I need some help folks

[Squidley]

We are working on one of the members RSTD's here at Houstons MD. We have an '05 TD that has zero vacuum when we tried to carbsync it. The right side of the bike warms up pipes get hot. The left side is VERY slow to warm up. We took the carbs off, set floats, checked jets and the whole 9 yards. I know about checking for a massive vacuum leak, we have checked all I know to check.

 

I understand that vacuum is created on the intake stroke of the piston and all that. I am totally at a loss for why we dont have vacuum. my brain is somewhat fried rigt now from 11 hours of MD, if any of y'all have some words of wisdoms or had this happen to you, what did you do to correct this issue. Thanks in advance for any help you can give.

[Marcarl]

Try resetting the butterflies to '0'. Could be that only some are working and the others are too far open,,, I know, it's crazy, but crazy happens.

[eusa1]

Seen the t/p sensor damaged or misaligned keeping things from opening properly , after carbs were removed from the rail.??

[MiCarl]

Try resetting the butterflies to '0'. Could be that only some are working and the others are too far open,,, I know, it's crazy, but crazy happens.

 

That does happen.

 

Bottom line, the vacuum problem is because some cylinders aren't pulling their weight. Possible causes:

 

- Way out of sync as Marcarl says. If you don't want to pull the carbs back off you can pull the slides out and airboxes off. Have a look down the throats (throttle closed) and the butterflies should at least look the same. If you can see any difference they are WAY off.

 

- Carburetor mixtures off

 

- Ignition problem (plugs, wires, igniter). Fuel fouled plugs may spark outside the engine but will no in the cylinder. New plugs is a cheap test.

 

- Major mechanical problem (valves, rings etc.)

[footsie]

Have you checked the compression, on that side.

[BlueVenture87]

Clogged exhaust? I had pickup that wouldn't breath. It had a bad catalytic converter.

 

Best!

 

--JK

[Venturous Randy]

Are you saying it has zero vacuum on all the cylinders?

RandyA

[Squidley]

Are you saying it has zero vacuum on all the cylinders?

RandyA

 

YES

I'll fill in some of the blanks, at idle rpms, there is no vacuum on the carbtune. When I tried to set the sync at a high rpm (about 3000) I would not get much vacuum, but got some. We did pull the rear plugs and both sides sparked with the plugs that were in them when they were outside of the cylinders.

We actually did make some headway, when Mark rode in he had to run with the choke on or the bike just wouldn't run. It also would die when you gave it throttle. When he left tonight it would run without the choke on and he could give it throttle and it not die, so we made some headway. I fought with it for 30 minutes at high rpm with the carbtune and got somewhat close to a sync, but with very low vacuum.

We are going back tomorrow and play a bit more. I am going to do a compression test on the cylinders. I will also run through y'alls suggestions and try to get this figured out. I usually don't get stumped on these bikes, but this one has me scratching my head

Thanks for all your help

[BradT]

My bet is on the carbs, need be to be torn apart and need a little cleaning and setting up.

 

Brad

[crowrod]

was a valve adjustment done on the bike? may be a valve stuck open from wrong size shim?

[Eddie]

was a valve adjustment done on the bike? may be a valve stuck open from wrong size shim?

 

This is also my guess , I would do a compression test for sure

[Trader]

Exactly the same as what I had on my bike in the fall of 2011

Ever since I got it, It would only idle when choke was on.

MarCarl was helping me with it and we did a complete on-the-bike carb clean.

 

When we went to set it up after, we couldn't get any vacuum at idle to sync carbs.

 

 

I can't remember for sure....but I thought it was Squid that Carl called with the problem....maybe it was Dingy.

 

Anyway...if I remember right... we got a reasonable sync at higher rev's and got me back on the road.

 

I've been seafoaming it regularly since and it runs just fine!

I bought a carb tune and am going to do it again soon.

[StarFan]

Squidley.

 

Check if both the springs that are in the synchronizing screw mechanism are in place. Have once lost one of these and that made the bike act pretty much the same to your description. Cold cylinder and running like cr#p. Took me days to figure that one out . If you have a missing spring then make sure to put it in the right side of the plate - don´t ask me how I know

Picture attached.

 

Wish you luck - you will figure this out I am sure.

 

Friendly regards from Iceland,

 

Jonas

[Condor]

Give this a shot. Try backing off the sync screws on the right side. Even the balance. Then back off the #1 screw on the left. Set the idle to 1000rpm using #2. Should run crappy, but it'll run. Turn in the #1 screw until the idle picks up a tad by ear and back it off a tad. Hook up the carbtune. Balance 2&1. They should be close. Balance carbs 4 and 3 on the right hand side.. It'll start running better and the idle rpm will start to increase. Bring it back down to 1000 as needed. It may even backfire and fart as 3 and 4 balance. Once 3&4 are in balance balance them with 1&2. Should be good to go with a more responsive throttle...

[gunboat]

I was not there until late Saturday but I don't belive a valve adjustment was done on his bike.

regards

don c.

[crowrod]

does carbtune have restrickers in the lines if so maybe they got turned or plugged did you check with another carbtune?

