Surging idle on Manco Big Cat
- Thread starter binaryterror
- Start date
- Tags idle manco surging
First a common cause,, check for leaky carb/intake gaskets make sure bolts are tight then you can hit them with carb cleaner to see if it revs. If reves there is a leak.
Other possibilities.
throttle/choke shafts warn.
air bleed restricted.
damaged o rings.
fuel pick up restricted
idle port restricted.
damages adjustment needles.
incorrect float height.
fuel inlet plugged.
Have you taken the carb apart and cleaned it? on the bottom of bowl there's a nut, it has two holes on the side the one at the top is really small. clean both with a strand of >copper< speaker wire and blast everything on the carb with cleaner then air and replace parts with rebuild kit if needed.
Other possibilities.
throttle/choke shafts warn.
air bleed restricted.
damaged o rings.
fuel pick up restricted
idle port restricted.
damages adjustment needles.
incorrect float height.
fuel inlet plugged.
Have you taken the carb apart and cleaned it? on the bottom of bowl there's a nut, it has two holes on the side the one at the top is really small. clean both with a strand of >copper< speaker wire and blast everything on the carb with cleaner then air and replace parts with rebuild kit if needed.
Thanks for that fast reply! Now let me know if this helps narrow it down...
I noticed that the little butterfly valve right by the choke is the one moving forward and back. It doesn't stay still. Basically it looks like someone is revving the bike then letting it off since the butterfly arm (I think that is what it is... it is literally RIGHT by the choke).
Thanks!
I noticed that the little butterfly valve right by the choke is the one moving forward and back. It doesn't stay still. Basically it looks like someone is revving the bike then letting it off since the butterfly arm (I think that is what it is... it is literally RIGHT by the choke).
Thanks!
The "butterfly" nearest the engine is your throttle and has a little wound spring on the shaft, sounds like it unwound. you'll see a little leg at the bottom and top of the spring.
Sounds like you need to wind the bottom around one revolution then hook the leg on the carb.
Is it not retracting/ closing when you twist it? (sping loaded?)
get back quick and I'll take a pic for you.
Sounds like you need to wind the bottom around one revolution then hook the leg on the carb.
Is it not retracting/ closing when you twist it? (sping loaded?)
get back quick and I'll take a pic for you.
Bwahaha I list all that and it was something simple that wasn't listed. :doah:
OK, here's two styles of spring stop, the clean carb doesn't use an "L" and hooks to the front top (Red) and the dirty carb uses an "L" to hook on the middle top of the carb.(green)
Make sure the top is hooked (yellow) then wind the bottom around once and hook the bottom. you'll need a little screw driver or dental hook and and small needle nose to wrestle with it. :thefinger:
Then make sure it the throttle springs back and stays put every time. :thumbsup:
Sorry about the bad pic, us "old guys" can get shaky.
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Alright man sounds good, thanks so much!
I will let you know how it goes tomorrow morning when I start messing with it.
EDIT: I forgot to ask again... what are your thoughts on removing the governor on these motors?
EDIT x2: Where is a good place to buy replacement parts for either the Big Cat or the Thunderbird?
I will let you know how it goes tomorrow morning when I start messing with it.
EDIT: I forgot to ask again... what are your thoughts on removing the governor on these motors?
EDIT x2: Where is a good place to buy replacement parts for either the Big Cat or the Thunderbird?
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Not good, do it like I said either remove it or stiffer spring on the arm. You don't want it hanging there ready to break up in your engine. (good bye engine)
The gov works by spinning inside with weights on a plastic gear, then the arm pulls back on the throttle when the RPM's hits a set limit. Using a stiffer spring or holding the spring with a wire keeps the gov in it's place yet stops it from pulling back. I still like to remove them and keep the arm for the throttle (better on the throttle body and looks stock) but if you do the spring , make sure the engine is off or it will take off on you! The stiffer spring has some give and looks stock. :thumbsup:
All stock engines can blow if you over rev them (usually the cast rod gives)
The gov works by spinning inside with weights on a plastic gear, then the arm pulls back on the throttle when the RPM's hits a set limit. Using a stiffer spring or holding the spring with a wire keeps the gov in it's place yet stops it from pulling back. I still like to remove them and keep the arm for the throttle (better on the throttle body and looks stock) but if you do the spring , make sure the engine is off or it will take off on you! The stiffer spring has some give and looks stock. :thumbsup:
All stock engines can blow if you over rev them (usually the cast rod gives)
Dont worry about it, pull the governor! Thats the first thing i do! Gokarts and minibikes! I have NEVER thrown a rod! Not saying it couldnt happen. But it would be tough!
YouTube - Grand Prix Minibike Burn Out
YouTube - Grand Prix Minibike Burn Out
First, did the spring solve the problem?
The points would be inside the flywheel, EI would be on top of the fly wheel only.
30w oil is best for above freezing and 10w/30 below. I use plain old GTX 30W. and feel it's better to change your oil often then buy $$$ oil and not change it much.
the spark plug is Champion CJ8 and you can also use J8C (taller)
The points would be inside the flywheel, EI would be on top of the fly wheel only.
30w oil is best for above freezing and 10w/30 below. I use plain old GTX 30W. and feel it's better to change your oil often then buy $$$ oil and not change it much.
the spark plug is Champion CJ8 and you can also use J8C (taller)