2007 Final Year of Honda CR Line 2 Strokes
- Thread starter Chili
- Start date
I don't know why you guys are surprised by this. If you look at their history over the last 40 years it's pretty clear that Honda has ALWAYS been a four-stroke company that only built two-strokes to support their competion efforts. Except for the short lived MT250 and a couple of cool Japanese market niche bikes they never built a two-stroke street bike line. Their industrial market engines have always been four-strokes as well.
Yamaha on the other hand brought us the DT series, RDs, two-stroke sleds, two-stroke out boards etc. They have always been very much of a two-stroke company. From a business standpoint it makes no logical sense for Honda to continue to build two-strokes, and it makes no sense for Yamaha to STOP.
Yamaha on the other hand brought us the DT series, RDs, two-stroke sleds, two-stroke out boards etc. They have always been very much of a two-stroke company. From a business standpoint it makes no logical sense for Honda to continue to build two-strokes, and it makes no sense for Yamaha to STOP.
motometal said:
Care to explain ?
Big H and the 2 strokes...
:laugh:
Inner Sanctum memo at Big H:
Our CR line is gettin' older and we aren't making money hand over fist anymore. What should we do?
(Tick, tock, tick, tock)
Aw forget about it. Accounting says we make more money on the thumpers. Push those! PR just called and said to call it an environmental move. :whoa:
Planning just called and said to release a statement. Sales will rise. If were low on 2007's we'll just build more! :ahhh:
:laugh:
Inner Sanctum memo at Big H:
Our CR line is gettin' older and we aren't making money hand over fist anymore. What should we do?
(Tick, tock, tick, tock)
Aw forget about it. Accounting says we make more money on the thumpers. Push those! PR just called and said to call it an environmental move. :whoa:
Planning just called and said to release a statement. Sales will rise. If were low on 2007's we'll just build more! :ahhh:
The UniCam has not exactly been a slam dunk reliability/maintenance cost wise due to the intake valves. I acknowledge that sometimes we must move backwards first to go forwards. In my opinion, Honda has sacrificed some of the values the company was built on. Not limited to four strokes...comparing a 2001 and 2002 or newer CR250 side by side shows a real contrast, in my opinion.
MTK, do you have any thoughts on this since you own two bikes similar to my reference (I used to)?
For example, the cheesy DID rims on my '03 developed flat spots within a month or two of riding, the rims on my '01 (these may have been Takasago) were still great after two seasons. When I sold the '01, I swapped wheels (shhhh!). Some of the changes were in pursuit of reduced weight, some were in my opinion also to decrease build cost. My friend uses his rear brake agressively, on his '00 never a problem but on the newer Honda it was constantly overheating and fading.
Sorry, off topic a bit but still Honda.
My next new bike may be an '06 or '07 YZ250. Even if it doesn't handle quite like a Honda, a great overall pacakge from a company comitted to keeping the 2 strokes going, for now at least.
MTK, do you have any thoughts on this since you own two bikes similar to my reference (I used to)?
For example, the cheesy DID rims on my '03 developed flat spots within a month or two of riding, the rims on my '01 (these may have been Takasago) were still great after two seasons. When I sold the '01, I swapped wheels (shhhh!). Some of the changes were in pursuit of reduced weight, some were in my opinion also to decrease build cost. My friend uses his rear brake agressively, on his '00 never a problem but on the newer Honda it was constantly overheating and fading.
Sorry, off topic a bit but still Honda.
My next new bike may be an '06 or '07 YZ250. Even if it doesn't handle quite like a Honda, a great overall pacakge from a company comitted to keeping the 2 strokes going, for now at least.
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motometal said:
I know you are aware that has nothing to do with it being a single or dual cam design, it's a function of material costs and performance/design decisions. It's something every company has to contend with if they want to make competitive power and still sell at a competitive price.
High rpm four-stroke singles that make 140 + horsepower per liter will be by their very nature maintenance intensive when compared to engines that made half that power at 70% of the rpm. Simple math really. Maintenance will always be proportional to how fast you spin an engine, and more importantly how fast you need to accelerate the valves to make it breath.
If customers expect higher specific outputs and more usuable power spreads each year while at the same time demanding that the price increases be kept to a minimum something has to give and in this case it's the service life of some critical components due to material issues. The same thing has happened to two-strokes over the years, but the power levels have remained consistent long enough for some people to have forgotten how long pistons, rings and cranks used to last.
Kettering said it best, "the price of progress is TROUBLE" :)
Introduce a direct injection two-stroke MX bike with it's associated costs and teething issues and people will be lining up to bitch about that soon enough. ;)
True and True.
