240lb custom frame build

[eric82930]

This is my 8th custom build with either a frame hack or full custom frame. All have the engine moved back until the paddles touch the case and the foot pegs mounted to the track side panels as close to the sprocket as possible.
I'll post better pictures later. I've been riding it 3 days a week since November but haven't had any sunny days for good photos.
This one is the lightest at 240 dry and 275 with the 6 gallon tank full. It is a ktm 360 on a riot back end. The 360 engine is supposed to be 8 pounds heavier than the new ones so just imagine what a factory could do with some carbon or even plastic. We are talking a 220 pound 60hp bike. They need no quit messing around building kits.

 

[Sheetmetalfab]

This is my 8th custom build with either a frame hack or full custom frame. All have the engine moved back until the paddles touch the case and the foot pegs mounted to the track side panels as close to the sprocket as possible.
I'll post better pictures later. I've been riding it 3 days a week since November but haven't had any sunny days for good photos.
This one is the lightest at 240 dry and 275 with the 6 gallon tank full. It is a ktm 360 on a riot back end. The 360 engine is supposed to be 8 pounds heavier than the new ones so just imagine what a factory could do with some carbon or even plastic. We are talking a 220 pound 60hp bike. They need no quit messing around building kits.

Have you considered direct drive?

 

[eric82930]

These were before I modded the lower frame to lower the pegs and moved to cross brace to get rid of the vibration in the bars .

 

[eric82930]

Have you considered direct drive?

Yes but extending the counter shaft would be heavy and complicated. My chains are short And I might some day build a jack shaft hub like the mountain top uses. Putting the pegs behind the drive axle would be too extreme rearward cg.

I weighed a bunch of parts during the build:
Stock steel 1996 frame 20lb
Stock sub frame 4lb
My New steel top frame from behind js to top ball joint including seat frame 6lb
New steel lower frame with peg brackets and cross brace 6.5lb
Ts center parts-sa block chain adjuster slider and aluminum extrusions 8lb gone
Strut rod 2lbs gone 1.2 pounds of chain gone sa bolt 1lb gone

 

[eric82930]

I wanted to weigh my tunnel cooler, I swear it's heavier than 2 radiators but the weight is back and low.
Depending on shock pressures I have about 100lb on the ski. I run 75psi in the aer fork and 50 in the rear shocks.
The snow this year has been insanely deep but it's been MUCH more dense than we usually get so the puny 120 track holds it's own against bigger tracks with more weight on them. Haven't needed my long track much at all this year.

 

[300mxc_dave]

That looks awesome Eric. The handling and light weight of that setup has to be night and day better that a kit bolted to a dirtbike frame. You are 100% right the OEM's are wasting our time with these 'kits' but unfortunately I think they make way to much money on them. A real 'purpose built' dosen't seem to make business sense for them at this point. Its to bad Polaris bought Timbersled when they did or we would have factory purpose built already with an awesome BRC engine powering it. Don't get me wrong I love my '18 300XC/ Brc500 with gen2 ARO3 bolted onto it but the retarded length and somewhat poor handling of it leave alot to be desired. I want half the approach angle of the track up under my feet where it should be. Like on a sled. My 129'' setup is 4'' longer from ski tip to track end than an 850 Summit 154'' That's just not right to me. I want to be able to do re-entries, bowties and pivots like on a sled but the kit setup's with the track so far behind my feet/ body's CG its incredibly hard and very sketchy.

What is the overall length of your build? Looks like you saved around 8-10 inches from a traditional kit? Also the weight savings is very impressive!

 

[300mxc_dave]

Whats your take on the Ruffian purpose built and those Gnar bikes and that Slabs73 guys setups? They all look like the pegs are around 3-4" or more behind the drive shaft center. So a little shorter again than yours.

I've read you talk about this some before and how going to short/ to rearward CG can negatively affect the handling. I would think the ski pressure and turning ability etc. could be tuned with the rear suspension. Front and rear shock lengths, spring pre load, air pressure ect. Also moving the forks up or down in the clamps.

If these pictures will upload properly I absolutely love the looks and design of this Ruffian BRC500 build. Also really like the simplicity and possible efficiency of his direct drive setup


The videos I've seen of those gnar bikes in action, look like they handle incredible and exactly what I'm looking for. Also the other guy (Slabs73 on Instagram) with a very similar custom frame setup has videos on a Snowbike facebook group page that look very impressive as well.

Unfortunately it is very hard to find any clips online of these full sized Rufffian EVO's in action. There is however getting to be some decent clips of his little Ruffian 'mtn light's' in action and they seem to handle really well. Same basic design and geometry of this full sized one. If nothing else the Ruffian guy is a very talented frame builder and tig welder. His frames and that brc build are an absolute work of art in my opinion.

