Bonneville America Forums Forums Technical Forums General Tech Misbehaving...

I think I'm having an ignition problem.

Rough, or erratic at idle, and just off-idle whether stopped or rolling - barely crack the throttle from full-closed and she bogs, pops, or stumbles. Try to hold her at, say, 1500 rpm and it is real noticeable.

Most noticeable at idle, or leaving a stop, or while trying to cope in slow traffic.

Idle speed has no effect. I had an o-ring stuck on the left idle adjuster screw 3 weeks ago, and wound up changing plugs then so they are new.

I am now wondering about the plug wires and/or coils. What symptoms might bad plug wires bring about?

She runs a lot better at speed, but I suspect there is still some mis-fire taking place as I detect some vibration in the left grip that has not been there. She'll run though...but wants to pop as the idle speed rises and drops when I get to a red light.

Any ideas?

fuel??? possibly filter or valve but i would bet to say filter first.

I'd go back and check that O-ring you mentioned again and make sure all your rubber nipples are on tight and in good condition.

Dodgy plug, even these days you still get them..

check the squirrel condom vacuum caps for tiny cracks too.

I'll be tinkering with her today...I need to sort it out for a big ride Thursday.

The more I think about it the more I suspect the mixture screws and o-rings, too.

I sprayed WD-40 around checking for vacuum leaks and am satisfied that is not the case.

I'll vote for the fuel filter. When mine acted up we first thought it was missing on an ignition stroke or somthing. It turned out to be just a tiny bit of crud in that dumb little hidden filter.

Being as it runs better at speed, I'd say fuel delivery isn't the issue. Sounds like you've got an air leak.

First off, you have to determine whether you have an ignition or fuel problem.

It sure does seem like you are running on one cylinder at times. Poor fuel flow to the carbs could cause this; ie starving for fuel due to a filter, plugged petcock, screen, fuel line, etc. This probably isn't the problem since you run ok at speed. How does the bike run when the choke is pulled? Have you tried opening the carb drains under each bowl to see if you have good flow? If this is ok, pull the float bowls and see if there is any dirt in the pilot jet. Don't forget to pull the mixture screws and blow the circuit out.

Also a vacuum leak could give you the same symptoms especially at idle but since you already used WD40 to check..... Make sure the clamps are tight on the carbs. One other source for a vacuum leak is the diaphram which raises the slide. Never heard of one failing but a small crack in the diaphram could cause issues.

Also, pull the plugs and note the colour. Ignition problems will cause a plug to turn dark or even wet. If it appears you are running on one cylinder, try to isolate each cylinder by pulling the plug wire and grounding to the frame. Only do this once you are sure the fuel system is ok otherwise you will end up chasing your tail.

One fix at a time.

I'm not ruling out a fuel issue, but it is definitely only the left cylinder.

I pulled the left plug wire and she runs fine on the right side.

I pulled the mixture screw back out, and the o-ring looks seated okay, but she started popping again at idle, from that left cylinder - like she was doing 3 weeks ago before I was able to re-seat the o-ring and changed the plug.

I don't know what symptoms a plug wire or coil might show, but this is definitely just the one cylinder so I don't think it would be the fuel filter.

While looking at it Sunday morning, I found a big nail in the rear tire, so looks like my plans are made for me. I'll drop her off at the local Independent bike shop here by the house (CYCLE SPORTS), then hitch a ride back home before driving to Natchitoches.

He can change the tire for me and sort out the performance issue for me while he has it. I have to work Friday and Saturday, so I may not get the bike back until next weekend, the 22nd, unless I can hitch a ride to the shop next week sometime.

I will have the pilot jets bumped up if the job entails pulling the carb bowls - I still thnk she is running too lean judging by the plug color, or lack there-of, even though she has been real fun to ride - maybe she could be made better.

I ordered the TRIUMPH special tools to do the valve adjustment from BikeBandit about 2 weeks ago. If they show up while the bike is in the shop, he'll do that for me, too while she's there. Get it over with. Sounds reasonable, and I trust him - I know it will be done right. And, I won't have to interrupt riding season again to get that done. It's overdue.

I just dropped her off at CYCLE SPORTS. Told them to flush the fork oil and brake hydraulics, get her tuned out right, and adjust the valves if I get those tools in, and change that rear tire.

She'll be there most likely until Saturday/week, so I put my jackets back in the closet for now.

Trying not to think about it.....

Here is what I DO know to this point:

The small micro fuel filter hidden between the carbs was 1/2 full of crud.

The small vacuum line running between the carbs had a pinhole in it.

He had the carbs off and completely broken down on his bench when I stopped by last Thursday. I'm upping my Pilots to 45's, and going to up the Mains to 140's while I'm at it - just to see what happens.

