Squirt Timing Adjusting Techinque


15 replies to this topic
  • xorron5

Posted November 21, 2008 - 09:27 AM

#1

Hi,my bike is coming in parts an it is resambled in the store where i am planning of doing following things:
1.gresase ewerything necessery
2.put r&d powerbowl on place,
new accelerator spring,
jd-jetting red needle..
since the carb is off the bike allready..
and at the same time to make shure the squirt timing is correct...
so my QUESTION IS :CONNECTING ONLY FUEL LINE FROM TANK AND
THROTTLE CABLE ,and other wise have the carb still OFF
THE BIKE i woud be able to see where the AP squirt hits
the slide when whacking the throttle and looking inside
the carb mounth...is this an ok technique to get the job
done for seeing if the timing screw needs adjustment.

and what about the tps sensor its said that when removing the carb u shoud not open the tps screw because u will loose the factory adjustments..
in this case the tps might be off allreday since ewerything comes in parts
does that mean we have fiqure out the adjustment of the sensor ourselves..
sorry this all new ball game the questions newer end...:thumbsup:
and buy the way GRAY if u are reading what do u think about using the red needle from jd..ower here in thailand is it going to give better out put than stock needle?

  • fredbob

Posted November 22, 2008 - 06:18 AM

#2

Adjusting the TPS requires a multi-meter. On most models, there is a line painted at the factory to restore the general settings if you have to remove it. Adjustment is made by turning the TPS until proper ohmage is achieved. FOr the ohm specs, download a manual. Links for manuals are available in the model specific forums (ie: yamaha) for each bike.

BTW, tps adjustment, along with accelerator pump adjustment, does tune some of the bogging out of throttle response. But if you're an old two stroke rider like me, you will never get over the bog of the four stroke. Even a completely tuned four stroke will die if you simply hammer the throttle to the stop while the bike is sitting still. This annoys anyone who raced before the four strokes.

  • grayracer513

Posted November 22, 2008 - 06:52 AM

#3

Adjusting the TPS requires a multi-meter.

It's a little more complicated than that. Testing the TPS requires an ohmmeter. Adjusting it requires that the TPS output voltage be set to a particular level at a particular RPM, so that requires that you have a tach, have the idle mix reasonably well adjusted, and back probe the TPS to measure the voltage per the procedure on 6-6 of thee manual.

The fun part of all this is that in order to change or lock down the TPS adjustment, you have to take the carb back off to get to the retaining screw.

And fredbob is absolutely correct in that the best way to cure the bog is to learn not to cause it. Rolling the throttle is an essential skill that all riders of big bikes used to have to learn. Instead of snapping the throttle open from closed to WOT instantly, you break it open a little more slowly just at first, opening it faster the farther it opens, and the more the engine responds to it. After a while, you get so you don't think about it at all, and the engine responds quickly and smoothly.

  • jeffboyd47m

Posted November 22, 2008 - 07:48 AM

#4

Even a completely tuned four stroke will die if you simply hammer the throttle to the stop while the bike is sitting still.


My 08 450 can be sitting at an idle and rev instantly with no bog when the throttle is hammered wide open.

  • gtxkid

Posted November 22, 2008 - 08:15 AM

#5

I think the bike should be warmed up so you get a proper reading.
I have remember some guys using a video camera.
Fuel sould be at the same state the normal engine is running at. (Temp)
My 2008 is good but once in a while (not often) I can blip the throtle and it will die.
I run a Rekluse clutch and that stoped the killing the motor in the corner's mud or whatever, it is a dream.

  • William1

Posted November 22, 2008 - 08:58 AM

#6

A video camera is used to time the duration of the squirt. A videop camera typically shoots at 30 frames a second. If you want a one second squirt, you film the squirt. Replay on a computer, counting frames. If the frame count from beginning to end of the squirt is 30, you have a one second squirt. This can ve varied with the AP diaphram (different length rivets), a model airplane collar (older FCR's) on the AP shaft and with the leak jet.

The timing screw simply adjusts when the squirt starts.

  • xorron5

Posted November 22, 2008 - 09:16 AM

#7

1 second squirt sounds long , anyway i understood that the timing screw simply adjust the distance of the squirt tighter =shorter, looser=longer,
ideal just to miss the slide...whell u all know that but i simply was curious of the metod to see the squirt when u wack the throttle ,and that u cant observ
when the carb is mounted unless u have some candid camera...

  • Kasjok

Posted November 22, 2008 - 09:26 AM

#8

Do I remember correctly that when using O-ring mod, you should turn the adjuster srew as far out as you can with out it coming off?

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  • William1

Posted November 22, 2008 - 10:04 AM

#9

1 second squirt sounds long , anyway i understood that the timing screw simply adjust the distance of the squirt tighter =shorter, looser=longer,
ideal just to miss the slide...whell u all know that but i simply was curious of the metod to see the squirt when u wack the throttle ,and that u cant observ
when the carb is mounted unless u have some candid camera...


Carb on bike, tank on, sub frame moved to the side, you can easily see the carb throat and see the squirt. Nail the throttle, tweak the timing scew (1/4 to 1/2 turn at a time), nail the throttle (engine off of course).

  • William1

Posted November 22, 2008 - 10:05 AM

#10

Do I remember correctly that when using O-ring mod, you should turn the adjuster srew as far out as you can with out it coming off?



No, that is incorrect. Read the O-Ring Mod and AP Tuning. If the screw is backed out and loose on the spring, you must either or shorten it or replace the screw with a shorter one.

  • Kasjok

Posted November 22, 2008 - 10:32 AM

#11

When I did my O-ring mod in this spring, I turned the timing screw couple of turns out. The squirt didn`t hit the slide and I have had zero bog problems during the whole season, unless the throttle is whacked wide open, of course.

As I understand the squirt should be as early as it can?! When using a camcorder with slowmotion you could time it just to miss the slide.

By the way, I think the regular frame rate of camcorders is 25 f/s. At least that`s the case with my 2 recorders.

  • William1

Posted November 22, 2008 - 12:21 PM

#12

No, you want the squirt to just misss the slide as it goes up. Every bike I have worked on that had AP timing off, the squirt was hitting the slide. This does not happen all the way up rather in the first 25% of travel.

  • 642MX

Posted November 22, 2008 - 07:00 PM

#13

Do I remember correctly that when using O-ring mod, you should turn the adjuster srew as far out as you can with out it coming off?


Thats wrong. Leave the adjuster alone if the fuel is not hitting the slide.

  • 642MX

Posted November 22, 2008 - 07:16 PM

#14

I have had zero bog problems during the whole season, unless the throttle is whacked wide open, of course.


You should be able to wack it wide open with no bog. I can find the rev-limiter on both our bikes without any bog. I think you should probably turn the accelerator pump timing screw back, it will probably run better. :bonk:

  • Kasjok

Posted November 23, 2008 - 01:39 AM

#15

When riding it, I pretty much can. Only on a stand, when using my lightning fast wrist movement, it bogs.
I can`t recall the exact number of turns I turned the screw and I don`t think that "leave it alone" approach is the correct one. Some fine-tuning is always welcome, question is what exactly should I be chasing.

My own logic tells me that it`s the best when the squirt starts as early as it can without hitting the slide.

Manual has also a way to set it, what to think about that?

  • William1

Posted November 23, 2008 - 03:56 AM

#16

If the bike does not bog when riding, leave it be. It is not like you win races with the bike on the stand under no load.





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