carb sync question

Hey BigFitz! This seems too obvious to me, but what the hell...should the carbs be re-jetted before I even attempt to do anything besides cleaning the carbs in and out and adjusting the valves to spec?

 

The solution to having you Bike run well when you install Pod Filters IS NOT solved by re-jetting, ... alone.

The FUEL supplied by the Larger Jet NEEDS to find its way into the Intake Stream.
Atomized.
Not in near "Droplet" form.

To make that happen, the Intake Flow needs "Form & Speed"

Plus, Main AIR needs to be delivered to the Passage to aid in the Siphoning of Fuel from the Main Jet Feed.

Re-jetting.
Further re-jetting.
And more re-jetting after that, ... is not enough to overcome performance issues.

No kidding.

 

Right, but in order for me to be able to get my carbs synced with my new exhaust and pods would it need to be re-jetted first or after once it's all tuned (presumably to "stock" running conditions) in order for it to be right?

 

Step 1 adjust the valves. Pods and exhaust have no effect on valve adjustment but valve adjustment has an effect on tuning whether or not you have pods, stock air box, stock exhaust, or an after market exhaust.

 

Well put.

Get the bloody valves in spec first. FIRST.

Then make sure everything else about the carbs (cleanliness, float levels, bench sync, etc., ) is perfect.

While you're rebuilding the carbs, re-jet in accordance with the guidelines in chacal's catalog.

Then at least you'll have half a chance at getting the bike tuned (well, sync'ed up anyway) before diving into the seventh ring of hell (rejetting for pods and a pipe.) Maybe you'll get lucky and it will be close enough, jetting wise, that you'll be happy with how it runs.

But even then, like I've said before: Don't get into a heads-up stoplight throwdown with a pure stocker. You'll be on eBay looking for an airbox...

 

Thanks guys...sometimes I need to be kicked a few times before I learn.

 

As you toil, with the idea that you're going to fix-up this Bike to truly enjoy, ... it's going to be a daunting task to Fine Tune the Bike when you have BOTH Pods and Free-flowing exhaust.

If I was you ... I'd be shopping "Airbox", ... seriously!
Give yourself a fightin'-chance at getting that bike running decently.

Seca 750RJ Airbox

Ebay: $40.00 Buy-It-Now

http://cgi.ebay.com/ebaymotors/82-Yamah ... ccessories

 

Okay first...I apologize to mafia101 for hijacking his thread...with that said I checked my clearances and here is what I came up with:

1st cylinder EXT: 0.15mm, INT: 0.08mm;
2nd cylinder EXT: 0.18mm, INT: 0.13mm;
3rd cylinder EXT: 0.18mm, INT: 0.13mm;
4th cylinder EXT: 0.13mm, INT: 0.09mm

(I'm posting these up in case something doesn't sound right to any of you.)

Tomorrow I am going to try the "Zip-Tie" or "Wire" method and check the out of spec shims and do the calculations.

 

Looks about right for valves that haven't been done in a while.

#1 and #4 are tight on both intake and exhaust; 2 and 3 look fine. One size down on the shims for the tight ones and you'll be good to go.

 

I almost forgot to ask since this is a budget rebuild for this bike. Is it okay to skimp on the shims and get the repro's or is this the type of area to splurge money on if you can. Same question for valve cover and float bowl gaskets, drain plug screws etc.

 

anyone know if this will work on an 82 XJ1100 as well? PO put pods on my bike as well but the more I read the more it seems like I'd be better off going back with the air box.

 

Nevermind, found another one for $10 more.

http://cgi.ebay.com/ebaymotors/AIR-BOX- ... _500wt_956

 

You don't need NEW Shims.
Salvage Yards.
Used.
Online Shim Pools.

Check with Techs at Repair Shops.
Some guys will have Bins of used ones they'd be happy to get rid of.

 

Alright...using BigFitz's pictorial wisdom I pulled the out of spec shims from their respective buckets using the "Zip-Tie Method". Which, by the way, worked like a charm. So here are the shim numbers for each:

1st. Cylinder: Exhaust: Y273; Intake: Y285

4th Cylinder: Exhaust: Y280; Intake: (Y)280

Side note: The "Y" on the 4th Cylinder Intake shim was non-existent with only the numbers printed on the shim. So for the sake of posting my results I put it in parentheses here.

Rick - I read somewhere that using old shims or used shims was basically just pissing in the wind. Even more frightening, I read somewhere that some guys were trying to grind the existing ones down to a more manageable size. (All found around this site of course.) What are your thoughts?

Thanks again to everyone!

 

The Shim is harder than the Cam.
Other Sites have "Shim Pools"

That line of thinking would preclude moving a Shim from one Bucket to another.

Grinding Shims isn't a good idea.
Experienced Machinist's may be inclined to shave 10-thousandths off a Shim for themselves.

Bringing a Shim to have shaved is LAME.
The Machining will cost three times the price of a New one.

 

Interesting...well by the looks of it then, and according to the chart I can swap at least one used shim I have in place of one that I need. I'll check out some of these shim pools and see what I can dig up. Otherwise I'm anxious to move on to my carburetors, syncing and whatnot. Thanks again Rick.

 

Alright here's an update... or more of an excuse for me to stare at this site for hours on end while I A.D.D. myself away from tearing apart, cleaning, and rebuilding my carbs.

Various parts were ordered from Chacal and the bastard valve shims will be swapped and checked again for the proper clearances.

Rick pointed me to look out for "shim pools", I did a quick search on this site and found a few threads on the subject and with a few people that were willing to help as well.

So far, besides my one bad float bowl gasket, the rest of the carbs are pretty clean inside. I'm using Rick's awesome guide to carb cleaning glory as well as referring to my Haynes for pictures and any/all correct nomenclature. With great success so far, in due time I shall let you know how it all fares out when the parts arrive.

 

Valves are now in spec! Valve gasket is back on and valve cover is tight and with new "donuts" to boot. Carb sync here we come. Can't wait to rebuild my carbs and get the manometer out.

 

My bike is still running lean--Here is what i have done so far
Verified valve clearance---
cleaned carbs(probably not as good as I could have)---
Attempted to sync by ear.
The end result is that the bike goes like hell,does not backfire or hesitate, usually starts right up unless it is wet.
It runs like a dream and gets o.k gas millage but the plugs are still white, still running lean. The small mixture screws are like 4 turns out. As I move them out I really do not hear much change in the RPM`S. I would expect the cylinder that I am messing with to change rpm`s as I move them in or out but it does not seem to happen. I backed 1 screw almost all the way out and really no change. I put them all at 4 turns out and called it a day.

 

Unless the Pilot FUEL and AIR Passages were cleaned and the Pilot FUEL Jets are clear and passing Fuel, ... getting Tuned-up is going to be impossible.

Likewise, ... the Main AIR Passages and the Center Emulsion Tubes (16~20) Drilled Ports need to be Clean and Flushed, too.

You NEED the Pilot Passages Clear in order to run the Bike and make the Bike IDLE without MAIN Jets kicking-in.

Clean those Carbs thoroughly CLEAN and "Clunk Test"
Bench Sync with Quarter-Inch Wide strips of 3X5 card.
You MUST make the Bike IDLE adjusting Pilot Mix Screws

You can perform a HIGHLY ACCURATE Vacuum Sync using only ONE Vacuum Gauge.

"STUFF" the YICS Passage:
http://xjbikes.com/Forums/viewtopic/t=4 ... +yics.html

"ONE GAUGE SYNC"
http://xjbikes.com/Forums/viewtopic/t=2 ... +sync.html