I finally got the old fl350 together and running. Did all the heat cycles and now it's time to get it dialed in and drive it. I drove it around the yard and did a plug chop at a quarter throttle and the new plug looks kinda grayish. Any advice on how I should go about jetting this thing? I'm not running an EGT so I'm restricted to plug chopping and this is my first time jetting.
I'm kinda hoping that the stock Jett's will be fine due to the fact that there's no aftermarket stuff on it other than the wesico piston and clutch. Words of wisdom welcome please...

Fill us in on the details.....

Have you modified the intake system at all?

What size Wiseco piston?

What is your altitude?

What are the jets that are in it currently?

Rand

No intake mods, im running 80mm wesico. My altitude is 482ft and im running a 142 main and a 45 pilot.

Lid on air box?

Yes the lid is on and I used my old stock yfz 450 foam filter on it for the time being. Seems to fit good.

That my good man is an air system modification. The FL350 filter is very dense and restricts flow. The YFZ450 filter probably flows a lot better.

How many turns out is the air screw?

Rand

I have the screw out 1.5 turns. Just to be sure is the airscrew the one with the spring on it?

If you can see a spring on the outside of the screw, then it is not the air screw. The screw with the spring on the outside of it is the throttle stop screw or idle adjustment screw.

The air screw is located on the same side of the carburetor as the throttle stop screw. It is just above the float bowl on the intake side of the carburetor. Initial setting of this screw should be 1.5 turns out from a seated position.

Do not screw it in tightly! Gently screw it in until it bottoms and then back it out 1.5 turns.

For adjustment, screw it in to richen the mixture and screw it out to lean the mixture. This screw effects jetting from closed throttle to just before 1/2 throttle.

Rand

So what size Jett's would be a good starting point?

Here's a little carburetor 101.....

The carburetor has three circuits.
1.) Idle circuit (closed to approx 1/3 throttle). This is controlled by the pilot jet and the air screw and the "e" clip position on the needle, more so by the air screw and pilot jet.
2.) Mid range circuit (1/3 to 2/3 throttle). This is controlled by the "E" clip position on the needle, needle jet size and main jet size. The clip position on the needle has a lot of influence here.
3.) Full throttle circuit (2/3 to full throttle). This is controlled by the "E" clip position and main jet size. The main jet has most of the influence here.

Remember all of these circuits overlap so an adjustment on one circuit will effect another.

Start here.....

What groove on the needle is the "E" clip in? You should start your plug chops with the "E" clip in the center groove of the needle.

Set your air screw to 1 1/2 turns and do your 1/4 throttle plug chop again.

If you air screw is already at 1 1/2 turns try 1 full turn and do another 1/4 throttle plug chop. If it still looks gray, bump up to the idle jet next size.

As far as the main goes, I would step up to a 145 and try a WOT (Wide Open Throttle) plug chop. If it looks lean, then bump up to a 148 main.

Rand

Thanks a lot Rand, that's a big help.

You're welcome!

Rand

Will a WOT (Wide Open Throttle) plug chop hurt my fresh top end? I've only ran maybe 3 gallons of fuel through it since rebuild.

1st General Rule.....Run a full tank through her before you really get on it. A stock tank only holds 3.8 gallons so you are almost there. By the time you finish 1/4 throttle jetting and 1/2 throttle, you'll be ready for full throttle runs.

2nd Rule.....Jetting should always done from the bottom up.

3rd rule.....Before you do any jetting, make sure you go ride around no more than 1/2 throttle until she is up to operating temps (about 10 minutes). Don't try to jet a cold Engine. After that, you may begin your jetting procedure.

One thing to remember, the info I give you is just ballpark jetting which is pretty close to what the manual tells you. These settings should be close but you are the one who has to read your spark plug correctly and get a seat of the pants feel for how it is running.

Now that I have made you paranoid......good luck and have fun!

Rand

Yes. You need to putt the ody around to break it in before plug chops. I would put in a 150 main jet. It will be fat. Take the ody out for a 10 min cruise varring the trottle but no more then 1/4 throttle then bring it it and let it cool down til its cool to the touch. Repeat process giving it more throttle everytime. For example afte 1/4 throttle you will do up to hafe throttle. Then after cool down go up to 3/4 throttle then after cool down WOT (Wide Open Throttle). Then do plug chops.

Thanks for the info guys. I feel like I can do this, just wondering if I should use one plug or get a couple more plugs? Again thanks for y'all's advice...

Get a couple plugs get 9's they are colder plugs

Just did some 1/4 throttle plug chops with a 138 main and the plug is still greyish. I turned the screw in about a half turn and no difference. Should I screw it in some more or get me a 150 main?

Is the 138 a typo or are you actually using a 138?

Stock jet for an FL350 is a 142.

Size steps in that range are.....
142 (stock)
145
148
150

If you are having issues at 1/4 throttle then the main is not the culprit....its your pilot jet and air screw settings.
How many turns out is you air screw?
What slot is the "E" clip in on the needle?

Post some pictures of your plug if you can.

Rand

Yes it was a typo, its a 148 main. I put the air screw out 1.5 turns and the clip was in the middle. I screwed the air screw in about a half turn and the plug was still grey. I then moved the clip down one notch and no difference. I changed both jets up one size. I forget the pilot jett size but its one up from stock.

Did you get the Engine to operating temps before you did the plug chop?

How much distance did you cover while doing your plug chop?

Have you done a "Leak Down Test" to assure you don't have any air leaks?

Please post a picture of your plug from the plug chop.

Rand

Warmed it up for over 5 minutes and the ride down the trail is about half a mile. I did about 50 yards per plug chop.
Correction my pilot jet is a 48 and the main is a 145. Did leak down and no leaks. Ill post pics of the plug when I get inside the house.

is it fully broken in yet? Its very hard to do plug chops on new plugs.

its grey but is any part of the electrode wet?