Sometimes you have to break out the big (steam) guns!

Good day riders and fans of the blog! In my last post, I described a little project to install an OEM exhaust system on the XJR. That post is the third part of a four part series of projects to undo some of the previous modifications that were done to the bike somewhere in its lifetime. The other two parts of the story are part 1 and part 2. In this post, I tackle one of the most daunting parts of this project series. With the new exhaust system in place, I have to ensure that the intake side of the engine system is properly dialed in to maintain the balance between the "in" and the "out". I'm hoping that by doing this work I can get better cold starts and improved gas mileage. Read on to see how it all went!

Step one in the process is to pull out the carb bank. This was the first time removing a four carb bank like this. My previous carb work involved singles and twins. Getting the carbs off the bike wasn't as much of an issue as I had prepared myself for. First thing off was the bike seat. Next was the tank. Side covers and airbox side covers followed those pieces. These were the easy parts. I didn't quite plan this properly as I had almost a full tank of gas. The tank very heavy and ungainly with the weight of the fuel inside. Since the XJR was now down for the count while these repairs were being done I managed to use the tank to fill up the Cub when it got low. The choke cable came off relatively easily. The throttle cables came off easily also. Actually the return throttle cable was already disconnected. On my last long ride with the XJR something felt wrong and the throttle suddenly became slack. I'm guessing that the return cable disconnecting itself was the cause. Now with everything out of the way, I loosened up all of the airbox boots and carb insulators and pulled the whole carb rack out with much less stress than I was planning for. Off to a good start!

As expected, the carbs were coated with years of grime and gunk. While coated with junk from road use, the carbs themselves were intact except for one of the casting bosses on cylinder three's carb. My old Kawasaki Ninja 250 race bike had a cracked carb top cap giving me tons of headaches chasing air leaks and hanging throttle. Nothing like that with these. All of the linkages were working well and there were no signs of fuel leaks. Amazon Japan to the rescue! I picked up this household steam cleaner for the princely sum of about $40 US. I cleaned the outside of the carbs with just the steam cleaner at first. While I was able to blast off a bunch of big chunks of crud, it didn't get the film of road grime off. I pulled the fuel hoses and idle adjustment fittings off the carb rack and started cleaning old school. I broke out a bucket of warm water and simple green and scrubbed the whole lot with various brushes. Once the simple green did its job, I went back over the carbs with the steam cleaner and concentrated on the nooks and crannies that I couldn't quite get to with the brushes. This seemed to do the trick and in the end I was left with a nice looking set of induction devices ready for the next step of the project. 

After removing most of the outside junk, I cracked open the carbs and compared the jet sizes and settings to my service manual. The manual is very detailed. It gave me jet sizes, mixture screw settings and just about everything you'd need to make sure the bike will run as designed. I picked up some steel trays to hold the individual carb parts from the local dollar store. All in all the carbs looked as if they had been rebuilt in the last few years. None of the jets were stuck. All of the float bowl and carb cap screws were stainless Allen head pieces. The only thing that could possibly explain the fouled plug issue I have had was the mixture screw settings. The screws are supposed to be 2 turns out according to the manual. Mine were only one turn out. This would richen the mixture on these particular carbs. I think that the previous owner did this to help the bike run better after putting on the custom exhaust pipe. 

Once again I broke out the steam cleaner. I ran the steam through all of the passages. Luckily I wasn't surprised with and big chunks of goo oozing out of the various ports. I wasn't expecting anything as the bike ran well all around, but it was nice to know that the carbs were clean inside and out. Once all of the parts were clean I reassembled them using some parts from a generic rebuild kit also from Amazon Japan. I was a bit worried that the cheap parts would be of exceedingly poor quality or would be so generic that they wouldn't work for my specific carbs. I was very pleasantly surprised to find out that the parts were good and fit perfect my carbs. I reassembled the carbs and then got everything back on the bike without too much hassle. Putting the bike back together took longer than getting it apart of course. While I was there, I also changed the air filter. The old one had been drilled to let more air in. Also to probably help with the "tuned" carbs and custom pipe.

The final verdict? The bike runs awesome. Cold starts are a breeze. Just a bit of choke is all that is needed to get the bike running on a low idle. Before doing all of these projects, I'd have to run the choke for about a kilometer before the bike would idle at stop lights. As I mentioned in the muffler post, the sound of the bike is so much more quiet and polite. I actually have gone to work without earplugs. I could hear the road noise from my tires. I was even able to hear the wind whistle in my helmet vents! Stop light starts are also much easier. I don't have to rev the bike up as much as I used to to get off the line. Gas mileage is still to be determined, but initial mileage seems promising. I need to get the bike out on the freeway to see how it feels at higher speeds, but as it stands now I am very satisfied with the results. 

The weather here is back into the single digit Celsius numbers warming up into the low double digits. For my American readers, the temp is between 40° and 45° F in the mornings and it warms ever so slightly throughout the day. Every few days we have some light rain. I have been working on my rain and cold riding here in Japan. Back when I lived in SoCal, I could skip a riding day if it was like my current weather and still have plenty of riding. If I skipped every day in the 40°s or every day with precipitation I'd have an overly short riding season. My heated gloves have made all of this possible. Layering my gear also makes getting out on days like this something to look forward to. Hopefully you, good reader, can still ride. If you can, please ride safe! 

Mat