250F 07 WR 250 F Jetting
- Thread starter Rack
- Start date
Agreed Onelugnut 
Did you do all the freebie modes, like cut the Grey wire, open up the exhaust, air box, etc? Drop that thing off in my garage and I'll tune it for you. But I might need to keep it a few days to make sure it is setup right. 
250, I think there is a 1:30 Sat in Sept that this would fit into...
Did you do all the freebie modes, like cut the Grey wire, open up the exhaust, air box, etc? Drop that thing off in my garage and I'll tune it for you. But I might need to keep it a few days to make sure it is setup right. 250, I think there is a 1:30 Sat in Sept that this would fit into...
I bought the bike and it had already had the following modifications........
When the original owner purchased the bike he had the dealership install the GYTR jet kit and GYTR end cap. He also removed the charcoal cannister and overflow catch tank. Other than that I am not sure what has been done to the bike by the previous owner. I purchased the bike with 137 miles on it.
When yama_dawgg first rode the bike he thought everything was fine. A few weeks later Mike in Fresno rode it on the Bass Lake 250 D/S ride and said it seemed under powered and didn't have any snap or pop.
So two weeks ago yama_dawgg is telling me its bogging and dieing on him. So I jump on it and give it a go and sure enough it runs like crap.
In talks with Mooney he says bring it over lets check it out. Turns out it has a 165 main jet in it. So we/Mooney changes it out to a 172.
The next day we go riding and everything seems to be just right!
The reason for my post is to try to gain a little more insight as to what the "ideal" jetting set up would be, if there is such a thing.
One last thing, we discovered at Mooney's house that yama_dawgg over oiled his air filter
.
When the original owner purchased the bike he had the dealership install the GYTR jet kit and GYTR end cap. He also removed the charcoal cannister and overflow catch tank. Other than that I am not sure what has been done to the bike by the previous owner. I purchased the bike with 137 miles on it.
When yama_dawgg first rode the bike he thought everything was fine. A few weeks later Mike in Fresno rode it on the Bass Lake 250 D/S ride and said it seemed under powered and didn't have any snap or pop.
So two weeks ago yama_dawgg is telling me its bogging and dieing on him. So I jump on it and give it a go and sure enough it runs like crap.
In talks with Mooney he says bring it over lets check it out. Turns out it has a 165 main jet in it. So we/Mooney changes it out to a 172.
The next day we go riding and everything seems to be just right!
The reason for my post is to try to gain a little more insight as to what the "ideal" jetting set up would be, if there is such a thing.
One last thing, we discovered at Mooney's house that yama_dawgg over oiled his air filter
.
I feel there is no such thing as a "Ideal" setting when it comes to jetting a bike, there are way to many variables that come into play when jetting a bike, air temp,elevation.humidity etc etc, it's possible that you can find a good setting(where your at now) then use fuel screw to dial it in for different circumstances, when I was on a 2stroke I was constantly changing my jetting, now with my 450 I get it set for average conditions in my area and leave it unless it gets real bad, this carb is to big of a pain in the ass to get off to be screwing with it all the time
+1 on no ideal. All you can hope for is the best compromise. You can jet for a mid point of perhaps change it a bit for winter vs summer. The main only really adjusts wide open. The two most useful change are the needle and the pillot screw. If I have the time I will drop the needle a step for high altitude riding for places like KM where I'm riding 7000-10000ft.
I can get by with no changes since I'm on a big bore. It's more important for a 250. Remember regardless of jetting you loose power at high altitude. It takes air to push that piston. Less air means less push.
I can get by with no changes since I'm on a big bore. It's more important for a 250. Remember regardless of jetting you loose power at high altitude. It takes air to push that piston. Less air means less push.
Rack perfect timing cuz i was just looking in my book today to find out how to set the jetting up for my yz250, It seems that it is set up for so-cal (cuz that is where i got the bike) and now that i have it in las vegas it burns to rich, and next week i'm going to take it to KM and am worried that i'm just going to go threw plugs so i will be working on this tommorrow and think i need to bring up the needle jet up more i tink it said so it won't run so rich. I think?? I'll have to read it again
But any advice would be appreciated
EDIT: Oh and do you think i will have any truble with my wr400 up there at all?
But any advice would be appreciated
EDIT: Oh and do you think i will have any truble with my wr400 up there at all?
If it's rich in Vegas it will be way too rich at KM. Turn the needle in and drop the needle one clip position. You move the clip one step up and that drops the needle. With the needle further down less fuel can get by. Compared to the step of one jet size, one position on the needle is a big change.
The 400 should be fine.
The 400 should be fine.
I knew there was a reson I liked this place
Can't tell you sizes of the jets, but can tell you that I have mine jetted for 3500 to 4000'. Seems to do well unless I get up really high, say around 9000' or so.
Okay, i am trying to figure out what the "GYTR Jet Kit" update sizes are. That is what was supposed to be in the bike and according to previous owner was recommended by Yamaha at the time.
The OEM specs call for
170 Main. As I had mentioned earlier it had a 165 Main in it when we took it apart. That was replaced with a 172 Main.
I have no idea what the hell I am doing
The OEM specs call for
170 Main. As I had mentioned earlier it had a 165 Main in it when we took it apart. That was replaced with a 172 Main.
I have no idea what the hell I am doing
Go back to stock. What mods are done? Sounds to me that you have too big of a main jet in there. Also go to Dirt Rider's web site, they may have this bike on there with a write up and sometimes they list the jetting they did. If you are running a stock exhaust with just the min mods you should be fine with stock and just an adjustment with the fuel screw.Okay, i am trying to figure out what the "GYTR Jet Kit" update sizes are. That is what was supposed to be in the bike and according to previous owner was recommended by Yamaha at the time.
The OEM specs call for
170 Main. As I had mentioned earlier it had a 165 Main in it when we took it apart. That was replaced with a 172 Main.
I have no idea what the hell I am doing
From what i understand the "free mods" were done to the bike. The previous owner used this
http://www.yamaha-motor.com/sport/accessories/acscitemdetail/5/66/55/2301/all/all/6228/0/detail.aspx
http://www.yamaha-motor.com/sport/accessories/acscitemdetail/5/66/55/2301/all/all/6550/0/detail.aspx
And I was told this. But don't know if that is true as I don't know what to compare it to.
http://www.yamaha-motor.com/sport/accessories/acscitemdetail/5/66/55/2301/all/all/6587/0/detail.aspx