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

[RIDE-RED 250r]

Billy, I have a pair of OEM reedcages. They are a 1 piece design as apposed to what we are used to with our R's. Meaning the reedcage itself is laminated to the intake boot. The reason I replaced them with VF-3's a while back was because one of the reedcages was de-laminating (separating) from the intake boot. If I recall, one cage was still in good shape and useable, at least as of when I put them in a box.

Either way, you are welcome to have one or both if you like. I'll run out and check on the condition of them to make sure I have one that would be in good shape and safe to use. I'll let you know what I find.

[Billy Golightly]

A little teaser until I can do a proper write up here soon.

[Billy Golightly]

Full update/write up on the base gasket surface machining, drilling and tapping the cylinder stud/bolt holes, and setting it in a frame, here:

http://forums.everything2stroke.com/...424#post535424

And also here:

http://forums.everything2stroke.com/...425#post535425

Let me know your thoughts!

[Billy Golightly]

Billy, I have a pair of OEM reedcages. They are a 1 piece design as apposed to what we are used to with our R's. Meaning the reedcage itself is laminated to the intake boot. The reason I replaced them with VF-3's a while back was because one of the reedcages was de-laminating (separating) from the intake boot. If I recall, one cage was still in good shape and useable, at least as of when I put them in a box.

Either way, you are welcome to have one or both if you like. I'll run out and check on the condition of them to make sure I have one that would be in good shape and safe to use. I'll let you know what I find.

That one that is seperating might be just what I need actually, as the angle of the oem intake boots from what I've seen is too straight forward anyways. I'm going to have to make something probably similar to the cast aluminum boyesen rad valves with the round rubber boot on the end. Are the cages aluminum, or what are they made out of?

[RIDE-RED 250r]

I was away from home all day today so I did not get an opportunity to go pull the reedcages out of the box and snap some pics.

Yes, you are right about the intake boot angle. They are straight on, no angle to them.

I will get some pics tomorrow and send them your way. If you would rather I not post pics here in this thread, PM me an email address and I'll send pics there.

Spark plug clearance: First, are you doing this on an '85 or '86 chassis? If '86, there is a little more clearance for the spark plug to begin with. Pantera1975 has an '86 with an ESR top end with the straight sparkplug hole. He doesn't have alot of trouble using the typical NGK cap. But me and my '85 with an ESR top end, there is less clearance between the spark plug and frame brace. I ended up using a small, basic weedeater plug cap. It's the kind that has the little spring with the hook on the tail to press into the plug wire. It is small enough and flexible enough that I can run standard NGK plugs with no issue. And surpisingly, that little cap has not given me a bit of trouble.

All of that aside, both of our engines are stock stroke. This setup being +4 stroke, and if the head is a bit thicker is putting you in a bit more of a pickle. But if you have clearance enough to thread a spark plug in and out, one of those little caps like I use should be very workable.

Are there going to be any clearance issues with the RAVE valve??

Just a suggestion and a greenhorns guess on port timing/deck height: .25mm equals .010". Running a 250r +4 crank is only going to have your port timing .3mm low. Plus, the piston might be coming too high and possibly a hair out of the cylinder for a possbile compression issue. Maybe just running 2 base gaskets would bring you right in where you need to be?? Running thicker spacer plates would raise the port timing more and give you a bit more top end (not that you don't already know that)... If it were me and I was looking for more low-mid I might try and see if simply re-chambering the head would suffice, so long as the piston doesn't protrude out of the cylinder??

IDK, just some thoughts and ideas to bounce off ya.... I think this build has some real potential to be some real competition for some of those bigger "cat" cylinders..... Those sled engines make some serious HP right out of the box.

[Billy Golightly]

Na that'd be fine, feel free to post em up here!

[Jason Hall]

What crank will you use? The Hot Rod +4mm has a long connecting rod. You Might need to make a spacer plate? Or does the piston you chose have the correct Deck height for the added rod length? Make sure to check rod clearance with the stroker at the top of the cases. Every long Rod stroker I have built needed the cases relieved in the area where you added material in the front.

Also, a +4 stroke crank is really +2mm at the rod pin.. So plus 2mm up, and + 2mm down = 4mm.

[Billy Golightly]

The frame I wanted to put this in is an '85. I suppose I *could* make an angled plug head...hadn't really thought about that. The plug wont thread in, it just barely catches on the very end. With just the one bottom motor mount bolt through I could wiggle it around enough to get it in and out, but that'd be a pain in the ass.