Fork Oil Replaced, Brake Hydraulics Flushed, Rear Tire Replaced.

The spanner wrench and pins for the valve adjustment arrived
yesterday, too late for me to get them up to the shop. The jets (from Brent) may not get here until after Thanksgiving.

I spent all day today at the IMS riding other bikes - see my post in the Other Bikes forum. I sure miss mine.

Whoa there Blackwind! Slow down!
Before you go changing jets, see how she she runs without
the vacuum leak and fuel blockage. Then, only change one
thing at a time so you can see the effect. The mains and
pilots have an influence on each other. Check carb balance
as well. You have the tools, do the valve adjust while you
are at it.

Good Luck!
Uncle Charlie

With the Holiday approaching, and pretty weather to boot, and places to go, people to see......that is what I've been thinking all day. Get the valves adjusted, and then do the jets later - no sense waiting on them when everything else can be done and I can make sure that the "problem" is behind me.

That cr*p in the fule filter may be from the filler neck peeling paint - mine is pretty bad, although I swear I never tap the fuel nozzle on the filler neck - I think it may be from the fumes, but I don't know. If that paint does not dissolve in the fuel when it hits the fuel in the tank, I guess it has to wind up somewhere....

Do you know the size of your pilots?
I don't think you're that far off.
Got a pair of 132's if you want 'em.
I'd go to those, or 135 max.
Uncle Charlie

The pilots are marked 42's, just like the specs say they would be.

I changed mains from 120's to 125's, then to 130's. Noticeable change each time to be sure - a lot more change than I had expected or anticipated. Thing is, I have never felt the bike ran "poorly" (other than this recent issue - hope it is just the crap in the fuel filter and/or the hole in the vacuum line). I was happy with her stock, and then after changeing to the TORs, felt I needed to rejet to keep her from running too lean - the same as I feel now. I just want to protect the integrity of the motor as much as I can, and if that gets me better performance, that's great, as long as it doesn't cut into fuel economy too much. I had a completely open air box, bottom cut out, filter bottom cut out, but after some trouble in the rain on more than a couple of occassions, I installed a new UNI filter and left the bottom intact, thereby closing the box.

I haven't seen it but the one time, but I did have the speedo needle pegged at 120 mph last year while outrunning a thunderstorm...and that was after the new filter had been installed. I never saw that with the more open air box. I think the atmospheric stuff must have been just right, I don't know. Wide open interstate, runnng from Katy back in towards Houston, in the HOV lane.....stable as she could be, too. I don't open her up for that long, that often, but I haven't seen the up-side of 110 in a while.

I sure hope I can pick her up tomorrow, or early Saturday.

Now I'm disappointed, but it will all work out in the end.

When I stopped by the shop last week, he had the carbs out on the bench. He said the oil pressure switch broke when he "wrestled the carbs out". He had never loosened the air box from the rear fender so he could slide it back giving him the room needed to get the carbs out of the rubber boots, and therefore broke the oil pressure switch inadverdently. He had "glued" it back together - I hope it works, but won't know until we get it running.

Today I get a call telling me I need to aquire a right side engine cover gasket (alternator cover). I asked why, and was told that that was where the timing marks were, so that cover had to be removed. It was already done, so he dumped out the fresh Rotella I just put in there this month, and said the gasket had broken in two places.

British-USA says they will have one in Tuesday. I'm about to call British-USA back and add that oil pressure switch to the list, just in case.

This shop (an independent) has the service manual for our bikes. I took them my own when I took the bike in, but they already had one. Sounds like they need to read it before jumping off into something they've never done before.

I really trust this shop, and the two guys there (owner-tech and tech), and I feel confident it will be right when done, but this mole-hill has become a mountain and I'm wishing I had just tackled the valve adjustment myself. I was just concerned about having to run all over town chasing shims, and figured they had what they needed here already.

I should have read the repair manual again myself. The alternator cover does come off to find the timing mark on the alternator rotor - it matches up with the split in the engine cases, and puts the timing marks at the top.....only required though if the valve(s) under the oil pipe are out and need adjustment.

I picked her up yesterday, and she runs and sounds great. I think the biggest improvement is the upgrade from 42 to 45 slow jets - that really made a difference in on/off idle throttle transitions - really cut down on the decell popping from the TORs that I never could adjust completely out before, and gives the pipes a deeper, lower rumble that I would have previously thought only attainable by going to different pipes, like BUBs or SS.

Carbs and fuel filter completely cleaned and gone through, Pilots Jets increased to 45's, inline fuel filter (90-degree filter) added, fork oil changed, brake fluid flushed/changed, valves adjusted (includes oil change with my oil/filter/gasket), and a State Safety Inspection sticker - all for only $616.00.

Merry Christmas to me.....