I will start by saying thanks to the forum, I was lucky in finding a former XJ member who had no further need for his carbtune and colortune due to selling his bike. So I went into my first sync with excellent tools. I have not gotten a repair manual or the XJ CD (yet), but with links from the xj page I had printed off, there was enough information for me to feel comfortable performing this myself (I have been a mechanic for about 15 years on 4 wheels).

I bought the bike about 2 months ago, and it sounded fine and seemed to run ok. No maintenance history came with the bike, and it had a little over 25000 on the clock. The mileage had started dropping in the last few weeks, and the idle wouldn't stay below 3000 when the bike was warm. With this knowledge and looking over this forum, it seemed like it was time for a sync and possibly new plugs. I acquired all of the tools, found a day that the wife would be gone, and carb sync session began. And remember the bike is still running good in my opinion.

I get the carbtune hooked up, and there is a difference of about 12 (not sure on exactly what it is measured in, but would assume cmHg). I adjusted 1 to 2, and 3 to 4. These settings were within 3, but adjusting 1&2 to 3&4 there was a major difference, but the closer they came together the better it sounded, and the bigger my smile was.

With this step accomplished, next came the colortune. Started in the first cylinder and it was set about 2 rounds rich. Fixed that and it sounded even better. The second cylinder was only about 1 round too rich, so that did not make much of a change in sound. The third cylinder ended up being about 2.5 rounds too rich. This made a remarkable difference, but we are not done yet. The last cylinder was about 4 rounds too rich. What a difference that made. When that last cylinder was getting closer to set where it needed to, the smoother the bike ran, and likewise the bigger my smile was.

I guess I was lucky while using the colortune in that the readings on the carbtune did not change that much (took 1/8 turn one time to keep sync within acceptable limits). During this process, I also changed the plugs, because by the looks of it, these plugs may have been in there for way too many miles. I went ahead and put in the NGK iridium plugs. I will respond later as the how good they are after some miles.

With all of this done, I had to go for a ride. Just a little short trip about 15 miles. I never knew a bike could be this smooth. Everytime I pulled the clutch in, dropped to idle at 1200. This seemed like a totally different bike, and remember I thought that it was running ok to start with.

The wife came in last night and I was admiring my accomplishment, and her first question was "Did you get a new bike?". I said no, just a couple hours work on the XJ. She said it sounded like a totally different bike.

Drove it into work this morning (about 37F). It did not seem that cold, maybe because of the enjoyment of riding this bike after the sync, and knowing that I was the one to make it this smooth (well I did the manual labor, but I give much of the credit to everybody here for the information).

So my suggestion to any newbies is to sync the carbs and set the mixtures, even if you think your bike is running ok. If you have any mechanical knowledge, with all of the help here and the links you can do it. It may take a little while the first time, but set aside a day and if you get it accomplished before the day is out, just ride and enjoy the remainder.

Great post


I haven't synched mine yet, but have been experiencing similar high idles. My thought was that it had more to do with air leaking into the system from faulty carb boots, but now, I'm not so sure.

I've been waiting for the carb boots I bought on ebay to arrive, so I can swap them out and see what, if any, difference they make. Also, I thought that would be the best time to attempt a synch, after assuring any likely air leaks are sealed.

They might even show up today - so your post was very timely. Thanks

I thought my boots were leaking too, but after spraying some brake fluid around them, it turns out they are not leaking, just look horrible.
I plan on replacing them on the next sync (about 2500 miles), because from the looks of them they may not last much longer than that.

Out of curiosity (and inexperience) why brake fluid?

Was it just a handy liquid, or is that what you should use on rubber? I thought you had to use soapy water, like on a tire..

Great to hear a good story about home tuning. It's really satisfying when you hear the bike getting smoother as you go. I recently balanced the carbs on my XJ900 using this home made sync tool:

http://www.powerchutes.com/manometer.asp

The only thing I did different to make it was cable tying the tubes right up against each other on a half inch strip of alloy to negate the need for ruler marks (you only need to see that the levels are the same when synching). Started by balancing carbs 1 and 2, then 3 and 4, then balanced 2 and 3. It works a treat for under $2......

I've been looking for a Colortune plug over here in Australia, but it seems no one imports them. There's always a few on Ebay in the US or UK, but forking out $$$$ and waiting for the thing to be imported has not inspired me to act. Besides, I got the XJ running pretty sweet through a bit of experimentation with the mixture screws.

Yeah, pardon my inexperience too, but why use brake fluid for the leak test?

Hillsy, Top link on the home made manometer. Got me thinking on a modified version for four carbs which I'll build and test on the weekend.

I am also in Australia and bit the bullet on a colourtune. They are made in england so I ordered one on a Friday and it arrived the following Tuesday. Cost including exchange rate was less than $50AUD.

My mistake however was not checking plug sizes and ordered a 14mm plug so now I need a 12mm adapter.

If you want to order one let me know as there are a few places that sell them but some of their postage rates are ridiculous. Eg. 45 Pound for anything up to 2 kg.

My colourtune cost 2 pound postage and 18 pound for the plug. Make sure you order from a place that deducts VAT for export orders.

Cheers
HG

I used the brake fluid because it is flammable and will make the engine rev slightly if there is an air leak. It is also much safer in my opinion than using starting fluid (ether). It was also recommended by the experienced (old) mechanic at my local yamaha dealer.

I've had good luck with using contact cleaner to find intake leaks over the years.

An update relating to Hillsy home made manometer link. Made one up over the weekend using clear pipe and a four way connector to do all four carbs at once.

Hooked it all up and fired up the bike to find was so far out of sync that one carb sucked all the oil from the other three lines. Quick adjustment to the offending carb, drained the oil out of the manometer(Too many air bubbles after that) refillied with a lighter oil and synced the carbs nicely. Used a home made YICS tool as well which made it even easier.

Colourtune adapter arrived today so followed up with a quick mixture adjustment. this arvo.

Results are spectacular. The extra power is amazing. Still doesn't idle all that well but I'm putting that down to the engine just being tired. (only got 2300km on the clock,already been around once ;) )
Good winter project to strip and rebuild. :D