cub problems

[tomtunas]

Hey guys, I posted about 2 weeks ago but here we go again. Went riding and the motor was fine for about 10 mins and the motor is bogging very bad. I checked the carbs, reeds, jetted down from a 150 main to a 148, and also got race fuel" 112", and still the same thing. I noticed some coolant coming out of the top of the overflow of the cap dripping on my pipes, temp didnt get over 150. Its a 421 cub 35mms shearer pipes. Any ideas?

[91banshee]

Hey guys, I posted about 2 weeks ago but here we go again. Went riding and the motor was fine for about 10 mins and the motor is bogging very bad. I checked the carbs, reeds, jetted down from a 150 main to a 148, and also got race fuel" 112", and still the same thing. I noticed some coolant coming out of the top of the overflow of the cap dripping on my pipes, temp didnt get over 150. Its a 421 cub 35mms shearer pipes. Any ideas?

is it a new motor ? how much run time is on it ? was there any trash in the float bowls ?

[Malott 1]

Hey guys, I posted about 2 weeks ago but here we go again. Went riding and the motor was fine for about 10 mins and the motor is bogging very bad. I checked the carbs, reeds, jetted down from a 150 main to a 148, and also got race fuel" 112", and still the same thing. I noticed some coolant coming out of the top of the overflow of the cap dripping on my pipes, temp didnt get over 150. Its a 421 cub 35mms shearer pipes. Any ideas?

Are you running a cool head? Possible you have a oring problem.

[tomtunas]

Yes it has a cool head with 20cc big bore domes. I went with race fuel but it didnt help. Thats what i thought mabye a o ring blew out with the coolant issue. Just one problem after another with this thing. Just put 15,000 in this bike from custom painted fenders to the motor .the motor has about 10 hrs on it. Im starting to get sick.

[tomtunas]

Yes it has a cool head with 20cc big bore domes. I went with race fuel but it didnt help. Thats what i thought mabye a o ring blew out with the coolant issue. Just one problem after another with this thing. Just put 15,000 in this bike from custom painted fenders to the motor .the motor has about 10 hrs on it. Im starting to get sick.

also the coolant has milky spots in it, Im running engine ice. Need some help guys.

[MFIC]

Hey guys, I posted about 2 weeks ago but here we go again. Went riding and the motor was fine for about 10 mins and the motor is bogging very bad. I checked the carbs, reeds, jetted down from a 150 main to a 148, and also got race fuel" 112", and still the same thing. I noticed some coolant coming out of the top of the overflow of the cap dripping on my pipes, temp didnt get over 150. Its a 421 cub 35mms shearer pipes. Any ideas?

 

When you say bogging bad is it from half throttle to full, just at WOT, or as soon as you give it gas?

[CRAZY-SHEE!]

first off, ditch the coolant bottle. useless. Second off, drain your coolant. Then after that, go through all your coolant pipes, valves, and check your water impeller. Make sure nothing is pinhed or clogged. Cause if the impellar is not spinning, your coolant could be standing still and getting too hot and boiling. causeing it to expand and overflow your coolant bottle. if you dont have a mega flow impeler for ur cub, i suggest u get one. Then check your compression. 20cc domes normally dont require race gas, and if the compression is below 170, u dont need race gas and it would be bad for it to run race gas. Then remove your head. Check to see if the head is leaking coolant. Look for any burn marks on the head, abnormal carbon build up on your pistons, etc. Do a plug chop. You could be running lean or too rich. When you first got it did you do the heat up/ cool down sequence to set the seals? Then finally, take off the flywheel.stator cover, and make sure that your adjustable timing plate didnt come lose, or the screws didnt back out, etc. That happens sometimes. if you dont have one, i suggest u get one. Relatively cheap for all that power. Check ur spark plugs, make sure theyre not fouled. Thats about all i can think of right now.. cheak all that stuff.. its probably one of them.

 

edit- oops u said coolant cap, thought u said coolant bottle.

Edited May 6, 2007 by CRAZY-SHEE!

[cam2]

also the coolant has milky spots in it, Im running engine ice. Need some help guys.

that is typically a sign of oil in your coolant. have you checked your tranny oil? does it look normal? did you do a leak down test after you built the engine? is there an abnormal amount of smoke coming out of your exhaust, (white)? how does the plugs look? are they really wet looking without much oil or carbon build up? like the others have said, you may want to pull the head and check your o-rings.

[tomtunas]

Thanks for the info guys. I have a adj timing plate set at +4, and the billet impellar, but thats what it seems like the engine is getting hot and the coolant is not flowing, and thats why my temp gauge isnt getting over 150. Would a o ring leak in the cool head cause all these problems? And would it cause the bad bog. would it be the cdi box mabye, or something electrical?

[chris1992]

did u take the head off? u need to do that.. u can take out the spark plugs with the plugs on them kick it and see if your getting a weak spark.. also did u gap the spark plugs correctly? they need to be a certain gap. I have no idea what it would be for a cub, but the stock is .20-.30. u can pick up a spark plug gapper at your local auto zone for like 4 bucks.