I ditched the cheap RTR pipe on it(one only knows where it came from) and filled the tank again. Open header sounds MEAN and loud....but the dead spots vanished. Carb is on top of head, fuel tank is about 1.5" lower. Also found 22tooth is way too tall. It screams and would be GREAT for a GT car, but not much low end snap. Thinking trying an 18 and a 20. 20 first. After that tank, temps idling were 250ish, right after multiple hard full throttle pulls, ~360. I think I have the tune right, it was singing, not falling apart and temps are reasonable from my airplane 4stroke uses. If I could get the clutch to grab, or gearing right, it'd be a blast. I"m also digging the 15 min runtimes on 120CC's.

EDIT: I"m also using a 10% 4stroke airplane fuel. Thinking I can run a 5% mix of nitro and Klotz castor to make this really cheap to drive.(I blend most of my fuel when I can find nitro)

Storydude,
What kind of clutch are you running, 2-3-4 shoe? If so reverse the clutch shoes if you havent already. They will then act as a lockup type clutch setup. And what size spur are you running? Im at 45 spur, and tried 15-22t clutch bells. I found the 15t to have awesome bottom end, but not enough top to compete with 2 strokes. Best over all is the 18t bell, but still lacking top end on big 1/8 tracks. Start getting into the higher bells, the clutch will heat up fast and it kills bottom end as you found out.

3 shoe and I'm going to try that tomorrow. Spur, IIRC is a 46 tooth. I'm not looking to keep up with the 2 strokes, this is more of a fun scale-like basher...my SX8 with a Speed takes care of the go-fast addiction. Like I said, the 22 tooth just kept climbing and climbing in speed and I honestly ran out of room before it started really moving. In an on-road setup, this would be killer. I may be leaning towards a GTP-type car or WRC clone before this is all done....The platform I chose as a testbed isn;t really the best handling off road vehicle in existence.

It already brought a smile to my face today and that makes it all worth it....now to get some 5/16" brake line and make my own exhaust tomorrow.

I can see the potential of this motor though...even geared way too high for anything smaller than 400 foot straights, it just PULLED. I was digging the scale-like acceleration and sound too.

Video evidence?

Massive FAIL tonight. No Video, but it would have been cool.

Turned clutch around, grabbing better, but still slipping like death....And the cause of massive fail.

Zinging in the parking lot tonight back and forth. From a dead stop, clutch is slipping for a good 50 feet@ WOT..When clutch grabbed, it was like a rubberband effect....20mph to 40+ and climbing(still 22/46) and quickly running out of room. Engine RPM did not change but slightly during this so I know motor is WOT and wound out, just clutch cannot handle it.

So, 3rd pass, someone comes into the lot as I"m doing a highspeed run away from me, right at the entrance I"m by. I lock up brakes and as it slows, try to slide it sideways to power back towards me to avoid them.....Not figuring it was doing 40.

Do a barrel roll!


About 30 of them to be exact


Damagereport:
1 bent front shocktower
4 blown body posts
1 broken front universal
1 broken knuckle
1 shattered ego


This testbed chassis handles like crap to begin with...Thinking time to convert the Jammin X1....At least that doesn't handle like a 1977 SuperWinne.

Conclusion:
Needs to drop about 3-5 teeth on clutchbell. no need for that much speed for what I'm looking for. Should allow clutch to not slip as much, should improve acceleration, and should save clutchshoes(4 sets of carbons and one set of aluminum Max Lifes so far in testing). If this won't work, I'll find some of those integy shoes with the setscrew weights and fill with lead shot.

Might need super firm springs to keep them off the bell, but I know they'll grab then.

Cooling doesn't seem to be an issue with this motor too much. Still getting 240-250 at idle, and 350-365 after a few hard pulls. Of course ambient temps are in the low 50's too.

I'll snap pics and video one of these days

Now you know that crash would have been great on film..

New test bed would be good.

I too hope to see videos/pics.

SUCCESS!!!

MIP heavy 3 shoe clutch FTW. Spun around as leading shoe, stock weight spring and 18 tooth bell=Happiness.

Little wheelspin on Grass from a dead stop, acceptable speed with he 18 tooth bell and killer run times(15:52 on the ground, about 50/50 idle-WOT about 4 min on the box tuning/adjusting). I lost my Aircleaner somewhere today, so once I pick one of those up from the LHS, I'll get pics and video posted.

I'm happy. Very happy

After about 10 tanks slobbering rich, compression actually increased after rebuild almost to the point of my bumpbox stalling. I have 2 extra rings, 2 conrods and Boca Ceramic rear on order. I put in a new OS bearing when I rebuilt, not sure if I should swap. I adjusted valves after running today and it only opened up .01MM. It should be good for another 2 gallons before any more adjustments are needed.


Anyone interested in doing this be prepared for a big smile once done, but also be prepared to toss money at issues.

Sounds like your having a good time I remember when i first started driving mine, couldnt get enough of it. Just wish it was warmer out here, time to start electric racing indoors now.

subscribe.....

Like I promised.....PICS.

This is mounted on the X1 buggy after a few hours of swearing at parts. 18tooth Clutchbell better work....because no other bell will fit without milling out mounting slots....I tried 3 different styles of motormounts.. Cannot get the motor far enough back to get 100% engagement on spur, so I shimmed as close as I could and gonna run it. Gotta get an airfilter next LHS trip...I wanna drive this.





Not the best, but best I can do with my crappy camera.


EDIT: Oh, I"m putting a spring on throttlelinkageV2.0. I have just found something to allow me to raise the throttle mounting point to allow clearance with brake linkage.

Looks great Storydude!
Have you considered using a carb from a .21 two-stroke?

I just got a little more runtime with my project last weekend. Unfortunately the weather is beginning to be so bad here in Denmark, that i'm not going to get much more runtime this year.
But I tried to change my clutch bell from 22 tooth to a 20 tooth, which was a big improvement! Better acceleration, lower temps and still ok topspeed. I'm still running the standard 48 tooth spur on my Hong Nor/Jammin' X2 CRT truggy, but I also have a 44 tooth spur from the X2 CR buggy. I'll try that later on, so I maybe can run a smaller clutch bell and also can mount the engine closer to the centerline.
I also have some plans to get more revs out of the engine (improving the flow through the intake manifold and mounting a fuel pressure regulator).
A friend of mine ran his Hobao Hyper 7 buggy with a 3 port .21 engine and as my 4 stroke truggy began reaching the optimum workingtemp I began to outrace him on topspeed! He was quite impressed and began to "feel the pressure" from the 4 stroke power!

I haven;t seen a .21 carb with a small enough throat. This isn't a converted Airplane engine, but an OS 40CX. It revs higher than any 4 stroke I've heard. Plus, with the carb being mounted on the head, a linear slide carb would be hard to hook up.

I'll try and get some pics with body and Aircleaner mounted.

I"ve found heat isn't that big of an issue with this motor. I've had it to well above 400* F with no loss of power, just hard starting if it flames....And not because it has no compression, but because it vapor locks due to the boiling fuel I've run it hard like this for 5 tanks now, still blowing smoke and oil nicely and so much compression I cannot turn it over by hand...Hot or cold. Hot it seems to get MORE compression(probably due to iron liner expanding more than piston).


The big test will be next spring if it still runs good when it's 70F out...and not 50F.