XSively Frustrating

[James England]

I'd replace the coils.... even if you haver to borrow a set from someone... a fellow XSive with some spares? The Mixe'sXS coils all sound like junk to me.You really do get what you pay for.

This may even be a combination of factors....the worst kind of glitch, IMO.

1. Junk coils/leads/HT caps
2. Bad split/hole in diaphragms
3. Unchecked float levels
4. Non-removed float needles/hemisphere filters

I would therefore:

1. Borrow some known good coils and try them out. Same with caps/leads
2. Replace the diaphragms with new or, again, borrow some if required
3. Check float levels on all four carbs
4. Do a 100% complete carb strip and clean...removing everything except the butterflies or splitting the bank of carbs.

[BA80]

All good suggestions James but the only one there I see that could possibly cause loss of vacuum is diaphragms. I do agree that it could be a combination of malfunctions though.

[DGXSER]

At Idle, in gear or in neutral it barely misses every now and then. As soon as you put it under load though, it sputters horribly. I di not notice anything on the carbs, but will give them a thorough inspection. As it does nto seem to be cylinder specific, I am trying the coils first. Swap mine for his to see if it changes. I agree on replacing the diaphrams, but it is not my budget being spent. As to the float levels, while I agree I should have checked them, I would be surprised to find they changed from there last setting. The float needles and screens I would also not suspect as it has plenty fuel on the top end.

But all good ideas, one step at a time. Eliminate what it is not till you get to what it is, in an educated fashion anyway.

[BA80]

Two more thoughts Don.

First, disconnect the vacuum advance and see if that makes a difference with the sputter. I know you said you checked the pickups but it wouldn't be the first time something was missed.

Second, if you have a known good rack of carbs you can throw on there for a test do it. That will either comfirm or eliminate a carb problem.

[Rickrod3]

At Idle, in gear or in neutral it barely misses every now and then. As soon as you put it under load though, it sputters horribly. I di not notice anything on the carbs, but will give them a thorough inspection. As it does nto seem to be cylinder specific, I am trying the coils first. Swap mine for his to see if it changes. I agree on replacing the diaphrams, but it is not my budget being spent. As to the float levels, while I agree I should have checked them, I would be surprised to find they changed from there last setting. The float needles and screens I would also not suspect as it has plenty fuel on the top end.

But all good ideas, one step at a time. Eliminate what it is not till you get to what it is, in an educated fashion anyway.

If your pulling the carbs and want to check the diaphram lift the piston cover the top oval hole on the back of the carb to see if the diaphram is working.
Problem under load could be the diaphram.
Good luck narrowing it down sounds like a pita.

[James England]

the only one there I see that could possibly cause loss of vacuum is diaphragms.

Did he say there actually was lack of vacuum then? I missed that bit. Has that been diagnosed as the cause of the misfire?

[motoman]

Two more thoughts Don.

First, disconnect the vacuum advance and see if that makes a difference with the sputter. I know you said you checked the pickups but it wouldn't be the first time something was missed.

Second, if you have a known good rack of carbs you can throw on there for a test do it. That will either comfirm or eliminate a carb problem.

+1 on that first statement. As you know, under load, timing advances. With that slight rotation of the advance plate, the odds of STILL having an internally broken pick-up coil wire is still better than average.

[BA80]

Wokring on another memebrs bike, issue is a low end miss. Idles nice with an occasional pop or sputter but over all smooth idle. Synchs up nicely, but as it is idling every now and then all four will drop off to about nothing on the Carbtune.
Running about 2k turn the throttle and it starts missing, more throttle you give it the more it misses. Adding choke does not help. As it gets up to maybe 3k or so it seems to lessen the miss, but may just be running faster so it is less noticable.

So far, we tried colortuning, synching, no change. Checked the pick-up coils, when I tugged on the white wire of the lower coil the bike died. So we swapped pick-up coils with a known good set. Now the coil wires have no effect, but it still has the same miss.

So we pulled the carbs off. I found one diaphram had a pin hole which I put RTV over, I found another where about half the seam where the main diaphram meets the lip was able to see through it, RTVd it also. Also noted the diaphram in no 4 was soaked with gas, like it dripped off of it. And that no 4 mix screw was black at the tip.

Checked the pilot jet, main jet emulsion tubes all looked fine. Still the same mis under load in low RPM.

Any suggestions are welcomed.

First post James....

[James England]

First post James....

Carbtune?? I've not heard of one of those....does it mean vacuum gauges?

[BA80]

Carbtune?? I've not heard of one of those....does it mean vacuum gauges?

http://www.carbtune.co.uk/

[James England]

Blimey, and it's made here in the UK too. I use dial type vacuum gauiges but this looks like a good bit of kit. Is it any good then? It looks realtively inexpensive

I like the look of this.....http://www.carbtune.co.uk/fibrescope.html

[natemoen]

Really! No one over there talked about that thing?! It is absolutely worth the $100! Amazingly simple and accurate!

[DGXSER]

Blimey, and it's made here in the UK too. I use dial type vacuum gauiges but this looks like a good bit of kit. Is it any good then? It looks realtively inexpensive

I like the look of this.....http://www.carbtune.co.uk/fibrescope.html

James, I can tell you that I am a world class cheapazz. I was content and happy with using my mity-vac attached to a PVC plenum moving the vac hose carb to carb to synch for years. Well, I finally ponied up for that Carbtune tool and I have to say, I love it. It has reduced my time and I do admit increased the accuracy of my synchs as well. (I still say my old way was good enough for an average street rider, but I do see and hear a difference.)

As to the boroscope, looks pretty nice. One piece of advice, if you stick the probe in a hot engine cylinder for peaking around, that end will get hot. Just a friendly word of advice.

[Yard Dogg]

I used that closed loop set up with the clear vacuum lines and oil in em. In theory it should work right? I had trouble though cause one of my pilot jet holes didn't seal too well, and I probably needed to set my valves too.

[WMarshy]

Sorry in advance b/c I have not read all the replies but, your issues sounds suspiciously similar to another members that I recall reading about... Long story short, he discovered he had a crack in the body of a carb and when the carb got heated up the carb would lean out and cause an intermittent misfire. Examine your carb bodies very closely... good luck.