Problems with Predator 212

[Cesar]

Hey everyone I just recently upgraded my predator with a new 14cc head, billet con rod and billet flywheel. It turned on the first time I turn it on then I turned it off and it wouldn't start. The pull string is so hard. when it doesn't have a spark plug it pulls easy. The air that comes from that plug hole blows put then sucks in. What could be the problem with my engine

It has upgraded exhaust,air filter,jet,18lb springs

 

[cavfire]

I'd start by double checking the valve lash on the compression stroke.

 

[Poboy kartman]

Cam not properly. timed....valve lash off....carb screwed up....

 

[Cesar]

The valves are set at .003 the cam is lined up so both dots are matching.

---------- Post added at 07:35 PM ---------- Previous post was at 07:13 PM ----------

What would you recommend for valve clearance on my set up?

---------- Post added at 08:28 PM ---------- Previous post was at 07:35 PM ----------

Well I checked my valves again I could fit a .018 in it. They keep getting loose.

 

[Poboy kartman]

Well....I HAVE to say this: you DO know you have to set valve lash at TDC on the COMPRESSION stroke....right?

EDIT: And if you haven't changed cams..... .003 is the proper lash.....if you HAVE changed cams, it should have come with specs.....

 

[Cesar]

Yep I set them at tdc but Its wierd. I set it .003 and they are good and I rotate it to tdc again and they are tight to the springs..then I rotate to tdc again and they are at .003 I rotate again and they are tight and so on.

---------- Post added at 10:09 PM ---------- Previous post was at 10:08 PM ----------

And I still have stock cam

 

[Cesar]

That is the connect rod I used

 

[Poboy kartman]

Yep I set them at tdc but Its wierd. I set it .003 and they are good and I rotate it to tdc again and they are tight to the springs..then I rotate to tdc again and they are at .003 I rotate again and they are tight and so on.

---------- Post added at 10:09 PM ---------- Previous post was at 10:08 PM ----------

And I still have stock cam

Ummmm yeah....that's what I'm getting at....when you said your engine sucks and then blows....(I thought you we're talking about another members engine....)

.....BUT....that's the deal...the piston not only has to be TDC...it has to be on the COMPRESSION stroke (intake valve open on the downward stroke....closed on the way up) soooo...as the piston comes up....the valve is closed, and it builds COMPRESSION! On the exhaust stroke, that valve is open...so as the piston comes up....it DOESN'T build COMPRESSION....but the air goes out of the tailpipe.

(You don't have a buddy that posts YouTube videos as BDL , do you?)

 

[Cesar]

Nope no buddy. Thanks for the info I called it quits for today my head hurts lol. Will give it a go in the morning.

And just so I don't do it wrong..which is intake and which is exhaust

 

[Poboy kartman]

The intake will be closer to the carb, the exhaust closer to the muffler....

 

[Cesar]

Thanks cartman it is working now but the rocoil pull start always yanks back hard and Flys out of my hand. Any ideas what could be the cause?

 

[Poboy kartman]

That's pretty much always a timing issue as well....maybe someone else can help now....(it's not that I don't wanna, or have an idea....just want someone else's opinion as well)...

 

[Cesar]

Ok thanks for all the help. It turns on and runs so I'm happy with that just gotta work on putting a new throttle cable on now the one on it almost got me ran over...the throttle was stuff on open is wasn't open to much but it took off like crazy I'm glad It didn't hit anything. I can't wait to see how fast it is on full throttle. Cheers!