Hi,

if you had a choice between an OS26V2 and an OS30 tuned as mentionned all along this thread, what would you choose and why ?

If you are planning on using it in a car.. go for the OS26V2. The cam timing is optomised for usage in a car.. it has a higher rpm than the 30

Hey DP anything new in the thumper world?

Unfortunately, no. I plan on using the old FS26C in a SC truck next season, but it'll just be an extended GT2 with SC10 bodywork - nothing really ground breaking. It should be BIG TIME FUN, but it's not anything new, engine-wise.

The 8th scale engine project has been stalled for a while, waiting for me to build up enough motivation to continue working on it.

any chance to have one by spring?

I found out through a racing buddy that xtreme racing makes a carbon fiber SC10 length chassis for the GT2! So, technically, you could make one right now.

There might be parts of the 8th scale engine made by spring, but I don't plan on racing it early next season... I hope to have the parts made sometime next year to see if everything fits together, and if it does, then I'll worry about seeing if it actually runs.

Hi all!

I have finally begun the work on improving my 4-stroke Jammin' X2CRT project again (with the modified OS FS.56 Alpha). The latest improvement i've made was to smooth out the flow through the intake manifold and the intake port in the cylinder head.
As the intake manifold I use was round and the intake in the cylinder head is oval I have smoothed out the difference between these, so the intake, where the carb sits still is round but it transitions smoothly to an oval shape that fits the cylinder head. This also means that the diameter is bigger close to the carb and slightly smaller in the cylinder head, so it's kind of tapered/conical shaped. I hope this results in the air/fuel mixture to be compressed more through the intake port and also increase the speed of the air/fuel mixture on it's way to the combustion chamber.
And in the process I have also slightly increased the diameter (area) of the intake port. So hopefully i'll be able get more air/fuel through to the combustion chamber. Now I just hope, that the intake valve is big enough to handle it.

I'm also planning to reduce the rotational inertia in the driveline slightly by using a smaller spur gear (44 vs 48 tooth spur) and using a smaller clutch bell, thus also being able to mount the engine closer to the centerline of the car. I just need to calculate which size of clutch bell I need? I'm using a 20 tooth bell with the 48 tooth spur now. So i'm guessing something like an 18 tooth bell should work fine with the 44 tooth spur? Hopefully these modifications will help the engine rev up faster and create a better balance in the car.

I'm also considering increasing the passive cooling of the engine with coolingfins from a computer (like the coolingfins from the processor in a computer). It seems like the ventilator driven by the crank shaft just isn't sufficient to really keep temps down.

So far I have been running with an OS muffler from the FS .91 engine (the F-4020 muffler). But it seems that this is restricting the engine, so 'ill try running it without the muffler next time. I'm thinking of making a longer header pipe keeping the same diameter "all the way", so I can route the exhaust tip outside of the bodyshell. This might get louder, but if it works, i'll figure out a muffler for it later. I have found a company specialised in making flexible steel tubes with different types of thread and nuts in the ends, so I can fit it directly to the header pipe or maybe the cylinder head. Hope they will help me out.

I'm also considering increasing the exhaust port diameter also. What do you guys think?

Have any of you guys tried to raise the compression on a 4-stroke? I measured the head gasket and it was 0,2mm and it made me wondering if I can get a 0,1mm head gasket?

So far I have been running with the pressure pipe from the muffler to the tank, but reading the first pages of this thread I realised this is not so good? So, i'll try running it without pressure to the tank next time.
Finally i'm also getting the Perry VP30 fuel pump, so I hope this will help in creating a constant and reliable fuel pressure.

Long post, sorry, but I just wanted to share the progress of my project and my ideas with you guys to get your opinions and experiences.

I have attached a before and after picture of my intake-work.

Not so sure about the bigger engines, but I know the FS26C likes having higher compression. Look 7 or 8 posts back to see details on what I did.

Here's an update on my GT2 - SC10 conversion:
It's done! Waiting for dryish dirt to try it out on.

