JohnP2

I bought my 11 year old son an Exceed Forza (I believe it has an18 CXP. Full disclosure: it has been 20+ years since I've done anything with nitro RC cars, so am almost back to a 'beginner' level. ;-)

Anyway, I had trouble starting it the first time. The second time I started, I jacked my con rod (see attached photo). I believe during initial start, I flooded the engine (as the pull start was very tight). I pulled the glow plug and released the fuel. I actually did this procedure several times...primarily because the nitro is clear, my eyesight is poor...and the short story is I flooded the engine about 3-4 times.

When I finally DID get it to start, things went bad. Very bad. The car went into FULL throttle (I think my hand must of hit the carb and opened it wide open). . The second time I started it...same thing-car went into FULL throttle for about 10 seconds and then suddenly stopped. This second time, howeve, I was sure my hand did not touch the carb...

Upon inspection of the engine, the con rod ended up breakingI was able to find a new one.

My questions:
1. Any idea why the car went full throttle in its first start? Obviously I hit somethingassume the throttle linkage would have moved back to position after being moved? It was also tuned to factory settings, etc. What do I need to check for to ensure it does not go full throttle when I start?

2. It seems pretty simply replacing the con rod (so I think). Just ensure the 'oiling hole' on the rod is facing the front of the piston? Is there anything specific I need to be aware of removing the piston pin?

Thanks in advance!!

LjCraft12

your right con rods are easy fixes buy 2 and change it out the first sign of wear... next time loosen the glow plug 1/8 - 1/4 turn and start it like that new engines like that or atleast the ones I have delt with....

Argess

Only time I broke a conrod, the carb servo horn was loose (rotary carb) and although the servo, etc. were in the correct idle postion, the carb was at WOT. Before I could get it shut down, the rod broke. Most unfortnate, as this was a friend's vehicle. I told the warranty people what happened and they covered it as there was the possibilty the servo horn had been loose from the factory.

to avoid breaking the rod on start-up:

1/ Periodically check everything for tightness

2/ Always have your radio gear ON when starting the engine and make sure the carb is in the idle position

3/ Using the radio throttle trim and opening the throttle a tiny bit for cold starting works great, but be very ready to move the trim back down if it revs too much when it first starts. ON a slide carb, I increase the throttle (using the radi trim) until I just start to see movement of the rubber bellows. Usually this is good, but I'm always ready to throttle back in a hurry if need be.

proanti1

My Feedback: (2)

That is a piston port motor, make sure you replace it with the hole facing the right direction. It's ALWAYS a good idea to start the engine with the glow plug loosened about a turn, this alleviates a lot of the compression. Once it starts, snug it back down. The best way to fire up a dry engine that has not been primed is to loosen the plug, put on the glow warmer, put your finger over the exhaust stinger, and yank on it a few times with your wrist. You will see the fuel make its way into the carb, another couple cycles and the engine should fire. You shouldn't pull the recoil starter all the way out, you only want to pop the engine over about 3 cycles at a time.

As for the throttle, remove the filter and make sure there is about a 1mm idle gap with the controller in it's neutral position.

JohnP2

Many thanks to your replies. I checked and did indeed notice the carb was wide open at idle, so I set it to the 1mm opening. So much for factory settings.

With that,I did receive my con rod, but it was the wrong piece. Everything fit perfectly except the top hole of the rod was a fraction to small for the piston pin. ;-( It is a CXP 18 engine, and the place I ordered (online) claims that it is the rod for that enginebut it obviously is not.

I did find a rod for a VX 18 engine (I've heard they are similar if not exact). The rod does look exactly like the one I broke (http://www.rc-tradingpost.com/r007.html) so might order that one.

If that does not work...I am SOL as I cannot find the rod for this engine.

The good news in all of this is that I learned a LOT about the engine. I'm already thinking of upgrading and using this car to tinker with and learn on.

1QwkSport2.5r

I didnt see it discussed, but when you were trying to start the engine, you did make sure the Transmitter and Receiver were turned on and operating properly didn't you? If you didn't, make it a point from now on to turn on the Transmitter and Receiver, verify the throttle and steering are operating properly. I personally run both Throttle and Steering full lock to lock several times before starting the engine. This way you will know before the engine fires if there is a linkage problem, or if the servo is moving slow/erratically.

Also, always make sure you're starting the car on the ground. Keeping a foot in front of it will help prevent it from taking off should something falter in the throttle linkage/servo. If it does randomly go to WOT, at least having the tires on the ground will buy you a little time to shut it down before it grenades again. Glow engines run WOT with little to no load on them "shaft run" and the rod usually pukes.

Hope this helps you..

JohnP2

Thanks for the reply yes, it does help.

To answer your questions: I did have the receiver and transmitter on when I started and checked the servo to ensure the throttle linkage was functional. I think it was the perfect storm in that I primed the engine (flooded it), released the fuel, primed/flooded/released quite a few times with the glow plug in but the starter out.

