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boost or bust?

Started by CanDman, May 12, 2012, 04:37:43 PM

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CanDman

May 12, 2012, 04:37:43 PM
Hi gang......took CanD for a good run today....and found some deserted stretches where I was able to really open her up.......wow.......I don't think I have taken the tach this high before..........was reeeeeaallyyy coooooooool........but   something happened that has caught my attention and I am hoping someone knows what it is........ I hit 2nd gear at about 6500 revs....I really opened it up....and she took off.......at about 9500.....there was a flat spot(like a spit....or pop) so I shifted into third ......again rolled it up and as soon as I hit 9500....hit the same flat spot....it only lasted for a second and the power came back on with a jump.......and again I shifted........into 4th....... On another stretch I went through the same procedure...but instead of shifting this time ...I continued up to 10500......revs........it popped again....but when she came back she really jumped and I had to hold on. Now I know it was not the clutch as I upgraded the clutch with Barnett discs plates and springs last year..... .....there was zero slide to it at all....no.......this was a power issue.....so I began to wonder how the boost and vacuum hose works...........it almost felt like the vacuum hose lost its vacuum.......I am only theorizing
Kev   
Never regret your choices in life ! There is no way to go back to do it again and compare. Make the most and do your best with every decision you make

fj11.5

#1
May 12, 2012, 07:13:39 PM
rev limiter cutting in maybe
unless you ride bikes, I mean really ride bikes, then you just won't get it

84 Fj1100  effie , with mods
( 88 ) Fj 1200  fairly standard , + blue spots
84 Fj1100 absolutely stock standard, now more stock , fitted with Fj12 twin system , no rusted headers for this felicity jayne

FJmonkey

#2
May 12, 2012, 07:17:31 PM
Quote from: fj11.5 on May 12, 2012, 07:13:39 PM
rev limiter cutting in maybe
I don't think our FJ's have a rev limiter, Kookaloo till Kaboom.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

CanDman

#3
May 12, 2012, 08:47:32 PM
does anyone understand how and when the boost  works.....what's supposed to happen.....?
Kev
Never regret your choices in life ! There is no way to go back to do it again and compare. Make the most and do your best with every decision you make

Pat Conlon

#4
May 12, 2012, 09:00:01 PM
 :empathy3: Boost? As in forced induction?
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

racerman_27410

#5
May 12, 2012, 09:50:16 PM
The tach on the FJ is notoriously slow.... I would bet money you were bouncing off the rev limiter.


KOokaloo!


Frank

FJmonkey

#6
May 12, 2012, 09:57:14 PM
Quote from: racerman_27410 on May 12, 2012, 09:50:16 PM
The tach on the FJ is notoriously slow.... I would bet money you were bouncing off the rev limiter.
KOokaloo!
Frank
I have a rev limiter, but it is my shitty second gear issue...
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

CanDman

#7
May 12, 2012, 10:27:59 PM
Quote from: Pat Conlon on May 12, 2012, 09:00:01 PM
:empathy3: Boost? As in forced induction?

Hey Pat....good to see you ....hope all is well.........well actually when I was taking my girl apart...I looked at my shop Manual(service) and got to the section 7-48 where it shows the boost control hose routing.....I asked a few shops and apparently there is a boost hose running into no.2 carb that is a vacuum hose and somehow does something to ignition timing and opens something up and gives the FJ a little bit more in the upper revs....I think it was a precuser to the now popular V-BOOST found in the V-MAX. I read Bob Shamas's write up on his turbo project and he does mention the boost hose and how it becomes "unusable" after he threw his turbo on his bike......so I was hoping that some of the more experienced FJ er's would know more about it....
Kev
Never regret your choices in life ! There is no way to go back to do it again and compare. Make the most and do your best with every decision you make

CanDman

#8
May 12, 2012, 10:32:36 PM
Quote from: racerman_27410 on May 12, 2012, 09:50:16 PM
The tach on the FJ is notoriously slow.... I would bet money you were bouncing off the rev limiter.


KOokaloo!


Frank

Hi Fankie........is there a remedy for that........is it possible that it could be a vacuum pressure jet?
Never regret your choices in life ! There is no way to go back to do it again and compare. Make the most and do your best with every decision you make

CanDman

#9
May 13, 2012, 09:48:37 PM
thanks everybody for all your great comments......looks like there isn't a problem at all.....
Kev
Never regret your choices in life ! There is no way to go back to do it again and compare. Make the most and do your best with every decision you make

RichBaker

#10
May 15, 2012, 12:52:02 AM
Yamaha calls it "boost", but all it is is a vacuum advance.  V-boost is a heck of a lot different..... It lets the V-Max breathe thru 2 carbs per cylinder, over ~5k RPM, via a flap in the airbox.
Rich Baker - NRA Life, AZCDL, Trail Riders of S. AZ. , AMA Life, BRC, HEAT Dirt Riders, SAMA....
Tennessee Squire
90 FJ1200, 03 WR450F ;8^P

andyb

#11
May 15, 2012, 08:14:57 AM
Thought it was 6k?  The fun trick there is to change the trigger to see both coils firing, which makes it come on at half the rpm.  Or just use a switch to trigger it manually... makes the idle sound like you've got really big cams in the motor.  :)

RichBaker

#12
May 15, 2012, 08:20:22 PM
Could be, I'm just going by memory from 20+ years ago....  A couple friends had 'em. 1 was an '85, the 1st & fastest of 'em all.
Rich Baker - NRA Life, AZCDL, Trail Riders of S. AZ. , AMA Life, BRC, HEAT Dirt Riders, SAMA....
Tennessee Squire
90 FJ1200, 03 WR450F ;8^P
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