Help Please

have about 400 miles on my seca 750 so far took plugs out to check them. 1 &2 plugs are black and sutty 3 is showing some signs of tan and 4 is medium tan with no sut. why is this and how do i go about fixing this.

 

Differences on your plugs like that are caused by air/fuel mixture usually, they just need to be adjusted.

 

You need your YICS tool and gauges (home made or purchased), then adjust the carbs.

 

now the yics tool gauge shuts air supply off to something and what are the gauges? where are the adjusting screws for air/fuel?

 

RickCoMatic has a fantastic write up on the whole process of rebuilding and synching carbs, but I can't find it. Perhaps someone else can point this out? I just read one a day or two ago and for the life of me I can't remember how I found it.

 

Just do a search for Ricks old school carb cleaning. You'll find it

 

Could you give more info. Hows it run, start, and idle? When was the last time the valves were set? Plugs correct for your bike?

 

Here is a nice tool with pics

http://www.xjbikes.com/Forums/viewtopic ... tml#134136

Here is the definitive one gauge guide:

The Old School Method
Single Vacuum Gauge Synchronizing of Carburetors
by: Rick Massey
Special to XJBikes.com
All rights reserved.

First, you need one vacuum gauge. (There's none better than the one sold at Sears for $19.95) and your home-made YICS tool.

A couple of Electric Fans to keep the Old XJ from overheating while you do the tuning-up. Two. Aimed at the Engine. High speed for Max cooling!

You need some vacuum line. Get ten or twelve feet. You'll be making-up lines to run from each carb out to the side of the bike where you'll hook-up the Vacuum Gauge.

You need a few small, hollow, plastic-barrel vacuum line connections. (Those little things you use to plug one vacuum line into another.)

One small, inline fuel filter; with ends that will fit the hose.

One red plastic spray tube ... like the one taped to a can of carb cleaner.

Four regular Golf Tees. (Just steal 'em from your dad's golf bag)

5-minute epoxy.

Masking tape and a "Sharpie"

OK kids ... Let's ROCK!

Prep:
Fabrication of the "Vacuum Restriction Valve." (Absolutely necessary)

Take the skinny red tube and run it through one of the hollow, plastic hose connectors.
Seal that hollow connector with epoxy; leaving a length of the red tube extended from each end.
(This fabricated little-metering device will be the all-important "Vacuum Pressure Restrictor" that will allow you to read the vacuum gauge without the extremely WILD fluctuations on the meter you'd get if you tried to get a vacuum reading without it.)

When the epoxy hardens; cut-off the extraneous ends of the red tube -- flush.

Using a short length of vac line ... attach the restrictor to one end of the medium-sized fuel filter.

(Now you have a restrictor attached to the fuel filter. You just made what you NEED to get the needle on the vacuum gauge "Quieted-down" enough to get an accurate reading without the meter being so wildly fluctuating as to be useless. You have Baffled-Restricted-Regulation and this softens the harsh, impossible-to-read fluctuation, the indicator would have, without it.)

Hook-up and Sync:

The rest is by the book.
YICS tool inserted.
Four Vacuum lines run from the Carb Intakes over to where it will be convenient for you to connect these four lines up to Vacuum Gauge ... each marked with a little tape label for one through four. Stick the golf tees in the ends of these lines ... and get ready to sync the carbs.

Attach your "Old School - Baffled Restrictor" to the vacuum line coming from Number - 3 with the red tubed restricted end plugged into the vac line coming off the engine.

Plug the Vacuum Gauge into the Fuel Filter end. You're officially restricted and baffled for testing ...

So, let's do it!

Run the bike and get the vacuum reading of Number 3 (Three) ... to check for good vacuum on three and to observe how the needle of the gauge is still going to MODERATELY "Vibrate" as it measures engine vacuum.

Sneak the rev's up to 14 > 16-hundred rpm's and the fluctuation will become rapid enough for you to read the vacuum that the hole is pulling.

Mark the gauge face with a short strip of masking tape and mark the tape with a check-mark. Don't let the tape strips block you from seeing the vacuum gauge needle during the sync.

Authors Note:
It's a good idea to practice pulling a golf tee out and covering the hose with your thumb. This will keep the engine from stumbling and possibly stalling.

Checks and adjustments:

Read the Vacuum being pulled by Number 2. Mark maximum vacuum drawn by 2 with line of tape.

Get your magic fingers ready to do the "Carb-Shuffle!"

Pull-out the baffle and block the vacuum with your thumb until you can insert the golf tee you have ready between your lips or behind your ear.

Measure the vacuum being drawn by Number 1. If the max vacuum being drawn by Number 1 is NOT the same as you have MARKED for Number 2 --ADJUST the SYNC SCREW on Number 1 ... until the Vacuum drawn by ONE is the SAME as the Vacuum drawn by TWO!

Two down ... two to go! But, here's where it gets tricky.

Plug-in to Number 4. Set the Vacuum drawn by Number 4 -- to -- the BASE Vacuum you measured for Number 3. (Actually check 3 again ... adjust 4 to match 3 -- because 3 is the Base Vacuum Port, has NO sync screw adjustment, and usually has the petcock vacuum hose connected to it.)

At this point you start TWEAKING. From here until the rack's in-sync ... it's all down hill!

The engine should be sounding pretty darn good; right about here. But, we need to finish it off!

Just hook-up to Number 2, now ... and bring the vacuum being drawn on Number 2 -- UP or DOWN to match the value of Number 3.

They'll be no need to adjust Number 1. Number 1 is connected to Number 2 and goes right along for the ride when you sync Number 2 to Number 3 ... and you ...

HEAR the results of synchronizing all four of your carbs with only one vacuum gauge.
Let what I have outlined, here, be your guide ... but, don't be afraid to get creative with where to have the golf tees ready to pop-in the lines!

When you wrap-it-up ... the One - through - Four ... Final Measurement should be all right on the same value -- right across the board.
Yes? DONE!
No? Tweak until you nail it!

Can you believe that we used to have to do it this way? Compared to the MotionPro Carb Sticks -- It's like being in Bedrock ... spending a little time with Fred and Barney doin' a little Stone Age Tweaking'!

 

starts with choke and in the morning does not like to idle to high after sitting for few minutes with choke off. after riding it warming it up idles great right were it suppose to. doesnt like to start after riding it and getting it real hot have to give it gas to start up and crank on it a few times. i think it's running semi smooth being a little boggy at highway speeds. plugs are correct bp7es and the tell ya the truth i dont have a clue when the valves were set.

 

Definitely check the valve clearances but really, it sounds like you only need minor carb adjustments. The mixture screws for the 2 sooty cylinders. The problem is, your carbs may still have the brass anti-tamper plugs in place which means you'd have to remove your carbs and drill them out so that you can access the adjustment screws.

 

where are they located on the carb bodies themselves?

 

Little towers engine side of carbs. May have brass plugs in them. If not the screws are down inside.

 

hard to drill out