Then when I started (I only primed with two short pulls finger over exhaust) with the glow plug starter in (glow plug was"snug" but not too tight). I had the balls of my feet on the rear tires....but she took off once I started. The car was flying around my garage...ha!

After all this and with some research, Icheckedthe carb opening at idle, and it was 3/4 open. Not sure if something I did to adjust this, but that seemed to be the obvious reason based on what I've learned. I took it to the LHS and they confirmed for me.

Of course after that I could not pull the starter or turn the flywheel, which is when Itook apartthe engine and noticed the broken rod.

So from this I learned: ALWAYS pull the air filter and check the carb openingfor the servo'sidle/WOT/brake setting. Of course, because I cannot find a new con rod, I have yet to start it-but I'm learning nonetheless. Thanks!

proanti1

My Feedback: (2)

The CXP engines and the Vertex engines are identical... although I do not know who manufactures them. The conrod should work. You can just buy a Toki (Shuwa) engine on ebay for like $45.

JohnP2

The Toki looks interesting (you can't beat the price). Is it able to fit ona 1/10 scale buggy (specifically my Forza?) Forgive me as I am not knowledgable (yet)on whatis involved withreplacing engines. i.e. is there a standard out there to follow...or how does one knowif the engine he is purchasing will fit on his car?

Thanks!

proanti1

My Feedback: (2)

It should drop right in. Yours is a side exhaust, pull start, rotary carb, short shaft engine. The Toki is also side exhaust, pull start, rotary carb, and short shaft.

To swap to a new engine, you will have to take the clutch off, which is pretty easy. There should be a little screw on the end of the crank, removing that allows you to pull the clutch bell off. A roller bearing will come off with the bell. Pull the shoes off, they should be held together with a band spring. Next is a pilot shaft nut, the easiest way to remove this is to gently grab the flywheel with a pair of channel locks (use a rag to protect it from the jaws), and remove the nut with a glow plug wrench. Yours does not use a collet, so the flywheel will just slide off. Now just install everything on the new engine in the opposite order that you removed it.

You may need to turn the carb around 180 degrees. To do this, loosen the little nut below the carb about 2 turns, tap on it with something plastic, then gently twist the carb until it slides upwards.

The only thing that may pose an issue is the crank length. Those vertex/cxp engines had a crank that was a bit longer than normal shortshaft engines, this was because the flywheel sat on the thrust washer. It should be fine though.

JohnP2

Awesome information, thank you. I'll take it as 'side exhaust, pull start, rotary carb, short shaft engine' are standards enough to pick an engine for one's car.? I have no problems investing time in to fitting itthat's part of the fun anyway, right? Just want to ensure it is 'do-able' for an eager beginner. ;-) Being a .27 it is a big-block, correct?

I spoke with the vendor where I purchased the con rod. He stated he's had 17 people order this part for the make/model of my car, and it's always fit. I sent him a picture that explained everything. He's checking with the manufacturer (SmartTech), which is an overseas company. In the mean-time I asked him to send me a new piston pin and holderso we can begin ruling out some things. He's provided tremendous customer-service, and has been great to deal with. I promised him if the piston pin and holder did not fit, I'd send it back and just get refunded or store credit.

At this stage, I just want to get the car running, and might invest in that Toki if not resolved by this weekend.

Regardless, I've already decided to invest in an upgraded car (I think I am developing a problem). Ha!  I've LOVED the time my son and I have spent on this project (he's only been into brushless) as we thoroughly enjoy the challenge of tinkering with a Nitro engine/car. There is a lot for us to learn, but we will get there.

Thanks again for your detailed responses!

proanti1

My Feedback: (2)

Here are the basic engine differences.

Crank: There are 3 general types, short shaft, long shaft and SG. Short shaft engines have a short threaded crank, designed for a pilot shaft clutch nut. Long shaft engines have a longer threaded crank, which is the standard length used on airplane engines, they are becoming less common because they require trimming with a Dremel. SG shaft engines incorporate the pilot shaft into the crank. A fourth type is a 'universal', or two piece crank, which uses a threaded insert. Universal cranks are not common.

Exhaust: Two types, side and rear. Side exhaust engines have a rectangular port on the side of the engine with two holes (like yours). Rear exhaust engines have a single round port at the back of the engine. A spring wraps around the engine to mount a rear exhaust manifold.

Carb: Two types, slide and rotary. Yours is a rotary, because it has a rotating crank arm. Slide has a cylinder that actually slides outward from the carb body.

Pull start: There are several types of rotary start, electric start, and pull start. Some small block, rear exhaust engines use a special 'big' block type pull start.

grrmisfit

on start heres a couple things.. i know it sounds impossbile but make sure your servo isnt reversed.. then my first experince with a on-road car was when a power failure happens or something causes the rx to loose signal.. get a return spring!!!! .. i cant stress this enough .. nothing makes your cheeks tighten like a vise like watching your car go full throttle with no control into the nearest inanimate object