HEMI Predator 212cc ISSUE stage 1 kit,billet flywheel,billet rod

[MINI-BIKE-BASHER]

Guys,

I just built this engine and did a few upgrades. Governor removed,Billet flywheel with 8 degree timing advance built in, arc billet rod stock length, and a stage 1 kit with air filter,jets,emulsion tube, exhaust. When I start the engine it starts fine and runs well at low power. Once I start revving it up to about half throttle it starts to hit what sounds like a rev limiter and backs itself down. If I power through it, it does the same thing. Am I getting valve float with the stock 18lb springs? Should I go to 26lbs? The plug looks a little lean as well. Any help would be appreciated. This is the first time I have done more than just a stage 1 kit. I build cars typically,but I'm stuck on this one. I attached a video to show what I am talking about. Thank you [video=youtube_share;_h7kaStCL38]https://youtu.be/_h7kaStCL38[/video]

 

[Davis]

What did you gap your flywheel at?

 

[MINI-BIKE-BASHER]

I just lapped it to the shaft and did the business card trick. I forgot about checking that. Thank you sooo much!! I think I need more gap. What about You?

 

[madtom421]

Stock springs are 10.8 lb on a hemi. I'm sure calling 18lb stock was just a typo.

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[osu1978]

Re-check your valve lash.

 

[MINI-BIKE-BASHER]

I did not know that. I apologize. Do you think that could be the issue? I was misinformed by someone about the 18lb springs being stock with the hemis. I believed it too because they do not give them to you in the performance kit like they do with the non-hemi. Either way, I just want to fix my issue.

 

[MINI-BIKE-BASHER]

It was .003 on exhaust and .004 on intake.

 

[madtom421]

It's the springs

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[TheDullCarbide]

Take off your air filter and see if it backfires through the carb. More than likely you're floating the valves with the stock 10.8 springs. Look into some 22 or 26lb springs. 18 lb springs are okay for stock lift cams but not much more coil-bind wise.

 

[Davis]

Cam?

 

[MINI-BIKE-BASHER]

Cam?

Stock cam. I wasnt planning on modifying that.

 

[MINI-BIKE-BASHER]

Take off your air filter and see if it backfires through the carb. More than likely you're floating the valves with the stock 10.8 springs. Look into some 22 or 26lb springs. 18 lb springs are okay for stock lift cams but not much more coil-bind wise.

Thank you. I will do that.

 

[MINI-BIKE-BASHER]

It's the springs

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Sounds right to me.

 

[MINI-BIKE-BASHER]

Take off your air filter and see if it backfires through the carb. More than likely you're floating the valves with the stock 10.8 springs. Look into some 22 or 26lb springs. 18 lb springs are okay for stock lift cams but not much more coil-bind wise.

I just rechecked valve lash and pulled the intake and fired it up. Backfiring out of the carb. I guess it's time for some better springs. I hate being misinformed about something and having it bite me in the ass. I will let you guys know what happens. OldMiniBikes is right down the street. Thank you.

 

[MINI-BIKE-BASHER]

One more thing. Should I do the cam since I did the rod and fly wheel? I'm just a guy who likes to have fun. I don't race,but I love power.

 

[TheDullCarbide]

Yup, you need springs. Don't get the 18 lb especially if you might throw a cam at it. The DynoCams CS seems like the popular one for your application. Careful not to order the CM. NrRacing does not carry the CS, only the CM. The CS is a torquey-er version of the CM and it runs better with a near-er stock engine than the CM.

Racing Cams and Parts | CS Grind, Clone, Hemi | CL-CS | DynoCams

 

[MINI-BIKE-BASHER]

Yup, you need springs. Don't get the 18 lb especially if you might throw a cam at it. The DynoCams CS seems like the popular one for your application. Careful not to order the CM. NrRacing does not carry the CS, only the CM. The CS is a torquey-er version of the CM and it runs better with a near-er stock engine than the CM.

Racing Cams and Parts | CS Grind, Clone, Hemi | CL-CS | DynoCams

You the man! I appreciate ya! Thanks for pointing me in the right direction. I will just grab the cam and Chuck it in since its not much money and I would rather not have to worry about my engine and stuff breaking. Should I just go right to the 26lb springs instead of like a 22lb?

 

[TheDullCarbide]

NR recommends 26lb but Dyno recommends 18lb. 26lb could probably rev you to 7500rpm and 22lb to 6800rpm. On a typical 196cc clone, you'd be playing with fire trying to use 26lb on the stock pushrods. I can't comment on HEMI Pred pushrods. As long as your rpms are tame, 22lb will work.

 

[MINI-BIKE-BASHER]

NR recommends 26lb but Dyno recommends 18lb. 26lb could probably rev you to 7500rpm and 22lb to 6800rpm. On a typical 196cc clone, you'd be playing with fire trying to use 26lb on the stock pushrods. I can't comment on HEMI Pred pushrods. As long as your rpms are tame, 22lb will work.

Perfect. Thank you for the information. I may upgrade to stainless pushrods,but not at this time. I generally limit my rpms so that I don't do internal damage so they will be tame for the most part. I will go with the 22lb and see what happens. Thank you again.

 

[EVOL Tweety Bird]

Along with the more then likely valve float, recheck your lash. You should set it spin the motor over a couple of times and recheck it to be sure it's where it needs to be. If memory serves, and check on this, you go slightly past TDC to set the valves on the Hemi. And from what I understand these engines will actually open up the lash as they get hot.

I'm using the 22's on my Hemi, billet rod/flywheel, no governor, I went with the Mod 2 cam, (it works for me, I know, I know) bigger jets, (yes you have two) emulsion tube, filter and header. Seems to love it, runs like a scalded dog. And the plug looks great.

Going similar on my non Hemi, minus the cam.