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RFS = Racing Four Stroke

yea, get a cheap 2 stroke and have fun. My buddy has a 94 YZ250 with a fly wheel weight bark busters and and skid plate he bought for like 1300. It rips.

RFS = racing four stroke.
LC4 = liquid cooled 4-valve per cylinder / 4 stroke

Although sold in the USA as for high-performance / racing, the RFS motored bikes are sold by KTM in the remainder of the world as street-legal, dual-sport bikes. With Husky bringing all of their new bikes in to the US as street-legal last year, KTM had to respond. Before this, KTM guys would buy the wiring loom (harness) for a European spec'ed 525 or buy an after market wiring kit to add turn signals, etc.

The RFS holds about 1.2 quarts of oil. The LC4 (not SXC models of >=2003) holds 2.1 quarts. Oil does three things: carries away heat, lubricates, and carries away particulate matter (metal shavings) and acidic combustion byproducts. The shavings get stopped in the filter. Oil additives keep the pH from going acidic.

The big concern with a lower capacity on oil is overheating, as the oil doesn't stay in an external reservoir to cool off. Hot oil is thinner and doesn't form the protective film that is what forms a sliding surface within the bearings. On my 01 LC4, the down tube of the frame is the oil reservoir. On a Harley, the oil tank is under the seat. Most cars have a wet sump design, where cooling occurs by air passing over the oil pan under the engine. Motorcycles tend to use a dry sump design. Liquid cooling helps with cooling the oil, as oil that is sprayed onto the inside of the cylinder walls is cooled to 220oF by the water jacket within the cylinder walls. The absorption of comb. byproducts can be dealt with by changing oil twice as often (with half as much oil ... ).

So now you have me jonesing for a RFS or TE.

Changing oil is easy. I don't want a machine that requires an oil change after one day of riding, but changing the oil every 1000 miles is fine.

I understand that the higher-performance engines with the tighter tolerances, higher compression, etc. will burn up faster, but what are we talking about? For example, should Daryl, with his TE510 expect to have to do a full engine rebuild within the next 3 years? I wonder what people who ride these bikes hard are actually experiencing?

Are we talking about a top-end rebuild every 5 years? If so, any guesses on what that costs to hire it out to a mechanic? I'd be willing to spend $1,000 every 3 to 5 years to keep a high-performance machine on the trail. $1,000 per year is too steep. Each person has their own line in the sand.

Should I be waiting for full EFI machines to come out on the market? I keep hearing rumors that these will hit the market very soon. 2008? 2009? EFI promises to eliminate the need to rejet for altitude, better fuel economy, and improved throttle response. Many ATV's already have EFI.

PS: I'm keeping my DR350 due to budget constraints previously outlined. However, I'm enjoying this discussion and the learning process. Thanks for all the input!

Troy, I am about middle of the road as far as maintenance goes. I just ran out and looked and my RFS 400 has 136 hours on it and 2980 miles.

I keep pretty good logs, so I wanted to give you a feel for what kind of numbers you are looking at.

My engine has never been apart for anything and runs stronger today than when I bought it new. Seriously.

I do not expect to replace the piston for at least 100 more hours (2500 more miles) and expect no valve work or major head work for 200 more hours. This is very realistic for bikes that have loved an easy life like my 400 has.

This bike has been to Moab twice, Arkansas four times, Coloardo once and Wyoming once. Almost all the miles come from these "moto-adventures". VERY little street miles...but it does have a few.

It will run over 100 mph in stock form and cruises at 60 without breaking a sweat.

Maintenance...since new:

9 valve adjustments (free)

11 changes of oil ($3 a piece)

4 changes of filters ($7 a piece)

24 air filters ($6 a piece)

It is on its third set each of brakes, sprockets and chain.

That is it.

FWIW, the RFS is a VERY reliable modern four stroke. By modern, I mean a lightweight, high HP racing engine. There are many 10K mile+ engines around with no major work, but dont expect DR-like maintenance intervals and longevity. The grins you will make come at a price.

To keep things in perspective...my 400MXC brand new was $4200 OTD. It was a "leftover" sitting on the dealer floor. If I sold it today, I could still get $3k fr it easy...so my $/mile ratio is quite excellent. I will keep it another 2-3 years and will probably ride it into the ground or until it needs major work, then part it out.

As to your long thread....

You notice I ave two bikes. I dont like it...but I know that one bike doesnt do it. My 200 is for racing and woods work and the 400 is for forest roads and ATV trails. My 400 COULD be capable of it all, but I just prefer the lightness and power of the 200.

