two weeks ago i pulled all restrictors and bumped my jet size to #67 the bike ran perfect i had a milk chocalate plug , then a week ago i decided it still wasent enuff power so i tore the bike down and ported ,polished the head and jug , i allso had a shop take .045 off the head, then i opend up the pipe by cutting two inches out of the cannister and rewelding now the bike is back together and it boggs and stumbles off idle i pulled the plug and its fouled powder black (to much fuel) iv tride every thing i can think of including checking the float . the one and only thing that i did and wasent sure about was, when porting i ground down the vacuum port inside the intake runner on the jug "the port that feeds the fuel pump" did this somehow incrase my fuel presure?

 

Did you change the idle jet (if it has one)?
I'm concerned about the pipe mod...
Sorry for my 50cc ignorance, but the 05 is a 2 stroke still right?

 

yes the 05 is still a 2 stroke , i dont see how the pipe mod would hurt? i toolk a close look at a fmf i still have more cubic inchs of canister space than the fmf . i know that 2 strokes are very sencitive to the shape and size of a pipe. but i opend the pipe up if any thing i should of created a lean condition not rich. im still thinking about the vaccuum port i wonder if the pressure is higher at the side of the intake runner than intoword the center of the runner? what do you think? oh , allmost forgot .. no idle jet that i know of ,only an idle screw that iv already tryed............

 

How much did you raise your exhaust port and transfers?
I wish I could see a pic of this vacum port you mention.

 

Just for a point of reference, how bout tryin the stock jet and doin a plug check. Just a thought.

 

Good thought Otis. [img]i/expressions/face-icon-small-smile.gif[/img]
I was wondering that myself after thinking a lil. My LT80 race motors go DOWN from 92.5 to 77.5 on the main so increasing jet size isn't always the case.

 

i dident raise any port , just expanded them to the sides and blended all edges with a small chamfer. and as im sitting here thinking back, i think i need to check the clip on the needle , i had afew beers the night i was putting the 50 back together and out of lack of attention im allmost positive i moved the clip on the needle the wrong direction.. gonna take it apart tonight, let every body know in a day or so............

 

If you didn't raise the exhaust port, you must have alot of compression.[img]i/expressions/face-icon-small-smile.gif[/img]

 

yha lots of comp, its a lil thumper now! any way i got into the needle and jets last night and had no luck my needle was in the correct possition and different jets only chainged the tone of its illness but provided no bennifit . this points me in one of three directions, vacc port, exaust mod, or i screwed up on porting.and sorry i cant post pics i dont know what it is with this comp, but me and affew buddys have tryed in the past to no avail. the pipe would be the easy fix if i had another laying around... any body got a pipe they wana get rid of?????

 

Wish I could'a heard the change in "tone" with the jet change. :-) If you only did minor clean & polish porting, raise the compression & shorten the pipe a couple inches it should still be tunable lean to rich. Might not be smooth thru the whole band but should show a change on the plug. I'd be surprised if the vacc port is a problem. They just need a pulse. If pump has too much pressure you should see fuel out the overflow tubes on the carb. Got me stumped too. Give the pipe change a try. Good luck.