Hi,
I have a 1999 roadstar 1600V. This problem started off with an electrical issue of the bike running on 1.5 cylinders if you will intermittantly. I limped it home, checked the fuel. It appeared there was somewhat slight water in the tank. I dumped the tank, blew out with compressed air, replaced the fuel filter, drained the pump and cleaned the carb. I put it together and seemed ok until a week later. Same thing. I again cleaned out the entire fuel system, and when I fired it up, it would only run on one cylinder. I tested battery voltage, connections, pickup coil resistance, coil resistance, checked plugs etc. I replaced the pickup (cheap insurance and I have seen these fail intermittently). I also found some wires that rubbed together up by the CDI. I repaired those and fired it up. Still one cylinder. I checked for the signal from the cdi to the rear cylinder and no signal. I replaced the CDI and all good. - SO figured I had this beat- wiring harness touched, shorted out CDI, - fixed both problem solved. I rode most of the summer where it would intermittently suddenly run on one cylinder, then suddenly be fine again.... I got sick of this- I put in all new components- battery, stator, coils, wiring harness, voltage regulator)- (CDI was already replaced). I put 20 hours on the bike everything was flawless. Suddenly on the way to work- starts coughing and running like crap- unless I was on full throttle then it was fine again- I parked it and going to diagnose this morning. I will update the following shortly.

I have two questions-

where is the best place to buy spark plug caps? These measured apprx .8ohms- I doubt this is the problem but I will replace anyway- Yamaha wants $60 ea x4..... not paying that.

SVS syndrome- would this not be consistent every time it gets hot? Mine rides a long hard 10 hour ride no issues, then this happens. Ive had the bike get hot many times and no issues then suddenly an issue when we hit a bump- almost 100% electrical- sounds like wiring- but we have replaced all that- my original thought is new CDI (Dyna3000) has a loose or cold solder that glitches- I will replace this with another one again and update. Also, bike idles and runs great with current jets (do not know whats in it- bought it that way)- snap throttle and does not bog or hesitate- plugs look good- but can smell unburnt fuel at idle- seems fine but now paranoid about SVS- is there a link on easiest way to fix or prevent this without pulling the head?

Thanks
Tim

Don't be paranoid about SVS, with a 1600.

I think you're still fighting an electrical gremlin.

Maybe a coil wire shorting out on the frame or throttle cables?

It sounds like you're going thru the same issue that I recently had. After messing with the carb several times, I finally discovered a bad plug wire arcing at the coil. I pulled the bike in the garage where I could better see the arcing in the dark. I was sure it was fuel related, and my symptoms sound similar to yours.
I've taken the bike out a couple of times, and my issue seems to be fixed.

gonna have to do the wiggle test. Start it and start wiggling the harness until you get it to run bad and if you can't it may not be electrical. Although it sounds like it is.

Unlikely that it is the cap resistors but you can remove them and replace with 2 ga stiff wire to check if it is. A few years back quite a few members did that as a mod so they would never have to be concerned with getting a bad resistor.

Good idea Dave thanks for the idea- tomorrow here's what I'm going to do:
-drain fuel bowl into a clean container and inspect fuel- run fuel from tank and inspect to ensure its not obvious water though doubtful.
-check battery voltage not running- ensure I have proper base voltage
-check voltage running- ensure reg and stator are working properly
-I've checked it running in the dark to look for arking etc- none found- but I will pull the tank and reinspect all wires and coils etc for obvious shorts- though both coils and wires are new. If it was a bad resistor cap- even if I had one out of two plugs on that cylinder firing it should still not misfire correct? (maybe weaker but not dead)
-pull CDI plug ins and inspect for oil- I will try another CDI I have just to rule it out
-putting new plugs in it as cheap insurance- I've had faulty new parts before- so I'm not ruling anything out
-I'll run it that way and see what happens- also do a ohm meter test on my pickup- but this is single phase- it should work on both cylinders or none- correct? if it works on one its not the issue.
-My other questions are - ignition switch, kill switch, kickstand switch- can these possibly intermittently short out? Obviously they can, unlikely though- but at this point I have to consider all- its killing my riding season and I've had 4 mechanics look at it and not be able to get to the route of the problem.

One last question- SVS- what years were bad for these? What is the solution without disassembling the head? I agree I do not believe this is the issue but just for my knowledge.

Also, what is the best source for buying spark plug caps etc? I've tried ebay- still looking for more sources.

Thanks for the help people- much appreciated.
Tim

SVS, is typically an early 1700 issue. I think the real problems with the tolerance issues for the valve guide was primarily 2005ish. However, with stock jetting on the 1700's and putt- ing around, others have had some problems.
As far as I know, nobody with a 1600 has ever had a problem with SVS, unless they had their jetting so far out of wack, they brought it on themselves.

Hi,
So here is an update and hopefully some useful information to help others in diagnosis. I learned the issue was not fuel related. I had lean jets in for my mod (35pj/165mj) and ordered in the baron kit, installed various jets, played with needle and seat, even bought a second carb. I pulled my intake and checked for leaks and resealed. wasn't intake either (this was also supported by using an infered gun to measure cylinder temps which leads me to my next discovery. Coming from the liquid cooled engine side, anything over 190-200F is TOO HOT! I measured my cylinder head temps and jugs and I was seeing 235-285 which made me panic. I made the assumption it was running too lean- and when I pulled the plugs it confirmed this. HOWEVER LET ME CONFIRM an air cooled engine may run up to 300 degrees F and this is normal. From measuring other bikes on my trip I realized there was no need for concern. No one I asked could confirm this when I reached for advise. This further more provides confirmation synthetic oil in summer months is a good idea as petroleum breakds down after 250 degrees. I was chasing carberation the entire trip. Turns out I finally had a cylinder drop out 100%- I checked for voltage at the coils- 12 volts present. Grounds were good. Replaced that coil as a long shot (and happened to have a spare)- fired it up and it ran like a champ the rest of the day- until the next morning - back to square 1..... so a couple more things I learned. Something is causing my coil to short out prematurely- it has to be on the ground side as it is just that coil- power side would effect both coils- Second, take coil temps with infared gun and compare- is one hotter? If so it is likely shorting. Third, I've checked all my resistor caps and they seem ok- however I highly suspect one is faulty when hot which is slowly taking out the coil..... with two spark plugs per coil, if I have 1 out of 2 firing it would give me that weak cylinder and an occasional miss as the coil intermittently failed. Also, when I pull my choke out it runs better- I can explain this too- there are two things that increase resistance for a spark to jump a gap- leaner mixture and higher compression. The spark will appear crisp and blue when you inspect it with the plug out of the bike- BUT add compression and a lean mixture a weak electronic system will show up- richen the mixture and there is now more fuel molecules for the spark to jump the gap..... I haven't found all my demons yet- but I'm narrowing it down. I am in the process of installing dyna coils (however I've found you still need to use resistor caps or it will burn out the cdi- so I've ordered some in- my wires are not solid copper core though- not sure if I need to get some so I don't burn out my coils?? I've looked this up but cannot find specfic info- anyone with this knowledge please PM me. Anyway, I hope this helps people and I plan to write an article when I get this issue 100% solved- thank you all for your help along the way.