Bonneville America Forums Forums Technical Forums General Tech Edmonton Bound and Trouble

Well Friday morning I took off for Edmonton to visit my son from Timmins on my Americe. Everything had been checked before hand, valves adjusted, oil/filter changed, chain replaced and adjusted, carbs balanced, etc etc. I ran the bike for a week before leaving with no issues. Good to go.

When I got a few kilometers out of the city, I noticed that the engine would bog down in the mid range. Idle was normal and full throttle seemed the same with a bit less power in the top end but the mid range would hesitate and bog down at times. I immediately thought I had a partially plugged fuel filter probably due to some bad gas. (I had topped up my tank with a liter of fuel before I left, from an old jerry can rather that go to the gas station for $1 worth of fuel.) I figured I could make it to Chapleau Ont and check it there.

Chapleau at the gas station I ran into Mike (Northernmac) and we pulled the fuel filter. Nothing wrong with it. We visually checked the intake rubbers and vacuum caps and couldn't find anything wrong. Figured it was the bad gas and filled up expecting everything to get better. It didn't.

In Wawa I filled up again and noticed I was getting excellent gas mileage but the midrange throttle response was mixed. Sometimes the bike ran good, other times it felt like it was going to die. The bike never cut out and always ran on both cylinders. Sometimes it would balk, backfire and run on again. Pulling the chock/enrichener did help at times especially when going down hills. (the bike wanted to die while going down hills and this would help cure it)

Left Wawa and ran to Terrace Bay where I stayed the night. Not having a lot of tools, I pulled the 4 straps from the intake rubbers and rotated the intake rubbers to check the backsides. Nothing wrong. I also pulled the small cover on the left carb to check the valve (that prevents popping on decel - forgot the name) and it appeared ok but I thought a small 0 ring was missing. Put it back together and went to bed minus 0 ring.

In the morning (Saturday) it was pouring and very windy. The bike fired up and ran ok until I began to cruise and noticed the same problem but worse. I also noticed that the bike would bog down when hit by a heavy cross wind or when passing a large transport. This would come and go.

Got to Thunderbay and pulled into a NAPA and replaced the fuel filter (second guessing myself). Borrowed the tools. While I was idling the engine I notice a whistling sound from the left carb. It was the missing 0 ring. Got one from NAPA and left thinking I had found the problem. The bike ran better but still acted up in the mid range. Idle was fantastic with no miss pulling through several gears. Only in mid range and believe it or not....in cross winds.

Pulled into Kenora and spent the night again wondering what the problem was. In the AM, I found a hose and tried draining the fuel from a carb to verify I had good fuel flow and I drained a glass of fuel with no issues. (Fuel filters were still good.....still second guessing myself)

Left for Regina with clear weather. Bike ran generally better with very good gas mileage. I noticed on the prairies that any side wind would cause the bike to partially die. Every time I tried to pass a transport the bike would begin to die just as I got to the cab and that wind barrier the trucks created. Frustrating. I could cruise at 130 plus with no problems unless there was a cross wind. While running at high speeds, gas mileage return to normal. Started to think there was a problem with the midrange circuit in the bike.

Got to Regina. Tonight I again pulled the 4 straps from the intake rubbers and wrapped the rubbers in electrical tape thinking I might have a small crack in the rubbers I can't see. I leave for Edmonton in the morning and if everything is ok, should be there Monday afternoon.

When I get there if I still have the problem, I'll be pulling the carbs at my son's house. My big concern is the engine burning a valve or punching a hole in the piston, but given the abuse these engines have taken and still keep together, I was pretty confident it would hold together. I'll keep you posted.

Really hope I find the problem. Remember the fellow who had a problem with side winds affecting his ride causing the bike to die at times? Did he ever find the problem?

Marty, you up for a visit?

Strange.

I don't think this is your problem, however just to rule it out, where specifically are the termination points of the carb & tank vent lines? Are you sure that the vent lines are not pinched?

I hope the remainder of your trip goes well.

Opps forgot to mention that the tank vent and float bowl vents checked ok. Physically blew through them and drove with the tank loosened off.

"the midrange throttle response was mixed"

This happens most noticeably when we pull the snorkel. Thus is seems you have a new intake source. You checked the carb to manifold rubbers. Check the carb to air box rubbers. (I forget if you are freaked or not) Don't you have a drilled air box? Well check to ensure the hole covers are in place too. Also, check the header pipes for leaks at the jugs. (why not eh)

Hum, You might want to pull your saddle to see is you are sucking something into your airbox. Like a strap for a saddle cover...

