[img]i/expressions/face-icon-small-confused.gif[/img]I put a Noss head on my Banshee,I have had compression problems every since I had it rebuilt, bored and ported,I put a set of 20mm domes on it and got the compression up to 125psi,then put a set of 18mm domes on it and now have 145psi,???? has the juggs been ported to much?? Also it dont seem to have any top end to it,it just quits pulling in the higher gears,should I put bigger mains in it?? I am running 270 mains and 30 idles now.I have FMF fattys and silencers on it with a adjustable timing plate, running +4 timing!!! I swear I think it run better when it was stock, When I put it back togather with the stock head it only had 107psi after I ran it enough that it should be broke in.I just dont know what to do next,I live where I am 500ft above sea level.I have pulled the plugs after a good WOT pas and they have a light brown color!!!! I B Stumped.

 

Your compression is way to low. Stock should be 125 to 135psi. If i remember right lower then 110 needs rebuilding. I had stock porting and 19 cc domes i had 175 psi.
Maybe when you had it bored they bored it to big and your new rings are not sealing up. Do both sides have the same compression? I dont know much about the porting.

 

[img]i/expressions/face-icon-small-confused.gif[/img]Yep,both sides are the same compression,I dont know much about porting either,but if the builder opened the ports up to big,that shortens the stoke so I think that mite be the problem, Like I said after I put it back togather with the stock head I only had 107PSI on both sides.And that was a fresh bore,+64.25 wiseco pistons.I am thinking the builder screwed something up, and its been hard to start since it was rebuilt.With the Noss and 18mm domes it should be 165++.I wish now I would have him just leave the Ports stock, he was just going to do a cleanup port!!!! How much clearence shoul the pistons have, I did notice they seemed pretty sloppy. I am thinking like you, that I am loosing my compression back threw the Rings.Thanks Eddie.

 

[img]i/expressions/face-icon-small-confused.gif[/img]I dont know much about 2 stokes,but looking at the intake ports, they look like they have been opened up pretty big, if the compression is made up of the distance from the the piston to the TDC and that is shorted it will lesen the total compression being build up from the total stock the less distance it has to to build compression the less PSI it will have, after I put it back togather thr compression I had,the builder builds drag motors,I wish I had a stock set of Juggs to start over,It just never run rite after the rebuild,I have looked at a set of stock port juggs and the ports look really opened up on mine,I think its not getting a good distane to build compression for a Psi reading,I am about to find a stock setof juggs and start over, the builder is well know, but I think he just got carryed away on these,and its always been hard to start cold.I have tried different jets all the way from 330 mains to 270,s it seems to just quit pulling in the high RPM,s, I have KN pod filters on it Tors removed, FMF fatty,s and sileners,high output stater+4 degree advance I have noticed it blows oil out the sileners,they drip oil off the end,I allso be running reg 2 stoke mix not syn,and it has about 400 mile on new motor. What should the clearence be on the pistons, when I had the head off they seemed to have a-lot of slop in them,1ths&2ths&3ths?????Please any help, I am about to pull my hair out!!!!!!!!!!!!!!!!!! Eddie.I also put new Boydson reeds in it.

 

who ported the cylinders? got any pics of the intake ports? i think clearance on wiseco pistons call for like .003-.005 but dont quote me on that. if you're only at 64.5 bore you shouldnt have any problems with losing compression there. how sloppy are the pistons in the cylinders?

 

[img]i/expressions/face-icon-small-confused.gif[/img]He,s a well known builder,he doe,s mainly drag motors!!!!!!! I dont want to give him a -, after I got it back togather with the stock head I couldnt start it without pouring gas in the cyinders,I think he opened the ports to big,I looked at a set of stock ports and they are a-lot smaller than mine.How can I check it to see If I am loosing the compression back into the crankcase,looking at the intake ports if they are enlarged that would shorten the distance the piston makes to TDC,mite explain why I have to keep building compression with a noss head,then it just doesnt run good,stoke is to short to develope good HP.I know the ports look 2 times as big as a stock set, hes took a bunch off of them.Even with the Noss head its hard to start Cold,Kick+Kick+Kick????????? Great Fire,and it doesnt seem to be burnig all the fuel good,blows gas+oil out the Silencers, It just doesnt run like a Banshee should,with all that work on it , it should just RIP. I have had it apart 5 times since I rebuilt it, the pistons move around pretty good but I havent mike them,I know I didnt have to use a ring squeezer to put them in,if he went 10ths bigger than needed that would do it, or even 5TH,s???? Thanks Eddie.

 

You normally don't have to use a ring compressor anyway, but the cylinder should be snug, no slop.

 

do you know the cylinders are bored to 64.5 or did he tell you that? look on the top of the piston and it will say what size they are if they're wiseco pistons. it should have some numbers stamped in the top and the o.d. will be in that stamp. if its 64.5 it'll have "6450" in the stamp somewhere. i know its a pain to take the head/tank/drain coolant and everything to get back to where you can see the top of the pistons but at this point it might be worth it. lemme know what you find.

 

you need to measure from the top of the cylinder deck to the top of the exaust port in mm. a trail or play port would be between 27 & 28mm. a dune would be between 26 & 27mm. anything less then that would be a drag port. you may have you oil mixed rich i recomend between 32:1 or 40:1

 

[img]i/expressions/face-icon-small-confused.gif[/img]I am sure its the rite pistons,but I will pull it down latter,the builder was suprized when I called him and told him about the compression problem, he said he was shooting for 130psi,It was bone stock before we worked on it!!!! 2005 model.He sent the juggs back with the piston kit and I put it back togather, I have worked alot on 4 stokes but this 2 smoker is new to me, even with a drag port it should run OK if I get the compression up rite????? I know the box the pistons came in said they where the rite ones, could I be trying to get to much compression out of it??? One thing I wasnt sure about, he said to run 330 mains in it when I put it back togather, that sounds like he really did a big port job on it.I put FMF fattys and FMF sileners on it,pod breathers,ricky stater,+4 ada plate.I think this thing should scream!!!!!!!!!!! And running 32 to mix gas, I looked at a set of stock intakes and mine have been opened up a-lot compaired to them.It just quits pulling in the higher gears,like it dont want to wind up!!! I swear it run better STOCK, and started good,1&2 kicks cold,1 hot. I have a set of 65.50 new piston set, if I knew it was the bore to big I would just rebore and put them in.But I am worryed about that port job!!! Man what a mess, I ride in the desert maimly at 3000ft above sea level,but here where I live its 500 ft above sealevel. Eddie.