IF you need one bike, the KTM 450 EXC-G is going to be your bike. Fast, powerful and can do it all. If you are not going to be on much singletrack, then get the 525. They are great bikes and you are looking at 7-10K miles of carefree riding. Just stay on top of the oil, filters and valve adjustments and you are golden. Remember, KTM RFS engines use tappet adjusters, so a valve adjustment can be done in 45 minutes (even by an ape like me).

Dang...forgot a couple other points...

I would avoid Husky to make sure they are still around. Great bikes, but the company is in really bad financial shape and will be acquired by BMW any day now. What happens to them at that point remains to be seen.

The other and quite cheap option is to really give your DR a face lift. For less than $500, you can really make her over.

I would...

1. service the forks and shock (stock valving is fine)

2. drop as much street stuff as possible, you can drop 20 pounds here easy...I mean dump it all

3. go to big bars

4. drop your gearing a bit

5. add some mild performance mods, airbox, pipe mod airbox mod etc...Jessee seems to really know how to get some ponies for a couple of bills.

THIS would get you a much more dirt oriented bike with next to no commitment and you still have the DR reliability.

If I were Troy...this would probably be what I would do. Ten ride it for another season, then upgrade when there are all kinds of 06/07 factory street legals floating around used.

Mike gave me a heads up on you wishing for a new bike. So I thought I would put my 2 cents in.

- First off the differance between the smaller engines and the bigger ones is not only stroke, but comp. ratio. The longer the stroke the more the low end torq, the more vibration. That is why a smaller engine will feal lighter, it has less distace to move up and down. The smaller engine will rap quicker and faster. As for comp. ratio., the higher the comp ratio=more effecancy in the engine=more heat. The higher the ratio the better the gas mileage. The range binifet is good on a bike, but it is common knoladge that the fuel effecency is out weighed by the cost of the higher oct. gas.

-be carfull with the husky's. They got the sex appeal thing down, they may be a complete blast to ride, but I have been told simple maitinace like checking oil is a pain. Parts availabilty is a real issue. I sold my husky for a ktm partly becouse the lack of parts scared me!!

-Finaly you get what you pay for. The european bikes cost more, but are a better quality bike than the japanise produce.

hope this is some help, Feel free to ride mikes lc4 400 and my 640 back to back if you would like. Now where the hell is the spell check on this thing?!??!?

I do have an 07 wr450 yamaha. It is sweet. It has been said, its like a yz450 with electric start. I'm very happy with the performance and have only made two changes, throttle stop and exhaust stinger. I'm planning on taller gearing to calm it down somewhat in the woods. I have been informed that Missouri will plate this machine but I don't know for sure.

It is my dirt bike and not a dual sport in its present configuration

When you are up to it, lets go riding and you can ride it.

MoRidin wrote:IF you need one bike, the KTM 450 EXC-G is going to be your bike. Fast, powerful and can do it all. If you are not going to be on much singletrack, then get the 525. They are great bikes and you are looking at 7-10K miles of carefree riding. Just stay on top of the oil, filters and valve adjustments and you are golden. Remember, KTM RFS engines use tappet adjusters, so a valve adjustment can be done in 45 minutes (even by an ape like me).

Mo,
Why a 450 and not a 525?
Why the comment on single track?
Does a 525 have too much power when in tight places?


Troy,
Tappet adjusters are the simple ones I wrote of. A couple of open end wrenches and possible a screw driver, along with a good set of feeler guages and you can do a valve adjustment. They don't stay set as well as shim and bucket, but they are easy to adjust. Trade off.

As to the mileage figures ... I bet you can get a lot of miles out of one if you don't race it.

Another item is an aftermarket oil cooler for the RFS bikes. It increases oil capacity and cools the oil. Both good reasons to get one. I would still ride a RFS off the showroom floor straight to AR or CO.

Mike...I think the correct term is gyroscopic precession...but I might have that buggered. It is caused by the rotating mass sitting just forward and below...well you know where. The angular momentum and the effects on one's ability to turn are quite evident in three KTM bikes.

If you ride a 400, 450 and 525 RFS (which are the same weight and same bike) you will notice that they feel DRAMATICALLY different in the woods. The 400 will lean over quite easy, but the 525 does not want to lean.

A KTM 453 (aftermarket) is a big bore, short stroke 400 and will turn about the same as the 400. The OEM 450 is about the same bore, but a longer stroke...you can feel the difference.

The 525 is is the shiznit in the power department. If you think a 640 feels fast...try a 525, it will literally pull your fingers numb. They are the bomb in open stuff and forest roads. They are capable on ATV trails. They are tough to turn on single.

