Predator 212 upgrades and issues on my trike

NJtrikes

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I am new to the trike/kart world so some of this may seem basic. But here is what I have and whats going on....

I have a brand new Predator 212 with a Mikuni 22M carb with .125 primary jet swap and upgraded exhaust header that will be going on my Drift Trike. Some things I am seeing

-Engine starts right up, and I am able to adjust the idle slightly but it seems to be running at a very high RPM.
-It is also crazy loud...like ear ring loud. not sure if aht is because of the header/muffler combo, but wow. my ears are ringing. It is a lot lounder than the 25 HP enging on my lawn tractor (this does not seem normal)
-Currently the engine is mounted on the trike, but the chain is not connected to the axle sprocket.
-I did not remove the governor, but it is essentially disconnected as the throttle cable goes directly to the Mikuni Carb.
-When the engine runs, the clutch spins. (not sure if this is normal since it has no resistance from the axle)
-When I rev the engine I do get some flames out the exhaust (cool looking, but i know thats not good).

So my question is what am I missing? What should I check? With the upgrades I have, should I be upgrading other parts? remove the governor from inside?

I am not an engine expert by any means (obvious by my questions here), but capable of doing whatever is needed. Thanks for your help in advance.
 

ezcome-ezgo

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One old stand-by recommendation regarding the governor is if you just "by-pass" it, the resulting ability of the engine to rev beyond the little mechanism's limits may result in said mechanism blowing apart inside the crankcase. The consequences of that are likely catastrophic for the engine.
 

Rat

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I have a brand new Predator 212 with a Mikuni 22M carb with .125 primary jet swap and upgraded exhaust header that will be going on my Drift Trike. Some things I am seeing
That carb is too small for that displacement, you need to be running 24mm minimum, 28mm is more ideal. Yes, 2mm size difference matters a lot and changes a lot.

Engine starts right up, and I am able to adjust the idle slightly but it seems to be running at a very high RPM.
-It is also crazy loud..
There's a few things that could be happening.

First a too small carb is going to run lean and need to be jetted crazy rich to compensate... the downfall being it is harder to tune and will be a lot more sensetive to ambient and altitude changes.

Throttle cable could be a little short and holding the slide up.

Idle A/F bleed screw needle might be set wrong

Pilot jet too lean

-I did not remove the governor, but it is essentially disconnected as the throttle cable goes directly to the Mikuni Carb
Fasted way to blow up an engine EVERY TIME!! If you don't or won't use it lose it, ALL OF IT. Plug the linkage hole in the case with a short bolt, just tap threads and run one in.
When I rev the engine I do get some flames out the exhaust (cool looking, but i know thats not good
Confirms lean fuel condition. When you run too lean the header gets extremely hot, hotter than usual. When you rev it up and drop the throttle it suddenly goes from lean to spitting fuel into the pipe momentarily which ignites instantly due to the excessive heat.
 

panchothedog

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If you are running any sort of muffler you shouldn't be getting flames out of the pipe. Straight pipe, for sure. Straight pipe is also VERY loud. Like you describe,
ear ringing. With the way the manifold mates up to the carburetor ( O ring ) it is very easy to get a air leak, which will cause the engine to idle high. I have a couple of built predator 212's. One runs a 22mm Chikuni and the other runs a
24mm real Makuni. I like the bigger one better, but there is no reason that your engine can't be made to run properly with that carburetor. Open up the case and get rid of the govoner. All of it. Drive the shaft out of the block with a punch
and light hammer blows. Fill the holes side and top where the arm was with a bolt. 1/4" x 3 /4" x 28 fine thread. Buy grade 8 and being hard it will cut its own thread into the soft Chinese aluminum. Just put the end in the hole and start turning with a socket. It will stay put. While you are in there remove the low oil sensor. That hole you should tap. 7/16" x 20 . Insert a 3/4" long bolt of the same thread and you will be good. Engine will no hold about 1 oz. more oil.
 

Rat

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you are running any sort of muffler you shouldn't be getting flames out of the pipe.
Depends on the muffler. If it's a short enough exhaust system overall, even a spark arrestor isn't going to stop a fireball from being ejected in the lean condition I mentioned that superheats the pipe.

If it's a lawn muffler, then yes those are pretty good about stifling fireballs, but I have seen the rare occasions where they can still spit.

His overall symptoms all point to a major lean carb condition, and if the carb is lean a leak is just going to make it that much worse.
I have a couple of built predator 212's. One runs a 22mm Chikuni and the other runs a
24mm real Makuni. I like the bigger one better, but there is no reason that your engine can't be made to run properly with that carburetor.
I agree it can be done, however the more undersized a carb is the more fickle it's going to be about being dialed in and there's less wiggle room to just call it close enough and leave it be.

