bluing pipes

[terrylee]

still need to know jet size

still need to know jet size

I still would like a idea from someone on the main jet size I should use on the 850 with Mac 4-2 and stock airbox and filters? Also am I going to have to buy a dyno kit or can I just replace the main jets? Thanks so much! terrylee

 

[Harry P.]

I have heard you need to go up 2 sizes on the mains, stock being 115's I think should put you into 125's and shim the needles, pods would need an additional 2 sizes. From what I've heard. Good luck.

 

[Nessism]

I'd get a couple of sizes and then see what the plugs look like.

 

[twr1776]

terrylee, I agree with Nessism & Harry P. and would recommend going to the 120 mains from the # 115's, bumping the pilots one size (42.5), with OEM Mikuni jets (not aftermarket) and shimming the needles. Some here will say you do not need to bump the pilot but it worked for me. I am running that set up on my 1000 with a K&N OEM filter and a V & H Street Megaphone. As I recall I am 2 1/2 turns out on the air mix screws. No decell backfire, pulls good in all ranges, plugs read a bit rich but I prefer to run slightly rich anyway to help with cooling. My pipe is more of the golden color with a touch of blue after approx 10K. I would be more concerned with your plug reads than pipe color.

Have you replaced the intake o-rings, intake boots, airbox to carb boots, exhaust gaskets and sealed your airbox? IMHO you must do that first before starting on the jetting to eliminate any air leaks and get accurate plug reads. Let us know how it turns out. Here is a link to the needle nose pliers I got at Sears for shimming the needles.

http://www.sears.com/shc/s/p_10153_12605_00945661000P?mv=rr

 

[terrylee]

Have replaced all boots, intake o-rings, and sealed airbox, and replaced exhaust pipe rings. I even covered holes in bottom of airbox with duct tape, and that seemed to help bike run better. The backfiring is really bad when letting off throttle. I have the mixture screws at about 2 1/2-3. Haven't had a chance to do plug chop yet. Will be able to do once I get my wife's 450 on the road. (She just passed her Abate class and is getting her permit tomorrow). Thanks for the advise, terrylee

 

[twr1776]

Today 03:17 PM terrylee Have replaced all boots, intake o-rings, and sealed airbox, and replaced exhaust pipe rings. I even covered holes in bottom of airbox with duct tape, and that seemed to help bike run better. The backfiring is really bad when letting off throttle. I have the mixture screws at about 2 1/2-3. Haven't had a chance to do plug chop yet.

terrylee, it sounds like you have done the necessary prep. I would uncover the holes in the bottom of the airbox, they are supposed to be open. Does your airbox have the "snorkel" still on it and is the seal around it tight? You can see it in picture # 4 in this ad, and if so you should be ready for the new jets.

http://cgi.ebay.com/ebaymotors/1983...1262361QQptZMotorcyclesQ5fPartsQ5fAccessories

 

[terrylee]

Airbox does have snorkel and seemed in good shape last I looked. Did sync. carbs. couple of weeks ago, used morgan just got (first time I used it). Will take tape off airbox. terrylee. Thanks for the help guys.