As for Troy...since he will not spend a ton of single track time, it may be the best bike. The 525 can carry a higher gearing and as a result, can limp down the highway at 60 mph at a fast idle. Plus he can pull man-sized wheelies and outrun most crotch rockets for the first 1/8 mile!

I really appreciate this technical discussion and the advice. I'm sure others will benefit as well.

troy wrote:I really appreciate this technical discussion and the advice. I'm sure others will benefit as well.

Yep, nice posts MoRidin!

MoRidin wrote:Mike...I think the correct term is gyroscopic precession...but I might have that buggered. It is caused by the rotating mass sitting just forward and below...well you know where. The angular momentum and the effects on one's ability to turn are quite evident in three KTM bikes.

If you ride a 400, 450 and 525 RFS (which are the same weight and same bike) you will notice that they feel DRAMATICALLY different in the woods. The 400 will lean over quite easy, but the 525 does not want to lean.

A KTM 453 (aftermarket) is a big bore, short stroke 400 and will turn about the same as the 400. The OEM 450 is about the same bore, but a longer stroke...you can feel the difference.

The 525 is is the shiznit in the power department. If you think a 640 feels fast...try a 525, it will literally pull your fingers numb. They are the bomb in open stuff and forest roads. They are capable on ATV trails. They are tough to turn on single.

As for Troy...since he will not spend a ton of single track time, it may be the best bike. The 525 can carry a higher gearing and as a result, can limp down the highway at 60 mph at a fast idle. Plus he can pull man-sized wheelies and outrun most crotch rockets for the first 1/8 mile!

Good description. Thanks for clarifying why the different bikes were made and bought.

"Gyroscopic effect" would be a better term. (Precession is the wobble in the spin axis: http://en.wikipedia.org/wiki/Precession.)

Mostly what I described as rotational inertia / rotational momentum / rotational kinetic energy. Rotational inertia depends on two things: the mass (weight) and its location WRT to the axis of rotation (radius). The larger either value, the more inertia. Inertia comes into play with both rot. momentum and rot. KE.

For bicyclists ... this is why expensive wheels are very light weight. Most of the mass is in the rim, the largest distance, and thus, the largest inertia. This mass resists rotational acceleration (translational ... forward ... acceleration) AND resists changing the axis of rotation ... turning right or left, or leaning the bike. The rotational inertia / momentum is what gives a bicycle or motorcycle its stability when moving. (This is why those basement trainers for bicycles work ...) Of course, if the rim is too light the bicycle has little stability. The same principles apply inside the motor with the spinning mass of the crankshaft, con rod, and piston. The relationship is a bit complex as the con rod and piston aren't exactly spinning ...

The KTM 450 and 525 have the same stroke (but different bores). The 400 doesn't appear to be available any longer.

If you want to geek out:
http://en.wikipedia.org/wiki/Flywheel
http://en.wikipedia.org/wiki/Rotational_inertia
http://en.wikipedia.org/wiki/Rotational_energy

Thanks again, Mo!

BGG wrote:Mike gave me a heads up on you wishing for a new bike. So I thought I would put my 2 cents in.

-be carfull with the husky's. They got the sex appeal thing down, they may be a complete blast to ride, but I have been told simple maitinace like checking oil is a pain. Parts availabilty is a real issue. I sold my husky for a ktm partly becouse the lack of parts scared me!!

Well my pain is under control now with new drugs, but I feel as drunk as a sailor on payday! I have looked through the thread and I feel like I have to defend the Husqvarna name. BBG who ever told you that checking the oil on a Husky was a pain is simpley wrong! It is a low tech method of taking out a screw (oil check screw) on the right side of the engine. If the oil drizzles out then it is full. Replace the screw and you are ready to ride.

The availability of parts is wrong too! What happens when you go to LetKo for a part on your KTM? They either have in stock or they order it. Well guess what! The same is true for the Huskys!!!! Here is another secret, Huskys and KTMs share a lot of the same components, for example brakes. There is also another route you can go and order all of your parts from Hall Cycles http://www.halls-cycles.com/ they will likely have it in stock and will be on your doorstep in two days. Please don’t spread rumors, get the facts first.

Now that I have that off of my chest Troy I would encourage you to search Thumper Talks Husqvarna message board. There have been several and threads comparing the KTMs to Huskys. Here is one example http://www.thumpertalk.com/forum/showth ... p?t=486115

Troy this may shock you but I think you should buy the KTM 525. It will handle the roads/gravel very well and will be above average on the single track. The close gear ratios on the Huskys just don’t avail themselves to easy riding on the longer stretches of gravel or the commuting to work. Don’t get me wrong the Husky can do these things, but I believe the KTM will do it better.

