Newoldschool Posted May 1, 2013 Report Share Posted May 1, 2013 So I bought this banshee, I absolutely love it. I took it to my mechanic to get tuned up, jetting, etc. And I was informed today that the motor only has 60 pounds of compression in each cylinder, I'm very upset, but I bought it used, and I guess that's what happens some times. My question is 1. What is normal compression for a banshee 2. What might I have to do to this motor now, I realize that is a broad question. But what should I expect, I of course wanna make things perfect, money isn't a huge issue. So what exactly might I be looking at. Thanks. I appreciate any help. Sam Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted May 1, 2013 Report Share Posted May 1, 2013 Bore, port, 4 mil. Pull the motor box it up Ship it to redline,FAST,wildcard,any sponso tell them you want to go fast. Wait a few weeks, pay money, install motor and hang on Quote Link to comment Share on other sites More sharing options...
Newoldschool Posted May 1, 2013 Author Report Share Posted May 1, 2013 Ok. Here's the deal. The motor is supposedly a 358 cheetah cub. That is yet to be determined. But the scumbag who sold me it said it was. So what is normal compression supposed to be. And to do things right, what kind of dollar figure will I be looking at. I don't want a drag motor. But I want a strong running dependable engine. Keep the suggestion coming. Thanks. Sam Quote Link to comment Share on other sites More sharing options...
oldskool Posted May 1, 2013 Report Share Posted May 1, 2013 just take your cylinder and have it measured to see if it needs a bore, If so. go up to next size. Should be around $80.00 for bore and $200.00 for new top end kit. Idk about comp on a cub, but a stock banshee would be around 125lbs psi Quote Link to comment Share on other sites More sharing options...
Starwriter Posted May 1, 2013 Report Share Posted May 1, 2013 How much do you trust your "mechanic"? If it truely only has 60PSI of compression, it should be almost impossible to get it running by kick starting it. Tell your "mechanic" you need to pick up the bike and think about it. Go to Sears, buy your own compression gauge and check it yourself. Quote Link to comment Share on other sites More sharing options...
Starwriter Posted May 1, 2013 Report Share Posted May 1, 2013 just take your cylinder and have it measured to see if it needs a bore, If so. go up to next size. Should be around $80.00 for bore and $200.00 for new top end kit. Idk about comp on a cub, but a stock banshee would be around 125lbs psi They're nikasil plated cylinders. You can't bore them. Have to have them replated if the bore is bad. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted May 1, 2013 Report Share Posted May 1, 2013 Post a picture of the motor to photo bucket. Copy the image link. Post it here. It'll tell us what cylinder you have. For a pump gas motor you would wanna be in the 130-150 psi range. Usually any more and you would wanna be on race fuel. That is only a general way to gauge what fuel your going to need. There are so many variables to calculate the uncorrected compression ratio and that is the best way to determine fuel but it means a tear down is needed. If the guy is right and you have a 392 cub, you picked out the wrong want ad I you don't want a drag motor. Quote Link to comment Share on other sites More sharing options...
Newoldschool Posted May 1, 2013 Author Report Share Posted May 1, 2013 There is a pic on this site already. It's under the "back to 2 strokes" thread. I don't know how to post pics. Also, it's a 358 cub supposedly. Not a 392. But who really knows because the moron I bought it from is shady as hell. My fault for trusting people I guess. Regardless, now I can make the motor how I want it. That's the only positive I have right now. Quote Link to comment Share on other sites More sharing options...
oldskool Posted May 1, 2013 Report Share Posted May 1, 2013 They're nikasil plated cylinders. You can't bore them. Have to have them replated if the bore is bad. Ahh, how much is it to have replated? sorry newoldschool So, if you have a 421 cub, it will always be a 68mm bore? Quote Link to comment Share on other sites More sharing options...
Newoldschool Posted May 1, 2013 Author Report Share Posted May 1, 2013 I know. I will take another pic and send it to the very nice person who posted it for me. It's a 358 cub Quote Link to comment Share on other sites More sharing options...
Newoldschool Posted May 2, 2013 Author Report Share Posted May 2, 2013 I sent the pic. It's not a good pic, but maybe someone can give me some insight. Question. When you have 60 lbs of compression, should you be able to run it at all. I rode the quad a little. It ran hard when it got the rpms up. Anyway. What normally needs done when you have low compression. I do have faith in my mechanic. He is very reputable. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted May 2, 2013 Report Share Posted May 2, 2013 If it really has 60 psi it won't even start. It could be cylinders for a 4 mil crank with a stock stroke crank and have that psi, and run like shit, but still start. A bad worn out motor will still have near 100 psi. Quote Link to comment Share on other sites More sharing options...
RadarRacing Posted May 2, 2013 Report Share Posted May 2, 2013 Many auto hauges will read very low on a quad. He may just not have read the comp that it really has. If it starts easy at all it does NOT have 60 lbs of compression. To check compression you need to have the motor warmed up and hold the throttle wide open and kick it over like hell. 60lbs wont start in my opinion unless you were to pull start it. You can kick them over by hand on the kicker if they get under 100. If plating is good on a cub you just stick new rings or two new pistons in em. That plating wears very little. Its tough stuff. Quote Link to comment Share on other sites More sharing options...
bluebanshee98 Posted May 2, 2013 Report Share Posted May 2, 2013 i dont think you would be able to kick start the bike with that low of compression.... if its not a site sponsor i wouldnt trust them. most shops are "reputable" and they take every penny they can. do yourself a favor. get the bike back, buy a good compression gauge and check it yourself. if you can take off the gas tank you can do a compression test. then if it is bad send it off to redline racing. he has a dyno and can tell you how much power its making ect. any of my engines are going to him no questions asked Quote Link to comment Share on other sites More sharing options...
Newoldschool Posted May 2, 2013 Author Report Share Posted May 2, 2013 Great advice. Thanks guys. Yes the banshee actually starts easily on the first kick mostly. Now I'm very Leary Quote Link to comment Share on other sites More sharing options...
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