4 mil banshee

[Dbro1216]

I am fairly new to the banshee world, I have a stock banshee with the usual bolt ons: pipes reeds filter cool head. I just recently traded a guy a 1984 200x for a 2004 banshee, the guy was sick of the banshee could not get the banshee to run right just put 2500 into the motor and it still would not run for him. So I took it off his hands, he told me the only way to start it was to pull in behind another atv and it would run he could not start it with the kick start, but when it started it would run wide open. So I traded him hoping it was something easy to fix. I got it home tore it down starting with the carbs got rid of the old ones put a pair of stockers on with stock throttle caps and everything. He also said that the left cylinder was popping bad but it was a brand new motor. So with the new carbs I took the old jets out of his carbs and he had a 25 pilot jet in the carbs and a 410 main. So I replaced the 25 with a 27.5 and the 410 with 350's. Upon further investigation I noticed a spacer plate under the cylinders, this is where I need the help. The banshee runs great now and starts on the first kick with the new carbs and jetting. It has PC pipes stock reeds that appear to be cut out or no reed stoppers anyway. I put k&n pods on it. Has a lot of aftermarket goodies ie. aftermarket radiator, g force extended rear axle, pro taper bar the fat ones. My question is how reliable are the space plates and how do I get rid of them? When I had the bike tore down I went to the cylinders they are ported for sure but have the stock head. I ride mostly back dirt roads some trails the plate does not seem to be my best option. Just wondering what I can do with it? Thanks for any help.

 

Also is my jetting close with the pods no air box stock reeds mod cages pro circuit pipes stock head 4mil ported I live in upstate ny 1000 ft above sea level?

[jriffe23]

Get the head milled or buy a cool head and have domes cut. It has to be a 4 mil with the spacer plate. Sounds like you made out good on the trade.  What carbs were on it?? Post a picture. Im interested. As far as jetting its not my cup of tea. I would be interested in pictures of the carbs that came off when you put stockers on. It they are bigger maybe we can help you get it running and breathing better with those bigger carb, if they are in fact bigger. Just upload a picture and measure the side that goes in the carb boot with a set of calipers. I know that wasnt in question but im interested if they are bigger and if someone on here could help with it.  Anyways back on topic, many site sponsor do head milling, F.A.S.T. is affordable. And for the more expensive route, a lot of site sponsors cut domes and sell the cool head shells for you to be able to get rid of the spacer plate

[Larry's Shee]

Might depend on what was done with the porting. When you remove the spacer the roofs will be lowered, timing retarded.

 

As to the jetting, I would highly suggest a leak test as 350 seems rather big.

[trickedcarbine]

If a motor has already been set up with a plate, you're sorta stuck with running it that way. Ya ya ya, some folks will tell you to yank the plate and get domes cut, but really what do you think is happening when the ports are being by 2mm of piston?

Edited September 5, 2014 by trickedcarbine

[jriffe23]

i do agree tricked. Just saying. He wanted to get rid of the plate at all cost it seemed like

[trickedcarbine]

Nothing wrong with a plate if you're not using the junk ass vegetable paper gaskets that most of them come with. We used a plate to salvage a set of cylinders on my buddies 4mm. Cometic was sourced for some of custom shims and layered gaskets. No leaks. More engine builders out there still actually prefer their motors set up for zero deck. The banshee guys cutting step in to the domes is only like a 8-10 year old trend. Still pretty new.

Edited September 5, 2014 by trickedcarbine

[Dbro1216]

I was just told that the plate is pretty unreliable and I was looking to have the most reliability with the motor. I do not really have any experience with the spacer plates but what I have read on hear people did not like running them but if they are ok to use I will keep the setup the way it is. I just thought it looked like a cheaper way to get the 4mil setup thanks for the help on this guys.

[Dbro1216]

Jriffe23 thanks for the input the old carbs were just stocker as well but with some crazy big jets in them. They had an air leak on the left side in that piece that guides the slide into place that was unpressed and leaking air that's all I found upon inspecting them. And he had a set of aftermarket throttle caps with steel braided line I think the cable was bent or stuck. Thanks for the reply!!!

[trickedcarbine]

Remember, if it's already configured around the plate then you're kinda stuck. No biggie if you put he work in to get it sealed up.

 

The other reason guys hav got away from the plates, it puts the ports up a considerable amount higher. So running he cylinder down on the case helps keep some of the low end. Not a big deal on a drag bike, but for a rider it helps.

[Dbro1216]

How do I figure out if it was build around the spacer? I will need to measure the ports or? Like I stated prior I am not good with this stuff once it gets into changing the port heights and stuff like that. Will it run if the ports are not the right height? Would I notice by sound performance? Thx again if it is to much or to difficult ill just take it to a builder and let them look into it! Think I still got a deal but need and want to find out what I'm working with.

[registered user]

never used a spacer on a banshee but used them on other engines. never had a single problem. spacer under banshee cylinders should be no different. just use a good gasket material and you wont have a problem. not chinese junk paper from the hardware store. normally i use alittle sealer also but you might get away without it

[trickedcarbine]

How do I figure out if it was build around the spacer? I will need to measure the ports or? Like I stated prior I am not good with this stuff once it gets into changing the port heights and stuff like that. Will it run if the ports are not the right height? Would I notice by sound performance? Thx again if it is to much or to difficult ill just take it to a builder and let them look into it! Think I still got a deal but need and want to find out what I'm working with.

Pop the head off. See where the piston sits sits at BDC. Should make the piston edge flush with the exhaust floor.

[poopstick]

You need to degree your motor on all the ports, where the exhaust opens and when the transfers open, port timing can make a good motor or a pos! I have seen so many cylinders ruined by porting, no matter what you do it's junk.