After posting and going back out to the garage to mess with bikes (again), I started thinking about performance vs. reliablilty. As you suggested, it becomes a matter of performance expectations vs. durability/longetivity expectations.
Although many of the mx bikes sold (I would guess a majority) aren't used for serious racing and are owned by play riders, the whole market is driven by racing and performance. There has been an expectation of quality and durability developed in our minds, becuase of how great dirt bikes have been for so long.
The other side of the equation...bottom line-these are racing motorcycles regardless of how any individual chooses to use them. Racing machines of most types are built to perform well through the race, regardless of what sacrifices must be made. If critical, expensive engine components must be changed every couple races in the pursuit of a few more horsepower, then so be it (on a full race machine). Another example...I mentioned damaged rims...a flat spot on a rim probably wouldn't prevent one from finishing a race, so the lightest possible rim would be best for racing even if it's ultimate strength is lower. Conversely, the average play rider expects the rim to stay round even with several hard hits, and doesn't really care if it weighs 63 grams more than the ultimate "racing" rim.
If it weren't for magazine tests and the readers egos (most riders could go just as fast with a few less hp but they either don't realize it or won't admit it to themselves), the mx bikes could come standard with a bit more conservative components (a bit milder cams, SS valves inteaad of titanium, pistons with longer skirts, etc.) which would give more than enough performance for 90% of the riders. The hard core A class racers or anyone else that feels they must have ultimate performance, could buy the bolt ons as required.
After posting and going back out to the garage to mess with bikes (again), I started thinking about performance vs. reliablilty. As you suggested, it becomes a matter of performance expectations vs. durability/longetivity expectations.
Although many of the mx bikes sold (I would guess a majority) aren't used for serious racing and are owned by play riders, the whole market is driven by racing and performance. There has been an expectation of quality and durability developed in our minds, becuase of how great dirt bikes have been for so long.
The other side of the equation...bottom line-these are racing motorcycles regardless of how any individual chooses to use them. Racing machines of most types are built to perform well through the race, regardless of what sacrifices must be made. If critical, expensive engine components must be changed every couple races in the pursuit of a few more horsepower, then so be it (on a full race machine). Another example...I mentioned damaged rims...a flat spot on a rim probably wouldn't prevent one from finishing a race, so the lightest possible rim would be best for racing even if it's ultimate strength is lower. Conversely, the average play rider expects the rim to stay round even with several hard hits, and doesn't really care if it weighs 63 grams more than the ultimate "racing" rim.
If it weren't for magazine tests and the readers egos (most riders could go just as fast with a few less hp but they either don't realize it or won't admit it to themselves), the mx bikes could come standard with a bit more conservative components (a bit milder cams, SS valves inteaad of titanium, pistons with longer skirts, etc.) which would give more than enough performance for 90% of the riders. The hard core A class racers or anyone else that feels they must have ultimate performance, could buy the bolt ons as required.
motometal said:
The original 1998 YZ400F was built with steel valves and was in many ways overbuilt for a race bike. The result was a bike that was a bit overweight and other than a few first year teething problems was stone reliable. The maintenance requirements were simple and it probably set an unrealistic expectation for things to come. As the bikes evolved we got a much higher level of performance. Along with that performance came more radical cam timing and lighter parts to survive the new levels of valve acceleration employed. Pistons got even lighter and lost a compression ring in the process to reduce frictional losses at high rpm. Specific output reached unprecendented levels, and in exchange for this amazing increase in performance we also got shorter maintenance intervals that can't be trifled with.
Was it worth it? It's hard to deny how good the bikes have gotten compared to the 98 YZF, but that performance has come at a definite cost. People who feel the OEM service intervals are a scam to sell parts often find out the hard way how short sighted that thinking can be.
It appears that Honda built the new CRF150R with steel valves which would imply more conservative valve timing than they could have used, and maybe a nod to reliability as a higher priority. I guess it remains to be seen what the future holds.
I have a CRF150R coming from Service Honda that I'll be ripping apart to see if some of the important questions can be answered before people start breaking parts.
