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fuel to air ratio sensor troubles


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jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: August 20, 2008 at 11:21 PM / IP Logged  

I dont know If anyone can help noticed mostly street bikes but I did some hp mods to my sons 2006 Yahamma Blaster I installed a Toomey R1 race exhaust kit  a boost bottle rejetted carb. Jet kit came with

Exhaust System added highflow airbox and filter And a motion Pro twist throtle. Now here begins the problem

in the kit you use the stock carb. you just replace jet and needle but you must  unhook the F&A sensor  and use a plug with a jumper wire to plug in its place It runs great for a while but then it will start to idle out of control way,way to high It cant even be ajusted by idle screw . the only thing that i found to stop it is put it on

1/2 choke but then you must keep it reving or it will die. The throdle is working fine not stickin choke is openning and closein' fully the only thing I can think it could be is something to do with this  F&A sensor

have called toomey but give me the run around  on how all there kits are dino tested and work.

I have lots of exp. with dirtbikes & 4 wheelers  Working on them & racing them But this problem

has got me pulling my hair out  has anyone had this problem or know anything I maybe over looking

Have been doin' this along time since I was 13 now in mid 30's but not to old to learn

have take it to a shop cost me 75 bucks to tell me they cant figure it out any help would be much appractied

My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,491
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: August 21, 2008 at 3:15 AM / IP Logged  
Are you using a K&N air filter? I know of several people that have had a problem with the oil used to clean the filters gumming up the TPS and causing similar problems.
KPierson 
Platinum - Posts: 3,526
Platinum spaceThis member consistently provides reliable informationspace
Joined: April 14, 2005
Location: Ohio, United States
Posted: August 21, 2008 at 6:05 AM / IP Logged  

I think it sounds like an a/f problem like you mention.  It sounds like the bike starts up in open loop and runs fine, then when it switches to closed loop it's either dumping fuel or cutting fuel because the a/f feedback isn't correct.

I would try plugging the sensor back in and seeing if it will idle correclty that way - at idle your mods shouldn't make a huge difference in the breathing ability of the bike.  If the problem goes away you can try to get a replacement "jumper" or get the bike retuned for the mods so that the a/f sensor will still function (if that is possible with that bike).  If you continue to have a problem I would doublecheck all exhaust flanges for leaks (however this won't explain why it runs great at first and then starts to idle high).

Kevin Pierson
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: August 21, 2008 at 9:35 AM / IP Logged  

i am an idiot wrote:
Are you using a K&N air filter? I know of several people that have had a problem with the oil used to clean the filters gumming up the TPS and causing similar problems.

Yes I do run a k&N air filter but I use a Filter lube called SX because of the issues you describe.

My wife thinks bagging a truck means you kick it in the truck nuts
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: August 21, 2008 at 9:41 AM / IP Logged  
KPierson wrote:

I think it sounds like an a/f problem like you mention.  It sounds like the bike starts up in open loop and runs fine, then when it switches to closed loop it's either dumping fuel or cutting fuel because the a/f feedback isn't correct.

I would try plugging the sensor back in and seeing if it will idle correclty that way - at idle your mods shouldn't make a huge difference in the breathing ability of the bike.  If the problem goes away you can try to get a replacement "jumper" or get the bike retuned for the mods so that the a/f sensor will still function (if that is possible with that bike).  If you continue to have a problem I would doublecheck all exhaust flanges for leaks (however this won't explain why it runs great at first and then starts to idle high).

Yes I have tried this but the bike will not start with out it being plugged in and if you unplug while it is running

It kills the engine.

My wife thinks bagging a truck means you kick it in the truck nuts
KPierson 
Platinum - Posts: 3,526
Platinum spaceThis member consistently provides reliable informationspace
Joined: April 14, 2005
Location: Ohio, United States
Posted: August 21, 2008 at 11:05 AM / IP Logged  
If you unhook the "plug with a jumper wire " and plug the original A/F sensor back in the bike won't even start????
Kevin Pierson
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: August 21, 2008 at 1:21 PM / IP Logged  

KPierson wrote:
If you unhook the "plug with a jumper wire " and plug the original A/F sensor back in the bike won't even start????

No I should have explaned it better Sorry, The sensor is not even on bike anymore the sensor was in the top of the carb. This was removed when the motion pro twist style throtlle was removed. If the plug that is in the factory setup is not  plugged with the jumper wire it will not start nor will it cont. to run if running. It must have some kind of engine protection function I was wanting to know if anyone knew how to get around this

I am along time KTM fan I still have a 1992 KTM SX  But my son likes Yahammah

My wife thinks bagging a truck means you kick it in the truck nuts
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: August 21, 2008 at 1:23 PM / IP Logged  
Sorry about type O when i installed not removed motion Pro twist throtle
My wife thinks bagging a truck means you kick it in the truck nuts
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: February 20, 2010 at 3:46 AM / IP Logged  
I thought  I would post the cause of this problem. The needle that came with motion pro throttle was .05 to small dia which would let fuel in no matter what you did. Now new needle saves me money on front tires. There never on the ground..........
My wife thinks bagging a truck means you kick it in the truck nuts

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