No idea on the RAVE valve yet, I might just have to cap it off, but I'd like to run it. The area that it'll have to go is tight anyways with the larger CR250 CDI box on the CR250 ignitions that I like to run, I can probably arrange it somewhere else if I need to make room.

I'm told that the combination of the +4mm stroker crank, a KTM rod (An extra 5mm longer than the long 250R rod if I remember, I have the part # saved) and the use of an 82mm odyssey piston gives you the right heights and timing. My deck height is lower than stock though, so I'll probably have to use a spacer plate anyways, which I'm OK with. I'd rather go the other direction if I can make it work without a spacer plate to keep the timing lower (I read somewhere these are like 192 degrees exhaust stock) and I'm not building a drag engine. I want a very all-around engine I can run crappy ass pump gas through and still have fun and kick butt with.

Basically I'm going to save the internal stuff (crank, rod, piston) until I finish working out the other stuff as thats about 500+ bux worth of parts that I don't want to buy until I know I wont have any other significant hang ups elsewhere. Thats my train of thought anyways

[ATC-Eric]

Good deal Billy, cant wait to see this done!

[Dave8338]

CRAZY AWESOME ! ! ! !

I love "things where you wouldn't/shouldn't expect to see them" projects. Keeps people guessing.

[Jason Hall]

If the power valve works good, you might not have to worry to much about the timing being high.

I have a little story about my experiance with a KTM 85 power valve cylinder. Anyone that has rode a Ktm 2 stroke knows that their power valves WORK!! KTM's usually make Fantastic low end power. So anyway, I bought a complete KTM 85sx that was blown up. The top of the exhaust port was HAMMERED BIGTIME.. The nicasil was trashed from the top edge of the exhaust port and up about an 1/8-3/16 of an inch lol. A new cylinder was Well over 500$ I figured what the hell, and i ground the top of the port until I had good material. The power valve fit very close to the piston, so I thought maybe it will run ok. I figured it was worth a try. When I first attempted to start the bike it had Very little compression as I would have figured, because i ground out 3/16 of a inch of its chance to make compression lol. I worried it would just scream and not have any low end power. Much to my surprise,, it had GLOBS of low end torque, and ran like a raped ape.. So if the rave valve works like the KTM you might not have to worry at all. Sorry for the book..

[Billy Golightly]

Thats my plan but no warranties expressed, implied or otherwise guaranteed as to the fact that it will run until such time it actually does....

[RIDE-RED 250r]

The Rotax RAVE valves have a stellar reputation for working very well with just using quality oil and a little bit of periodic maintenance. It's a remarkably simple design that works on exhaust pressure, no finicky linkages to keep in adjustment or anything like that. They have been doing exhaust valves a long time compared to most..

Jason: thanks for the reminder on the stroke issue... I suffer from swiss-cheese-brain sometimes!

Billy: Turns out, one of my reedcages actually has the boot completely removed. The other is somewhat intact with the exception of the delamination issue. (see pics below) You can see how they are a 1 piece design. FYI: V-Force and Boyesen use the conventional 2-piece design which makes it much more cost effective to address cracking carb boots than these do.
You are welcome to one or both, whichever your pleasure. I have no use for them any more as I don't have any sleds at the moment. If you want them, PM me your address and I'll clean them up and get them on their way to you.

[Billy Golightly]

I’m sure you’ll get it to run and after that you can fulfill my fantasy of mating up ten CR500 cylinders to a hand made double crankshaft V10 crankcase and stuffing it into a Ford Pinto!

Now we're talking! I've always wanted to get a 300hp outboard motor with expansion chambers in to a Geo Metro

[Billy Golightly]

The Rotax RAVE valves have a stellar reputation for working very well with just using quality oil and a little bit of periodic maintenance. It's a remarkably simple design that works on exhaust pressure, no finicky linkages to keep in adjustment or anything like that. They have been doing exhaust valves a long time compared to most..

Jason: thanks for the reminder on the stroke issue... I suffer from swiss-cheese-brain sometimes!

Billy: Turns out, one of my reedcages actually has the boot completely removed. The other is somewhat intact with the exception of the delamination issue. (see pics below) You can see how they are a 1 piece design. FYI: V-Force and Boyesen use the conventional 2-piece design which makes it much more cost effective to address cracking carb boots than these do.
You are welcome to one or both, whichever your pleasure. I have no use for them any more as I don't have any sleds at the moment. If you want them, PM me your address and I'll clean them up and get them on their way to you.

PM incoming.

I think I have an idea on how to fix this intake issue already