Stay tuned, it should be interesting. ;)
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Sorry as I'm sure this has been asked and answered many times, but regarding the CR450 conversion to SS valves (Kibblewhite, etc.), after an engine is switched over, is there a measureable horsepower decrease on a dyno? I can't remember if this requires stiffer springs. Assuming minimal power difference, this seems like a win-win proposition. If the engine with SS valves will run nearly the same on a dyno and the valves/seats last much longer, what's the real-world advantage of Ti valves?
motometal said:
Not on any dyno test I've seen. The published research I have seen agrees that frictional losses associated with valve spring pressure are minimal.
motometal said:
They require much stiffer springs made of much better quality steel and titanium upper retainers to keep the overall valve mass down. We are talking about a cost for springs and retainers that is nearly 10 times what they are currently using. You know from your work how much costs can change based on the level of processing a material needs to receive before going out the door. It's the same here. Start with better materials, handle them different during the manufacturing process and the costs can quickly skyrocket. Don't anybody think for a second that Honda doesn't have the engineering skill to understand this far better than I could ever hope to. Given free reign the engineers would blow your mind, and your life savings along with it. ;) It's a balancing act between performance, costs, and adhereing to company design standards and practices. The standards and practices part plays a far greater role than we might first think.
motometal said:
Simple question not so simple answer. The thread linked below,( one you participated in back when you were Motopuffs) does a pretty good job of addressing the "Why titanium" questions.
http://dirtrider.net/forums3/showthread.php?t=5278
Rich Rohrich said:
True, however it appears that this is a necessary design direction to insure the long term viability of the two-stroke- if for no other reason than to squash tree hugger objections over emissions. On the other hand, production four-stroke FI is just around the corner and one can reasonably expect the same initial teething issues to plague them as well.
motometal said:
I can't really say because my 2000 CR250 was a bank repo beater while my 2002 CR250 was a cherry used bike. I do know that I put a ton of money into the 2000 to get it back into shape; money I have no hope of recovering. Which is also why I sold the 250 mill from it and am in the process of transplanting a CR500 mill in it. ;)
With that said, I prefer the feel of the 2002 chassis over the 2000. It is narrower in the middle and just feels "right" compared to the 2000. On its own, the 2000 is a fine machine. It is only in back-to-back comparisons where it falls short of the other.
Of course the engine in the 2002 has never gotten the reviews the earlier mill did. But Eric Gorr worked his magic on my 2002 and it helped quite a bit. :cool:
Rich, you also left out the whole "XR factor" in the discussion of four-strokes. The XR has a well-deserved reputation for being bulletproof and it is a four-stroke. You and I know it is more due to the mild state of tune and not because it has camshafts but lots of folks equate that level of reliability with four-stroke bikes in general, while they associate two-strokes with the poor reliability of the early model dirt bikes. While that sounds simplistic, I can't count how many times I've heard "I had an old Honda four-stroke and it ran forever" from someone interested in a new MX thumper.
MTK
I had an '01 and an '03, the '01 would rev out higher but the '03 would win in a drag race. This was with both of them jetted but no port work. I've ridden a couple of stock '02s and they just didn't have the power but i'm sure with your port work yours now runs better than a stock '03.
I weighed the bikes side by side and could tell very little difference, but you are right they definitely feel different. The '02 and newer feel 10 pounds lighter! It must be about weight distribution and geometry.
Sold the '01, '03 now has a heavy flywheel, EG porting, MX Tech forks and it's geared down a few teeth on the rear sprocket. Great bike, would like a new one but really this one works so well I can't rationalize switching.
I had an '01 and an '03, the '01 would rev out higher but the '03 would win in a drag race. This was with both of them jetted but no port work. I've ridden a couple of stock '02s and they just didn't have the power but i'm sure with your port work yours now runs better than a stock '03.
I weighed the bikes side by side and could tell very little difference, but you are right they definitely feel different. The '02 and newer feel 10 pounds lighter! It must be about weight distribution and geometry.
Sold the '01, '03 now has a heavy flywheel, EG porting, MX Tech forks and it's geared down a few teeth on the rear sprocket. Great bike, would like a new one but really this one works so well I can't rationalize switching.
jimt_yz400
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- Dec 25, 2000
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What's the cost of the SS valves, Ti retainers and springs?
Is it extremely expensive? I need to rebiuild by son's MX CRF450 where he puts an incredible amount of time on it, so maybe this is a good bet for durability.
Is it extremely expensive? I need to rebiuild by son's MX CRF450 where he puts an incredible amount of time on it, so maybe this is a good bet for durability.
jimt_yz400 said:
Parts and labor (valve job, spring set up, assembly etc) for a cylinder head rebuild using Kibblewhite valves, KW springs and Ti retainers is in the $550 range most places. Some companies will give you Stage 1 blueprint type porting in that price as well.
Parts alone are in the $300-$350 range.
Replacing the exhaust valve guides (if needed) would be an additional parts and labor charge at most shops.
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