Author Topic: Easiest way for more power on your '82  (Read 4379 times)

Lucky

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Re: Easiest way for more power on your '82
« Reply #20 on: October 19, 2002, 05:24:21 AM »
actually Jason, almost all the 82 carbs have 120 front pilot air jets.
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jasonm.

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Re: Easiest way for more power on your '82
« Reply #21 on: October 19, 2002, 11:52:59 AM »
The 6 or so sets of '82 carbs I have had were with #130 air pilot in the front. One did have a #120. With the "flapper" update a #130 remains in front with a #135 ion the rear.
But since I have never seen a bulletin on putting such a small air jet in. I figured someone just screwed up on that one set. With #135 in both carbs the bike has more power everywhere. My statements are based on a bike with only 6k miles a clean air filter and clean carbs.
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jasonm.

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Re: Easiest way for more power on your '82
« Reply #22 on: October 19, 2002, 12:00:08 PM »
Also for those who don't know why the main jets are different front and rear on the '82. It's simply the difference in exhaust back pressure. They changed the front pipes in '83 to equalize this. '82 front 122.5,  rear 127.5. ...'83 #130 both.
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Cdnlouie

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Re: Easiest way for more power on your '82
« Reply #23 on: October 21, 2002, 06:22:49 PM »
Thanks Jason & Lucky for the info on the jetting differences.  Now I know where those 120's came from.  The 145's were added by some "Yahoo" (no pun intended) and the stock air pilots were 120's. ?Which leads me to my next question:

Since I do not have stock pipes (I have Mac headers), then I should have jetting that is the same in both the front and the rear, correct?

Today, I am running 135 on the air and 120 on the two mains, but with a slight stumble at 4000rpm. ?I still need about 6 turns on the air screws so I think we are still a bit too lean. ? The rear cylinder especially likes its fuel.

Tomorrow I will go to the 122.5 front and 127.5 rear main jets with two 135 air jets. ?I can now see why they needed to match the 130 jet with the 122.5 on the front and the 135 with the 127.5 on the rear in the update (as you have noted). ?I may need to put a 130 air in the front with the 122.5 or increase it to 127.5 like the rear.

This is certainly a very interesting and very helpful discussion to understand the history of Yamaha's jetting changes and then to make sense of it in light of different exhaust systems.

Things are looking up! ? ;)

Louie
« Last Edit: October 21, 2002, 06:36:50 PM by canadianlouie »

Lucky

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Re: Easiest way for more power on your '82
« Reply #24 on: October 22, 2002, 04:13:24 AM »
Mac exhausts generaly don't require jetting changes, but that doesn't mean it wouldn't benifit from jetting changes.
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Cdnlouie

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Re: Easiest way for more power on your '82
« Reply #25 on: October 22, 2002, 11:37:39 AM »
I looked at another vision today and it confirmed your point Lucky that 82's come with stock 120's in the air jets (F & R) and these two bikes both had the flapper update.  Now both of these bikes are for the northern climate of Canada, so for what that is worth.

My vision loved the 127.5 main in the rear as it now has a very definitive exhaust pulse (in combo with the 135air jet). ?I am going to pick up a couple of 130's for a few future trials.

I agree that the MAC handles stock jetting well, but I am guessing that some improvement can be gained with a slightly larger main in the front, perhaps a 127.5 or 130 especially in combo with the 135 air jets. ?The 135 air may also be a bit too lean for us Canadian boys and cooler climates. ?I am building on the assumption and recommendation made on the forum of the 135 air jets, but may need to go to 130's on the air jets for best performance.

The Vision is sounding real sweet! ? 8)

Louie


« Last Edit: October 22, 2002, 11:41:06 AM by canadianlouie »

jasonm.

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Re: Easiest way for more power on your '82
« Reply #26 on: October 22, 2002, 03:44:47 PM »
I am at a loss as to why some of the carbs have #120 front air jets. This is a big difference from stock specs. And there was no bulletin on this. I think the #120 was done first. Then later on the flapper was added. And the 120 should have been changed back to a 130 or 135. That 4000rpm stumble you have is likely the lack of proper main jet size. The main jets come online between 4500 and 5500. These bikes can  also be too rich. I figured this out during my dyno runs with a clean air filter. Highest power with no flapper. But still a slight hiccup at 5000rpm. So I have the flapper on my '82, but set part way open to start with. Now max power with no stumbles. I can't set my '83 this way. The '83 has such a small pilot gas jet. The flapper must be set to standard settings.
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Lucky

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Re: Easiest way for more power on your '82
« Reply #27 on: October 22, 2002, 05:58:00 PM »
both the factory manual an d the haynes manual call for 140 pilots on the 83's, and 130 on the 82's, but as far as i can remember all the 82's i've rebuilt have had 120 front and 135 rear.
I believe that the jet sizes listed in the yamaha service manual # lit-11616-xz-55 is incorrect (misprinted) and haynes simply copied this info.  for referance, the yamaha manual i am quoting from is the white coverd book with the line drawing of a faired Vision on the cover.  It is an 83 manual printed in 86.  it covers 82 V's with a supliment in the front for 83's.  
the reason I mention this at all is because I know there are other versions of this manual. (glen had a black covered service manual, and I remember that the same info could be found on different page numbers.)  IE: we would be on the phone talking, and i'd tell him "look at page 3-8 at the pic of the flywheel puller", and he'd say "no, that's on page 3-6 in my book"  (or whatever)  so other info might be different also...
--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Lucky

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Re: Easiest way for more power on your '82
« Reply #28 on: October 22, 2002, 06:04:43 PM »
oh, by the way, In have very hard to read scans of photocopys of the TSB's for the bike, and although i cant read the parts list for the carb update tsb, it does say that the MAIN jet was replaced not as a size change, but because the drilling on the originals may have been out of specs, and the jet included with the update was more precise.

I'd kill for original copys of those TSB's  if you guy's could check with your yamaha dealers to pry open their archives to find them and get CLEAR photocopys, that would be golden.  (I believe there were 13 in all)
--Lucky
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jasonm.

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Re: Easiest way for more power on your '82
« Reply #29 on: October 22, 2002, 06:21:14 PM »
I have every TSB of the '82 Vision my dealer could find. But I am still clueless as to how you have had so many carbs with 120 in the front> When I have only had one? I am sure that a 120 would make the front too rich. The choke on mine works properly also. Not like what you and I have experienced previously.
If there was a serious mistake in the manual. I would have thought that a bulletin would have been out on that.
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jasonm.

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Re: Easiest way for more power on your '82
« Reply #30 on: October 22, 2002, 06:23:30 PM »
I have every TSB of the '82 Vision my dealer could find. But I am still clueless as to how you have had so many carbs with 120 in the front> When I have only had one? I am sure that a 120 would make the front too rich. The choke on mine works properly also. Not like what you and I have experienced previously.
If there was a serious mistake in the manual. I would have thought that a bulletin would have been out on that.
looks aren't important, if she lets you play by your rules

Lucky

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Re: Easiest way for more power on your '82
« Reply #31 on: October 22, 2002, 07:03:04 PM »
Jason faxed me the TSB's, (bowing deeply) Thank You!

I agree that there should have been a correction somewhere, but who knows, I can think of a lot of "should haves" working for Ford for 12 years...

I can't tell you why all these carbs have 120 front pilot airs, but they do... (I have 3 here right now)

PS to Leather:  get in your jet and go bomb this M*th*r     F*ck*ng sniper!
1982/3 XZ550 Touring Vison, Gold on Black