Time to replace the coil packs?

OK I think I got it now...  Went out for a short ride around town today, and it was running nice and smooth when I left, but after about 15 minutes it got so bad that one cylinder was completely missing and I had zero power taking off from a light.  When I got home I was finally able to see the issue... all four of the front boots between the carbs and engine are cracking or split near the engine-side screws.  The heat made the rubber curl back enough to see it.  I only hear a real problem on the left side, so I must just be getting lucky that the splits on the right side are still somewhat sealed.  Hopefully that's the whole issue, and I'll get some new boots ordered tonight.

MEANWHILE... ugh that damn clutch cable popped off again.  This time I was about a mile away from home but somehow it was still giving just enough resistance to keep me going slowly down the street, so I was able to hobble back home.  This one is driving me nuts!  I tore it all down yesterday and cleaned things up.  The original cable was not actually broken, but that end crimped piece on the cable had popped out of the bracket down at the bottom/engine side.  Same thing happened again today.  The only thing I can think of is that the bracket opened up some where the cable slot is at, so maybe once I put the cable back in I can just squeeze it down with the channel-locks.

Has anyone else seen this before?  Am I on the right track or is there another solution I should be looking at?  The crimp fitting on the original cable looked fine when comparing it to the new cable, there's no indication that it got reduced in size like it had forced its way through the end whole of the clutch bracket.  Maybe if I squeeze the bracket down I can also get a zip-tie to wrap around the whole bracket to help keep it from opening up again (assuming I'm on the right track here)?  What do you think?

Oh I should also mention, the cable itself is still covered in grease, and when I put it back together the clutch level on the handlebars moved smoothly and had the tension I expected.  I did add a little new grease to both sides of the bearing plate.

bound wrote:

Did anyone ever mention checking for air leaks? On my 550 when I had an air leak it had very similar symptoms. It would heat up then it would start revving up then when I tried to lower the idle the rpms would just plummet and barely idle. Popping and backfiring are symptoms of running lean. If you have propane laying around you could check that way by spraying it around the carb holders. Sometimes you can even hear it.

 

I did call this out earlier but it must've gotten buried. I do imagine the the carb holders are one of the underlying issues with your build. Im glad you finally found it though! For the clutch cable - Is the bracket that holds the cable in place damaged or bent? There should be a spring and a cotter pin to hold in the clutch at the engine. If that cotter pin is missing that is probably your problem. 

Yeah no worries, a vacuum leak has been mentioned several times and I've been trying to figure out where the problem might have been but I just wasn't seeing anything.  And this is like the first time in forever that I didn't have carb cleaner or something sitting on the shelf to spray around and try to narrow down the search.

And wow... I am missing both the cotter pin and the spring!  The spring does sound familiar but I don't remember ever having a cotter pin there.  Where is it supposed to go?  I didn't see a hole through the end of the cable, is it maybe supposed to thread around either side of the cable?  I can grab another spring from the hardware store, I don't suppose you happen to have a reference for the diameter or length?

The spring is 55mm x 10mm with about 12 windings and here is a picture of how its supposed to look. 

Awesome, thanks!  I couldn't find any dimensional information last night on this but I figured it needed to be just large enough for that slug on the end of the cable to pass through.  And nw I see how the cotter pin is supposed to works, makes a lot more sense about how it keeps the cable from falling out again.  I honestly don't remember ever having a cotter pin there from the original build, I wonder if the spring tension is all that's been holding it in place all these years?

Well at least that's a pretty easy fix.  I hate the idea of having to remove the carbs once again, but crossing my fingers the new boots solve the vacuum leak.  Still some time for riding around town to test it out although there is a lot of rain in the forecast this week.  Ideally I have time to get out on the highway to work out any tuning issues so it's ready to go next year.

I wrenched my back Saturday evening so I'm just finally getting back to this...