Hi,

Does any body can help on what clutch shoes and springs should be used with an FS30 ? It seems that standard 3 points for 1/10 made for 2 strokes engines does not work well because revs of the engine are too low resulting in sleepering of the clutch.

what about centax ?

This has come up a few times in this thread, but I'll summarize:

Try installing your clutch shoes backwards - they grab much better that way.
If that doesn't work, I'll just refer you to the clutch setup I use: a 2-shoe MIP REVO clutch, installed backwards. It grabs hard and lasts a long time. You can adjust the engagement point by shortening the spring, and it has 2 holes for the clutch pins so you can have more or less slip, depending on how much traction you have.

For racing, I use the inner hole for more slip and a higher engagement point. It allows a higher idle, which makes it easier to tune the engine for a 30 minute race, and for 2WD the slipping makes it easier to drive once the tires wear and the track dries out during a longer race.

Hi,

I tune my OS 30 with 26C camshaft, 26C valves springs and a silde carbe. I use 20% nitro héli fuel. the gearing seems good (it's for a rc bike)

the clutch shoes is a BBF (TT 1/8). There are 3 springs when it comes from the factory. I only put 1 spring beacause with 2 springs, the engine accelerates but the wheel do not move. With 1 spring, the wheel rotates slowly when the engine is at idle.
http://www.6mik-racing.com/index.php?page=bbf

The result is not as good as expected. The bike is not very powerful.

Time for break in the engine seems long, does ther performance double after 1 gallon ?


how many revs your engine takes ?

what gearing do you recommand ?

I don' t know where my pb is (gearing, clutch, other)

I use the exhaust system provided by OS with the engine, may be this is not the best solution ?

Thanks for your help

This is not a high reving engine. I don't recall but max rev is in low to mid 20k. You need to gear it very high for it to have performance that you're used to getting from a 2 speed.

well guys, i signed up to this forum just to get in on this thread. ive spent several hours today reading every post stemming back to 2004. i gotta say, great work everyone, especially nolan and dp. its too bad os discontinued this motor and that development cant continue. i have always wanted a 4 stroke in a car, however when it was avalible i couldnt afford it, and i was racing so i wanted a reliable car without having to engineer the thing.

that being said, im no longer racing 1/10 scale, ive moved up running 1/5 scale with a small group. my race car, a nitro tc3, has sort of been my "project x". its seen 5 different motors now, the last smallblock being a rossi pixi black. when the motor died in that i wasnt racing anymore and didnt want to spend huge money to get a fast motor, i thought of a 4 stroke. unable to find one, i settles on converting to a rossi .21. the car was insanely fast, however i had to put aluminum diffs in and i machined the 2 speed hubs for hpi spur gears (37 and 41 tooth) and ran an hpi clutch bell with 19 and 23 tooth pinions. id estimate the car did 75+mph in about 3 seconds, just insane. fast forward just over a year and the .21 hammered the rod bushing, and unable to get parts im forced to get another motor. not wanting another run of the mill motor, im back to the 4 stroke idea.

i have a line on a stock 26 v1 still with the single needle carb thats apparently not running very well. being i cant find another one, im hoping to pick it up for a decent price. ill be happy if the crank, block and cam are ok i can always pick up an fs30 to swap some parts over. i have found a bunch of parts online in various places, so i think id be able to rebuild this motor. as far as the car goes, it already has very tall gearing in it, and i can fab up the rest of the stuff. a flywheel and fan kit might be an issue, however im sure i can come up with something.

just as a backup, anyone know of any fs26s-c motors for sale?

well the motor i had found didnt work out so im hunting for another. ive heard you can convert a 26 or 30 plane version wit hthe 26s-c valve springs, crankshaft and camshaft. ive found the crank, valve springs, an fs 40 manifold, however ive been unable to track a camshaft down. anyone have a camshaft they would part with??

Cam is the single hardest part to find for this motor.. Sorry to say, you have your work cut out for you