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SX Viper 1049cc

It's the reduction in inertia that's huge... and that can significantly aid durability and schmoooovness. I can afford them, but the younger me, which learned to do more with less, always wants to try and underdog it (relatively speaking).
I know you’re being general and in general I agree (nerdy engineer here) it all sounds good. Much to my dismay though, in real life you dont notice it. Also in that 3 banger less rotating mass will make more vibration then it already has without the reciprocating damper effect of more mass. In the 4cyl you might get by but in the 3 holer I think it would vibrate bad and be considered race only.

I used to get hung up on this stuff, I am learning that getting the project going faster is more rewarding then chasing grams and theory.

I also love to be proved wrong. We’re all learning here. So if they work out and you notice it’s revs slightly better then stock then great!

Custom Ohlins TTX44 w/ PDS for the 128" Mono.
Sick! Whats the latest? I'm itching to see this sitting in the sled (physically, not hooked up) just to see what issue you will run into to with steering, exhaust, intake, etc. Seems like you will have a ton of room.
Not much, it's finally spring here in New England... so many projects, so this will be slow to update.

There is absolutely tons of under hood room to play with, great for the intake and exhaust systems.

The only thing I've been mulling over is the fuel tank and pump. Placing an EFI pump in the stock tank won't be easy... but no matter the tank, the issue will be easily solved with an externally mounted fuel pump sump/surge tank. Fuel starvation will not be an issue, and if done correctly, it will be good to the last drop. There are two OEM Keihin external sumps that might just fit the bill. They come from Suzuki and Honda ATVs. I suspect the Yamaha pump with fit... but need to check. The Suzuki LTR 450 pump is on the left, is smaller, and holds less fuel. The Honda Rincon (and other Hondas) is on the right, it has a larger sump. I'll probably go for the Honda unit as the room to mount it exists, it also has the regulator built like the stock pick up. Hopefully flow and regulator are comparable, or easily swapped.
I did manage to score a low mileage super clean 128” mono skid for a couple hundred dollars, has DuPont slides even.
So what’s the plan for the 128” skid?
I’m unsure if anything terribly interesting will happen with the skid at this point... but there are always ideas floating around. Need to mull it over a bit more.

A nto 129x15x1.75” 2.52 pitch 2 ply track popped up… didn’t know such a thing existed. It’s a snocross track though, looks similar to the Back Country. Relatively cheap, but noise and slide wear tend to be an issue with those.
So I’ve been looking at the how Yamaha designed the bulkhead and 2 stroke engine mounting in the old pro action chassis. It’s not exactly compatible with the rearward lay down style of the 1049 Genesis Engine and mounts. A major part of the Proaction bulkhead/frame structure sits right where the 4 stroke needs to be. So rather than fiddle around with that, and mess with having to align the engine on multiple planes, I’m thinking that part of the FX Nytro bulkhead and tunnel will vastly simplify this build.
So essentially, the front cast bulkhead from the SX Viper, or more likely an SRX (so the shock towers can be easily fabricated and bolted up) will be joined via some fabricated parts to the Nytro bulkhead
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The front radius rods will be some sort of copy from the old Yamaha Snowcross sleds, with shorter uppers. Maybe use the Apex Deltabox steering arm swing set in order to eliminate bump steer.

I reopened my account with Ohlins, and while all the snow stuff has to come out of Sweden, I managed to pick up a few sets of nos TTX30 snow shocks here stateside. Eventually we’ll have TTX all around on this machine. I might let a set or two of the TTX30 go if anyone is interested?
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