Nyper build thread

[Nikolai]

Finished welding up the front. By the time I welded up the 1” tubes I didn’t have enough room left next to the bolt holes for a nut so I had to turn down two m12x1.25 nuts in my lathe and weld them on.

Finished trimming around the front mounts.

A couple years ago when I was gusseting the back I had cut gussets out of .090 plate and never liked it. It didn’t look very good and wasn’t going to offer much support. There are pics in previous posts on this thread. Anyway, after mock ups for a couple days I welded in 1/2x1/2 .035 square tube and then gusseted just the back with .063 chromoly plates. It was a little heavier than I wanted(0.287 lbs heavier than the old gusset setup) but I like the look a lot better and it should be significantly stronger this way. I think it got rid of the awkwardness the back had.

 

[Nikolai]

Wasn’t sure how I was going to finish the bumper. Ended up just rounding off the back of the 1x1/2 tube, cut and bent some end caps out of .040 plate, welded them and then ground the welds smooth.

 

[Nikolai]

Trimmed the upper tube to match the angle of the spars. This was just for weight reduction which was small, about .03 lbs but I’m not leaving any weight on the table. Anything that can be trimmed is getting trimmed. When I’m 100% done with the frame I want to be able to say I made it as light possible.

 

[Nikolai]

Coolant is going to run thru the chassis. The cross tube would have had a large dead space in the end and I wasn’t sure how that would affect flow so I made a tapered plug to plug off the end.

7/8 x .058 tube with a .040 cap fused on. Drilled 16 holes in it to reduce weight, total weight was only 42.15 grams. I tapped it in the end of the tube and then tack welded the outside.

I was get antsy to weigh it and see where I was at so far. New fish scale came in the mail yesterday. Checked it against my other scale and it was pretty close.
27.375 lbs as pictured

 

[Nikolai]

Finished the rear suspension front arm mount. This was another task I had been dreading. I didn’t want to use plate due to weight but I also didn’t want to sleeve thru the 1x1/2 rectangle and have the bolt head protrude into my boots and also require a longer bolt.

Made some caps from .090 chromoly plate and the tubes are 1.25 x .058, then welded them together with .040 filler.

Then fit the 1x1/2 .035 rectangle and notched for the tubes. Welded them up and then ground the backsides flat so the tunnel skin would sit flush(and sit flat against the jig). Total weight for both was 0.47 lbs.

And done. Doing the rear arm mounts next.

 

[74Nitro]

Beauty welds and fabricating.

 

[Nikolai]

Finished up the rear arm mount tonight. Some pics of how much the running board tube moved while welding the frame. Even with really good tube fit up it still warped.

Running board still flat against the jig at the bottom.

Back of running board tube raised off jig.

Rear mounting hole off from jig.

I knew this would be an issue which is why I made the temporary rear mounts out of 1” bar while building the frame. I cut the tack welds and removed them.

Made the permanent mounts of 1-1/4 tube which was large enough that I could notch further into the 3/4 tubes and get the holes to line up again.

Weight reduction from the temporary solid bar to the tubes was 0.2 lbs for both.

Next is to put the motor in and finish up the cooling system tubes in the frame.

 

[kinger]

Nice work!!! Love the every ounce counts theme!!

 

[kinger]

What coolant are you going to use? I am considering Evans waterless and ditching the overflow containers for both space and weight.

 

[93oilburner]

I am glad to see this build come back to life. I wasn't sure if you left the state or gave up on the 4 stroke sleds. We met a couple years ago, I bought a Nytro header off of you. Ended up selling that sled and bought a turbo Viper, would love to get it as light as yours will be. Can't wait to see the finished product when your done, great fabrication!

 

[Nikolai]

What coolant are you going to use? I am considering Evans waterless and ditching the overflow containers for both space and weight.

Probably just regular 50/50 from the auto parts store. I’ll run a fill bottle/container but no overflow. I didn’t run an overflow before and never had an issue.

 

[Nikolai]

I am glad to see this build come back to life. I wasn't sure if you left the state or gave up on the 4 stroke sleds. We met a couple years ago, I bought a Nytro header off of you. Ended up selling that sled and bought a turbo Viper, would love to get it as light as yours will be. Can't wait to see the finished product when your done, great fabrication!

Moved from Anchorage to Wasilla in October 2020 for a job transfer but that was it. We get out a lot in the RZR, almost every single weekend from May to October so our summers are swamped, especially with all the hunting, fishing, kids stuff ect.

It was really bugging me that the sled was sitting for so long but I did some really extensive mods to the RZR last couple winters and it’s setup perfect now so this winter it’s back to the sled!

 

[kinger]

Our XP 4 turbo keeps me busy in summers now too! Hard to work on sled anymore. I am getting it back in the shop this week and fired up to start working on it! Goal is get the Motec running, then add the turbo to the SC and see if I can hit 400+ on pump fuel with Toroco!

 

[Nikolai]

Need help on clutch offset, driving myself crazy, searched all last night and couldn’t find what I needed. I got my motor repositioned and am double checking the clutch offset before I make drivetrain plates.

Clutch offset from Yamaha is spec’d at 13.5-16.6mm. This is placing a straight edge on the backside of the primary clutch sheave and measuring to the backside of the secondary sheave. I’m using a piece of steel angle since it’s all I have right now. The secondary clutch has no spring in it but I have the sheaves closed.

Right now I have it set in the middle at 15mm but the secondary clutch is not centered on the primary clutch, it’s further in towards to the chassis.

Is this by design on purpose from Yamaha? I would think the correct offset would be whatever centers the secondary sheaves on the primary sheaves but if I do that then my offset would need to be 18mm.

What am I missing?

 

[RobX-1]

What I have done to measure offset since I don't have the proper tool is to place a straight edge between the two secondary sheaves and the other end should then be in the middle of the primary.