Resurrected?

[Rocket Man]

So my 1980 cb650c is ride-able and fairly enjoyable, but I can't decide if it is not always running on 4 cylinders. I have not done a compression check as the smaller spark plugs holes have been problematic. I do need to analyze my plugs again, so I'll place a picture up when I get to it. But here is the deal: At steady speeds it seems to be a little rough and it does not have 'clean' power from a dead stop (can stall). Could it be from the attempt to make them run more like a Harley by de-tuning? I did try and pull the plug leads while idling and found nothing decisive. I have ridden a bike that "kicked in" all cylinders and I keep thinking that may happen but it does pull hard when rolling on the throttle.

[cb650]

So you "detuned" it to run like a hardly? And now want help to make it right?
Undo what you did first.

[Rocket Man]

I did not de-tune anything. I have heard that Honda de-tuned their cruiser bikes to sound/run more like a Harley in an attempt to sell more bikes. Anyone else heard of this sort of thing?

[Folsoml]

That's the first I've heard of that.

[cb650]

Yes your post stated it. never heard of such crap before. Maybe the stupid shadows and such but thats more along the hardly design rather than a inline 4. They did go lean but it was a epa thing. Did you do any work or just looking for miracles here? Might at least need a carb clean and TANK.

[Rocket Man]

All my posts refer to what I have done to the bike. It has low miles and has been recently tuned up. Compression has not been tested yet and I need to pull the plugs. Anyone really good at reading plugs?

[usbear]

Hello Sir:

Welcome to the site.
Several Good and helpful Members and Moderator Here.

The Moderator just had surgery and is laid up for a bit.

Post Pics of your plugs and members will comment.

Some professional members and racers on this site so post pics and questions at will.

1) Clean Carbs w Sonic Clean and Clean and Prep Tank Before Anything else.
2) Do a Step by Step by the Book Tune Up.
3) Start With new Spark Plugs and Sandblast Clean your existing Plugs for a Spare Set. Shops will do it for a Buck or two when you buy a new set.(or Free)
4) Post pictures and members will Respond.

cb650 just put pictures of his bikes up and they are worth the look, he is very experienced member here and you would do well to take head his advice.

If you have not cleaned, repaired and tuned carbs before I recommend you have it done as it will be much cheaper over all and you will have an experienced set of eyes and hands looking at your set. As a result much better performance and fuel mileage and less engine damage.

If you post carb cleaning needed on this site you will get responses and instructions as well.

CB650 stated: clean carbs and tank at a minimum and that is correct first step advice, don't be timid with the elbow grease and it will run good.

Good Luck! Post Pics.

[Volker_P]

Welcome here!

Anyone really good at reading plugs?

First very basic check is if they all look equal.

[Bongskit]

ask me how i manage to get in the green zone...

with the help of the guys that just responded to you above.

good luck sir!

[Rocket Man]

Cool, that really helps a lot. I do have one plug darker than the rest. I will re-visit the spark plug leads as they are 33 years old and some are tight/short. This bike wants to launch, but at low RPMs it acts like a plug is fowling/missing.

[Volker_P]

Thanks, this is a really great picture!
A CB650 plug in stock setup typically looks like the "Slightly Hot" picture.
Not sure if this brown "Best" exists with unleaded fuel at all.

[Rocket Man]

Latest update, I went through the spark plug leads and worked all connections and tested resistance. While checking the timing I discovered one lead had only half the spark as the other three. So I added heat shrink tubing to the leads where the compression had reduced the diameter to keep the lead in the coil. It does seem to have a lot more power now but still bogs a bit off the line. Making some progress is better than none!

[Volker_P]

So it sounds these leads are your problem.
The shrink tube may have solved it partly, but things like that having a conssiderable effect even when dry indicate that replacement may be a good idea.

[Rocket Man]

Here are the plugs and it looks like #2 may have a bit of an issue. I did notice some smoke come out of an exhaust after riding it for awhile. It ran fine cold, but once warmed up it has trouble off the line and at steady speed it breaks up a bit. Accelerates hard enough, but all in all a bit hard on the clutch. I may change out a coil that has a crack in the plastic that I high temp siliconed and may go wonky after warming up. Feedback? Pilot jets look clean, eh? I also suspect the air cut-off valves like Totaled108 mentions.

[Volker_P]

Plugs look good, so I think you have an occasional missing only?

Do your carbs have air cutoffs at all? Only few have them. Check out beneath the circular cover of the outermost carb.