Pocketbike Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
87 Posts
Discussion Starter #1
i recently upgraded my cag to 49cc head kit, I got it to run but only at 1/2 -3/4 throttle with the choke on otherwise it dies. I let it warm up but still the same thing happens. if I turn off the choke it dies as well. im thinking off the top of my head get a bigger jet. thanks in advance for any advice.:thumbsup:
 

·
Banned
Joined
·
21,744 Posts
i recently upgraded my cag to 49cc head kit, I got it to run but only at 1/2 -3/4 throttle with the choke on otherwise it dies. I let it warm up but still the same thing happens. if I turn off the choke it dies as well. im thinking off the top of my head get a bigger jet. thanks in advance for any advice.:thumbsup:

If you have a welding tip cleaner tool you can open up the jet a tiny bit to give the engine more fuel

To prove you need more try lowering the c-clip to the 5th notch and see how the engine reacts........If it runs better keep it aas is if it improves enlarge the jet very very little.....A little bit goes a long way.If you go too much you cant go back.................Good luck
 

·
Banned
Joined
·
24,164 Posts
Do you have a 2 pc head/cyld kit, w/ extra ports?? Sounds like you need a bigger jet, there are kits w/ 4 or 5 jets for less than $10, if you get an HP exhaust you may need even a bigger jet, lol. A gauge drill set is $8 on line.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #4
yeah is a 2 piece head kit with the 4 port thingy and the piston has the triangle holes in it like this: /||\ . ill try the notch thing and report back.
 

·
Banned
Joined
·
24,164 Posts
Is it the finned head kit or round alloy head?? Since it has 2 triangle ports in the piston it must have a 12mm piston pin, I have a few of them, on FC cranks. Which means it has a Cag 49cc 12mm pin crank or a FC crank. Did you get a crank in the kit??
 

·
Registered
Joined
·
87 Posts
Discussion Starter #6 (Edited)
yes I upgraded to a full circle crank and its a machined round head. I already have the "race pipe" from mpr and fiberglass reeds and a ported carb from pbu. also the lightened flywheel from spfl, hope that helps.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #7
Oh, and I still have yet to move the notch. ill do that today after werk.
 

·
Banned
Joined
·
24,164 Posts
Buy the notch you mean rocket key, offset crank key for 10% advance in timing. Make sure you get the big key for P/Port engine and not the small key for a Cag reed port. Search under 49cc pocket bike parts. I have a 5 port Cag eng. w/ 3 upper ports which leads to a lot of piston wear, cause most of the upper cyld wall is gone. The best is one wide upper port but 2 is ok. The FC crank is good, it won't rev as high a 47cc w/ stock crank, but it has more low end torque a lot more mid to upper power, which means you can gear up for more top speed and still have a decent low end. The crank is much heavier than stock, but it fills up a lot of space inside the cases, so when the piston comes down and the reeds have shut it makes more pressure than stock, which means faster/better fuel flow. You have an hp exhaust a racing exhaust looks like this. All these people BS a lot, X18R Nitro, I have one there is no nitro.
5 1/2 HP, try maybe 3 1/2, 5 to 7 1/2 or more mod with the right mods.
 

Attachments

·
Registered
Joined
·
87 Posts
Discussion Starter #9
I had a rocket key somewhere but right now its stock, the notch thing I was talking about is for the needle that the throttle body cylinder thingy is connected to.
 

·
Banned
Joined
·
24,164 Posts
Your talking about the carb piston main jet needle, w/ 5 notches and a clip for height. All mine came w/ clip in the middle, clip down is richer, up leaner at idle to 3/4 throttle, then the main jet goes to work.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #11
well I moved the clip on the needle so it sits deeper in the hole at the bottom and its even worse. I got it to run for a minute for about 50 feet, but it wouldn't rev past 5k and that's at full throttle. so ill try to move the clip the other way and see what happens.
 

·
Banned
Joined
·
24,164 Posts
You lean it more put the clip on the 4th groove from the top, that will raise the needle out of the main jet tube, or more gas, it's tapered so the higher up the needle the smaller it is.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #13
well yesterday I finally got to mess with it and what I did was place the clip in the middle and it would run to about 5k with me on it and up to 7k with the back wheel in the air. I then tried to put it like EPR said on the 4th one from the top and it ran even worse. I want to try this again but with better and higher octain gas. the gas I was using I found out was old, so THAT might be the prob...face palm...
 

·
Banned
Joined
·
24,164 Posts
You need to clean the carb, there are so many additives in our gasoline, when they sit to long you get gummie balls and slimy stuff that get stuck in the main jet. Stock is about .64mm about .027" ID, spit will clog it. Flush out your gas tank with the old gas, lines too, Get some new gas & oil. In California, there is up to 23% alcohol in are summer gas, and it eats the China rubber and it swells, the stock gas lines can come apart inside and clog everything too.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #15
yeah that sounds like a good idea. I did replace the fuel lines a while back with automotive grade fuel line and new fuel filter.
 

·
Banned
Joined
·
24,164 Posts
In the cold you need bigger jets, when its hot you have to lean it some, cold air is denser so need more gas for a proper mixture. All of my B/B kit engines w/ modified carb bikes have .70mm main jets, needle clip in one of the 3 middle slots.
 
1 - 16 of 16 Posts
Top