Just an FYI Troy Halls has a 2006 TE 450 with 8 miles on it for $4,995.00. Check out their used bike section.

Daryl

Didn't mean to offend on the Husky stuff. I stand corrected on the oil level check thing. As for parts, When I was trying to rebuild the forks on my 610te e the parts were no longer available. Letko is the local source for both KTM and Husky, but there seem to be more Ktm's on the trail than husky's. I like security in numbers and would bet that all the ktm's out there will keep parts more availble..
-The reality is both the KTM 525 and the Husky 510 are more bike than 90% of us can use, but I sure like to try!!! Ether one would be a blast. MY only concern is witch one is less likly to get flats so I can quit using Troy spare tubes!!!-BGG

Consider the user community. Only KTM's come with http://www.ktmtalk.com as standard equipment. It's incredibly active, with thousands of posts every week. Standard mods, tricky troubleshooting, it's all there in detail. It's like having a real time moto encyclopedia. If you pull something apart and can't remember how it goes together, at, say 2 AM, just post it and some bloke from Egypt or Thailand will set you straight right away. The Husky's just don't have that many owners and that much active expertise.

I think the only thing the KTM Racing Four Strokes don't do well (but they WILL do it) is a 250 mile day on pavement. But who wants to ride pavement anyway? They are great, great on fire roads or single track or gravel. You can find a used plated 400/450 for maybe $3000 or less. People put all sorts of aftermarket stuff on these KTM's but they do it because they want to, not because they need to. They were ready to rock, straight out the box. The newer models have some advantages, but so what? You don't have to give up $7000 to get on an orange bike.

Greenboots wrote:Consider the user community. Only KTM's come with http://www.ktmtalk.com as standard equipment. It's incredibly active, with thousands of posts every week. Standard mods, tricky troubleshooting, it's all there in detail. It's like having a real time moto encyclopedia. If you pull something apart and can't remember how it goes together, at, say 2 AM, just post it and some bloke from Egypt or Thailand will set you straight right away. The Husky's just don't have that many owners and that much active expertise.

I think the only thing the KTM Racing Four Strokes don't do well (but they WILL do it) is a 250 mile day on pavement. But who wants to ride pavement anyway? They are great, great on fire roads or single track or gravel. You can find a used plated 400/450 for maybe $3000 or less. People put all sorts of aftermarket stuff on these KTM's but they do it because they want to, not because they need to. They were ready to rock, straight out the box. The newer models have some advantages, but so what? You don't have to give up $7000 to get on an orange bike.

Well Chris I have disagree again, thumper talk has a wonderful blog for the Husky community http://www.thumpertalk.com/forum/forumdisplay.php?f=79 I believe that is the second most active page behind the DRZ site. Check it out. Plus I like being a little different so that is why I went with Husqvarna. Either way Troy goes it will be huge step out for him.

Husky's are way under rated. They are solid bikes with a thin dealer network, but parts are not a problem as a rule. This from a KTM owner

I was seriously thinking of picking up a WR125 one time, then when I sobered up, I realized that was probably not a great idea

Hi Troy, thought I would give you my 2 cents. If you like your DR350, you will probably love the DRZ400. The DRz400 is Suzuki's next generation bike with a bullet-proof reputation and plenty of after market farkles. These bikes are plentiful and readily available used. The DR650 is good for moderate off-road use, but I'll be looking for a DRZ as my next bike for all-around use.
WR450F - one of the guys riding with us this weekend was on a WR450. Seemed to be a well-behaved machine, with plenty of power and a great suspension. He was from Idaho and his bike was street-legalized. The only drawback might have been fuel range, I would bet a larger tank is available.

One of my criteria for a bike is cheap maintenance. I'll take reliability and durability over a bike I have to wrench on after every ride or pay for expensive engine repairs after a relatively short amount of engine hours. I guess everything is a balance of plus and minuses.

Like you I had a DR350. Great bike, wish I still had one. If mine had the magic button, I would still have it. I know Mike S. has the KTM400 LC4. After riding with both 640s and 400s, I think I like the characteristics of the 400 better. The engines seems alot smoother.

Daryl Perry wrote:Either way Troy goes it will be huge step out for him.

You know, that sentence taken out of context could be embarrassing for me.

All this info is great. Any of the bikes discussed would be good for a "next bike". BUT---- just keep in mind that no matter what bike you get you're going to wish you had purchased the other one. Also keep in mind that more power could equate to more hurting body parts.

Good luck Troy, David H