The very same can be said about going with too large of a carb, but that is actually the more favorable side to be on in terms of tuning forgiveness.

The CMF calculation says my 208 has an ideal carburetor size of 28mm, but it likes the 24mm well enough I don't see the hassle or expense being worth it unless I luck out on a genuine Keihin PWK28 Air Striker for nasty cheap
 

NJtrikes

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Awesome feedback all. I will pull the oil sensor and governor this week.

so the high idle I think was caused by the the throttle slide not going all the way down. I fixed that it seems better now.

I am running a .130 pilot jet not the .125…do you think that’s enough?

here is a pic of the header/muffler I am running. Maybe the muffle is just junk? I did run it with and without the muffler and it did change the tone a bit but It just seems so loud. I never ran the engine stock so I don’t have anything to compare it to.

So with all that said…

It was recommended to me to do so major upgrades to keep the engine from grenading OR ago back to stock carb and exhaust.

billet fly wheel, cam, billet rod, new piston, heavier springs and miscellaneous gaskets etc to make all those upgrades. Cost would be $300 for all the parts and I was told it would get me 13-15hp total. The HP sounds fun but really don’t think it’s needed for this build.

Do you all think with the carb and header combo I am running with the governor removed I am creating a dangerous situation? I don’t want anyone getting hurt. If the engine blows up I’ll get another one, its not the end of the world. I can go through 2 more engines at the same cost of those other parts.
 

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Rat

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That header is more than short enough to spit fireballs even properly tuned without the sausage screwed in, and be loud AF even with it screwed in. If you have it popping fireballs with that muffler in than you are more than most likely lean on the main, but rich on the pilot.

Plug color says a lot about whats going on inside... if its any shade of sorta tanish grey or lighter its too lean, and the closer to white the worse off it is. If its chalky white with a white residue it's dangerously lean.

You want more of a light tan almost sand color.
Billet fly wheel, cam, billet rod, new piston, heavier springs and miscellaneous gaskets etc to make all those upgrades. Cost would be $300 for all the parts and I was told it would get me 13-15hp total. The HP sounds fun but really don’t think it’s needed for this build.
18lb springs is good regardless, the stock ones are only 10.8 and floating the valves is how you release the stock keepers and drop a valve down the bore.

Cam is purely optional, the only reason to get a mod2 is because you want to or want mo power.

Billet flywheel and Billet Rod, unnecessary if you plan to keep the Rpm under 5k.

Most stock flywheels don't fly apart around 5500 like the horror stories, but some have and others have let go at 4500 while others held 6500 without issue.

The billet connecting rod serves 2 functions, the first being less likely to shatter, and the second being well reciprocal mass which equals more room to rev.

Piston again optional, if yours has a dished piston then a flat top is going to give a negligible nudge to the compression, but again there's not much legitimate reason beyond trying to push the engine for more rpm.

The stock ignition coil alone will hold the rpm down and it will be unlikely any amount of tuning is going to break 4800 rpm as long as it's in use... which for a mild build without a governor is a good thing if you're not going all in.
Do you all think with the carb and header combo I am running with the governor removed I am creating a dangerous situation? I don’t want anyone getting hurt. If the engine blows up I’ll get another one, its not the end of the world. I can go through 2 more engines at the same cost of those other parts.
Dangerous? No, not any more dangerous than a gokart or minibike is just exsisting to begin with.

I run a Mod2 Cam, 22lb valve springs, stock keepers (split lock are ordered) stock coil (unrestricted are ordered) flat top forged piston, stock rod, stock flywheels, (unless I can put a different charging system in place or embed magnets in a billet one that will never change)
5.5mm hardened polished stainless steel pushrods, hardened stainless lifters, [old style] HD Champion 1:1 rockers, custom built exhaust and intake, and the aforementioned 24mm PWK copy.

I've got a tach that has clocked 4850 rpm more than once and all is well
 
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panchothedog

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Your engine is the hemi version, so it already has the flat top piston. Absolutely no reason to change it. If you have kids that are going to be riding it and you pull the govoner and add the stiffer valve springs, then the rod and flywheel can give you some peace of mind from a saftey stand point. And the extra money spent now will prevent the need for a 2nd or 3rd engine later. Many people don't. Some blow, some don't.
 

Rat

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Your engine is the hemi version, so it already has the flat top piston.
I was so focused on the exhaust I totally missed the tell tale Hemi rocker cover 🤣
In all fairness I've had a Hemi head on my very not a Hemi 208, and vice versa (16cc wedge on a Hemi)
 
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BrownStainRacing

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Awesome feedback all. I will pull the oil sensor and governor this week.

so the high idle I think was caused by the the throttle slide not going all the way down. I fixed that it seems better now.

