So to start with I recently rebuilt my predator 224, I already had a billet flywheel, cam, and 22lb valve springs, well I finally bit the bullet and tore it down to put in the new arc billet rod I had for it and some 26 lb valve springs but I got it back together and ran it for like 3 heat cycles and took the head off to find this im not sure how but it wasnt like this before, I also changed out for a higher compression head gasket, could that have caused this? Is it ok to run like this? Why did it do this?
Help with predator 224
- Thread starter aust9002
- Start date
Denny
Canned Monster
What did the engine digest? Polish out all the little raised spots to avoid detonation and get rid of that stupid spark plug for a conventional one.
pearl111
Well-known member
I agree, I had those plugs before and they only gave me problems.
So I put them in the trash, put a regular plug in.
Anyways it worked for me.
panchothedog
Well-known member
- Messages
- 2,788
- Reaction score
- 3,739
When you changed the rod, did you replace it with a stock length rod, or did you go with the longer length. They come in + .020" and + . 040" . Either one of those along with a thinner head gasket is a recipe for disaster. Well maybe not disaster, but clearance problems. Do like Denny suggest and polish everything out, then get the nice thick .040" fire ring head gasket , and give it a try. Denny doesn't like those plugs. I have them in 2 or 3 of the 5 of my engines currently in use. I think it's the head gasket that you changed that's causing your problem.
Rod is arc 6773 running a 265 hot cam, so upon further investigating I think some of my weld got down in the valve because i broke one of the exhaust manifold screw while trying to remove so I tried welding a nut on top but I guess I didnt cover the exhaust port, how do you recommend that I polish the piston and head? I am taking the head to a buddy tomorrow to see if he can get the exhaust bolt out theres only like a 1/4" sticking above now, also whats wrong with the plug? Is a performance 3910x autolite, i noticed the pitting was mostly towards the bottom of the cylinder and I found a little oval ball of metal that i thought was from the piston when I was dissasembling it but now it makes sense that some weld got down through the valve.
pearl111
Well-known member
Wow...... maybe it's me.... but I had those plugs, and they gave my engine problems.
So maybe it was bad plug or something else I don't know.
Anyway, I'll look to see if I have any lying around and try them again.
If so, I'll let you know how it worked out.
BrownStainRacing
Well-known member
- Messages
- 1,367
- Reaction score
- 1,482
You have to get a 70mm flat top piston to fit that wrist pin size for the rod.
Clean that head and piston up.
A new head and studs would be cheaper.
My 224 had piston to deck height at .006" . You need .030", for safety, so piston dont hit the head.
Measure piston to deck, and get a gasket that will get you closest to that .030".
Racing Cams and Parts | Cylinder Head, Ducar 224cc | 224-1115 | DynoCams
Explore a World of Parts: Find the Components You Need for Your Projects. From Mechanical to Electronic, Discover a Vast Selection of High-Quality Parts to Fuel Your Creativity. | 224-1115
www.dynocams.com
BrownStainRacing
Well-known member
- Messages
- 1,367
- Reaction score
- 1,482
When I 1st started using those plugs, they was fouling really fast.
I wised up and realized, it's 3 heat rannges COLDER then the standard ngk bp6es.
Since these 3910x plugs are really hard to get a good read on, I use a ngk bp9es plug and tune the carb to get a nice coloring the plug, then switch to 3910x plug.
pearl111
Well-known member
Did you do something different to get those plugs to work the way that you want them to... As BrownStainRacing did, In the above post number #12?
Im running a nibbi 26mm carb with a 145 main jet and 35 or 37 idle jet and it usually starts first pull I swapped over to those when I started building it I got 10 of them so I could "read the plug" but usually just ended up changing out the jets till i found the best one that didnt bog and let me go to the highest rpm but prob about 9-10 hours on that plug without any issues really that ive noticed
How would one go about measuring the clearance? If I need to get a new head which one should I go with? I need 26lb valve springs and maybe bigger valves? Trying to keep this under like 200 because ive already spent like 1000 on this damn motor
BrownStainRacing
Well-known member
- Messages
- 1,367
- Reaction score
- 1,482
Here's how I do it.
I got a dial indicator with magnetic base, but it's easier for me to grab a big allen wrench and feelers gauges.
A flat top for a tilly 212, or ducar 212, and I'm sure there's others, will fit that rod. Gx200, clone 196, and predator 212 use a different wrist pin, so those pistons will not work for you.
You don't need bigger valves.
That stock 224 head, exhaust studs, a piston ring kit, and whatever gaskets you need should only be around $70, if that.
You can swap your old head parts to the new head, if they are still good.
If you need help finding a piston, jus yell, I should be around most of the day.
Post in thread 'Measuring deck height' https://www.diygokarts.com/community/threads/measuring-deck-height.47553/post-596541
Would this head work? : https://www.gopowersports.com/tillotson-racing-cylinder-head-assembly-225rs/
And what about this piston? Is it the same wristpin?: https://www.gopowersports.com/tillotson-racing-flat-top-piston-212cc-70mm/
And what about this piston? Is it the same wristpin?: https://www.gopowersports.com/tillotson-racing-flat-top-piston-212cc-70mm/
BrownStainRacing
Well-known member
- Messages
- 1,367
- Reaction score
- 1,482
I don't purchase anything from GPS, anymore.
That head I posted in that link fr8m dyno cams, is the stock predator 224 head, it's perfectly fine.
My 224 will yank the gates off of hell with the stock 224 head and very mild port work.
I'm starting to think, you might be stuck using the stock dished piston.
That 58mm crank stroke moves the counterweights closer to the bottom of the piston skirt. The 212 flat top piston might not work, since it was designed for a 55mm crank.
I had to go a different route then you, I use a clone style +.020" longer rod and a pred 212 hemi flat top piston to get the counter weight and piston clearance.
I'll look around and see what I come up with.
Here's my "turd motor 224", it's gotta a hellava hole shot for a 20" tire and 4.6:1 gear.
