97 xt 350 power mods

Hey just wanting to know some info from some experienced people that has messed with there xt 350s. Just wanting to know what is the best most cost efficient or easy and reliable mods you can do for 350s. I already have a supertrapp that has a homemade quiet core in it. I know that going into the carbs and re-jetting is not always the best thing, from what I have read. Any hints? thanks

With the supertrapp, you need to rejet to get anything more than you have already. You can also pull the snorkle from the airbox. Get a Uni air filter if you haven't already

There really isn't much else you can do.

You can find all of this info with the search, but here are my suggested carb changes...

Jetting isn't too bad. You just don't have much to work with. Personally, I have left the secondary carb alone. I've messed with it, but it is now back to stock.

-Get a 130 or even a 140 main jet from a XT600. The 130 should do it though.

-Shim the neeedle with a tiny washer. I cut the eyelet off of an electrical connecter.

-Adjust the Pilot screw out to 3 1/2 turns out. you may need to go to 4, but after that, you really need to do something with the Pilot jet which is a problem. As far as I know there aren't any bigger ones available, and drilling it out has mixed results.

Just be carefull removing the float bowl. You don't want to knock the floats out of adjustment. There is a little hose going between carbs. Remove that first and it is much easier. Messing up the float height is a PITA to fix. everything else is pretty easy.

Web Cam sells cams for the bike but they are kind of pricy and I don't know how much they will give you.

Ok thanks that tells me some of what I wanted to know. Have you done these mods and seen some improvement over stock? And has it affected your mpg much?

Had a riding buddy years ago that put hotter cams in, but I'm not sure I would. Better performance can possibly be had by replacement carbs. Sudco used to sell a set of Keihins, jetted, ready to go that fit right in. You'll need to contact them. Mark at Thumper Stuff still lists things, so call him as well.

Ok thanks that tells me some of what I wanted to know. Have you done these mods and seen some improvement over stock? And has it affected your mpg much?

Yes and yes.

I haven't had a supertrapp on in years because someone stole it and I'm cheap, but I was running it without jetting changes(ran less discs) back then. It made a big difference.

Now, I've opened up my stock exhaust and airbox a bit and and rejetted and that also made a differance. Not as much power wise as the supertrapp, but it runs much better at all RPMs than the trapp did with no jetting changes.

Put the two together and you you should see some very noticable gains. It won't turn it into a fire breathing monster, but you should be able to loft the front end a bit easier.

Any time you rejet and add fuel, your milage will suffer. I'm still getting around 50+mpg on the street and maybe 40-45 on the trails with what I suggested. I can get it up to 55-60 it I try, but that's no fun so I don't.

I have no idea what MPG I was getting stock.

Ok man that sounds good, I think I will try to pursue that. I pulled my plug out the other day to see what color it was looking like (lean or rich) and even with stock everything, its look to be on the lean side. So yea, hopefully with a little more juice and air I can get it running better. One other question I had is that on the main jet needle, it doesn't have different clip notches like other carbs? And you only have to pull bowl off for jet and very top for needle shimming? thanks

Hey jsnmid, I just read in your profile that you did some grinding in header pipe? Can you elaborate?

If you look inside the pipe(s) where they connect to the head, you will see a weld bead where the flange connects to the pipe . I ground it flat with a dremal. Took a while and I have no idea if it helped anything, but it didn't hurt anything either.

I've done so many little things to the bike I've forgotten many of them. That was one I forgot.

Ok man that sounds good, I think I will try to pursue that. I pulled my plug out the other day to see what color it was looking like (lean or rich) and even with stock everything, its look to be on the lean side. So yea, hopefully with a little more juice and air I can get it running better. One other question I had is that on the main jet needle, it doesn't have different clip notches like other carbs? And you only have to pull bowl off for jet and very top for needle shimming? thanks

No notches in the needle(EPA crap). Pull the top black cover for the needle shimming and the bowl for the main jet.

Make sure te top is sealed back up. It's part of the choke circut.

Ok thanks for the heads up. I just need to go to my yamaha dealer and get a main jet for a xt 600? They must have the same carb manufacturer as the 350s?

Yep.

There are 2 mains available for the XT600 on the Primary side of the carb a 130 and a 140. I'd get both since you have the supertrapp. Start with the 130.

Depending on how thick the washer you us to shim the needle, you may need 2.

Ok jsnmid, thanks for all the help. Hopefully I can get some spunk out of my xt and not have to upgrade to a 650!

Hey jsnmid, how much did you shim the needle? Was it just one wire eyelet? Just wana make sure before I do mine.

has anybody ever stroked an xt350 Ive been working on a bored and stroked tt250 and right now I am running an xt350piston 87mm my bike is stroked 9mm approx over stock and has about 430cc, seems like something similar could be done to the 350

actually if you drill the pilot jet out 1 size larger than stock, it fattens up the bottom end nicely and the needle can remain in the stock position.

we just finished the jetting on mine and that is what it needed according to the o2 sensor. it is a bit fat on the bottom atm but i had the stock silencer on it at the time as the supertrapp needed repacking.

now that i have the jetting right, omg!! its an animal compared to a stocker. i have porting, uni, oversize stainless head pipe, supertrapp, tpi valves and snorkel removed, ss intake and exh valves (stock size), titanium valve springs and retainers, and custom webcams grind for better mid range. they only build your cams up when you send them to webcams. as i had an old set, i got those ones built.

i now need to put on my new cluster as it wants to run at 10,500rpm. springs moved the rpm up a lot as it now will bounce the needle off of the end of the gauge in the lower gears.

Dumb question but how did you tune with an o2 sensor? Weld in a bung or fab somthing up to go over the tail pipe?

i still have the stock head pipe, so brother welded a bung onto the head pipe right where the two pipes come together. it is at the reccomended distance for the o2 i used to tune it. if i was still using the stock pipe, i would have just put a plug into it once i was done.

Hey maim, thanks for the info. I would rather shim the needle and put bigger jet in so I don't have to drill it out. But to each his own. Does your xt run pretty good and have decent power?

Hey jsnmid, how much did you shim the needle? Was it just one wire eyelet? Just wana make sure before I do mine.

I don't recall if I ended up with one or two. Two, I think.

I'd start with one and see how it does.

yup. compared it side to side with a stock xt350 and mine walks all over it even with the taller gearing.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now