Help! Put in new diaphragms - dies at idle

[tz89]

I put in a new set of diaphragms. Had to trim the tabs a bit to get them all to seat right. Ended up pulling the covers twice to reseat them. Two pulled loose the first time, one the second.

 

Sprayed Seaform in everything from the top and side.

 

I've had it out for a ride. It runs fine (well a little rough) at speed.

 

At idle it promptly dies. If I give it full choke it will run somewhat.

 

Is there something I could have messed up (well sure) that would starve the idle? Did spraying seafoam into every hole do something I wish I hadn't? Or something else?

 

Thanks!

Edited August 23, 2014 by tz89

[KIC]

Did you re-sync the carbs ? you might have corrected something and now the idle adjustment might need adjusting and he carbs synced together.That is where I would start. I had to re-sync mine after new diaphragms.

 

Just a thought

[tz89]

No I haven't resynced yet. I had one pinhole in each of two diaphragms. The other two looked fine. I will sync when my brother sends my gizmo back, but this seems a too dramatic problem to be a sync/idle problem, but I'm no expert.

 

I also put on new port caps - though that should not be a problem. Just in case I swapped them out - nope - couldn't be that easy twice.

Edited August 23, 2014 by tz89

[Snaggletooth]

I have to ask....... did you use the Sirus OEM style replacement diaphragms that seat between the plastic washers on the slide or use an aftermarket diaphragm that required the removal/modification of the washers on the slide?

 

If the bike is dieing I'd have to suspect the Sirus set has one or more that is not seated properly inside the washers and probably rolling off the mounting point. If the Sirus ones don't get seated between and well inside the washers they will not work properly.

 

Either type would benefit from a sync after making sure all four are seated well.

 

I only had to make a minor sync adjustment after the new Sirus set and barely a tweek in the year since.

[tz89]

I used the Sirus OEM style. I used a credit card to push them between. But I don't know how to tell if I got them "right".

 

What do you mean rolling off the mounting point. I'm pretty sure the outside diameter is seated. But what I think you are saying is that if the inside diameter is not set right it will pull the outside loose.

Edited August 23, 2014 by tz89

[Snaggletooth]

If you don't see the thicker inner edge at the outside top of the washers you should be fine then. I've found a few that were "fixed' that were still at that point where they had not set inside the groove between the washers.

 

Putting them in is is pretty much an "eyeball" job. If they appear to be smoothly seated and no waves in the diaphragm body you should be fine.

 

Hopefully a sync should bring you back to where you want to be. Best of luck. You should be pleased with the performance when your finished.

[tz89]

Sounds like I will have to pull them in the morning to triple check.

 

Some kind of massive vacuum loss makes sense.

 

Thanks. BTW - love your signature slogan!

[Snaggletooth]

A poor seat on the slide won't pull the outside loose so you're fine there. If you pushed between the washers with a CC sounds like you took all the right steps.

 

(as long as you didn't tear the diaphragm off the inner sealing bead that goes between the washers.)

 

Odds are you're fine.

[Neil86]

Check for the small o ring that sits under the cover too.

[tz89]

Yes I was very careful with the o-ring. That's definitely in place although old.

[Snaggletooth]

And good morning Neil. Nice to see you around so much these days.

[MiCarl]

The holey diaphragms were adding extra air to the intake. Now the sync has changed and you're rich.

 

You need to tune the carbs for sure.

[tz89]

Will do. But I'm having a hard time understanding how a bike that was running well with 2 pin holes can't run at all with new diaphragms. There must be something else to this, imho.

 

Once that is fixed then yes a fresh sync. But I will check the mix screws to see if any had been set to an extreme.

 

I'm planning to reopen the carbs, blow out everything, reseat the diaphragms, check the mix.

 

No real way to check the sync if it won't run, is there?

 

Any other suggestions?

 

Thanks!

[Flyinfool]

Get it started and add throttle just enough to keep it running. Monitor the exhaust pipe temps to see if you can determine which cylinder(s) are not running at idle.

 

Did you remove any spark plug wires and forget to put them back on. I've seen it done.

[tz89]

Didn't pull the plugs but I'll double check. That would be a nice find.

 

I've got it opened up now, and in a few minutes will start at it.

 

Thanks!

[videoarizona]

I know.... I was checking my plug wires and found some corrosion on one wire. Cut it off and redid the connection. Thought I had it tight. Nope. Wire was not making contact inside the coil tower. Went through some lousy running issues until I took all the wires off and re-did them. Solved problem. Also solved one of my ignition noise issues in the audio!!

[tz89]

Fortunately plug wires were last month's project. I had diaphragms already so I couldn't leave well enough alone!

 

Anyway, two of them showed loose when I took off the covers this morning (for the 3rd time). I redid all 4 as best I can do.

 

I've checked marcarl's pics and others, but just to reconfirm, the ridge on the diaphragm fits down into the slot on the carb body - not out towards the cover. I would be embarrassed I have them in backwards.

 

I'm about to put the air box on and fire it up.

Edited August 23, 2014 by tz89

[tz89]

Whew. It starts. It runs. Now it needs a sync. That's a relief.

 

Thank you everyone. Best $12 ever.

[tz89]

Took it for a ride. I'm not done yet. It'll idle with the choke on a little. Definitely needs a sync. Maybe a mix adj. Then we'll see. Hope to get to all that in the next few days.

[frankd]

My bike idled great before I installed new diaphrams, but after I did it was way out of sync and sounded like it was going to self-destruct at idle. I checked the synchronization and it was way out. I synced it and it idled great again. The reason it sounded so bad is because on the strong cylinders, it would speed up, and on the weak ones it'd slow down, so all the play in everything was hammering back and forth. Sync it before you get too carried away.

 

Frank D.

[tz89]

Thanks. This is very encouraging. I haven't touched it yet - trying to get up for it - but this helps a lot. Now as soon as my brother sends my digital carb sync I'll get after it.

 

Here's the digital carb sync I speak of

http://www.venturerider.org/forum/showthread.php?t=73158

[tz89]

I forgot to close this off. Once the bike was synced it ran fine. Great even.

 

For my pre winter projects I've now put on a new K&N air filter (the old filter was looking nasty), all new diaphragms (2 had pinholes), all new carb port caps (at least one was leaking), and a new set of spark plug wires (one was corroded). Plus a sync.

 

Last nice days of fall riding here in Oregon. The bike is running strong. No wandering idle and no occasional missing.

 

Maybe I'll do the fuse box next although I have to figure out what the extra wires are for - I think they're for a hitch that never got installed by the PO.

Edited October 12, 2014 by tz89

[syscrusher]

You made it sound like someone's suggestion helped but didn't say which one?