CX 100 idle speed?

[McFly]

Hi y'all - I am getting the bike back on the road after getting over a back injury. I had a bike mechanic neighbor clean and tune the carbs last weekend. He proudly demonstrated than I can now start the bike without using the choke...

He is now out of town for 2 weeks - Well in 18 years of ownership, I have never been able to start the cold engine without choking it.

I test drove it to find that when warmed up, it runs between 2700 and 3000, about 50 mph in 4th gear. My recollection is that it should be around 800 rpm.

I checked for leaks (WD 40 around the intake manifolds) but no problem there, checked the cable for smooth routing, looks ok.

Process of elimination is idle speed set too high (rocket science prevails again).

Anything I am missing in this deduction?

TIA

Jerry

[oldbike54]

 Sounds like in the process of tuning the carbs so it doesn't require use of the choke in cold weather the mechanic did in fact set the idle speed too high . Any changes to internal components ?

 Dusty

[TOMB]

   Adjust the valves.   Check the auto advance probably stuck from sitting 8 yrs  check the timing is set check the advance is set correctly and actually advancing .
Then the carbs  are tbe last to adjust
TOMB

[webmost]

Floats fuel-logged?
Float seats cruddy?

[blackcat]

Idle speed should be 1000-1100 rpm at idle.

[Steph]

When it's idling at 3k, turn the idle screw counterclockwise 1/8 of a turn on each carb until you get 1000 rpm. Put a scratch on the carb & idle screw before doing this, in case you want to go back to the original setting

[McFly]

All - Thanks for these leads. Bike was sitting for 1.5 years. Carbs have new floats, seats look clean and smooth. No changes to other internals, valves were adjusted as part of the work done last week.Yes, thanks for the reset on Carbs Last - I think he followed this process.

I will throw a timing light on to see where we are at.

[McFly]

Stephan - Good stuff - thanks!

[radguzzi]

When it's idling at 3k, turn the idle screw counterclockwise 1/8 of a turn on each carb until you get 1000 rpm. Put a scratch on the carb & idle screw before doing this, in case you want to go back to the original setting

This.

I would bet that the idle screws are way in...  I would go 1/2 turns until you start to hear a change but you are safe with 1/8 turns...

Best,
Rob

[Steph]

Btw, I hope your neighbor used vacuum gauges to sync the carbs -Carb settings and cables adjustments. I could never do it so quickly that the engine didn't fully warm up...

[McFly]

Yes, he has the vacuum gear.

[80CX100]

Hi y'all - I am getting the bike back on the road after getting over a back injury. I had a bike mechanic neighbor clean and tune the carbs last weekend. He proudly demonstrated than I can now start the bike without using the choke...

He is now out of town for 2 weeks - Well in 18 years of ownership, I have never been able to start the cold engine without choking it.

I test drove it to find that when warmed up, it runs between 2700 and 3000, about 50 mph in 4th gear. My recollection is that it should be around 800 rpm.

I checked for leaks (WD 40 around the intake manifolds) but no problem there, checked the cable for smooth routing, looks ok.

Process of elimination is idle speed set too high (rocket science prevails again).

Anything I am missing in this deduction?

TIA

Jerry

I don't want to slam any good neighbour who pitches in to help you get your bike going,,, he obviously has a heart as good as gold,,, but there is an old saying, along the lines of, "if the bike's not running right, what did the last guy to work on it do?" I'd ask him very specifically what he did to your carbs? I'm concerned that he was proud, that he had them adjusted so rich that the chokes weren't needed for a cold start,,,doesn't sound like he knows what he's trying to do. There are only a couple of things he could've messed with,,, has the clip on the needle been moved? Have the air mixture screws been improperly set as well as the idle? I don't recall if it's even possible,,, but were the slides put in backwards etc,,, somethings not right in there,,lol.

I think Dave Richardson in Guzziology, mentions getting everything adjusted to spec first, timing,valves,,, proper jetting in the carbs, then fine tune the air mixture screw, idle, then balance last. He also stresses, that for your bike to run strong with a proper carb tune,,, it should be cold blooded and tempermental in nature when cold, and take a while to warm up and then run strong when hot,,, if not,,, you're probably too rich.

Not sure what carbs you have on your bike, my CX100 has the square body VHB30s,,, I used my vacumn gauges to really fine tune my air mixture screws, and went back and forth from them to the idle screw, getting the strongest combustion possible,,, then set the idle just above 1000,,, then balanced the carbs,,, needle clip in the middle slot pilot jet 50 and main jet 140, K&N's and Lafranconis,,, she runs very strong and sweet.

I did rebuild the carbs first completely, makes a difference,,, gives you a solid baseline to work from,,, worn cold starting circuit&seals and needle&seat and dry top gaskets can cause all sorts of problems.

If it ran good before,,, it will run good again,,,

Good luck getting the carbs on your bike straightened out, glad to hear your back injury is coming along,,, I haven't been able to ride my own CX100 for a while, due to my own neck injury,,,I'm planning to put on some superbike bars for next season, hopefully then I'll be able to get some more rides in on her,,, reading about you getting back on after a back issue, is inspiring, tks.

ride safe and take care

Kelly

[TOMB]

Is it possible that the main jet and pilot jet are both in the
wrong location?
TOMB

[Arizona Wayne]

Make the idle 1200-1300 rpm unless you want the clutch plate rivets to sheer off.  Don't ask me how I know. 

[McFly]

AZ Wayne - What is the correlation between idle speed below 1000 and clutch plate rivet disaster?

[rocker59]

Idle speed should be 1000-1100 rpm at idle.

Yep.  Thoroughly warm engine should be set to 1050 rpm +/- 50 rpm.

No, it won't idle at cold startup.  But then, it won't idle at 2500 when warm, either!!!   

First or second service on my Sport 1100 about 20 years ago, the dealer did this.  Set the idle speed without taking the bike out and warming it up first.  Yep, he was real proud of the cold idle.  Yep, a few miles down the road, bike warm, it was idling at over 1800 rpm.

Sh!te like that pisses me off...

[Chuck in Indiana]

AZ Wayne - What is the correlation between idle speed below 1000 and clutch plate rivet disaster?

The uneven firing order of the Guzzi is hard on clutch plates if the idle is set too low. Similarly, never sit at a stop with the lever pulled in. The two clutch plates and intermediate plate are loose, and rattle back and forth. This wears out the drive splines in fairly short order, and the clutch will start to feel "notchy."

[McFly]

Roger that Chuck - thanks!

[Arizona Wayne]

AZ Wayne - What is the correlation between idle speed below 1000 and clutch plate rivet disaster?

At too slow an idle speed the pistons pulse and over time it sheers the rivets that hold the clutch plates on the center plate.