Tempory Problem?

[missinglink]

I had an odd problem yesterday. While crusing home from work on the superslab, it suddenly felt like I was running on just 3 cylinders. Since I was doing 70+ I didn't reach down and grab the plug wire on #1 or #4 to check for spark. But I did pull the choke (oops, sorry), the enricher, out to the first detent and it smoothed out. I ran like this for a couple miles, pushed the enricher back in and everything was fine for the rest of the way home. Is this something that is going to come back to bite me at just the wrong time? This is on a 80G with about 48k on the clock. I've owned the bike since 1980 and all the miles are mine except for about 2k. The bike was resting for about 10 years in the garage and I put it back on the road last year. THANKS TO ALL THE GUYS AND INFORMATION ON THIS WEBSITE. I did all the standard stuff. Rebuilt the carbs, new seals on the forks, New SS brake lines, replaced fuse block, some new wires etc. I've put about 2000 miles on the beast since I resurected it last year. No problems up to now. I'm amazed how well it runs, still makes me grin.....
Could this just be a piece of dirt in a carb, stuck float (do they unstick) etc? I'm planning a trip up to upstate NY this summer and don't want to get stuck out in the middle of nowhere. And, Yes there are nowheres in NY.

[skids]

Re: Tempory Problem?

I have a bike that is like that and mine is due to fuel starvation. If I run 65-70mph it starts cutting out (sometimes) and if I turn the petcock to prime to fill the bowl, it immediately runs fine. I can usually turn the petcock back to "run" (standard) the rest of the ride. In your case, you used the enrichener to draw from the bottom of the bowls. I think the vacuum can drop at speen and as you let off the throttle the vacuum increases, opening the petcock valve more.

[missinglink]

Skids, Thanks for the idea.....One thing I have not done is rebuild those petcocks. I rarely (never) move them thinking I should let sleeping dogs lie. I'll get some rebuild kits and do that before my trip. I'm also toying with putting an inline filter in the line someplace. I was looking at some at Pep Boys and the package specifically said "not for use on motorcycles." Wonder why, how does the filter know its on a motorcycle instead of a car????

[Luxury]

Originally posted by missinglink
I was looking at some at Pep Boys and the package specifically said "not for use on motorcycles." Wonder why, how does the filter know its on a motorcycle instead of a car????

I've seen that warning and I figure those filters must have a tight mesh filter and/or not much surface area, so they may not allow enough fuel flow on bikes, since bikes rely solely on gravity feed (cars have pressurized fuel systems).

I use inlines intended for lawn mowers (got em at Farm and Fleet). BTW, for those of you who run aux shut-off valves to control leaking petcocks, lawn mower gas valves are small and cheap.

[Geezer]

I use VW bug fuel filters. The come with a step in the plastic so you can cut them off if you need to use them on a 6mm line, or leave them as is for use on a 5mm line.

I use them on all my bikes and several of the bikes I've worked on. I've never had a problem and at a buck fifty each, they're hard to beat.

Odds are you had an airbubble in the system. I wouldn't worry about it.

Geezer

[GNEPIG]

.. hey Geezer, any chance we can get a picture of your favorite inline filters?

..

[Geezer]

Just ask your local auto parts store for one.

Geezer

[missinglink]

OK, just ordered two rebuild kits from Old Bike Barn.... I'll try to find those VW filters. Somehow it don't seem right to put lawnmower parts on my beast....
Thanks for all the suggestions.

[skids]

Fram makes good in-line filters. They are metal and they are compact enough yet big enough not to have plugging problems.

Originally posted by missinglink
Somehow it don't seem right to put lawnmower parts on my beast....
Thanks for all the suggestions.

[missinglink]

Just wanted to post an update. I rebuilt the two petcocks, ran the fuel lines out of the petcocks into a tee, down to one of those Volkswagon filters, back to another tee and into the carbs. I syncronized the carbs with a mercury stix from JCwhitless, put everything together, and boy did she scream.

I ran her up to redline for the first time in a while with zero hesitation. Put a big grin on my face, (or was that a grimace from fear). I have no idea how fast I was going (stupid 85mph speedo) but the beast ran great. I think the biggest thing was the carb sync. I had done the twist tie method when I rebuilt the carbs but it was still off quite a bit according to the mercury stix. I can't wait to get some miles on to make sure everything holds.

Thanks again for all the help from you guys on this site.

[andreashweiss]

If you want to replace the 85 mph speedo let me know have gauge cluster for standard or just speedo for standard. 240kmp/160mph meaning the kilometres is bigger than miles but both very visible used parts but work fine. andreashweiss@yahoo.com

[missinglink]

Thanks for the offer on the speedo. I may do the change.
I put some miles on the bike today. Still runs like a scalded dog from 3k up to red line. Pulls the whole way up. It idles fine at about 1100rpms but when I give it some gas from idle or cruse around the neigborhood the engine seems like it hits a flat spot from 2k up to ~2500 rpms or so. Not bad but just a little stumble or roughness that wasn't there before (that I noticed anyway). I added some Seafoam to the gas (1oz/gal) when I had the tank off. Could that cause this? It could be the fuel filter rigg too I guess. I ran the fuel lines from the petcocks to a tee then down to a filter that I put in the little space behind the engine just above the rear break peddle stop. Then to another tee into the carbs. I had a little trouble getting the lines primed the first time but seems ok now. Could this be causing the hesitation? I guess I could take it back out but I that would be a pain.

Any ideas?

[TopCatGr58]

Hey Jim,

IF it'll run to redline, then your fuel routing isn't a problem. Also the SeaFoam shouldn't be causing any problems, it should actually clean out the carb passages to allow it to run better!

You said it's an 80G, rebuilt carbs and petcocks. I'm assuming you're still stock with pipes and airbox? Where did you set your pilot screws....1&1/4 turns out ?? OR...are yours still capped with the brass plugs?? You might want to try turning them 1/2 turn out, and then retesting it's response?

You've ridden your machine since '80, so I'm not going to tell you how to run it, but I'm amazed at the number of folks that want to "LUG" these things at 2k in 4th and then expect them to pull strong, smooth, and evenly from there? Aside from pulling out from a dead stop, I never run it below 3K. Yes, these machines have power and torque, but they aren't H-D thumpers, and like to run at slightly higher rpms !

How's the vacuum advance module and timing plate moving? No holes/cracks in lines? No airleaks around intakes?
T.C.

[missinglink]

Hey, TopCat,

Yep, still running the stock pipes, airbox etc. and I have never messed with the pilot screws. They are still capped.

I hear you with the lugging in fourth (which I rarely do) but sometimes you have to go slow. The speed limit in my neighbor hood is 25mph with a cop living in every other house (seems like anyway) and riding in shopping center parking lots scare me so I go slow there too.

I think I'll put the fuel system back to standard just to satisfy the "last thing changed before problem" rule. I'll take a look at the vaccum advance stuff too and check for leaks at the intake boots. Those things are getting pretty ugly.

Anyway, thanks for the input. I'll post back when I find something (or not).

Or maybe I'll just speed everywhere

[LoHo]

Hey TopCat, I hear you on the lugging engine thing, but I was wondering about long ride fuel conservation. Doesn't the last/third/biggest fuel jet come into play above 4K? Would keeping it at or near 4000rpm take it easier on the gas? For a long time I shifted at 4k because it sounded wound out, but further study makes a 5-6000rpm shift seem more in keeping with the design. I've never been on one of the new crotch-rockets that wind up to 11- or 12K before redlining, so I think I'd need to make an adjustment in my thinking...