What should i do i need help guys

[416 racer]

I have i bone stock yfz except the baffle out and a 13 tooth frnt sprocket now i changed the sprocket for more bottom end im getting the cam mod done full sparks pipe sparks super cgarger air filter kit and jet kit with a leak jet and a sparks bypass plug im wanting to know when i get it done would i have enough bottem end to go back to the 14 tooth sprocket i ride very tight trails anybody got any suggestions thanks

[jshtex]

We race XC and with the same basic mods have always run the 14 tooth. At one of our tracks I put a 15th on for more top end because about a mile and a half was in a dry lake bed, but other than that all 14th.

[nicker71]

I race XC also and run with stock gearing. It just seems like its almost to high with stock gearing in the tight stuff. I also have a +8 oz flywheel. I didnt like what the cam mod did to the bottom end so I put it back to stock. I run a uni open air box and a drd pipe with the stock leak jet. (what does the leak jet do) Mine is a 05. WHat year is yours?

[yfz450bk]

the leak jet is where the fuel from the ac pump comes through, its the path of least resistance for the fuel.

[jshtex]

Originally posted by nicker71
WHat year is yours?

We just retired our 04 after three long years of racing. I happened to get a real good deal from a sponsor on an 05 450r that he still had in the crate so were going to try that for a while. I just hope it holds up, and wins as many races, as our yfz.

You change the leak jet to help with the bog some yfz's (and other bikes like the honda with the fcr carb) get when you stab the throttle. Ours did it a little but my son just got used to it and rolled into the throttle instead of punching it wide open.

[nicker71]

yeah mine would do it but you really had to stab it. It worked fine when gassing at a fast moderate speed, if that makes since. Right now Im having a problem of the quad cutting out at half or more throttle. It cuts out badly dosnt want to run. But anything under half works fine. The thing is it doesnt do this right away. It did it first at the first race this year, it was super muddy like no other and water as deep as the tank. I worked fine about half the race and then started to cut out. I just thought it was the from the mud and water in my airbox. Only half the people finished that on. I took it home clean it up and worked fine. The next race it ran fine at the pratice and first lap. While in the second lap it started doing it again. I was like WTF> it wasnt a wet and muddy race like the first. So I know something is wrong. I had some electrical probs which cost me the race later that lap ( Broken battery internally) fixed that and when ridding one sunday and everything is suddenly fine again. Well I went ridding again this past weekend and it started to cut out a little bit, After a couple hours of ridding. I stopped and checked the fuel 3/4 tank, I switched it to reserve and it startedt to run fine again. It acts like it starving for fuel. So Im going to check the petcock valve and look into the carb and check to make sure the jets are clean, I thought maybe I would change the leak jet out. What size do I need?
Sorry for the long repley

[morningracer626]

Hey Nicker 71, what exactly does that +8oz flywheel do for ya? Not make the power hit so hard & wear ya out so fast? just curious...

[jshtex]

I can't help you with the leak jet. If nobody here does you might check one of the dedicated yfz sites.

I have fought cutting out problems a few times over the years with ours. I have had both electrical problems causing it and fuel problems.

A couple of quick things to try....

Put the airbox lid on it (if you don't run it) and see if the problem gets better or worse. That will tell you if it is jetting and which way to go. Or if you run it take it off.

If you don't run the lights, try running it with them on not just plugged in but actually turned on. That can tell you if it has an electrical issue. Some bikes actually run better with them on, ours did for a while untill I replaced the stator and regulator. When the lights are on the bikes electrical system will actually charge at a higher rate.

Also check the simple stuff, like make sure the gas tank vent is working.

There is a pigtail ground wire about three inches up the ground wire from the negative battery post. It is easy to pull apart (when removing the battery or rear plastic) and the bike will run like crap with it disconnected.

Make sure you don't have water in the fuel / float bowl. You can drain the fuel out of the bowl and see if it gets better.

Good luck.

[nicker71]

I had the airbox lid on for the first two races because it was wet. Its jetted for a open airbox. The last time It went ridding I had it off and it cut out just a little until I turned it to reserve. I run with my lights on all the time and at every race. I also checked that wire next to the battery you were talking about it looked good. I run a cbr 600 battery so it will crank over a bit stronger. I really feel like its a fuel problem.

The +8 flywheel helps keep alows me to keep the motor from reving up so fast which helps with better traction. And will help me from stalling out as easy. I can run a higher gear in the woods and it wont stall as easy as with a stock. I wish I would have went with there +12oz because I can hardly tell the difference.

[jshtex]

The part about turning it to reserve reminded me that once we had a problem, with ours cutting out and running on reserve made it better. There are actually two pickups on the petcock for normal and reserve. I guess it could be that the normal pickup screen gets dirty.

I replaced our petcock because it started leaking about the same time. There is a rubber gasket under the knob that controls the fuel flow and ours broke.

We run the ytz10s battery also.

[YFZ450 11x]

I have a couple of leak jets if you need. pm me if your interested