So... I'm going downstairs now to start on project 4 stroke Ultima ST!

Wish me luck... we may hear that harley sound at the track before snow flies this year!

I've seen 4 stroke powered monster trucks, in the magazines.

What engine you gonna use?

You still planning on doing a nitro XXX-4?

I still have the nitro XXX-4 idea kicking around... I decided I wanted to race it the rest of the season, so I haven't hacked it up yet. I just removed the engine I plan on using for it from my gas truck though!

An FS-26C will go in the truck something like this:


The carb will be right behind the gas tank.... I just need to figure out how to fabricate a 180 manifold... hold on, I think I just figured that out.... Anyway, here's the approximate carb placement:


I need to make new motor mounts (not too hard), and figure a way to mount the fan. Just from test fitting stuff with a mock-up clutch on it (need different shoes and bigger clutch bell to gear it taller), I can tell everything is actually going to fit without changing any of the stock kit parts I am using. The air filter will probably sit above the throttle servo, or somewhere near the radio box.

/edit/ - Oh yeah... Exhaust will be straight piped out the back to keep the goop off the side of the truck, and to give it that open header bad boy 4 stroke sound!

DP thank god you didnt decide to start building bombs. Thank you for RC racing

daymn dude I wish you all the luck and hope to see that monster onthe track soon.

Heh. Small, recreational bombs are cool too, but they don't last very long. I'd rathar spend gobs of time making something bada$$ I can race in a half hour main!

Soon, the locals will learn to PHEAR THE 4-STROKE!

Kidding, the locals are too fast to fear anything I drive...

I finally figured out what the problem was with my truck pushing like mad.... I kept replacing the clutch bearings, took 2 rounds out of the spring, shimmed and re-shimmed, but I should have just stuck some good old metal shielded bearings in instead of rubber sealed bearings. Too much friction, and they never really free up. It makes it seem like the clutch is dragging when it's not.

That will be cool good luck on you project DP

Hey, Les, if you see this, and if it works like I want it to, would you like to do some 4 stroke port work, probably this winter? It's really primative, so there's LOTS of room for improvement!

DP- F1 - NW - FRI - OK

Sweet break out the F-1's I cant wait to see them in action....... I will do my best to be there

Doc - OK. Just make sure you are there. Don't screw me like some other people did at Winter Heat.

Well, I cut out some engine mounts and figured out how to put a smaller (steel - 4 strokes need HEAVY flywheels to idle good) flywheel on it to lower CG as much as possible and work with the new mounts.

That's it for tonight. Need sleep.

UPDATE TIME!!!

So, flywheel, clutch, clutch bell and spur gear are all figured out for a much higher gearing. Engine mounts done, here's pictures:

Flywheel clearance through the bottom of the chassis:


Rear engine mount:


Front engine mount:


higher gearing:

Lookin Good man lookin good... Cant wait to see and hear it run....

haha...looks great Damon.
When are you releasing a production version?

VERY limited run.... ONE Kyosho GP Ultima ST Type R-4

Price: Not worth what you get.

Prototypes are always VERY expensive. Not to mention the engine is discontinued.

BTW, if you think that's freaky looking, there is a possibility (if it works good enough to bother with) of laying the engine down to lower the CG. There would easily be enough room if I moved the gas tank forward and rotated it 90.

It scares me to imagine what the engine mounts for that would look like. The ones I just made were hard enough to get the right size, hole alignment, and stuff.

Another update: It now has an exhaust!

Now on to the intake manifold...... Anyone know if you can bend 5/16" aluminum tubing 180 degrees in a 5/8" radius... or even a 3/4" radius? That's what I'm up against right now. Going to go to the House of Hose tonight.

You using a wicked fast Hitec servo on that truck?? LOL Let me know what the status is...thanks dj

HAHA!!! Nope, just a 605MG. I want to buy your wicked fast 5925 though. See me this weekend at NWRC. I'll be racing 1/12th in the FALL FURY!!!!!!!!!!!

I doubt I'll be there at all this weekend. I'll try to make it over though. How are entries looking for that race? I would really like to see a bunch of on road cars run at the same time, most I've ever seen race at once was 6...Hey dp, you oughta upgrade your 2wd buggy to a B4, I know somebody that has a totally dialed one...lol

Why bother when I have no competition? B-sides, I spankity-spanked on Scott Benson's B-4 the last time he showed up at the track.

The only car I might think about replacing the Kyosho with would be an old TRX-3. Drive one and you will know why. (they corner like a 4mod)

Update.... well, sorta.

House of Hose had nothing. Their bender wouldn't even do as good as my $5 Harbor Freight special....
But, a Home Depot dude told me how to make the bend I need, using sand, 1-1/4" pipe, and a propane torch. I'm not kidding. Really. I'm going to try it tonight after I get some new brake line stuff from Napa.

