Tune up and TPS

[speedy]

I have not had to much to input for you folks up until now, but I feel this may help some...After doing alot of research and alot of testing some of the issues people are having, make sense. If you have (as I did) pulled the carbs, cleaned the jets, set the fuel screws to 2 or so, you found all the settings different. The reason is the butterflys were not synced perfectly before mounted on the motor. The factory then set the fuel screws to match the butterflys to get a acceptable exhaust reading. Now once again if you set the fuel screws to 2 or so, you now have atleast 2 cylinders not perfect @ idle. If you went the next step, sync the carbs, the idle will clean up but guess what just got screwed up..Timing..The TPS will need to be set...Mine was .690@idle, warmed up and not running, set to .765 and motor purrs all the way to 10,500, no funny pops, no feeling hot, performance has improved...If you played with the carbs or had a tune up done the last thing needed is a TPS settup...

Speedy

 

[Prairie Dog]

I've checked my tps when rejetting, but all I did was do a sweep with the ohmeter to check the pot. I never really understood what exactly it does. I thought it was just some computer sensor to compare throttle position with rpm or something and tied in with the tors?

Anyway, I didn't give it much thought. Are you saying it changes the timing curve and is critical to tweak?

 

[LazyBastard]

Spark advance changes as a function of BOTH rpm AND throttle position.

 

[speedy]

Again if you had the carbs tuned at all the TPS needs to be atleast checked. I used 2 straight pins and pushed them up in the connector with the wires. This was a noticable improvement in low end.....

Speedy

 

[speedy]

I would not be surprised if some of the oil use issues are a dirrect result of timing not right. I would like to hear from you guys that have oil use issues---Did it start after a carb clean and or tune up? Have you checked you TPS @ idle.--1350rpm

Speedy

 

[Gilbey]

I cleaned the carbs and have been using oil since. I didn't get my carbs synced at the TY ride though, and no changes in fuel screws or timing. Figured would look at it this summer as long as it ran ok for the remainder of the year.

Brad

 

[speedy]

When you cleaned the carbs did you set the fuel screws? if so you changed the rpm to throtle position ratio...in other words the idle adjustment will be different for 1350 rpms..you just changed the timing curve...

Speedy

 

[Gilbey]

I didn't set the fuel screws. My symptoms at the time were just related to a cylinder blowing gas through the exhaust.

Symptoms I have seen since are for the first five minutes of start up. Wants to gurgle until run down the trail a bit, almost like it needs a little high powered get upu and go and then it will run like a top all day. So this is only after the first start up of the day. Tom thought it may be the screws.

 

[speedy]

OK -- When you check the fuel screws they will be all set different if not they have been set by someone. Your manual says 2.0 turns out I believe.
Set them to that but you will need to sync the carbs to get it right and then check your TPS. Make sure it is between .710 vdc and .775 vdc @1350+-100 rpms...

 

[RX1Jim]

Ted Jannetty and Supertuner did quite a bit of experimentation with the TPS setting last year. I don't remember what they concluded but if you do a search you will find their results. If I remember correctly they were looking a the effect of the TPS setting on HP and top end not for smooth running. There was some discussion of putting a switch in series with the TPS so you could have 2 different settings for different applications: drag racing vs trail riding.

 

[banjo04414]

So how do you set them?

 

[speedy]

I would expect that from the factory they would be very close. The problem starts after the carbs get touched...the TPS is on the shaft the butterflies are on, any change to the position of that shaft will change TPS output voltage. Again problems start if this vdc gets below .710. Mine was below after a carb clean and sync. I also used oil for the first time in almost 6,000 miles...I have used Klotz 4x since 1000 miles. I have put 80 miles on since setting the TPS and no oil use, it runs much smoother and sound better out of the exhaust (aftermarket) .

 

[banjo04414]

Dealer sync'd my carbs, that's why I asked. I seem to have a power loss after that.

 

[speedy]

I would take a quick check and see what ya got....

 

[speedy]

banjo--
Let me know what you get for a reading, please.
Thanx...are you using any oil?