Atomck1

Success!! This is long winded but…. I wanted to make sure that I came back on and posted my results since I read far too many threads that had no conclusion. In my opinion threads with no conclusion are an insult to all the people who tried to help and defeat the purpose of the tech talk section. Included is a little history of the repairs, so here goes. Between hurting my back, again, and being out of town for an extended period of time I let the bike sit for too long. I had put Stabil in the tank the last time I ran it, about 6 months ago. Upon returning home the bike would not idle without using the enricher and it had very poor low end performance. I had very little experience with carburetors and zero with CV carbs, so it was off to the internet. My searches pointed me straight to this great site, Thank You! Prior to posting I did my homework by searching numerous threads. The info I found about checking the carb slides and diaphragms along with syncing the carbs got the bike idling fairly smooth at 1000 rpm and much better low end performance. Also I was able to determine that I had a blockage in the pilot circuit for cylinder # 3, it’s amazing how well it idles on 3 cylinders! Posts by V7Goose were especially helpful, Thank You! The first thing I did was to do the sea foam treatment. While that was soaking I pulled the air filter to check operation the slides. The slide for #2 was not moving like the other 3 when I revved the engine. I shut her down and found that I could not move the #2 slider to fully open by hand, as I could with the other 3. I pulled the cover to find the diaphragm assembly in pieces, the brass insert had separated from the slider. The diaphragm was in good shape, no holes or tears. After a good cleaning of the parts I put a very light coating of high temp silicone inside the slider and on the brass ring and slid them back together. I let it sit for a full 24 hours with a 2lb dive weight on top of it to keep the parts together. Before installing I tried to pull it apart with a good amount of force and could not. After reinstalling the slide functions properly and it has held for over a week now. Next I moved on to syncing the carbs. I used two cheap vacuum gauges from Harbor Freight with a vacuum pump and a plastic tee for “calibration” of the gauges. I was not so concerned with the accuracy of the reading on the gauge, I was more concerned with having the gauges match each other. They were off by about a half inch of vacuum out of the box, not too bad for a couple of “cost effective” gauges and they were easy to adjust. I found the sync to be way out of adjustment. After some tweaking I got all the cylinders very close to spec. While doing the sync I noticed that the idle speed would not change when pulling the vacuum cap for cylinder #3. Next I moved on to the pilot screws. After drilling out the caps I lightly bottomed out the screws while counting the number of turns to bottom. In order, 1 thru 4, they were: 1.25, 1.5, 1.5, 1.75. I then backed them out to 2 turns and did the sync again. For adjustments I started with #3. As suspected there was no change in idle speed at any point from bottomed out all the way to 5 turns out. I then adjusted the other three in order and ended up at 2.75, 3.0, 3.0 turns. The bike was now idling nicely at 1000 rpm with much improved low end performance. Vacuum reads a steady 11 inches across all cylinders at 1000 rpm. While I had the diaphragm cover off I made sure the air port was open by spraying sea foam thru it so I knew that was clear. That brought me to posting my question about the pilot screw. Since I have to sell the bike I did not want to possibly screw myself at the last minute, pun intended, by not being able to get the screw back in. This morning I pulled the screw, sprayed sea foam in, let it sit for 2 hours and then blew it out with the compressor set to 40 psi. I put the screw back in and set it to 3 turns out. After warming the bike up I could tell right away that the obstruction was cleared because my idle speed was abut 1600 rpm. I re-synced the carbs and fine tuned the pilot screws. The screws ended up at 2.5, 2.75, 2.75, 3.0. Idle is now very smooth and the engine sounds much more happy. Took it for and spin and WOW!! Better than ever, Thanks venturerider.org!!! Now it’s going to be harder than ever to say goodbye!! Again Thanks!!!

Thank you for the quick replies, I will give it try.

Hello all, I’m new to the site and very happy I found it. Thanks to all those who maintain it and to all those who post such helpful information. 1989 XVZ13DWC. Unfortunately I’m here because I have to sell the bike and I wanted to get it running right prior to selling it. I have found enough information here to help me get the bike running better than ever despite determining I still have a clogged pilot circuit on cylinder #3. I really don’t want to pull the carbs at this point and I want to try and clear the obstruction while the carbs are still on the bike. I was wondering if it is possible to remove the pilot screw and more importantly, if so, can it be reinstalled while the carbs are still on the bike? I’ve tried the sea foam routine and I’ve tried to spray carb cleaner through the passages in the carb throat, to no avail. Any advice would be greatly appreciated. BTW maximum vacuum on cylinder #3 is 21”. Thanks, Atomck1.

Hoochster, did you try the last test suggested by Goose? What was the outcome?

Great post Goose! Great site too!! I'm new here and I've been searching for some info to help me get an 89 running right, unfortunately so I can sell it. Your post on engine vacuum explained it perfectly and turned the light bulb over my head on, so to speak. It helped me get the bike running better than ever despite determining that I still have a severe blockage in the pilot circuit for cylinder #3. Thank you!