I have a carbureted 2007 Bonneville T100. When I first start it cold, it idles fine and runs perfect. About 4 miles down the road it starts choking at about 5k rpm. Then it will start choking so badly even throughout lower rpm range that it is a struggle to keep it running at all. I don't know if it is because it is heating up or what the problem is. I just had it in a shop and had the carbs removed, cleaned, reinstalled. I guess when they started it up it sounded fine but maybe didn't run it long enough to encounter the issue. Any ideas? They did mention that the tank liner was disintegrating. When I got it home I washed the tank out thoroughly, dried it, and put in a quart of phosphoric acid to kill any rust. I rinsed it again, dried it and put fresh fuel. If I leave the petcock open when sitting, fuel leaks from the tank but closing the petcock stops that issue.
Well I would be straight back to the shop if it were me. Maybe the broken tank lining got into the newly cleaned carbs, do you have fuel filters? If so have a look and clean them. Float height check? Sticking choke/ enrichment? Tank breather blocked, try with cap open. Easy stuff first so not in this order, just my thinking.
There is a filter in the tank on the petcock fuel pick up tube. I cleaned it and the hose for the tank breather is clear, no obstruction. The tank should be free of any debris as I cleaned it out and the ospho, phosphoric acid kills rust and converts it to iron phosphate. No in line filter is present and I did run it with the cap off.
Since the bike starts cold and runs as it should I assume that I can rule out any plugged fuel line, vacuum leak, or faulty jets in the carbs. It is only when the engine heats up that the trouble starts to show. Any thoughts or ideas on what the problem can be?
If there is a split in the rubber it wll allow air in weakening the mixture, on cold start with choke the mixture will be OK. So if there are any splits or damaged gaskets from the carb work it could impact the fuel air mixture and give poorv unning when warm.
I wonder if that could be tested by spraying some starting fluid on them after it warms up to see if there is any change in idle speed.
Providing you could keep any spray going anywhere near the air intake! Ot her wise you could get a false reading. Splits in the rubber tend to be pretty obvious and a visual inspection should highlight any problems.
OK, I gave it the test again today. I cranked the bike up cold. No issues, it idles, accelerates and returns to idle perfectly. Run down the street to 6k rpm, no problem. Engine warms up and shuts down like it is choking. Start it back up while hot and spray carb boots with carb cleaner and get no accelerated idle as there would be with cracks allowing air in. Baffled. Need help.
Sticking choke? Coils Is there a crank position sensor on your bike On the triples they break down and engine won't restart when cold.
Choke works fine when cold it starts as it should. Closing the choke reduces engine rpm. Starts good when cold, hard starting when warmed up.
What are you getting? Starting System Symptoms: Weak battery symptoms: -- Slow cranking. -- Stops cranking suddenly on compression stroke with button pressed. -- Starts when starter button is released at end of cranking. Repair: -- Charge/Test/Replace battery. Failure Modes: -- Loss of capacity. Appears to charge, voltage good but no reserve for starting. -- Won't hold a charge. -- Low voltage/cell failure. Preventative Maintenance: -- Check fluid levels regularly -- Maintain full charge: Regular riding, trickle charger. Ignition Coil failure symptoms: -- Hard starting/misfiring during cranking. -- Rough idle that can't be tuned out with carb adjustments and carb cleaning. -- Idle misfire clears with new sparkplugs, returns in a few hundred miles Repair: -- Replace: Preferably with Nology for higher reliability than stock Gill coils. Failure Mode: -- Shorted turns in secondary resulting in weak spark. Preventative Maintenance: -- None Testing: Pickup Coil failure symptoms: -- No spark at all -- Spark quits with engine hot, returns when engine cool. -- Note: Pickup coil failure is total. There is no random misfire spark loss. Repair: -- Replace pickup coil Failure mode: -- Thermal intermittant with long (15-30 minute) period. Preventative Maintenance: -- None. Get a spare. Testing: -- Ohms checks hot and cold. Worn starter symptoms: -- Sometimes won't crank until the bike is rocked in gear. -- Excessively noisy cranking with a grinding sound. -- Click from under seat but no cranking. Failure Mode: -- Brush wear progressing to commutator damage. -- Bearing failure related to brush wear. Repair: -- Rebuild or replace. Preventative Maintenance: -- Maintain battery in peak condition. -- Follow proper starting procedures. Neutral, clutch in. -- Crank 5-10 seconds at a time max., switch off for twice as long before cranking again. Worn sprag clutch symptoms: -- Very loud rattling when cranking -- Starter spins but engine doesn't turn Falure Mode: -- Breakage Repair: -- Replace sprag clutch Preventative Maintenance: -- Maintain battery in peak condition. -- Follow proper starting procedures. Neutral, clutch in. Worn starter solenoid: -- Click from under seat but no cranking. -- Won't crank after rocking bike. -- Starter continues to run after bike starts and won't stop until the battery is disconnected. Failure mode: -- Internal contact damage resulting in non-conduction. -- Internal contact damage resulting in contacts welding shut. -- Internal damage/wear prevents solenoid core movement. Preventative Maintenance: -- None. Repair: -- Replace starter solenoid. Testing: -- For no cranking, short across solenoid high-power terminals. Normal operation denotes failed solenoid contacts.
I chased problems like this on 2 old Triumphs. One for a couple of years. Turned out to be ignition coils on both bikes. Triumphs have about the worst coils I have ever seen. Something to think about. ...J.D.
Oh yeh ! Heat is the most common reason a coil fails. That is what is making me think it could be the issue. If you decide to replace them, you don't have to buy the expensive ones, but I WOULD recommend you replace them both. But I have found they do not have a real long life, especially in hot climates. ...J.D.
I ordered 2 from Amazon. https://www.amazon.com/dp/B09SVV3BVY?psc=1&ref=ppx_yo2ov_dt_b_product_details