Just thinking out loud Greg.

I am wondering if you don't have a small hole in one or both of the slide diaphrams. OK with no need for vacuum and ok when you have a lot of vacuum but mid range not good. Just a guess mind you.

Appreciate any idea fellows so thanks in advance. Ian the diaphram rubbers are on the check list as soon as I get some tools. Moe I never thought about the carb to air box rubbers but what you suggested really makes sence especially given the sensitivity to cross winds.

My bike has always been sensitive to cross winds ever since I pulled te snorkel. I just clamp the tank with my knees to mitigate the problem since I prefer the increased throttle response. One day I'll futz around with some wind mitigation ideas but for now I just put up with it.

I do wonder about the atmospheric vents and how rerouting the tubes might work out.

Yup Greg,I'm around.If it turns out to be the rubber on the carbs I just happen to have a spare set complete carbs lying around.My garage and tools are yours any time ya need em.

And oh yea,a visit would be great.Hope to see ya soon.

Well fellows, made it to Edmonton yesterday afternoon with minimal issues. The bike ran like a champ yesterday but there were minimal winds blowing. I'm pulling the intake rubbers this morning to check them closely because the bike ran 100% better after I wrapped them in electrical tape so I suspect a small crack somewhere.

Moe's comments caused me to check the air box cap for the AI removal and it was good. I also check the plugs on the two air box drain lines and one was missing....(is this the extra air supply???? seems too small to be an issue but I plugged both again). I'll be pulling the box back and getting to the carbs later this morning to check the airbox to carb and carb to intake rubbers closely. I'm thinking that I might reseal the airbox to carb rubbers with silicone seal since the original sealant is long gone and those rubbers are loose on the box.

Thanks for the post Keith. It helped along with Ken's comments about vent lines. I looked at the termination points for the two vent lines and noticed something. The last thing I did before I left for this trip was to cut the vent line to the tank at an angle to prevent the cutting out problem I had in heavy rain. Well guess what....I cut the wrong vent line. I cut the one to the carbs at an angle that would cause a siphoning effect which would try to draw air out of the carbs??? Would this give me my cross wind issue??

I think I might have a couple of minor issues that are causing these mid range problems and cross wind issues.

Marty, thanks for the offer and I hope to give you a call when I find out what the family is up too. Going out to a ball game tonight with my son. My wife and other son arrived also so I'll have to see what they want to do. If I need the rubbers and they aren't available at the cycle shop I'll take you up on your offer.

Thanks to all for the suggestions.

I'm going to suspect the atmospheric vents as one of the culprits. They provide the air pressure that pushes the fuel up into the main jet, a small atmospheric depression there could stymie the fuel flow into the venturi. It is commonly assumed that the vaccuum sucks the fuel out f the bowl, that's technically incorrect as the air pressure pushes the fuel through the jet and emulsifier tube and then the vaccuum sucks it thru the venturi along with the air charge into the cylinder. Maybe you could try maneuvering the hoses so the end is shielded from the wind and see how that treats you.

I have to agree with you Ed. When I realized that I cut the wrong vent hose and that the way it was facing would probably cause a vacuum, I felt pretty sure it could be the problem, confirmed by you and the others. Now all I need is a test run.

Here is what I found this morning.

I pulled the carbs, opened them up and found nothing wrong. Diaphrams ok, slides and needles ok, float bowls clean, floats and needle valves move freely, mains and pilots appear to be clear, and intake rubbers are fine (pulled off the tape I had put on). Made sure those were put on correctly (so easy to put on backwards, ie - facing the intake rubbers in the wrong direction).

I inspected the airbox and rubbers and found nothing wrong with any of them other than the 2 unplugged drain hoses (plugged now). I noticed that the crankcase vent hose was ready to fall off but I don't think that was an issue. If it would have come off, then I might have had a problem.

I recut the carb vent hose and placed it where it was before I had any problems. I'm going to go for a run in a while to see if everything is OK but I really won't be able to tell until I see some cross winds.

Keep you posted.

Well just went for a 30 km run and all seems well . No bogging down in the cross winds or when passing a transport.

As I think back on this problem it really was speed related. Slow speeds in any gear saw no problems but at around 80 kph and up it acted up. To all of you that have similar cross wind problems, I'd zero in on the carb vent location and orientation of the hose for a solution before pulling everything apart like I did.

PS - thanks for all the input.

Here's hoping you got 'er worked out. Yet another thing for us all to learn and be aware of. Thanks for sharing your progress on this problem. Oh, and say "hi" to Marty and Nanci for me!!! Wish I could be there!