[Kirby]

You've probably already done this but swap the lines to the carbtune and try again, just to be sure it isn't the gage.

[Gary N.]

Any updates on this problem?

[Squidley]

Ok...here we go

I had written out a nice detailed post and then the site timed me out, so I lost it all. Before I took a hammer to my computer , I turned it all off and walked away for the night

This is what we did,

Compression test, all 4 cylinders are great 200 lbs so that takes out the valves and rings from the issue.

Performed the test for the Throttle position sensor, if I read it right, which I believe I did, we are within the parameters that the manual specifies. So that's another thing to not interfere.

While we did the compression test, we installed new plugs. Mind you none of what we did had a difference. We took off the mufflers to insure they weren't blocked, no change and still no vacuum.

I know others had mentioned about insuring the carbtune was working properly. We tried it with 2 different ones that had been used earlier in the day to sync other bikes.

I believe that this is a carb issue, perhaps the butterflies are total out of whack and I couldn't get them right without taking the carbs back off. I'm also leaning towards the idle circuit in the carbs could be clogged up, the bike runs fair under acceleration and at cruising RPM's in the 2500 to 4K range.

I'm gonna have Mark bring it to my place and he can crash over here for the night. We'll strip the carbs off and completely go through them. Let them soak over night to really clean them and rebuild them. Then I can look at the butterflies and bench set them before we install them again so it will be closer to set with the carbtune.

So that's it in a nutshell right now, more to come, and Mark did make it home

[Marcarl]

before you go gung ho on us, think about it. The engine is basically a vacuum pump, or a pressure pump, depending on the end of the engine you are at. So in this case we have a vacuum pump and you say the the compression is fine so it's drawing vacuum, it's just that you don't seem to be able to measure it,,,, the carb would have very little to do with that, it's going to draw vacuum regardless of even if the carb is there or not. So what can have a profound effect on the vacuum measure???? the butterflies, seeing as they are the ones that close off or open up the port that makes the vacuum. In the process of measuring vacuum, we need to be on the vacuum side of the butterflies, hence below them, and I would suppose you checked that out, so you must have airflow, but it's not restricted by the butterflies to make vacuum, so they are open.

If even one butterfly is off too far, it can cause the others to remain open and hence have no restriction and then no vacuum. So, hook it up again and this time do things in reverse so to speak. Start with the cylinder that has vacuum and open it up until it loses it vacuum, then go to the next cylinder and pull the same trick. My guess is that by now you will be able to carry on as though you knew what you were doing.

This is all theory on my part, and I'm not re-reading it for the fear that I'll become all confused, so hopefully you find it interesting.

[MiCarl]

Carl,

 

If the carbs aren't working properly the butterflies will be too far open for the load and RPM. With the butterflies too far open more air gets in and the vacuum decreases.

 

I'd have suggested this as the first thing but got the impression from the original post that the carbs had been cleaned. Sounds like everything else has been ruled out.

[wes0778]

before you go gung ho on us, think about it. The engine is basically a vacuum pump, or a pressure pump, depending on the end of the engine you are at. So in this case we have a vacuum pump and you say the the compression is fine so it's drawing vacuum, it's just that you don't seem to be able to measure it,,,, the carb would have very little to do with that, it's going to draw vacuum regardless of even if the carb is there or not. So what can have a profound effect on the vacuum measure???? the butterflies, seeing as they are the ones that close off or open up the port that makes the vacuum. In the process of measuring vacuum, we need to be on the vacuum side of the butterflies, hence below them, and I would suppose you checked that out, so you must have airflow, but it's not restricted by the butterflies to make vacuum, so they are open.

If even one butterfly is off too far, it can cause the others to remain open and hence have no restriction and then no vacuum. So, hook it up again and this time do things in reverse so to speak. Start with the cylinder that has vacuum and open it up until it loses it vacuum, then go to the next cylinder and pull the same trick. My guess is that by now you will be able to carry on as though you knew what you were doing.

This is all theory on my part, and I'm not re-reading it for the fear that I'll become all confused, so hopefully you find it interesting.

Carl, I think we are basically on the same page. The theory on which we are working now is that since the bike has been sitting up for a good time the idle circuit is completely plugged and the butterflies are open wide enough the the engine is "idling" on the high speed circuit, thus not enough restriction to show manifold pressure (vacuum).

During the whole "endeavor" no one thought check the butterfly angles to see if they were completely closed.

The saga will continue later..... (wish I could be there!)

[Squeeze]

and the Vaccum Port in the Manifolds are clear and open ?

[Squidley]

and the Vaccum Port in the Manifolds are clear and open ?

 

It's funny you mention that Lutz, I had never thought twice about intake manifolds until this bike. All the bikes I have ever carb synced had wide open tubes on the intake manifolds. These did not, and 2 other bikes at MD didn't either. They had VERY tiny holes in what can be best described as caps over the tubes. I have don't literally hundreds of carb syncs and I never recall seeing tiny pin holes like these ones. They were clear, as I took a torch cleaning tip in all of them and they were clear.