XS 1100 bobber issue

[Tburnside]

Hi all! I'm hoping someone out there has experienced what I'm fighting with and can offer some insight. I'm helping a buddy get a 1979 XS 1100 bobber on the road. He welded a bitchin' stainless steel exhaust together and when this bike runs, it really sounds wicked. He also put cone filters on each carb. We are in the process of installing new diaphragms (as an effort to get it running well) to hopefully fix the issue. Here is what we're seeing: After sitting for months, he fires it up and it sounds like great and has a very quick throttle response. After it warms up (approx. 5 min), it runs like crap (if at all). The idle drops way off and we can't get it to rev vey highly at all. Could it just be the diaphragms leaking? Tried to vent the tank thinking it was building vacuum, no help. Float were set by a friend who knows what he's doing. Anything else we can try?
Thanks!!

[LAB3]

One of THE most overlooked places while looking for intermittent problems is the resistors in the spark plug caps, they tend to get worse once they heat up. They're made to "thread" on and off of the plug wire, just grab the plug wire and turn the cap counter clockwise until it comes off.

Check the resistance of the cap between the side that connects into the plug wire with your other lead touching the side that snaps onto the plug, it should be 5k ohm. If they're off by more than about 10% it's time to replace them. Let us know how that came out, there's a better method of replacing them available these days.

You'll probably see some corrosion on the end of the spark plug wire, go ahead and clip off about 1/4" of it to expose some fresh copper and reassemble by screwing the cap back on clockwise.

[Larrym]

he fires it up and it sounds like great and has a very quick throttle response. After it warms up (approx. 5 min), it runs like crap (if at all). The idle drops way off and we can't get it to rev vey highly at all.

Hmmm.....( •_•)

Iffin' I'm understanding the situation correctly, you may not have a problem at all. ¯\_(⊙︿⊙)_/¯

Lemme esplain...(O_O)

My bike needs to have the choke pulled out to full or half just to start. Cuz I've got the correct genuine Mikuni Jets installed and the carbs are synchronized I don't gotta twist the grip and open the butterflies just to get mOaR air like those who've installed the cheepee Taiwan Jets/Kits sold on Flea Bay. I just push the starter button and VROOM. ๑(◕‿◕)๑

But if I just let it SIT there and idle fOaR five minutes THEN turn the choke OFF? (O_o)

Totally G-U-T-L-E-S-S if I try to drive away. Stuggles to rev from idle up to anything respectable even in neutral. (⩾﹏⩽)

CUZ ITS (the engine...) STILL COLD even tho I'm in ARIZONA and it's 80 degrees out. (◔_◔)

My nurmal practice? (O_o)

Choke full to start. Push-da-buttton. VROOM!! 10 seconds later choke to half way. DRIVE away and when I've gone 3/4 to 1 1/2 miles away choke OFF. (☉_☉)

At 3 (THREE) miles away my ole 79 Special (3H3...) is a BEAST cuz she's at or near proper operating temperature. (^_^)

IMHO the only ways you can expect to get enuf power/torque to actually drive away after 5 minutes of idleing in the driveway/garage? (O_o)

Is IFF (If and ONLY if....) the choke is on half way. ( ‾́ ◡ ‾́ )

Note- UNLESS you've installed carb kits frum Amazon or Flea Bay and the jetting is so borked it'll run with the choke OFF after 5 minutes cuz those jets run so rich it's as IF the choke is always on. But then there'll be a whole LIST of things that don't wurky right when's the engine really IS at the operating temp it's s'posed to be. BTDT and HATED it. (︶︹︺)

[Radioguylogs]

Behavior is consistent with too rich (but not conclusive).

Have you pulled a plug to see how it looks?

[GNEPIG]

Quote:
"After sitting for months, he fires it up and it sounds like great and has a very quick throttle response. After it warms up (approx. 5 min), it runs like crap (if at all). The idle drops way off and we can't get it to rev vey highly at all."

All good advice so far so I will throw out some experience, check the oil= if it set for awhile the fuel might have over filled the crank case IE fuel valves left on or leaking and leaking past the floats... Just guessing.

[DEEBS11]

It's running rich. Either the carbs have an issue or it has weak spark. When a bike warms up it gets richer naturally. Also, when electronics warm up they increase in resistance. I apologize but the statement "He knows what he is doing" is something I have been told on countless motorcycle repairs and this is usually not the case. Do not discount the fact that your carbs were worked on but not completely correctly or they are full of Chinese parts.

[oldyam80sg]

Has anyone tried to sync the carbs? Could be another issue and also vacuum caps do crack with age.

[Larrym]

Am I the only one thmikin' the bobber issue wuz resolved wit' our expertise and the OP is just off somewhere's vrooming around happily ever after? (O_O)

Oh well....since there ain't no mOaR movement heres...(O_o)

Back to SKYRIM in VR!!! \(^_^)/

[Larrym]

FWIW.... I think we all did better than Chatgpt on this one. (^_^)


My question/situation-"My XS1100 isn't running well. What do I do?"

I'm sorry to hear your XS1100 motorcycle isn't running well. Here are a few steps you can take to troubleshoot and hopefully resolve the issue:

1. Check the Fuel System

• Fuel Quality: Make sure the fuel in your tank is fresh. If it's old, it can cause poor performance. Drain any stale fuel and replace it with fresh fuel.
• Fuel Filter: A clogged fuel filter can restrict the fuel flow. Check and replace it if necessary.
• Fuel Lines: Inspect the fuel lines for cracks or blockages.

2. Inspect the Spark Plugs

• Condition of Spark Plugs: Remove and inspect the spark plugs for any signs of fouling (carbon buildup, oil, etc.). If they are dirty or worn out, clean or replace them.
• Spark Plug Gap: Ensure the spark plug gap is set to the manufacturer's specifications.

3. Air Intake and Carburetors

• Air Filter: A clogged air filter can cause poor engine performance. Check the air filter and clean or replace it if necessary.
• Carburetors: If your XS1100 is carbureted, the carbs could be dirty or out of sync. Cleaning the carbs and ensuring they are properly tuned can make a huge difference.

4. Battery and Electrical System

• Battery Charge: Make sure the battery is fully charged. A weak or dead battery can affect engine performance.
• Wiring and Connections: Inspect the wiring and electrical connections for corrosion or damage.

5. Oil and Fluids

• Engine Oil: Check the oil level and condition. Low or dirty oil can cause engine problems.
• Coolant (if applicable): Ensure the coolant level is sufficient and that the cooling system is functioning properly.

6. Compression Test

• Perform a compression test to ensure the engine's internal components are functioning properly. Low compression can indicate a serious issue like worn-out piston rings or valves.

7. Check for Leaks

• Look for any fuel, oil, or exhaust leaks, as these could lead to performance issues.

8. Exhaust System

• Inspect the exhaust for blockages or leaks. A clogged exhaust can restrict airflow and cause poor performance.

If these basic checks don’t resolve the issue, the problem might be more serious, and you may need to take it to a mechanic. Let me know if you need more detailed guidance on any of these steps!

TBH.... Imma surprised Chatgpt didn't recommend "Powering the motorcycle OFF for 30 seconds" then powering it ON again. (O_o)

[bikerphil]

TBH.... Imma surprised Chatgpt didn't recommend "Powering the motorcycle OFF for 30 seconds" then powering it ON again. (O_o)

Chatgpt is a super smart computer that knows that our bikes don't have the type of computer where that is applicable. But then again , it wasn't 100% sure the engine is air cooled.