Still stumped on how to bend some stupid pipe. Tried the sand thing, and it didn't totally collapse on itself, but nowhere near good enough for an intake manifold. Funny how it's the simplest things that get you.

... So, I did the exhaust (revision 1) and the cooling fan. Take a look-see:

That chassis brace sure did come in handy! Kinda neat, since I thought it would be the biggest pain of this project, when it has turned out to be just perfect... Almost like Kyosho meant for me to do this.

DP how bout a nother update.

Well, I smashed a bunch of pipe and broke a 90 degree elbow I had that bolted to the engine.

Cast aluminum doesn't take too well to precision hammer manipulation. I was even using a dead blow instead of the BIG A$$ crescent wrench I usually use for blunt object smashing type adjustments!

So... No update, unless you count a new dent in my workbench as progress. (I used the wrench for that one)

well i have an idea it might cost a couple of bux tho have a intake machined out of bolck stock or somthing like that or will aluminum not hold up?

to machine something unless you know how to do it yourself and have access to the machinery.. costs out the rear..... Theres just a lot of work involved before you even step up to the machine.... then you have to plug it in to the machine... then and then.... you get the idea... and in the mean time you are paying the guy 50-75.00 an hour to do all this....

I thought about that. I'd have to buy a ball end mill, and then try to cheese it out on my 2 axis drill press. That could take days, with the way that thing cuts.

Other than that, I might be able to cut something out on the lathe, but it would end up being 2 pieces, square, and pretty heavy.

I'm just wracking my brain trying to find things that have 5/16" tubing with tight radius (5/8" - 3/4") 180 degree bends... like if 7-11 had big gulp crazy straws.... but they don't.

My brain hurts.

I got it....lol maybe but let me know what you think of this...

get some nylon rodding the same size as the inside diamater and shove it in there.. If you can not find Nylon Rod... try to find somthing that is solid but flexable.. Bend away.... Now your thinking I have this Nylon rod stuck in there and cant get it out...lol BAKE IT the Nylon will melt out and your good to go... In therory.... Let me know if you think im nuts or how things turned out...

Thanks
Jeff Ines

Hey DP,

Here are a couple of benders I found, no details on the radius of the bend, but they look smaller than the bender I've got.

http://www.eastwoodco.com/shopping/product...1&keyword=49002

http://www.eastwoodco.com/shopping/product...3&keyword=49044

Oh and thanks for the help with the idler pully at the Snake

The smaller one is 1" radius. That's what I keep finding everywhere I look. That seems like a really small radius, but that means it sticks 1-1/4 inch off the back of the engine, and the carb will be 2 inches forward of where it bolts onto the engine. That puts it right on top of the fuel lid.

-About the pulley- You're welcome. I would have finished about the same if I gave you the one in my car, because the motor mount screw came loose and jammed the belt about 2 minutes into the 3rd A-main. I'm sure I would have screwed that race up some other way (pun intended ), but it was a perfect race for those 2 minutes!

what kind of tubing are you using? you should use a 5052 h32 alum. tube and crimp one end of your tube, hard pack it with sand then crimp end. you should be able to bend a very small dia. this way. ( if you fill the tube with lead that works the best)

I talked with someone about this today and they suggested casting sand (very fine), and also wetting it to make it pack better. Any idea where I might get said sand?

The pipe I am using is 5/16" OD fuel/brake line from Napa. It's unfinished steel, and has a seam running the length of it. Anything 5/16" would work, but that's the most convenient source I have found. I would like to use something that won't corrode too much, so maybe steel isn't such a good idea.

I'm about ready to go get some large bendy straw from the grocery store just so I can see this thing run! I wouldn't want to run it on the track though, and I'm not even sure the fuel wouldn't eat it.

the best idea i have to find casting sand would be a craft store... maybe an art supply store...

I take it you didnt like my idea ...lol

I think I have a solution... Larry P hooked me up! He bent some 5/16" 5051 aluminum tubing into a really sharp radius. I also got a tubing bender from Napa that will do it. I should be set now. I just need to turn up an intake stack on the lathe, make a carb mount, and throw an air filter on it!

Probably tomorrow. Too tired tonight.

Hey right on... so when you gonna fire it up and test it out..lol or is there more to be hammered out....

Last night, I cut out the intake stack and carb clamp/mount on the lathe. I might redo the stack to shorten the overall length of the manifold, and I have lots of filing, drilling, and tapping to do on the carb mount/clamp, and I need to make another piece to actually bolt it to the chassis. Then there's the air filter and linkage details.

