Predator 212 top speed issues

#1
Hello everyone, so I had a brad new predator 212 non hemi version with a Mikuni carb with a 135 jet in it and I was able to hit speeds upwards of 55mph on my ct100u with nothing else done to it but unfortunately that engine started having some issues with it so I went and swapped it out. Now I have a 212 hemi version with the same carb and jet but cant break 35 mph. I thought I may have had a defective engine so I once again swapped it out for another hemi version but it is still the same story. The governor is removed on it so I'm confused as what it could be. Anyone have any ideas on what could be the issue or how I could get back up to that top speed? Both sprockets have not been changed, it has a 12tooth in the front and a 65 in the rear.
 

LIVIT

Well-Known Member
#7
I build only Hemi performance engines. I use the Wildcat 223. Your Hemi engine is going to flow differently and you may not be giving it enough fuel flow. First thing I do is pull the exhaust and carb. Then do gasket port matching. Check your valve lash, Predators are notorious for the lash being wrong. It should be no more than .003 on both. I actually run .001 on my exhaust and .002 on my intake, but this is on a performance engine.
 
#9
Also are you running a header? If yes, then are you using a muffler on it ? We need more info to help ya man :)
Gotcha sorry about that, Its a brand new hemi with a vm22 mikuni carb and 135 jetting, currently the stock exhaust and muffler is on there but im planning on switching it to a straight pipe. I haven’t checked the valve lash on it yet so that will be the first thing i do on it and the ill re jet it to a 140 or 145 to increase fuel flow. Its also using the stock valve springs and besides the governor gear being removed and the the carb it is all stock. But also I noticed that the power in the lower rpms is good but only once i reach that 30-35mph it’s doesn’t keep accelerating past that and struggles even at wide open throttle
 

LIVIT

Well-Known Member
#10
Before changing jet, running stock exhaust and breather on a hemi with a VM22 could be the issue here. A straight pipe can also reduce performance, until you have a much higher performance engine. I did a test on my WC223 hemi stroker. Ran it straight pipe and then with a small muffler, the improvement with the small muffler surprised me. Hemi heads flow differently, they actually flow better than regular engines, but they have to breath to do this.
 
#11
Before changing jet, running stock exhaust and breather on a hemi with a VM22 could be the issue here. A straight pipe can also reduce performance, until you have a much higher performance engine. I did a test on my WC223 hemi stroker. Ran it straight pipe and then with a small muffler, the improvement with the small muffler surprised me. Hemi heads flow differently, they actually flow better than regular engines, but they have to breath to do this.
Thats interesting how hemi and non hemi react to that, what do you recommend to get back up to that top speed? But again that’s interesting because my friend has a 212 non hemi and his got up to high 40’s with everything being stock except the governor removal.
 

LIVIT

Well-Known Member
#12
High 40's with a CVT/TAV or jackshaft ? Your running a high volume carb with a low volume exhaust. So I would say flow problem. It might actually run better with the stock carb. I'm sure Ole4 and others are going to get on here about this soon. Here is what I would do, put the stock carb back on. See if that changes. Then check your valve lash, regardless. When you got the better exhaust, then also put on the VM22. Least that's what I would try. I do not promote removing the governor without doing more !
 
#13
High 40's with a CVT/TAV or jackshaft ? Your running a high volume carb with a low volume exhaust. So I would say flow problem. It might actually run better with the stock carb. I'm sure Ole4 and others are going to get on here about this soon. Here is what I would do, put the stock carb back on. See if that changes. Then check your valve lash, regardless. When you got the better exhaust, then also put on the VM22. Least that's what I would try. I do not promote removing the governor without doing more !
It was hitting the same top speed with the stock carb so im not sure if its a flow issue. Even with my previous non hemi verson i ran the vm22 with the stock exhaust and it ran just fine.
 

LIVIT

Well-Known Member
#14
High 40's with a stock engine and jackshaft ? With a modified 223 10Tooth drive gear and 60 tooth sprocket and a CVT I'm pushing around 5500 rpm at 50 mph. So if your pushing a non modified engine to upper 40's with a jackshaft, amazing !
 
#15
High 40's with a stock engine and jackshaft ? With a modified 223 10Tooth drive gear and 60 tooth sprocket and a CVT I'm pushing around 5500 rpm at 50 mph. So if your pushing a non modified engine to upper 40's with a jackshaft, amazing !
Yea i guess i got lucky and had a strong engine, but im just curious on why the non hemi version would be able to do that out the box and the hemi isnt. Its using the same clutch, gearing and carb so i would imagine it should be able to or faster due to the different design
 

SAS289

Well-Known Member
#17
Wait. Didn't you say CT100? I'm wondering how you got to 55 with that gearing? Did the first 212 have stock valve springs? If it is a CT100 with a 14 inch tire and 12/65 gearing you should have been at valve float by the mid 40's with stock valve springs.

I thought that the CT100U's came with a 75 tooth sprocket?
 
#18
Wait. Didn't you say CT100? I'm wondering how you got to 55 with that gearing? Did the first 212 have stock valve springs? If it is a CT100 with a 14 inch tire and 12/65 gearing you should have been at valve float by the mid 40's with stock valve springs.

I thought that the CT100U's came with a 75 tooth sprocket?
I changed the sprocket from a 75 to a 65 but on my average top speed was the low 50’s high 40’s. The first 212 non hemi did have stock springs and was stock besides the governor removal and vm22 carb.
 
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