Yet Another purpose build

[eric82930]

I finally got to build one with the ball joint idea. All the tubing is either 1/2 or 3/4 square tube with. 060 wall thickness. Mostly straight pieces except a slight bend under the motor. If it doesn't break I'll machine the fork tubes down to the od of the top clamp all the way down and run a top clamp on the bottom without needing a shim. The rfs motor is 58 pounds with reverse gear. The track is an inch in front of the swing arm bolt. Seat height is 35". There is no strut or track frame. This is it. I ran the back half this way on my raptor and saved 30 pounds but wasn't enough gain to off set the heavy engine. Track is 137 yeti on a 17 mh le.

 

[aka Mr Floyd]

That is very cool. Definitely will want to see it in action when you are done!

 

[heliwrench]

This thing looks like the ticket. Looking forward to seeing the finished product. Looks like lots of room for a 2 stroke pipe to hide in the front frame area as well if you ever wanted to go that route.

 

[CB-BLR]

great idea moving the lower triple clamps down...much stronger.

Chris

 

[Mendomotox]

That's genius! Any plan for 2 smoke power?

 

[eric82930]

Yes if this design doesn't break I will be building one for my 2-stroke also. right now I have a 360 and a 380 but the vibration is really getting to me so it discourages me from opening the power-valve very often . I will probably just go with a modern 250 SX with the counterbalancer and a short track and just leave it at 9 thousand RPMs all day. Honestly the only reason I'm still wasting time on four strokes is because of the reverse gear availability from the four-wheelers that's really the only advantage I can see at this point.

 

[CHarding]

I have been interested in your last two atv based builds with reverse. I'm sure there are times that it would come in handy. I am looking forward to this build since it closely resembles what I might try. I have a low hour Polaris Outlaw with the KTM 525, 5 speed w/ reverse that I never ride. I have a Camso and a CMX for my Beta, I'm thinking I could put together a dedicated second snowbike between the two.

I'm open to ideas, keep them coming, you obviously have a lot of time and thoughts into these builds.

 

[suva]

I wonder if you could retrofit electronic reverse like 2 stroke sleds have onto a bike engine.

 

[eric82930]

It would only work in a 2 stroke but would need a 2nd pick up coil mounted on the fly wheel. The rest is just programming the cdi.

I use reverse a lot even when I'm not actually stuck. I drive into a thick of pines and think I see daylight but there's no way through. No problem.... I spent most of this season on the raptor and thank God it had reverse or my whole gang would need back surgery.... The only time it was truly stuck was when it was straight up a steep creek bank and the back wheels were under water in cobble rocks. If the bike can even go back 6 inches it's enough to eventually k turn out of the hole. The baseless junk snow we had all season put it to the test. You do need to have some clutch skills to keep from spinning the track. I did a hydro conversion on the raptor and it was pretty good. The first one I built on a kfx450 would always freeze up the lockout mechanism and didn't work half the time when it was deep.

 

[Mendomotox]

Yeah unfortunately they're aren't too many good 2 stroke options.. the newer ktm 250/300, BRC 500, maybe the chimera?real price though. There are good sled engines but packaging the cvt is a real problem. If you can find a way to get the primary behind the engine to narrow the engine up then you would have a pretty light weight 150hp engine with reverse.

I wish I was good at software. It sure seems like there would be a decent market for an aftermarket 2 stroke reverse. Lots of sleds get parked because they don't have reverse too. It's a real pain not having reverse on a snow machine. Even just for moving around the garage, loading and unloading.

Eric, have you tried your 360/380 with a track kit? How did you like it? I really want to do a custom build with an AC/suzuki 800. But I also think just bolting a kit to the 380 would be a blast

 

[eric82930]

Yes I've been running them for years. Stock the 380 was a dog only 49hp. The 360 always ran good. Fun playing around with the old iron. The two share the same cylinder casting but when you figure the 360 stroke is 3mm less it makes all the port timing much higher. Back in the day they said it was like a 60hp 125 on steroids... Just had to raise the port timing a LOT on the 380 and bingo! I've got both the 360 and 380 well over 60hp and both run about equal just the 380 doesn't Rev as high and vibrates more. Those engines are about 6-8 pounds heavier than the 03+ 2 strokes. I just need a tiny rear mount planetary reverse gear box to put on the jack shaft...

