WikedBaja

Here are pictures of my engine. Does it need rebuilt? I've been having problems getting it to start.

badz

My Feedback: (1)

You can check the ring gap by putting the ring into the cylinder and measuring it's gap it's supposed to be under .020...the ring could be worn...I do see you have some pretty good scratches on your flywheel...was your coil gap set correctly? Looks like the coil may have been uneven and hitting some...that'd make it hard starting...coil gap is set with a business card btw. There's some scoring it looks like by your intake port also can't really see how bad it is from a photo....This may sound dumb also but the piston ring gap is not where the pin is...and oddly where the piston ring gap is you have dark blowby lines on your piston...was the ring in right?

WikedBaja

Thanks for the response. I'm not sure about the coil gap since I just bought the truck and it was used. Can I just sand down the surface of the flywheel to clean it up or does it need replaced? BTW, when I was taking the engine apart, I noticed that the coil was riding on the flywheel. Per your instructions, there should be about a credit cards worth of space between the bottom of the coil and the surface of the flywheel?

Also, for the piston ring, I didn't move it around after removing the head, so the ring is most likely where it was at when it was assembled. Where should the gap be on the ring? Should it be above the pin?

Can this engine be just cleaned up or do I need to rebuild it.

Any comments would be appreciated. Thanks.

WikedBaja

I'm a little surprised by this forum. I would have thought that out of 80 people viewing this post, more than 1 person would have replied.

Bratch96

My guess, if you're having trouble starting it; I bet if you replaced the ring with a new one it will fire right up.
But do check the gap between ignition coil and flywheel, like Badz said about the width of the thickness of a business card. Make sure it's not hitting.

IONIC-M

The pistion and ring look ok. The marks on the pistion almost looks like it was ran alittle hard before it had a chance to warm up.. There is a little pin in the ring grove on the pistion that is where the ring gap goes. And you said it your self that the coil was riding on the flywheel. That sounds like that was the problem..Put it back together and it shoud fire right up!!

badz

My Feedback: (1)

I'd honestly just replace the top end they only cost around $50 for cylinder,piston and ring....clean the bottom end out really good and oil it up slap it back together...I'd say your starting issue was definetly the coil since ya said it was rubbing the flywheel.

Acs_guitars

My Feedback: (3)

I agree, it actually looks like the break in was skipped to me..... Since you have it apart, and it's cheap, you might as well rebuild.

kengentry5000

My Feedback: (2)

If you have an hour to put it back together, why not do so and set the coil gap back right. It might fire right up and save you time.

If you need parts, [link=http://www.davesmotors.com/]Dave's Motors[/link] is great. I had a blown head gasket. For $6 I got a ring and head gasket. I replaced them in 30 minutes including cleaning the combustion chamber and piston with mineral spirits and light pressure with a ScotchBrite pad. The engine fired up right away afterward. I got the parts from Utah in 3 days to North Carolina.

Make sure to wear clean latex gloves during the 'operation' to keep skin oils off the piston and head. Also use two-stroke oil to lubricate around the ring, piston pin, etc.

The coil gap is actually the width of a business card (not a credit card).

TheFgMan01

Badz is right! since that scaring is there in the cylinder i'd replace that and the piston with a ring... also get yourself another cylinder gasket which the new head may come with anyway. ) it will run alot stronger for you when your done

aluminum crusher

IF you build they will comeLOL

Bratch96

Don't rebuild your engine. Buy a new one. Then you will have a spare. Just my opinion.

aluminum crusher

I have done the same thing and the X-tra parts laying around will some day put a smile on your face.

WikedBaja

Thanks for all the suggestions.

Well, just for fun, I cleaned all the parts, re-adjusted the coil spacing, cleaned the spark plug and re-assembled the motor (using the old gaskets). I know I need new gaskets, but I just wanted to see if it would start. I noticed that the spark wasn't very strong so I cleaned the inside of the spark plug wire. That seemed to help a little. I finally got the car to start, but it would rev up real high and bog if I gave it any gas. After a few seconds it would die. EVERY time I started it, it would rev-up real high and then die after a few seconds. I also couldn't get it to idle. I also noticed that the tank seemed overly pressurized. The fuel was bubbling up in the tank which I've never noticed before. Could this be due to a gasket leak since I reused the gaskets?? (none of them were torn)

Anyways, I was thinking of rebuilding the motor, but I'm hesitant because I just want a reliable motor. I would hate to rebuild it and still have an issue like this. I could put the motor aside and work on it in the future.

If I buy a new motor, should I stick with a CY motor or a Zenoh motor? Also, the motor I have is a 27cc. Since I don't want to spend a lot of money, what motor would be at least AS powerful as the motor I have? Anyone have any great deals? I know Davesmotors and ONeils has motors.

Any suggestions would be appreciated. Thanks again.

badz

My Feedback: (1)

I'd almost bet that since your coil was rubbing it's worn enough that it won't work properly anymore, that's probably the weak spark issue. The fuel bubbling in the tank is a odd one....are the fuel lines hooked up correctly? It could also be something sticking or not working properly inside the carb, I'm unsure if a air leak would cause more pressure to the tank, I've always thought these are un-pressurized systems, since most have vent holes in the fuel caps. You can pick up a new 27cc top end off Dave's for $50 and a coil for $16 unfortunatly they are backordered at Dave's. Try firing a PM off to Earthsurfer and explain to him what the engine is doing, he's a engine builder and he may have more information than me which I'm sure he does.

JRexA

To me it looks like the plating is worn away on the cylinder. (1'st pic)

Even if replacing the ring, then the bare unplated alu will just accelerate the wear, and the top will need replacement VERY soon.

Get a new top, and you have an almost new engine.

Check the crank bearings, if they are worn, then get a "Long Block" engine, as that is easier and almost cheaper than getting a new top + new bearings and oil seals.
(Long Block is engine without ignition, clutch and flywheel)

WikedBaja

I think I might just buy a complete new engine and avoid any future issues (worn coil and possibly the clutch and ignition). Do I need to stick with the CY engines or should I buy a Zenoah motor?

sb racing

Both cy and zenoah are good engines but the cy will wear out faster than the zenoah so it may be worth while spending the extra on the zenoah.

Simon

Chop Suey

Man, that really sucks after so much hard work going into trying to fix it. Before you mount the new engine, you might want to smash that damn trouble-making one with a hugh sledge hammer, just to get even you know...

WikedBaja

Well, I think I've found a good replacement engine. Its a CY29RC engine from DDM. It makes 3.5hp and costs $189. This seems like a good deal. I would think the truck would be alot faster since the old engine was about 2 hp.

Does anyone have any other engine suggestions or comments about this engine.

Thanks again.

badz

My Feedback: (1)

I run 29cc race ported engines...they are awesome...heard some horror stories about the piston skirts getting beat up bad on 35mm bore engines but mine aren't that way so I don't know

IONIC-M

If you want Power and Speed get the 28.5cc motor. It is a screamer!!!!!!!!! I have that motor and I love it!!!

teamchrome

My Feedback: (4)

Alot of the people have gone to other forums on large scale and Bajas.
PM me and Ill send you info. Nothing against RCU but alot of very experianced people are gone now and some are here still.