 450 against a 250, how fair is that? And a 250 vs a 125, the old rule stinks, and forces the change, rather than having the choice.

 

[Lonewolf]

What i dont understand is why the four strokes in the 250 class went from a 400cc engine when they were first introduced in 1998 to a 450cc engine today? Why did they get to have 50 more cc?

 

[2smoke]

What i dont understand is why the four strokes in the 250 class went from a 400cc engine when they were first introduced in 1998 to a 450cc engine today? Why did they get to have 50 more cc?

Well they have always argued that the 4 stroke needed capacity advantage to be competitive with a 2stroke...but I always think they failed to take into acount the jump in 4stroke technology from F1 to MotoGP (all feeds down).

In my opinion its the same as why they chose 990cc fourstrokes to go against 500 two strokes in MotoGP. They want to push the new technology. Thus they never really wanted the old bikes to be competitive in the new class. In dirt bikes the two stroke can still be competitive...but look outdoors....just look at how much faster a factory 450 is getting to be than a 250. The 50cc increase in capacity was not necessary...it just made it a sure thing. Thanks FIM....wankers.....

 

[mxer842]

What i dont understand is why the four strokes in the 250 class went from a 400cc engine when they were first introduced in 1998 to a 450cc engine today? Why did they get to have 50 more cc?

When the YZ400f was introduced 550cc four-strokes were legal against 250cc two-strokes, Yamaha just felt the 400 to be the best place to start. It was only in the last few years that the maximum displacement was lowered to 450cc, that is why guys like John Dowd and Guy Cooper were riding 520sx's bored to 540's in '02.

 

[VB Racing]

The "old school" way of thinking is that 2 strokes have twice as many power pulses compared to a 4 stroke. Since they have twice the power pulse they make twice the power for the displacement. That would mean a 125 2 stroke would be able to compete with a 250 4 stroke. The 250 2 stroke would be comparable to a 500 four stroke. We all know this is out dated and not true anymore.
When I ice race in the winter time, the classes are 125, 250 and open. ALL 250's whether they be 2 or 4 stroke run the 250 class. You would be amazed how well 250f"s do on the ice compared to 250 2 strokes. To those of you who have never been on the ice, you have more traction than on pavement,SO, Power rules!! The 250f's fare pretty well. The 450's , on the other hand don't do so well against the 500 2 strokes and big rotaxes in the open class.
AMA needs to rethink their position on the 4 stroke rules, especially in the 125 class. My 2 cts ;)

 

[motojonny]

Shig,

You need to check your math! Also, with 200 hours on that motor, it's days are numbered unless you replace the top end and valves...$$$$$! Do you know how? I don't.

It costs me $100 to replace the top end on my YZ250(doing it myself). $400 to have it ported(mine isn't). On a tighter track or in the woods, the 2 stroke is an advantage as is.

MJ

 

[Studboy]

Remember your racing a 450 against a 250, how fair is that? And a 250 vs a 125, the old rule stinks, and forces the change, rather than having the choice.

Steve is right, the cc rules were written when the best 4-Stroke technology was modified XR's.

 

[Shig]

MJ,
Here's the math. 2002 CRF 450 x two years of hard track riding a MINIMUM of two hours per week equals a MINUMUM of 200 hours (100 weeks x 2hrs). Add five, A-Class hare scrambles in the second year of ownership. During this period I wore through two sets of brake pads, two sets of chain/sprockets, and about 8-10 rear tires. The motor was still strong enough to allow me a 4th place finish in the series.

$400 for porting sounds like a good start for a 250, then add a pipe, reed cage, case matching, gearing, head shaving, etc. and you are still several ponies shy and with about 1/2 the powerband.

Earlier, someone said that race gas made their 250 as fast as a 450. It must be Flubber if it can add 10 ponies and triple the width of the power band. I'd like to get some for my 450 so I can make it a 1-speed. Fifth gear only, that is.

Maintenance: I'm ashamed to say I never adjusted the valves once. I changed the oil and cleaned the filter about every two rides or so. Frequent oil changes are roughly the same cost of buying Maxima 927 for my last 250. The CRF ran great when I sold it, and it had the original plug in it. I will give you this though, my 04 will get a valve adjustment soon and a new piston at about 100 hours just to be safe.

I don't know how to do a top end on a thumper, but I've done about 30 top ends on two-strokes over the years. Here comes the math again. If I only have to do it half as often, who cares if it takes twice as long or costs twice as much?

Thank you MXer842 for pointing out the part of the diplacement argument that doesn't pass the sniff test. If more displacement were really an advantage in an open class (which is really what the 250 2-stroke class has become), then the 500 2-stroke class wouldn't be extinct and Bubba wouldn't be turning the fastest lap times in the world on a 125. Surely, you guys must have Open Pro and Vet Pro classes where you race. How many big-bore two strokes are dominating those classes? If you come to the line on a CR 500 everyone thinks you are at a disadvantage.

 

[motojonny]

Shig.

Sounds like your happy with the 450. You were smart to sell the 02. I only do 1 top end a year on my 2 smoke and it's going strong. One of my good riding buddies has an 02 450 that sucked a valve and the bill wasn't pretty.

Hopefully your 04 will treat as well your 02. You have to admit, there is an issue with the Honda valves and that is where it gets pricey. If they don't grenade, you laughin! Just talk to the guys at Sun Honda.

The CRF's aresweet bikes! The 05 will be nice with the new frame as well.

In the past year I have had an 03 YZ250F, 03 YZ450F, and a CRFX. The 2 strokes just work better for me. At tracks like Lakewood and Berthoud (before they tightened it up), the 450's do work really well. I ride a lot of woods as well and like the flickable 2 smoke in the tight stuff and need the ponies at altitude compared to a 250F.

It's all good! By the way, I'm in Edwards, CO. You must do the Bethoud HS and/or Millikin.

MJ

 

[Shig]

It's all good MJ. Yeah, Berthoud HS, which is really more like a desert-style MX than an eastern HS. Being 200 lbs and riding that type of terrain at this elevation makes a 450 the only logical choice for me. I'm the first to admit that there is luck involved with 4-stroke ownership. I'd probably be on a 2-stroke too if I rode primarily woods. I'm heading to Erie on monday to practice for the RMXA championships. Send me a PM if you want to meet up. I'll be #64 on the "lucky" 450.