 

[eric82930]

I rode it today. It didn't have enough ski pressure. I need to put the stock soft spring back on the center shock. I had a truck spring on it for the raptor. Smashed lots of rocks to check my welds.

 

[fgauvin7]

Well this is a nice build! Looks like we will have two very similar build soon haha I'm in the process to build one to with this fork ball joint idea! I think it is the ticket to having a strong and light chassis with a lot of room for component.

I'm still a long way from done on mine, it will be a long build for sure since I realy want a clean result with bodywork on this one! But it is a lot of work,... Here is a quick preview of the bodywork and the first triple clamp made on my manual mill. You will be surprised how both of our framework will be close in design!

Enough derailing your post haha I will start a new onw when I will have a bit more done. I will be folowing this build for sure, keep up the good work!

 

[eric82930]

I'm riding it today in some pretty good spring snow. Jumps are hard landings but nothing broke yet and it feels really light. The cg is really low which helps a lot in the spring.

 

[eric82930]

 

[flatspeed]

Yeah unfortunately they're aren't too many good 2 stroke options.. the newer ktm 250/300, BRC 500, maybe the chimera?real price though. There are good sled engines but packaging the cvt is a real problem. If you can find a way to get the primary behind the engine to narrow the engine up then you would have a pretty light weight 150hp engine with reverse.

I wish I was good at software. It sure seems like there would be a decent market for an aftermarket 2 stroke reverse. Lots of sleds get parked because they don't have reverse too. It's a real pain not having reverse on a snow machine. Even just for moving around the garage, loading and unloading.

Eric, have you tried your 360/380 with a track kit? How did you like it? I really want to do a custom build with an AC/suzuki 800. But I also think just bolting a kit to the 380 would be a blast

I built an aftermarket ignition controller to add reverse to the old arctic cat m7s, Firecats etc. It does it all through software, no second igniton pickup needed. I'm not sure how it will work on a single cylinder but I'm going to find out with my own build (polaris scrambler 400 turned single ski). If it works, its possible it could work on the KTMs too. I'll make my own thread at some point.

 

[ruffian]

I rode it today. It didn't have enough ski pressure. I need to put the stock soft spring back on the center shock. I had a truck spring on it for the raptor. Smashed lots of rocks to check my welds.

nice build eric, do you like the track where it is? would you move it forward on the next build?

 

[eric82930]

Right now the track paddle is an 1/8"from the engine block and the paddles actually swing down forward of the swing arm bolt. The only way I could move the track more forward is to raise the engine about 4"and then the paddles will go completely under the block. I'm not sure it's worth the trouble and I'm really liking the low cg. Right now my ski is almost too light and I'm running softer springs in the front track to compensate. I'm riding spring snow in terrain way steeper than in typical winter so the steeper it gets the more it wheelies just like a bike. But on the flats it's still light on the ski. It even feels good riding in dirt and mud. Doesn't rattle my teeth when I hit a rock with the carbide.

 

[Answ3r]

Any reason why you didn't move the ski closer to the track ? Seems like the engine package would allow for it and maybe the shorter wheelbase would be quicker handling ? What's your thoughts ?

Right now the track paddle is an 1/8"from the engine block and the paddles actually swing down forward of the swing arm bolt. The only way I could move the track more forward is to raise the engine about 4"and then the paddles will go completely under the block. I'm not sure it's worth the trouble and I'm really liking the low cg. Right now my ski is almost too light and I'm running softer springs in the front track to compensate. I'm riding spring snow in terrain way steeper than in typical winter so the steeper it gets the more it wheelies just like a bike. But on the flats it's still light on the ski. It even feels good riding in dirt and mud. Doesn't rattle my teeth when I hit a rock with the carbide.

 

[eric82930]

I tried moving the ski closer on my last build. It was better in hard snow but worse in soft. This build was specifically for deep soft snow so I kept the ski forward. It's actually stock distance to the swing arm bolt but the track is 4 inches closer to the swing arm bolt so it is much shorter than any other 137"stock bike. Our snow finally melted so no more testing until October.