Boggin Down

[mcncoic]

This is my first post so bare with me. I have a 99shee with a BOSS racing intake (its like adding 1/2" spacers) that has a built in crossover tube, K&N filter w/adapter plate, stock everything else (including carb jetting). The airbox I had to modify so that it would fit the factory bolt holes to allow the engine coolant overflow to remain in place. The airbox now has a 1" gap around the sides and bottom and no snorkel. I was still able to put the airbox lid on but can only use the back locking tabs.

 

Here is the problem: the motor seems to bog down once I go past half throttle in any gear. Runs strong and hard up to that point. I was told that I need to rejet the carbs (but what size mains? I got some 400, 410, 420s on the way. Is this too big?) It has more power than I had before I did the mod. I also plan on putting different pipes but unsure what brand.

 

Another problem that happened was that the motor seemed to run away while stopped. It started to rev up and would not stop. I was able to lower the RPMs by putting it in gear and trying to stall it. But as soon as I bumped the throttle it would stat again. It had been running fine until then (it would start and idle fine before this last time)

 

Anybody out there that can help it would save me some headaches.

Thanks

Ronnie

[oldturtle]

With K&N, no snorkle, and some carving on air box lid you are way too lean. Depending on exactly what the air box lid situation is, correct jetting now is main 260 to 310, pilot 27.5, adjust air screw. Start rich and work down. With most pipes you would be at 330 to 390 on mains and 30 to 32.5 pilot, air screw. Start rich again. No way to tell you exactly where to be. The 400 to 420 are probably too fat. If you are thinking about pipes then get them now and only rejet once with pipes and air filters. This should take care of the bog.

Regarding the reving out while stopped, this is common problem. Some have cured this by cleaning carb slides very well and not allowing any throttle cable lube to get into the slides. Most on this site will also rec'm that TORS be removed.

First rec'm you study jetting FAQ's on downloads here. This explains jetting and TORS. Also don't ride anymore until you get things richened up. You could fry the top end.

And welcome to Banshee HQ. Usually a lot of old hands jump right in on questions like yours. They more than likely are recuperating from a weekend bash. Now you will probably here some different opinions from some of our real experts.

[mcncoic]

oldturtle

 

What I did to the airbox was take about 1 1/2" out of the center. Then I cut some plastic strips from what I cut out and used them to hold the two halves together. The lid I did modify. I sits pretty nicely on top. The BOSS Racing intake is pretty nice it eliminated the need for the boost bottle. On the pilots how can you tell what number they are? Are the numbers stamped on them somewhere?

 

You say that the 400-420 might be too large could I use the needle clip position help change this at all? The Yamaha shop here locally sucks. Put it this way I asked them the same questions and they wanted to sell me a $140 power up kit that could or could not have the right size jets that I need. Didn't say anything about doing a plug chop.

 

I have had the shee since it came out of the crate and now getting around to doing some mods on it. I have no problem at all doing the hands on stuff but need some help with the knowledge of how it really works. Jetting throws me for a loop sometimes. I guess it the same concept as a holley just smaller parts. Thanks for the insight.

 

Anybody else that can help I am always listening.

[XTShee]

Jetting throws me for a loop sometimes.

Benbb wrote this primo FAQ on jetting, give it a read, it sure helped me out a whole lot

 

http://www.dfn.com/benkaren/jetfaq.html

[oldturtle]

Pilot and main jets have number stamped on side or bottom. Stock pilot size is 25, next is 27.5 then 30. The needle clip position is important but it cannot compensate altogether for incorrect main and pilot.

Toomey's are probably the most popular pipe on this forum. If you bought a set of T5 or T6 Toomey's they would also give you advice on where to start with the jetting and I believe they will sell whatever jets they recommend. Toomey is a very respected pipe builder I think you could trust their advice. I have FMF Gnarly pipes because they came with the used bike and give a little better low end than Toomey's but lose out on the top. I requested jetting info from FMF and all I got was BS.

Another idea would be to first deceide if you are going to install pipes now or not. Then re-ask for jetting opinions on the jetting topic list. I think the best jetting minds are not seeing your question and are not getting in on this. Include elev and temperatures you normally ride at. Good luck.

[mcncoic]

Thanks oldturtle for the help will let you know how things go as I start to work on this issue. Gotta try and find some different jets now. Do you happen to know where I could get some different sizes to include the pilots? Once again thanks for the help.

Ronnie

[oldturtle]

White Brothers has sold Mikuni jets in the past. Prob still do. Toomey sell jet kits but where I checked did not include pilots. I'd call them both. If they don't have what you want they might tell you where to check.

[mcncoic]

oldturtle,

 

I found out which style pipe that I have is. It a FMF Fatty. I got it from a buddy. In an early respose you mentioned different size jets with what I have which size do you think would be a good starting point?