First Gen Carb Help

[Atomck1]

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.

Edited November 13, 2014 by Atomck1

[Prairiehammer]

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 with 21,400 original miles.

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.

 

Yes the pilot screw can be adjusted, removed and reinstalled while the carburetor is on the bike. If, however you are actually speaking of the pilot jet, then no, the pilot jet cannot be removed while the carb is on the bike.

[MiCarl]

I have had some success opening pilot jets by removing the screw and blowing in compressed air (high pressure from a compressor, not an air can). They often re-block though.

[Atomck1]

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

[videoarizona]

Guitar high "E" string is good for cleaning out passages and stuff. Very thin but strong enough to push through debris. And it won't make the holes larger...

 

This probably won't help you at this point...but if you can use it...they are less than $2.

[tz89]

Many on here would probably say bite the bullet and do it right. Or at least be careful when you do it the other way, which many on here have. Me, too.

 

When I got my 89 #3 was blocked and not firing. My mechanic pulled the pilot screw and cleaned it out that way. I got lucky and it worked.

 

Be careful about compressed air. Be careful what you spray in there - some carb cleaners will eat the rubber diaphragm.

 

Leaving the carbs on the bike means you can't get all the circuits clean, the float bowls may be completely fouled, and the jets may be so blocked this method won't work. You can't do much with the enricher.

 

If you get lucky, you can remove the pilot screw, remove the diaphragm, spray and clean as best you can from the side and top.

 

Drain the bowl.

 

Then re-install the diaphragm. You'll probably need a new one but we are hoping for 100% luck.

 

Put in the pilot screw. If you didn't count the turns from bottom before you took it out, set it to 2.5 turns from bottom. Some good advice says set to 3 then turn in until you hear the rpms drop then back out a bit but that's an advanced course. This is luck.

 

Go buy a new resistor cap for the plug and put that on by clipping just the end off the existing wire. Heck replace all the wires and plugs.

 

Put a lot of seafoam in the gas.

 

Starts right up. If you are lucky. Let her run on the seafoam, then ride it like you stole it, and let it sit overnight will all that seafoam.

[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!!!

[videoarizona]

Appreciate the write up! Glad you found the problems.

Nice to see someone go through their scoot in a logical sequence, then report back the results. Thankfully, most people here do that as well...

 

Sorry to see you go.

david

Edited November 13, 2014 by videoarizona
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