 

[eric82930]

I still have not been able to see or ride a ruffian or gnar but they both look like the cg is too high and to far back. My newest build has the engine higher and farther back than my last one which was a 450 so it had a lot of weight up high compared to a 2 stroke so I purposely kept the 450 farther forward to get it lower. My raptor 700 was a top heavy pos and it was only 325lb but the weight was too high in the chassis.
My 360 has flipped over backwards twice now and I couldn't stop it. But it has a vicious hit when the pv opens.I'm thinking that might a problem when the snow gets hard.
As for the direct drive being more efficient I would totally ignore that and call it negligible, not with doing unless it helps with the location of the foot pegs somehow. The frame on both gnar and ruffian could be made lighter of they do the ball joint thing like mine and combine the seat frame as part of the main backbone.

 

[300mxc_dave]

Yes the CG does look high on the Gnar and somewhat on the Ruffian but the Gnar bikes heavy and top heavy, like you say 4 stroke would only make that worse. The 2 stroke in the Ruffian frame looks more promising and he says its around a 35'' seat height. Also the fuel that low and far back on the skid should greatly help. My 2 Timbersled setup's are about 40'' seat heights and the majority of the 11 liter's of fuel in the main tank is up very high above the engine. With how far back the pegs are on his, that 137'' might be the way to go? He says in a comment that BRC build is 250lbs dry which seems hard to believe but I think is possible. Thats a 10'' wide 137 yeti track and he was first with the single arm rear ARO style skid before the Gen2 ARO3 lol.

As far as the flipping over backwards on some climbs, I think I would take that trade off any day for how nimble, playfull, and light to no ski pressure handling they look like. I could also care less how poorly it might turn and handle going down a hardpacked road or trail getting to the powder. I'm an aggressive rider, ride and race enduro/ harescrambles in Vet Expert and Motocross at a vet Intermediate level. Rode sleds in the north Coastal mountains of British Columbia for 13 years and now snowbikes for 4. I think I could figure it out lol.
The BRC motor also hits hard when the PV opens but that motor is incredibly smooth and managable for how much power and torque it has. Alot of that has to do with the very tall primary gearing Riley uses on them I think, The real magic of that motor is the counterbalancer though. I vibrates considerably less than the previous generation Ktm 250/300 motor's and is close to the amazingly smooth 2017 + 250/300's

For the direct drive, yes it probly is negligable for being more efficient. Its more the simplicity and less moving parts I like. The belt drive on my new ARO3 is just 90% marketing in my opinion. Riding it back to back and on the same day as my '17 250SX with ARO120le, I can't feel any difference in efficiency or spool up like they say. The main and only advantage to me really is a little weight savings and less maintenance.

 

[eric82930]

So the ruffian in the photos is 250lbs with a 137”?
My seat height is 35"and the pegs and motor are only 5"back and the total length is 5"shorter than a stock mountain horse 120. I have tried pulling the ski in closer but it's not worth it. It turns crazy sharp radius as it is way tighter than a kited bike.
5"might not seem like much but the factories brag about mounting the kit 1"closer -yawn... Moving all the gas back makes a bigger difference than 1 inch.
The pipe sure fits tight in the ruffian frame, looks like a service nightmare. But if money didn't matter I would probably try a ruffian and then just mod the upper frame with lighter materials spread out more with the ball joint idea.

 

[eric82930]

I just noticed the ruffian uses an old backcountry ski. I'm a big fan of the old ski and don't think we need a monster fatty ski on a lighter bike with less ski pressure.

 

[fgauvin7]

I love this version a lot! I was a fan of last year version with an RFS engine and this one seem to be better in every point! And the final weight is pretty impressive too. This design has certainly a lot of potential and I don't think there is many other way to built them as light as this with normal diy budget.

How long do you end up having between the ski bolt and the track drivers axis? If my memory is correct I think my first build with a 250 was around 31in and my last one with a 450f is around 33in.... Both of mine seem to be shorter on photo, If I was te rebuild the front end I think I would try going another 2in longer but I feel like I'm close to the sweetspot between too much ski pressure and too little. Maybe I'm off by a lot too, very interested to learn!

 

[eric82930]

Its about 40” horizontal from ski boot to drive axle. But my rake is now 33 degrees. It pushed the ski 5 inches farther forward than stock head angle without adding much frame weight. My rfs is 30deg. I originally wanted to keep it short and steep but now feel like the 33 is better. It's probably a tad more twitchy in hard snow but in soft snow it feels amazing and can turn crazy sharp switchback's. The 33 angle digs the side of the ski in hard when you turn sharp even if the bike is not leaning much(like a slow speed switch back) keep in mind the spindle needs to change when you make a crazy head angle change so the trail will be correct and the rear ski bumper is correct.

