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Edited Date/Time
12/20/2018 7:30am
So the Yz250 aluminum frame thats very similar to the steel frame is a fairly universally loved frame and its light weight. Why didnt Yamaha or any other brand use an aluminum frame in this style vs using the box aluminum style ones? If the KTM steel frame is fine youd think this could be fine too holding a 250f. Anyone know what the deal is? Anyone ever do a swap? Maybe this could be a way to get close to steel frame performance from Japan.
Vs
Vs
By the time the YZ smokers got the aluminum frame, the thumper revolution was in full swing. It appears the YZ frame is cast for the most part (more on this in a bit)....
The 4 stroke frame isn’t cast, therefore, can be altered far more easily, cost effective, year to year, as the bikes progress. People are buying this new found MX miracle in droves because it’s the end all to be all, so let’s us the OEM, have it to where we can alter a chassis yearly if need be with very little R&D money spent. The entire chassis isn’t all box tubing, but the biggest portion is....easier to alter the geometry on the cast pieces when all your doing is welding them to tubing to achieve your goal.
Now the smokers..... In my opinion, Yamaha tossed the aluminum frame on these to keep an interest in the two stroke. Period. The new generation wasn’t really buying them near as much, so, let’s give it an aluminum frame to help it stay modern. We can make it cast, and continue to use the molds for the frames, year in, year out, until this 2 stroke era dies out. No altering, no changes, this mold can be our money maker for years, or until folks quit buying smokers. Regardless, we will get our money back in tenfold, and never really have to invest any money into 2 stroke development because it’s rapidly becoming a dinosaur. Molds cost God only knows, box tubing is cheap, building new molds every other year gets costly......
Did any of that make sense??? I know, I think too much into this shit. Bash away......
The first frame even allows a center port exhaust in an aluminum frame... something Suzuki only just now figured out for 2019. Wtf is going on here are we being duped?
KTM 250sxf frame for reference
Vs
Yz250f perimeter aluminum
The Shop
For Yamaha 4-strokes in particular, since they are fairly committed to the backwards-engine architecture, twin spar perimeter frames are really the only practical design.
Like I said, I’m far from being smart ?. Just throwing out a opinion, merely for conversation sake, and whoever reads humor. That whole speculation came to me while watching the kids decorate the Christmas Tree.... and I needed a distraction from wondering how I’m gonna pay for all the shit the wife is putting under it....
Yamaha had it before the reverse engine. Also everyone else does this style too. Yamaha has the only “steel like” aluminum frame for their Y zingers, which were the premier bikes when it came out. Any more guesses? Michael?
Non reverse Yzf
One thing of note the KTM steel frame geometry is closer to the newer Yzf perimeter frames than the older alum 2 stroke frame. This is just maturation of design as older steel frames had the yz geometry.
Vs
But then also now the yzs run the fuel tank and air boxes in funky places so maybe thats still it. Who knows lol
It was too stiff and resulted in a harsh ride they stuck with tubing at first because they were really paranoid about them cracking.
So they figured out that using more cast sections gave more flex. Like the first gen CR it was mostly tubing sections with a small section around the footpegs that was cast.
So by the time the 3rd gen CR frame came about the entire area from the lower frame cradle up to the shock tower was cast. Which offered optimal flex.
The YZ frame is a combination of cast sections and extruded tube sections. To get the best flex characteristics possible.
Center section the Y piece and frame spars and shock tower are cast. With extruded section between the lower part. The frame cradle and section on top and one one the bottom are extruded tubes placed top of the large cast sections. From the head tube to shock tower and underside of headtube to the exhaust Y.
Yamaha used a similar frame build style on the 06 through 09 YZF's. Where the long weld along the cast section and extruded tube. On the underside from the head tube to the Y sections where prone to cracking down the weld only on the YZF's the two strokes didn't really have this problem.
04 yz125 frame next to the 05 yz125 frame.
Pit Row
The Yamaha YZ125 frame looks very similar.
Link to YouTube race: https://youtu.be/3-rYhhz5QzU
Kawasaki perimeter frames where know as very good handling bikes - Also again feed back was the perimeter framed Kawasaki's where much better handlers than the old mono style - Never heard anyone say any different - Went through the Kawasaki change to perimeter the perimeter version was way more coveted and improved - There is a reason why the majority of performance motorcycle use perimeter frames - Road Included ! It is a good sound structure to use as a bike frame the engineering logic is good. Perimeter is stronger than mono that is just a fact - Why perimeter and triangles are used everywhere in engineering versus single columns.
Yamaha tried for a long time to have their own original not copy design but eventually they caved and those eraly perimeter framed YZ250F where know as to be very good improvement on the previous designs. Many a testimony from those that got a new yz250f every year ... that 2010 was very good
V
Single beam Soap box frame design.
When you look at the future of body design, the multi-material approach is going to be the future as we see it. This means a mix of aluminum's, steels, and other plastics and composites. In this multi-material world, aluminum is going to be the predominant material. There are many areas, especially in body-in-white, where aluminum has advantage—and we intend to keep it.-- Future of vehicle construction. ---- from engineering.com
I own both (aluminum and steel) framed bikes...and I love both...
Late to the thread but dang that’s rad I’m going to go down that rabbit hole and try to find a picture ! Hello, google images !
Going to Aluminum wasn't to save costs. Aluminum costs more than steel.
At first guess it's logical to think it does, but using only one material on the assembly line doesn't reduce costs significantly.
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