I am running a .130 pilot jet not the .125…do you think that’s enough?

here is a pic of the header/muffler I am running. Maybe the muffle is just junk? I did run it with and without the muffler and it did change the tone a bit but It just seems so loud. I never ran the engine stock so I don’t have anything to compare it to.

So with all that said…

It was recommended to me to do so major upgrades to keep the engine from grenading OR ago back to stock carb and exhaust.

billet fly wheel, cam, billet rod, new piston, heavier springs and miscellaneous gaskets etc to make all those upgrades. Cost would be $300 for all the parts and I was told it would get me 13-15hp total. The HP sounds fun but really don’t think it’s needed for this build.

Do you all think with the carb and header combo I am running with the governor removed I am creating a dangerous situation? I don’t want anyone getting hurt. If the engine blows up I’ll get another one, its not the end of the world. I can go through 2 more engines at the same cost of those other parts.
That muffler has a plug in the center of it. It's jus as restrictive as the stock muffler.

Did you drill it out???

I put 3) 3/8" holes in it and punch it out with a 1/2" extension.

Here's a pvl flywheel, performance coil, and timing key (pred hemi ONLY) that will give you piece of mind, and take care of the ignition timing. You will never need to worry about it or check it again.
The pvl flywheel is all I use on my personal builds, it's be tried, trusted, and proved to work for many, many years

DIY is Dover Power, straight up good people, my #1 supplier.


As mentioned, pull your plug and you will see how lean or rich it is. I'm thinking lean on the low side, also.
 

NJtrikes

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Your engine is the hemi version, so it already has the flat top piston. Absolutely no reason to change it. If you have kids that are going to be riding it and you pull the govoner and add the stiffer valve springs, then the rod and flywheel can give you some peace of mind from a saftey stand point. And the extra money spent now will prevent the need for a 2nd or 3rd engine later. Many people don't. Some blow, some don't.
So I thought I had a non hemi…even the model number on the box is for the non hemi? Wrong engine in the box?
 

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NJtrikes

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That muffler has a plug in the center of it. It's jus as restrictive as the stock muffler.

Did you drill it out???

I put 3) 3/8" holes in it and punch it out with a 1/2" extension.

Here's a pvl flywheel, performance coil, and timing key (pred hemi ONLY) that will give you piece of mind, and take care of the ignition timing. You will never need to worry about it or check it again.
The pvl flywheel is all I use on my personal builds, it's be tried, trusted, and proved to work for many, many years

DIY is Dover Power, straight up good people, my #1 supplier.


As mentioned, pull your plug and you will see how lean or rich it is. I'm thinking lean on the low side, also.
i did not drill it out, had not seen that recommendation yet... i just looked in it and ya...there is a TINY hole. so you basically drilled out the center where the small hole was?
 

BrownStainRacing

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i did not drill it out, had not seen that recommendation yet... i just looked in it and ya...there is a TINY hole. so you basically drilled out the center where the small hole was?
That's up to you.

Drill 1 hole, and get er a try. You don't like it, drill another hole.

Take it off before drilling, so you don't get metal pieces in the exhaust runner.
 

NJtrikes

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well decided I am already way out of budget so whats another $250...LOL. I just order the parts and now it will be a stupid fast drift trike! Figure I can always use the engine on another project down the road.

Now i need help with the PVC Sleeves. I tried twice to buy some off ebay and the first ones were way too big The second set is two small..by only a little. I used a vacuumm pump to suck the air out of the tire and it was sooo close to fitting but need another 1/4. Two things i am thinking...

1 - warm the tire up to make it softer so it compresses more when i use the vacuumm pump.
2 - cut the sleeve so it opens/flexes a little. install it and then attempt to glue it back together. Just not sure if it will hold up to use.

These are the tires I am using...

SunF Go-Kart & Kart-Racer Slick Tire 11x7.10-5, 4-Ply, Smooth Tread, Tubeless


I tried these sleeves -
 

NJtrikes

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cutting the sleeve was last resort for sure. I'll try the heat first. fingers crossed
 

Rat

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Two things i am thinking...

1 - warm the tire up to make it softer so it compresses more when i use the vacuumm pump.
2 - cut the sleeve so it opens/flexes a little. install it and then attempt to glue it back together. Just not sure if it will hold up to use.
Splitting the sleeve is the fastest way to shoot yourself in the head with PVC shrapnel... please don't be a moron.

Option 1: Absolutely SAFE and SMART

Option 2: Absolutely ridiculous Fatality risk
 
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