 

[goforbroke]

Awesome to see how you and others are pushing the snowbikes!! Sweet build! I still have yet to ride one, but it sounds like they are moving in the right direction

 

[fgauvin7]

Its about 40” horizontal from ski boot to drive axle. But my rake is now 33 degrees. It pushed the ski 5 inches farther forward than stock head angle without adding much frame weight. My rfs is 30deg. I originally wanted to keep it short and steep but now feel like the 33 is better. It's probably a tad more twitchy in hard snow but in soft snow it feels amazing and can turn crazy sharp switchback's. The 33 angle digs the side of the ski in hard when you turn sharp even if the bike is not leaning much(like a slow speed switch back) keep in mind the spindle needs to change when you make a crazy head angle change so the trail will be correct and the rear ski bumper is correct.

Well I have something to try now! I have the stock ''yz'' head angle at around 25-26deg... That is a lot steeper than what you use. I was thinking at reducing trail to gain a bit of a relax feeling, but the more I think of it the more I realize that it is mostly the ''race bike'' head angle that I use that create a very reactive steering.

I'm looking to improve in a way to have a somewhat light steering with a comfortable feeling, I'm not all in to the optimal performance, I just want a nice setup to cruise around that inspire confidence.

That said, I might go to around 30deg on my next chassis that is in design at the moment! We get snow that is hard a good portion of the winter here so I would not be too tempted to go as crazy as 33deg, I think it might be too much ski bite as you mentioned.

By the way, very clever to reverse the fork bottom tube to build the spindle!

 

[eric82930]

We got a chance to ride in some snow with no base for a change about 8 hours south of here and I was blown away by how good my newest bike worked. It can float on anything it seems. I did have a chance to compare back to back with yz450 riot and the feel is night and day different. The yz is super top heavy and front heavy. With no base you have to say a prayer to get it going first before it starts to float. When you crack the throttle, the back of the yz just goes down and plows snow with the ski. Honestly it felt like there were no paddles on the track. If you can pray/paddle enough to get into second it will start to plane out and if it doesn't get steeper your good. When you crack the throttle on my custom frame riot, it jumps forward with no track spin or digging at all. If the powervalve opens it will dig and wheelie at the same time but somehow I can still steer it.
I'm hopeful to start seeing ruffians west of the Mississippi some day. The kit frames definitely need to change to advance this sport.

 

[z987k]

We got a chance to ride in some snow with no base for a change about 8 hours south of here and I was blown away by how good my newest bike worked. It can float on anything it seems. I did have a chance to compare back to back with yz450 riot and the feel is night and day different. The yz is super top heavy and front heavy. With no base you have to say a prayer to get it going first before it starts to float. When you crack the throttle, the back of the yz just goes down and plows snow with the ski. Honestly it felt like there were no paddles on the track. If you can pray/paddle enough to get into second it will start to plane out and if it doesn't get steeper your good. When you crack the throttle on my custom frame riot, it jumps forward with no track spin or digging at all. If the powervalve opens it will dig and wheelie at the same time but somehow I can still steer it.
I'm hopeful to start seeing ruffians west of the Mississippi some day. The kit frames definitely need to change to advance this sport.

I just don't see how they have enough power to be useful in deep or even hilly terrain. Seems like it'd maybe work as a kid's toy around the yard.

 

[Sheetmetalfab]

I just don't see how they have enough power to be useful in deep or even hilly terrain. Seems like it'd maybe work as a kid's toy around the yard.

Ruffian makes 450 powered bikes with 129 camso tracks……..

Basically a kid’s toy though.

 

[z987k]

Ruffian makes 450 powered bikes with 129 camso tracks……..

Basically a kid’s toy though.

They did but they took those off their website at some point.
They were advertising that 600 last year and I emailed them about it. No reply and shortly after it wasn't on their site either.

Seems to be just the little air cooled 200s at this point.

 

[Answ3r]

We got a chance to ride in some snow with no base for a change about 8 hours south of here and I was blown away by how good my newest bike worked. It can float on anything it seems. I did have a chance to compare back to back with yz450 riot and the feel is night and day different. The yz is super top heavy and front heavy. With no base you have to say a prayer to get it going first before it starts to float. When you crack the throttle, the back of the yz just goes down and plows snow with the ski. Honestly it felt like there were no paddles on the track. If you can pray/paddle enough to get into second it will start to plane out and if it doesn't get steeper your good. When you crack the throttle on my custom frame riot, it jumps forward with no track spin or digging at all. If the powervalve opens it will dig and wheelie at the same time but somehow I can still steer it.
I'm hopeful to start seeing ruffians west of the Mississippi some day. The kit frames definitely need to change to advance this sport.

I love your threads, but action videos would be nicer even !!! haha