Power loss

[motoman]

I've checked and cleaned the primary AND secondary ignition to the point there's nothing to check anymore and nothing had changed. I started leaning out the fuel out and it started getting better.

I fail to see what's so confusing other than why the engine is asking for LESS fuel. A wrinkle in the time space continuum?

Don't you just hate those time space continiums.............especially doing a ''lazy' shift.

[trbig]

No Harry, it started before the pods. I switched to the pods because I've been pulling the carbs so much trying to cure the issue and they are easier to deal with.

I pulled a set of 127.5 jets out of an oddball set of Mikuni carbs I have in the pile-o-parts. I have no idea what they are off of but they have the same style jets. I'll install those and see how it is and if it's too lean I'll start drilling these until I get where I need to be and buy a set that drill size.

My friend Ken here in Tulsa (can't remember his site name) is having a very similar problem with his 80G. I'm starting to think it's a gas supply issue. As in gas station supply.

Didn't those 79s come with 110 mains on the outside cylinders and 120s on the two inside?

[Bigfoot]

I thought that was the 80's Tod. Seem to recall my midnight special having that jetting.

[IanDMacDonald]

Didn't those 79s come with 110 mains on the outside cylinders and 120s on the two inside?

Yeah, Harry is right, even though I used to assume Specials were different carbs. I do believe the needle jets are different from #2/3, and #1/4. But, the SF carbs should be 137.5 on the main's, and 42 on the pilot.

[BA80]

Didn't those 79s come with 110 mains on the outside cylinders and 120s on the two inside?

137.5 all across

I thought that was the 80's Tod. Seem to recall my midnight special having that jetting.

Yup, the main jets dropped in size to 110/120 in the later carbs, XJs went to a 112.5 all across

Yeah, Harry is right, even though I used to assume Specials were different carbs. I do believe the needle jets are different from #2/3, and #1/4. But, the SF carbs should be 137.5 on the main's, and 42 on the pilot.

Yes, my carbs have needle lets with less air holes in the center. The pilot jets are 42.5 78 -80, 81 went down to a 40, then the XJ went up to a 47.5.

[XJOK2PLAY]

Greg,
The only fuel-related changes I know that occur twice per year at refineries is summer blend / winter blend.

But I'd think if it was a gas station fuel issue change, you'd see a difference with all the different stations you've bought fuel at since this started happening...

Usually if carbs are rich enough to the point they cause a performance issue at certain throttle / load situations, you'll see black smoke out the exhaust when it occurs. But I don't remember riding behind you much on the trip, so didn't notice that.

Bog down is usually fuel related.
Stutter under load acts like ignition.
Bad coils usually get worse as they get hotter, better cold.

Weak ignition would probably want a leaner mixture, wouldn't it?

Sounds like you've tried everything short of swapping coils...
With all the carb swaps, jet swaps, etc., it's the only explanation I can think of why it runs better if you lean it.

[BA80]

Read back through the thread Bob, I've changed coils 3 times. I've changed a LOT of stuff one thing at a time with not a lot of success.

[BA80]

Just tried it with 127.5 mains.

The stutter at WOT in low gear is still there but not near as violent.

WOT in high gear it accelerates smooth up to 85 - 90 then starts to gurgle again.

An improvement but still seems not lean enough. Soon I'll be down to 110's or 120's like the late carbs.

[mikubuilder]

So, I've been following this post because my bike all of the sudden started to have same symptoms. Do you have any definite conclusion as to why the bike is behaving the way it is, or are still in the hypothesis stage?

At first I thought it was electrical, because the symptoms would show up and "fix " itself randomly, but I'm leaning towards fuel starvation now.... My guess is the petcocks or inline filters clogged up.

That's my .02

[BA80]

Mine is all of a sudden rich. Go back and read all my posts and you'll see what I've done. I'm now at 127.5 mains, that's 10 steps DOWN from the 137.5 stock jets for the 79 F engine I'm running.


Here's the plugs L to R after a hard run of about 8 miles with the smaller jets.

[dbeardslee]

Mine is all of a sudden rich. Go back and read all my posts and you'll see what I've done. I'm now at 127.5 mains, that's 10 steps DOWN from the 137.5 stock jets for the 79 F engine I'm running.

4 steps down - 2.5 for each jet size. That's still a lot, though.

[ViperRon]

Food for thought My bike was running fine good color on plugs good start etc etc but I had for the longest time been getting E0 from a station down the road. Needed gas today and did not want to go the extra distance the opposite way of travel so I go premium gas at Sheets. Now Idle is off an intermittent gurgle and stumble on acceleration and the gas smells more like fuel oil or diesel than gas. And guess what my plugs look a lot like yours now Greg. Me I'm sure its bad gas. New blend of winter crap!!!!!!

[BA80]

New blend of winter crap!!!!!!

That's the direction I'm starting to lean also Ron but in years past I haven't experienced this.

Just finished taking another run on the same course with the filters removed.

The low gear stutter almost gone and I couldn't get it to gurgle in high gear.

Definitely still on the rich side.

[BA80]

4 steps down - 2.5 for each jet size. That's still a lot, though.

I was counting each .1 mm but I suppose you are right.

[dbeardslee]

That's the direction I'm starting to lean also Ron but in years past I haven't experienced this.

Just finished taking another run on the same course with the filters removed.

The low gear stutter almost gone and I couldn't get it to gurgle in high gear.

Definitely still on the rich side.

If you think it's the gas, here's a little something for you to try. Mix 1-1.5 oz of acetone to five gallons of gas. It will break the surface tension on the gas and make it atomize better. I always run it in Betsy, as well as my lawn mower and chipper. I really notice the difference with the chipper. Without acetone it will bog down on big branches, but with acetone it chews right through them.

Some people will say, OMG! It'll eat the plastic and rubber parts in your fuel system! Which is BS. I've been running it for years without any deterioration of fuel system components. At such a low mixture I don't see it as a risk. But you don't want more than a max of 1.5 oz to 5 gallons of gas. At higher mix rates you start to loose the benefits - one of which is better gas mileage in some cases.