Hop-up Parts For a 68120 Pred

Sterling B

New member
Now that my Preditor has been identified as a west coast model, I would like to hop it up a little. I by-passed the governor and noticed a good bit of flutter at high RPM. Can I work with the factory carb or do I need to change it and if so, to what?
 
Now you need to richen it up hi spd. jet, lo spd. jet, emul.tube; W/stock carb: It will give you some insight into carb theory &application, Dependent upon your specific altitude and air density
 
Ya gotta give us more info Sterling! ie: What 'high' rpm under what conditions...loaded...or, unloaded? (I'm still not sure what 'west coast' model tells us??) Does it hv a nylon or steel cam gear and what size is the carb venturi? Have you removed/replaced the 'stock' air cleaner, muffler and fuel tank? The 'flutter' cud be caused by 'many' things! Also...Where are you going w/ 'hop-up'?
 
Screamn, the "west coast" comes from someone back in my original post identifying the model number 61820 as being a west coast varity. As for the cam and venture - I have no idea as the motor is completely stock. I have not done a single thing to it. I like to see what I'm getting into before I go tearing something apart. The high RPM question would be "loaded" - riding in the kart.
 
When you say you removed the governor, do you mean you just took the governor throttle setup off the engine, or do you mean you removed the sidecover on the engine and took the actual governor gear and rod out of the engine? I would reccomend pulling the sidecover off and removing the nylon governor gear that is on the back side of your flywheel inside the engine, and remove the shaft that comes down from the top of the block, at the very least. Last thing you want is these parts getting worked loose and beating around in your engine. While you have the sidecover off, you can tell us if you have a nylon or steel cam gear, as it will be one of the first things you see when you pop off that sidecover.
 
Screamn, the "west coast" comes from someone back in my original post identifying the model number 61820 as being a west coast varity. As for the cam and venture - I have no idea as the motor is completely stock. I have not done a single thing to it. I like to see what I'm getting into before I go tearing something apart. The high RPM question would be "loaded" - riding in the kart.

I understand, and 'assumed' you had pulled the side cover as 'Weddle Racing' mentions in post #8, of which is a SHOULD do! Hang-in there, 'we' will get you home..:)
 
No need to pull the valve cover and back off the valves or anything, just remove the sidecover and take out the governor parts. You do need to remove the flywheel and use some type of cold chisel with a point on it to knock out the pin that holds on the governor gear, then remove the gear from the pin, and knock the pin back into the hole it came out of, to keep the block sealed and from leaking oil. Also, you will need to tap out the hole on top of the block once you remove the governor shaft and thread a screw or something into it so it doesnt leak either. I have seen some guys use that top hole as a pulse for the fuel pump, and put a fitting in the hole to attatch the pulse line hose to it. That is a good idea if you dont want to just tap it and put a bolt in it. I would also remove the oil sensor that is located at the bottom of the block, with 2 bolts holding it in, and just plug the hole where the oil switch wire runs out the front of the block by using a nail or something like that and some glue. What i did was took out the oil sensor plug at the front of the block and threaded a short bolt into the hole and used red loctite to keep the bolt snug in place so it doesnt work its way loose with the engine vibration and fall out, causing you to run the engine dry on oil. Removing the governor parts and oil switch can all be done in less than 20 minutes. You just need a new sidecover gasket, you might not even need that if you have never pulled the sidecover off before.
 
Now that my Preditor has been identified as a west coast model, I would like to hop it up a little. I by-passed the governor and noticed a good bit of flutter at high RPM. Can I work with the factory carb or do I need to change it and if so, to what?

if by west coast, you mean a CA motor... this one is not a CA motor (nor is it a CARB motor)... not that it has anything to do with the flutter, just wanted to point that out... thought i saw somewhere, where someone told you that...

would the stock valve springs cause an issue at the higher rpm also?
 
Just remove the wire clip that holds the govenor gear on, don't take the pin out and put it back in. Make sure you get the last thrust washer.

Stock springs at 7000RPM will most certainly be your problem.
 
ive posted them...
test
IMG_5166.jpg
 
this is a 68120 and the main difference i can see if the fuel tank... its a 48 state motor, it is epa approved but not CARB... not available in CA... and the tank is good for mini bike related installs, but other than that... i dont know that it is different than a 69727

image_9667.jpg
 
Jst kid'n w/ya! I just finished a 69121 and I see No diff either w/the 727! BTW...why change from the stk hemi flat-top too the Wiseco.....'weight'?
 
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