1978 750cc - 2nd cylinder misfire?

[Maloy]

Hey you guys, I'm new to not only the GS community but the motorcycle community as a whole and i'm having a rough time getting my bike running. My 750 is having a tough time starting and and even tougher time staying running.

My step dad and my real dad both came to the conclusion that my second cylinder is misfiring, but they've left it to me, to fix. I figure I need a new seal for the cylinder, but aside from that I have absolutely no idea where to even try and begin...any helpful hints, or ideas relating directly to my problem?

I'll appreciate any positive feed back, I need to get this bike out on the street

[BassCliff]

Greetings and Salutations!!

Hi Mr. Maloy,

Let me dump a TON of information on you and share some GS lovin'.

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Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

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Thank you for your indulgence,

BassCliff

[MisterCinders]

Go through the stuff in BassCliff's list. Especially the valve clearance and carb cleaning.

Tell us more about your bike. Mileage, work done, whether it ran at all?

Check the No. 2 spark plug. If it is not firing, the plug will be wet (no fuel) or dry (no spark).

If it is firing, but not consistently, that could be compression, timing, bad spark plug or wire, or a problem in the No. 2 carb.

Basically, the forum can help you through this, but we need more details.

[earlfor]

ON a 79 750, the number 2 carburetor has the vacuum fitting for the hose that goes to the vacuum nipple on the petcock. When the petcock seal goes bad and starts to leak, the vacuum line flows fuel into the #2 carb intake, creating a rich condition, black spark plug and misfires. Eventually, it will foul the plug and cause #2 to stop firing at all. Ten to one you need to replace the petcock.

Earl

[Big T]

ON a 79 750, the number 2 carburetor has the vacuum fitting for the hose that goes to the vacuum nipple on the petcock. When the petcock seal goes bad and starts to leak, the vacuum line flows fuel into the #2 carb intake, creating a rich condition, black spark plug and misfires. Eventually, it will foul the plug and cause #2 to stop firing at all. Ten to one you need to replace the petcock.

Earl

Sorry Earl, but a 78 750 has VM carbs with the vacuum port on the #3 carb

Unless, of course, the OP's bike isn't a 79 (or the vacuum line is on the vent)

Maloy, detail how you came to the conclusion that #2 is bad? Compression test? Plug chops? Putting the spark plug lead on your tongue?

[earlfor]

Sorry Earl, but a 78 750 has VM carbs with the vacuum port on the #3 carb

Unless, of course, the OP's bike isn't a 79 (or the vacuum line is on the vent)

Maloy, detail how you came to the conclusion that #2 is bad? Compression test? Plug chops? Putting the spark plug lead on your tongue?

You are correct. I've been searching for this post I made to correct that error and just now found it.

Thanks
Earl

[SqDancerLynn1]

Try swapping #2 & 3 plug wires. Have you checked the plug caps ?