mercfocus

iTrader: (3)

So I had to rebuild my OFNA Force 28 engine.

I got these new parts: Crankcase w/bearings installed, Head & head button & bolts, sleeve & piston w/ rod attached.

The whole rebuild went very well except the carb. I used my original carb from my old crankcase and it was really tight coming out. it was way too tight going in to the new crank case and strangely enough, it was too tight to go back into the crank case it came out of.

It's like it grew too big for the hole it came out of. I don't understand it at all.

I'm not buying a new carb so I sanded around the base of it until it was finally able to be forced into its hole. I got it about half way then piled up copper ATV all around it and pressed it in the rest of the way. I couldn't even use the O-rings that are supposed to be in there. It was that tight.

I don't think that's going to work out very good.

I had it out once before to seal it and it was no problem. Went out and back in easy and I used Racer's edge air seal to seal it.

This time, no way. It was a b*tch.

I had to rebuild because it over-heated.

Any ideas why this happened?

xrayracer1

iTrader: (1)

You may find that the little sleeve that clamps the carb onto the crankcase may have moved slightly. Loosen the screw and make sure the sleeve is flush with the crankcase.

Hoese37

iTrader: (5)

For the price, you could have gotten a whole new engine.

mercfocus

iTrader: (3)

Of course that was loose. I even took it out completely just to see the carb sizing in there. Why would I not have that loose?

I guess I should have mentioned that in my original thread. Too make sure that little clamp thing wasn't the problem, I took them out of both crankcases, new and old one. It was my first suspect.

The carb still didn't go back in even without that piece at all.

mercfocus

iTrader: (3)

These parts I got were only $66 shipped for everything.

Can't get a new engine for that. Not this one.

I priced these parts at their regular price and they're actually more for these parts than a new engine. I wouldn't have rebuilt this for that much.

I have a Picco 21 I want to rebuild but won't because the only sources I found for its parts are more than the engine is even worth.

The cost doesn't even bother me as much as the stress of parts not fitting like they should.

Tug Driver

Glad to hear you got it all back together. Most rebuilds don't go as far as changing the case bearings, let alone the case.

Did the neck of the carb get warped? My first .25 in my savage ss kit I didn't know any better and way over tightened the carb clamp and crushed the carb neck. It became permanent after that.

mercfocus

iTrader: (3)

That was one of my guesses too.

I left that detail out to see if anybody else would say that. I just didn't think that was even possible. I do have a really bad habit of over tightening things.

Did you ever get that same carb to work again?

The way I ended up making this work is kinda messed up. I think it's completely sealed though.

I think I'm not going to tighten those anymore.

I now see why team Associated does their Reedy engines the way they do.

My ST-RR EVO

iTrader: (5)

I have seen that on two engines. I really don't even like taking the carb out for that reason. It helps to use a heat gun to heat the block and a helper hold the car steady while you use brute force to stuff the carb in. It is a pain especially since the carb is so small and you are basically only using your thumb.

If I had to do it again, I'd take the engine out and use a vise and some wood to press it in. I'd be willing to risk my engine.

mercfocus

iTrader: (3)

That did cross my mind: heating the block.

I ended up with what you see there in the attached pics. I havn't broke it in yet so I have no idea how this is going to go.

Not too sure how clear the pic is if the all that orange crap can be seen very well.

xrayracer1

iTrader: (1)

Where did you get that flywheel from? Or is it custom?

mercfocus

iTrader: (3)

It's a Fioroni. FR-111 or something like that.

I have 2 of them.

They're around all over internet: I think even A-main has them.

Tug Driver

That engine was burned up and junk so I pulled it and put an os 30vg in the savage. I only discovered it when I was stripping that block down for the roto start and one way. I was going to pull it all the way down but there were some stripped screws. I pulled the carb thinking I would keep it for the .28 and found the neck crushed. The os manual says to tighten the retainer finger tight then an additional 1/4 turn. They don't need to be that tight and can place a lot of crushing force on the carb neck. It's easy to see why it happens.

xrayracer1

iTrader: (1)

Cool! I might have to check it out.

mercfocus

iTrader: (3)

Wanted to show off a little update on my rebuilt Force 28.

It's kicking a**!!!

Well past the break in and it never sounded or ran better.

Here is some pics of it running the other day.

The first one is it just pulling wheelies and the second is with it running against my EB4.