I'm hoping to try it out this weekend if all goes well.

if you want to run at the hank track on sunday i can come down and watch ill bring my mugen down and run with ya.

yeah DP let us know and Ill bring my mugen out too...lmao

More refinements to the intake stack:

That thing started out as a round piece of aluminum with a flange and a hole. The rest I did with a file and a hand drill. That's what I get to do to the round thing in the next picture, only a whole lot more.

Here you can see the unshaped/drilled/tapped carb clamp/mount and Larry's mega bend pipe:


...And here's how it should look when it's put together (except the big round thing will be shaped):

sweet cold air intake more power!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Not really an update, but here goes:

I managed to mangle the carb clamp/mount with the drill press. That, and I worked on cleaning and organizing the garage this weekend instead of making another carb clamp.

On the up side, I now have a VERY WELL LIT garage with lots of workbench space, and a bench grinder that's actually bolted to the bench! To top it off, I won't be tripping on the lathe's extension cord anymore.

It's winter. Put that thing away and bring out your 1/12th scale.

seeya at the races

ti

Not yet... Real life stepped in and broke the bank. It might take me a while to reestablish my racing cash flow.

I do have good news though, I finished the project!! Receiver, transmitter, and starter box batteries are charging now so I can terrorize the neighbors tomorrow. Hopefully it will run good enough to take to the track. I shall see.

OK, so it ran long enough to shake its fan mounting bracket apart. I just figured out where the needles needed to be for it to idle, I revved it up, and the fan fell off. Oh well.

It's acting like the intake tract is too long. I suspected I might have that problem, but I won't know for sure until I can test it some more. If that's the case, I might have to get extreme with it and order another head that I can modify to change which side of the head the intake is on. That will allow me to stick the carb right on the intake port and still have it pretty well centered on the fuel tank. I know it works that way, because that's how I have run it before.

/update/

Made a stronger fan bracket and tried it again last night. It's really acting funny, like something's seriously out of adjustment. Tried different (new) type F glow plugs, had the needles all over the map. All I got it to do is idle, and rev OK, but it will not go back down to idle without dying first. On restart, it idles fine. I'm going to check the valve lash tonight before the meeting. I have a feeling it is too tight (valves don't close completely when hot) and because of that, doesn't have compression to idle when it gets up to operating temp.

/update/
Valve lash checks out perfect. I'll try it one more time this weekend, but it looks like I will need a shorter intake manifold.

HEEE-HAAAAAAAAAW!!!!!!!!!!!!!!!!!

I put the carb back in the stock manifold just to test the engine in the truck with the gearing I put on it... It's WAY overgeared! Even with the clutch slipping like crazy, (hey, what's that smell?) it still does about 50MPH! Since the clutch slips and it's overgeared, it's not too impressive off the line, but the engine runs CLEAN and HARD! It really likes Sidewinder 30%. I gotta try some 40% after I get everything figured out.

The turn left = lean, turn right=rich gremlin was definately there, but it was tunable to where I didn't really notice it. I could probably stick the carb right next to the tank and it would be a little better without doing exotic engine mods, but I'm probably still going to try to relocate the intake port for the shortest intake possible.

Oh yeah, and it sounds really cool too.. like a really little, high revving YZ250F!

I'll post a picture of the working setup tonight.

/edit/ No picture, I already took it apart to design a new manifold. It's most likely going to have to be CNC machined, so it might be spring before this thing sees the track. Then again, it might be easier to buy another head and drill an intake port in the left side of it, (between the studs) sleeve it, and put a plug in the old port.

I've also been looking at the FS-30, and the case looks identical to the .26. They use the same head too. I just looked at the manuals, and the only difference is the .30 has 1mm bigger bore. If that is just the sleeve and piston, I might go BIG BORE!

/edit again/
Big bore is going to have to wait for my bank account to recover from fall cleanup / winter tires & wheels.... So, I took the head off and removed the valves, rocker arms, etc... and since there's so much wear on it, I'm going to deem it disposable. That makes it a perfect candidate for EXPERIMENTATION in the form of relocating the intake port! It will be as good as free even if I do destroy the head.

In my best mad scientist voice:

MUAHAHAHAAAAAAHAHHAAAAAAA!!!!!!!!!!!!!

Ahem.. I completed the above mentioned head mods. It's sick looking, I'm really jacked about it, as long as it doesn't fall apart!

I used Loctite 680 to bond the pieces together, I hope fuel doesn't attack it. I'll find out whenever I have enough light to test it. So, here are the pictures of the head and engine in the truck with a SLIDE VALVE carb!!!

Head:



Engine installed in truck:



This is the way the head should have been designed in the first place, and I'm guessing the carb will work better than any other I have tried so far.

DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP DP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I forgot about my cheering section... Where's Mike and Tibby?