dirt bike yapalım (ktm 450 fx ve yeti 303 marka bisikletin evrimleşmesi :P )

**bur-k@** · 02 Eylül 2009, 04:18

bu interneti kim keşfettiyse allah razı olsun . Solid works katı modelleme ile ilgili ilginç çizimler ararken bakın ne buldum

ah bide inglizcem ordaki yazıları buraya akıcı bi şekilde tercüme edecek kadar olsa süper olacak ama daha vakti zamanı var bizi izlemeye devam edin

Well, a friend of mine, Dustin Griffith, and I are working on degrees in Industrial Design, and we had to come up with a final project........

A good while ago I saw the promotional video from www.fxbikes.com here on the forum. Its basically a motorcycle that uses lightweight components from the downhill industry to create a new market segment. It really interested me because I have a background in freeride mountain bikes, and have since switched over to dirt bikes.

and, Dustin practically grew up on a dirt bike.......

So its been about a year and a half since we really decided to go forward with this project.......we're calling it Project M85

We began with comparisons of motorcycles vs downhill bikes and came up with some measurements to stick to:

We then started research about parts in both industries. What could be adapted for this purpose and why it was the best choice.

We started with the motor. The FXbike runs a punched out xr50 motor: simple, air cooled, torquey, but slow and heavy. in our opinion this is the first place the FXbike could improve.

We looked at two strokes for their weight, but were worried that the powerband would not lend itself well to this application. We found that the modern kx85/100 is a powervalve motor and is easily tuned for a mellow trail application.

We decided on the 85cc because we were a little worried that the 100cc would be too much, but if needed we could always bore the 85 to 100cc. We had the cylinder decked and ported for low-end power (THANKS JOSH) and added a 10oz flywheel weight.

We then looked at suspension and found that little in the bicycle world would really hold up to the demands of this application. While these components are overbuilt for mountain bikes they don't allow much adjustment in valving or spring selection, basically they will allow for a heavy rider on a 50lb bicycle and no more.

We then found Craig Seekins at Avalanche Downhill Racing and realized that he made the components that we needed. Craig started as a dirt bike suspension tuner and then took his knowledge to the downhill industry. His shocks and forks could be compared to scaled down motocross units. The forks are the equivalent to Honda CR250 forks that weigh 11lbs. and bolt to a mountain bike.......

Craig helped us out with the forks first and valved them for a 180lb rider on a 125lb bike, to get the proper spring rate he modified springs from a mini motocross bike. These forks give us 8 inches of travel with compression and rebound adjustment.

We discussed the rear suspension with Craig, as we originally thought about going with a single pivot design like KTM and the FXbike. But the only way to make that work would be with a dual stage valving shock (without the use of complex valving you would blow through the travel and have little benefits from damping). No bicycle shock could be valved to work well on a single pivot design. In our opinion this is the second place the FXbike could improve.

So we went looking for rear suspension geometries that would work. Since we knew that we were going to be using a bicycle shock, we wanted to use a system from a mountain bike. It is easier to adapt an entire proven system rather than start from scratch.

Most high end bicycle suspensions are concerned with eliminating pedal-bob, and in doing so the swingarm pivot's relation to the crank is completely different than what would be desirable in a motorized application. We needed a system with pivot relationships that could be adapted to the kx85's countershaft and swingarm pivot, all while leaving enough room for the shock, carburetor, kickstarter, ect....

We found that the Turner DHR had a well designed linkage system that is simple yet effective.

The DHR has 8.5 inches of rear travel, we were wanting something in the 10 inch range. So we drew the system up in CAD and scaled it 18%. This adjustment appeared to give us enough room to fit everything around the motor.

Suspension systems rely on a ratio between the axle travel distance and shock piston stroke. So if we increase wheel travel by 18% we have to increase the shock's piston stroke by the same. Craig was able to provide us a shock which was scaled appropriately and is sprung and valved for our needs. It is adjustable for compression, rebound, and preload. THANKS CRAIG

With the power and suspenders figured out we wanted to get it to the ground somehow. We decided on using a motorcycle type rear wheel/tire (bicycle components wouldn't be able to apply this type of power). We had a KTM mini-bike rear hub laced to a 21 inch excel hoop, then spooned on a (edit) Michelin, THANKS DAN, trials tire. If anything would get traction this thing would.

Front traction is handled by a Michelin dual compound downhill tire on a FUNN downhill rim/hub. THANKS BOBBY AND NYLE FROM MOJO WHEELS for downhill parts support.

Rear brake is a mini-motocross Formula setup (THANKS THOR AT KHS) and the front brake is a Hope downhill hydraulic disc setup. Its the strongest bicycle brake we could find, but it may be a weak point as it was never deigned to stop anything like this.

We had a huge rear sprocket made for it, to bring the top speed down from over 100mph (theoretical) to about 55-60.....

With the main components decided on we went about sketching, and coming up with concepts as to what the thing would look like.

[img]http://i225.photobucket.com/albums/dd122/projectm85/webb/c1.jpg[img]

Next was the design of the suspension, using Solidworks we created a 3d model of the entire system. THANKS TO RODNEY CLARK AND DEVIN LENZ for structural analysis

With the concept finalized and the suspension designed, I called on some of my friends at a machine shop to help us out. THANKS STEVIE & ALL OF S&K SUPPLY. We had the swingarm parts cnc'd out of 6061 then welded and heat treated. While the linkages were cnc'd out of 7075 for strength. THANKS JOHN

**wert_35** · 02 Eylül 2009, 04:46

çevirmene yardımcı olmayı çok isterdim burak ama şuan çok uykum var ve sabah erken kalkıcam belki ilerleyen günlerde bişiler yaparız tabi özet olarak çok uzun çünkü bu

**bur-k@** · 02 Eylül 2009, 04:51

wert_35 adlı üyeden alıntı

çevirmene yardımcı olmayı çok isterdim burak ama şuan çok uykum var ve sabah erken kalkıcam belki ilerleyen günlerde bişiler yaparız tabi özet olarak çok uzun çünkü bu

az çok anladım ya motor falan seçemiyolar ilk başta 2 zamanlı mı 4 zamanlı sonra diyo biri la olum bak crf 450 iyi motordur falan

sonra arka maşayı ve sispansiyon sistemini solid de tasarlayıp cnc veriyolar tabi şanslı dötoşlar adamların arkadaşı cnc sahibi :D

sonra allem edip kallem edip bu hale geliyo aha da çevirdim

**wert_35** · 02 Eylül 2009, 04:54

bur-k@ adlı üyeden alıntı

az çok anladım ya motor falan seçemiyolar ilk başta 2 zamanlı mı 4 zamanlı sonra diyo biri la olum bak crf 450 iyi motordur falan

sonra arka maşayı ve sispansiyon sistemini solid de tasarlayıp cnc veriyolar tabi şanslı dötoşlar adamların arkadaşı cnc sahibi :D

sonra allem edip kallem edip bu hale geliyo aha da çevirdim

vallaha üşenip daha okumadım bile ama sen çevirdim diyosan sorun yok hadi sana iyi sabahlar