Putting things in places they ought not to be (250R Hybrid Motor build)

[fabiodriven]

Is a RAVE valve Rotax's power valve? What actuates it?

[Billy Golightly]

Its spring loaded, basically just the exhaust pressure itself either raises or lowers it.

[MIK6]

I'm thinking I'll call it the Rotonda

I LOVE IT!!
I cant wait to see that thing at TF! Good luck on the startup!

[RIDE-RED 250r]

Yes, the Rotax Adjustable Variable Exhaust (R.A.V.E.) is arguably one of the best, simplest, and most reliable exhaust valves going.

It works on exhaust pressure and is widely and easily adjustable to the user's liking by adjusting the depth of the red inner spring retainer, or changing to stiffer or lighter springs. I have had a few Ski-Doos in my day and have a fair bit of experience with them...

As with any exhaust valve though, they do require a cleaning every now and then.

[Billy Golightly]

Since I will (hopefully) be to that point soon - where is a good place for me to buy some different springs to try out? Are these things numbered like main jets?

[RIDE-RED 250r]

Since I will (hopefully) be to that point soon - where is a good place for me to buy some different springs to try out? Are these things numbered like main jets?

Unfortunately they are not numbered like jets..... Probably the best place to get springs would be from a BRP OEM parts supplier.. They only run $6.. http://www.skidoopartshouse.com/oemp...reed-valve-793

I could have sworn Crankshop sold mod Rave springs... but it seems they no longer offer those..

But what you will notice is that there will be different part numbers for the Rave springs for different models that use the same engine.. IE: MXZ800 and Summit 800 in the link I provided.. The Summit is a mountain sled and the Rave springs are likely to be lighter for high elevation operation.

It looks like your only option for different spring rates would be experimenting with different springs from another model running the same engine. I don't think there is a difference as far and length and diameter with the springs in the smaller 500, 600 and 700 cc engines.. But Im not 100% positive on that so I don't want to suggest running springs from a 500 on your 800 cyl...

But, I doubt you would find the need to run different springs. The Rave adjuster cap offers a pretty wide range of adjustment

[Billy Golightly]

As Honnerlaw said - 20lbs of in a 10lb box, basically.

[El Camexican]

I think it would look super cool if you passed and welded a metal tube through the pipe and routed the coolant hose through it. Like running steering rods through the oil pan of a Hemi

[ironchop]

Call it The Hotax.

Sounds like something the Bunny Ranch owes the IRS

[Billy Golightly]

I think it would look super cool if you passed and welded a metal tube through the pipe and routed the coolant hose through it. Like running steering rods through the oil pan of a Hemi

My old man actually suggested that a pass through for it.

I'm gonna just run it off the left side and use a -ton of coolant line. I have to mod the cylinder some more to make that happen even though.

[bkm]

And I think my Pro-x 250r is cramped. lol Working on that thing would send me into lunar orbit.

[RIDE-RED 250r]

As Honnerlaw said - 20lbs of in a 10lb box, basically.

But I'm going to bet that's going to be 20lbs of hard hitting s***!

[Billy Golightly]

I'm starting to get some parts in. Enough that I can work on finishing buttoning up a few things while the rest is in transit (hopefully).

My new cylinder is here, so I get to build the water spigot interface on it, and the helicoils came so I can finish 2 spots on my case there and have them ready to work on the needle bearing around for my shifter shaft also over the course of the next couple days.

[Billy Golightly]

I am still waiting on parts with the Holidays - so the 1st of Jan was a bit ambitious perhaps


Looking more like middle/end of January realistically.

[Billy Golightly]

Haven't gotten to do much yet, my shift shaft needle bearing hasn't shown up so eff it, I'm gonna assemble without.

I finished heli-coiling the back to cylinder studs, as a precautionary mostly. I think the threads in the cases I did originally with a tap would have been okay, but it would have sucked to have gotten this thing all the way together and lifted the cylinder off the deck

And I just finished doing the final lapping on my cases, I did have one minor air leak in the counter balancer chamber which is very very common in my experience in any set of cases thats been worked on or repaired or not had an easy life (these literally were in the scrap aluminum pile and got kicked all around the shop and barn for about 4 years before I started this project). I had worked on these before using a couple squares taped down on a piece of thin glass but didn't get the results I needed or really wanted.

I've been wanting a granite surface plate just for this kind of work bad, and I just haven't been able to make myself justify buying one, so I wound up using a large marble dinner table

I learned a tip from John Tice over @ www.everything2stroke.com about using a big belt sander belt, instead of trying to tape together shitty sand paper squares to work from. I bought this 18x36 belt off of McMaster Carr for like, $13? Cut it in two and clamped it to each end of table.

I then took a sharpie marker and went over the entire gasket surface to black it out, so I could see where my high and low spots were. After about 15-20 minutes between each case, I had the counter balancer chamber area sufficiently evened out and pretty much every other spot, save for the area around the drain plug I had to weld up and re-tap, but oil is a lot less likely to leak than air in the vacuum of the crank case. Each half has 2 places on it welded. Let this be a lesson that cases are salvageable, although for any other build you'd probably want to just buy ESR ones. Send your damaged 250R cases to me if you're going to throw them away!

Partially there, still have some low looking places that need addressing.

Completed! Pretty much everything resolved.

Basically, I need to pull all the old bearings and seals I used to mock up with. Clean the hell out of the cases, and then put in my bearings and start assembly. I still have not completed the water spigot change on the new ready-to-use nikasil cylinder I bought as I just can't decide exactly how I want to do it. I am going to go ahead with bottom end assembly (Including the new +4 crank) and then do the water spigot on the cylinder last I guess since I keep procrastinating/figuring on it.