83 venture questions need some advice/ ideas

[van avery]

Picked up an 83 venture a couple weeks ago. Last year I helped PO clean the carbs and couldn’t get the carbs to sync well at that time. But ran out of time to work on it then.

He quit riding it last summer and I now have the bike. Had to use starting fluid to get a cold start up. When I pulled the plugs 1,2,and 4 looked about right but #3 was more black.

I adjusted the valves and replaced the fork seals this week. It now starts up without the starting fluid. I noticed that #3 does not heat up as quickly as the others. I removed the YISC system and plugged the outside ports with caps and installed bolts in the center two hoses. Replaced the vacuum hose off #2 cylinder to the (vacuum advance). Bike still has the original TCI.

Now the idle is not consistent will set a around 1000 RPM and it will run for awhile then ramp up to around 2800 RPM. When I readjust the idle it will hold for awhile then it may decay to around 500 RPM or die. Kinda acts like #3 cylinder kicks in when it revs up.

Vacuum readings on one and two are pretty consistent but 3 and 4 don’t want to settle in. The other thing is the readings at 1000 RPM are about 4 to 5 Inches and 3and 4 are lower at 1000 RPM and all four will go to around 11 inches when it runs up around the 2800 RPM. Seems low if I remember correctly show be closer to 9 inches ar 1000 RPM.

I sprayed starter fluid around the intakes and really didn’t see increase in RPMs.

Wonder if I need to pull the carbs again? Could it be the old rubber plugs in the carb jet holder?

The gas is from last summer but I added about ¼ can of B12 chemtool to it only about ¼ tank left.

Just looking for other ideas. Maybe need to put it back together and run it some with some new gas.

Sorry or the long history . Thanks in advance.

[DragonRider]

You need to have the 2 left side pistons connected with a splitter for the vac. advance hose for it to run properly. Its okay to block off the right side completely, but for it to run right you need the 2 left connected to the advance.

[timgray]

You need to check if you have spark on the cold cyl. these bikes will run perfectly with 3 cylinders and actually decently on 2. I made it 150 miles on 2 doing 70 with a passenger and full cargo load. The stock TCI has a known problem where they will die due to corrosion. you may have a dead output.

 

And I sound like a broken record here, but go get a can of SeaFoam and try to get a lot of it into the carbs. there are some very tiny jets in the carbs on the bike that are not easy to clean without a full soak.

[Marcarl]

When you replaced the vacuum hose did you reinsert the restricter that was in the old one?

Also, you might want to start your sync from scratch. For that you need to make sure that #1, the left front cylinder (as you sit on the bike) is your lead cylinder, so that is the one adjusted with the idle screw, then the one behind it is adjusted accordingly to it. Same on the right side and then the right side to the left side.

Often times things get mixed up, and one tends to have the left rear cylinder closed right off and then can't get things synced up, it almost works, but not quite. So look inside the left front carb, and watch the butterfly down inside as you turn on the idle screw, make sure it's open, not much, but it needs to be open. Then with the left side sync screw, do the same for the rear carb. Now start the bike and sync the left side, but don't turn down the idle just yet. Make sure they are both drawing the same before you adjust the idle. Then go to the right side. Sync the rear with the front and then the front to the left side front.

Hope I got it right.

[Flyinfool]

I would start by getting rid of that old gas.

Even though I store my bike with Seafoam and Stabil, my bike still runs like crap till I get all of last years gas out of it and get that first fresh tank in there. I give it another shot of Seafoam in that first tank just to help clean things up.

 

You do not want to adjust the engine to run best on stale gas.

[van avery]

You need to have the 2 left side pistons connected with a splitter for the vac. advance hose for it to run properly. Its okay to block off the right side completely, but for it to run right you need the 2 left connected to the advance.

I don't understand this. The original only has a vacuum post off #2 to the "Vacuum advance" the YICS chamblers does not interconnect between #1 and 2 Cylinders? Please explain? Also with this how are you connecting #1 and #2 cylinders together? Are you using the YICS ports instead of the regular port off the Carb on #2 ?

 

Marcarl, There was no restrictor in the vacuum line to the "Vacuum advance" line so I stole one off my 87 to see if it would help. Did not seem to make much difference. Is this just a very small hole to dampen the vacuum fluctuation. I did not see it listed as a part you can buy anymore ( at least on the site I was looking at Cycle parts warehouse).

 

 

 

It still will not hold a steady idle will set at around 1000 RPM's and it will be fine for a little while then, all be itself, will ramp up to around 2800 RPM. When I readjust it down it will hold a little while then may decay down and die. Reving it up with the throttle it seems fine but the RPM's seem like they drop slower than I would expect.

Checked the idle mix jet screws and they are all set at 1 and 3/4 turns out.

 

The vacuum is still around 4 to 5 inches when its running at 1000 Rpm shouldn't this be closer to 9 inches? But I do have them all in the same neighborhood.

 

Timgray, I do have spark on # 3 cylinder. It was almost out of gas so I added a a couple of quarts of fesh gas and about 1/2 can of B12 chemtool and will let it set overnite to see if that helps.

 

Thanks again for the ideas and advice. We'll keep trying.

[Prairiehammer]

It still will not hold a steady idle will set at around 1000 RPM's and it will be fine for a little while then, all be itself, will ramp up to around 2800 RPM. When I readjust it down it will hold a little while then may decay down and die. Reving it up with the throttle it seems fine but the RPM's seem like they drop slower than I would expect.

Checked the idle mix jet screws and they are all set at 1 and 3/4 turns out.

 

Sounds like a classic lean condition. I think you should enrichen the idle mix jet screws by turning them out to 2¼ turns or more.

[mraf]

Get that old gas out of there. The gas now is junk. Do the easy things first.

[frankd]

Yes, the normal vacuum @ 1000 RPM is little over 9" of mercury.

 

Frank D.

[van avery]

I readjusted the idle mix screws and it didn't seem make any difference the bike would hold idle for a short time then rev up all by itself.

The vacuum is somewhere alittle over 4 Inches at 1000 RPM.

I had a IgniTech aftermarket TCI that I purchased for another bike a couple years ago and since I had things that far open I replaced the TCI with the IgniTech TCI and plugged the vacuum port On #2 now she holds the idle.

Put the seat on and took it for a short ride and it seem to run well. I've got some other things to do before I dress her back up.

Thanks all for the help.

[KIC]

When I bought my 87 I finally got it running and it would idle then rev up to 8K RPM. i also had noticed that when starting it the throttle would "rock" back and forth.

 

I finally found that the previous owner had connected the front left cylinder vacuum hose to the cruise control Go figure... why...I guess I will never know ...but it isn't the only stupid thing he had done... the surprises just keep coming....