OK this seems like a worse problem now... I took the assembly apart again over lunch and found that the cable is actually still in place this time, however it looks like the plate jumped over the bearings to the next position.  The photo above seems to show the position the level was in when I opened it, however I have to roll mine back clockwise for the cable length to correctly fit to the clutch lever on the handlebars, with the center adjuster a little over half way expanded.  That's just where it has always been so I didn't think much of it?  After re-assembling everything the clutch lever feels good again, I just don't know if that little spring will be enough to prevent it from going too far once more.  Maybe I need to leave a little slack in the clutch so it doesn't pull the cable as far?

So far leaving the cable a little looser seems to be working.  I've done a couple of 15-20 minute loops staying close to home and it hasn't slipped again.  Feels like it fully disengages when I pull in the lever.  The new carb boots don't arrive until Thursday, but if I keep it down to a 15-minute ride then it keeps running OK with only minimal popping.

And I'm definitely liking how it is running so far.  Cold starts are pretty easy, I haven't had to choke it more than the middle notch.  Idling is smooth (at least until the engine really heats up) and it isn't trying to die on me when I stop (something I constantly fought with).  One of these days I'll get it out on the highway so I can open it up and see if it goes lean  I'm starting to get more confident that I'll be able to get it running well before putting it away for the season.

The new carb boots arrived yesterday.  Working from home today so I pulled everything apart at lunch.  Got the new boots bolted in place before I ran out of time, so I just need to get the carbs back in and throw the gas tank back on.

And yeah, there was a bit of cracking in the old boots... like a couple of them were splitting 1/4 of the way around.  Don't ask me how I didn't see that before.  New ones are nice and soft so the carbs should go back in a bit easier.

Got that wrapped up and took it for for a test ride... and things are very different.  The idle is smooth through all temperatures now, definitely a big improvement with that.  I was out for about 45-50 minutes so it had plenty of time to get hot.  Also no trouble with the clutch, crossing my fingers that the spring made all the difference but we'll see.  Here's the really curious thing -- the exhaust is very "throaty" now.  Like it sounds like a big engine.  I've never heard it like that before.  Oh and a very nice change, I didn't come back smelling like gas exhaust, so yeah it was definitely running way too rich before.

OK so here's the issues... First off, I'm still getting some minor exhaust popping at low speeds (probably up to around 2000rpm?).  Very much reduced from what it was doing before, but it's still there so I'll have to see if I can find something to check for any further intake leaks.  And it's still really weak at low RPMs and off the line, not really lurching but it's close to it?  Not sure what to look for there.  On the other hand, it was doing well enough that I did a quick jog down the highway, and wow -- when it hits around 5000rpm it finds its legs and has got a LOT of power.

My big problem is that I built this bike up from parts.  I have never ridden one that was well-tuned, I don't know what it's supposed to sound like or how it's supposed to respond.  It makes it really hard when I have no reference for comparison, so I don't know if I'm chasing actual tuning problems or if I'm just getting closer to how it's really supposed to perform, so if I put out a comment here about something that seems normal, please also let me know that?  (And if I should start a new thread about any particular issue, give me a nudge).

And thanks to everyone for all the help!

Im having the same issues about popping except mine does it at idle... that means you're running lean at on your pilot circuit. It could be that your pilot circuit is clogged or your fuel mixture screws aren't set correctly. Maybe even a carb sync issue. You'll have to take a look at it.

Ah yes, the mixture screws are still set at the original 2 turns each.  I was having trouble getting good readings before so I just returned them all to that spot and left it.  Thanks for the reminder, I'll try to check those again when I get back this afternoon.  I also forgot to mention above that this is now happening on both sides rather than just the left, so it's most certainly a possibility.  Could also explain the stumbling at low RPM.

OK I think you might be right about the idle circuit being clogged or frozen.  The mixture screws don't seem to be doing anything at all.  I dumped some seafoam in the tank and just went riding for a couple hours, not sure if that'll clean things out or not but figured it couldn't hurt.

Otherwise the idle speed is still stable, I have it sitting around 1000-1100rpm.  I didn't notice any more of the popping today so maybe it just had some garbage in the system that needed blown out, but that low throaty sound *really* echoes through the helmet.  I did think to check this time, and that sound is all coming from the back of the pipes, not from the front of the engine.

Not sure what else to check, just happy to be back on the road again even though it'll only be for a short time.