Carb Tuning Related to Pipe Blueing??

I just fired up the 1260cc rebuild with brand new RS34 flatslides and it sounds mean! Everything seemed good except the pipes really turned blue. This is a brand new chrome header that I went through all of the trouble and expense to seal with Kreem Blue Shield. So much for that stuff!

Question is this - what condition is causing such blueing? I'm guessing it must be lean? I only ran it on the stand - not riding. Seemed very strong but definitely blued quickly, even with the shield. Is it the pilot jets? The mixture screws? Any suggestions what the blueing might indicate?

79MKII wrote:

I just fired up the 1260cc rebuild with brand new RS34 flatslides and it sounds mean! Everything seemed good except the pipes really turned blue. This is a brand new chrome header that I went through all of the trouble and expense to seal with Kreem Blue Shield. So much for that stuff!

Question is this - what condition is causing such blueing? I'm guessing it must be lean? I only ran it on the stand - not riding. Seemed very strong but definitely blued quickly, even with the shield. Is it the pilot jets? The mixture screws? Any suggestions what the blueing might indicate?

Stock compression ratio is 8.7 on '79KZ1000. What c/r is being run on the 1260cc rebuild? Higher compression ratio may result in more bluing.

Imo, on-the-road performance (from idle through redline) and spark plug readings are better indicators of good carb settings than relying too heavily on pipe bluing. If idle is steady and bike pulls strong from idle, the pilot jets and mixture screw settings are likely okay. If in doubt, could experiment by enrichening pilot mixture to see whether it improves idle or pulling away from idle.

How do the plugs look now, or is it too soon for a meaningful reading?

If not already done, would also double-check ignition timing and assure proper operation of advancer unit.

Good Luck!

Compression ratio is 10.5:1. Plugs are on the rich side for sure, but hard to tell just from idling with the occasional rev.

Is it a lean condition that causes the blueing or can being rich also cause it? I had always heard that a properly tuned engine will not blue the pipes. Maybe that's just not true?

I had a 1229 kit previously with same C/R and this pipe blued more in 5 minutes than that one did in 10 years. Have different carbs and major headwork this time. I guess it could be the high performance engine that creates more heat also??

79MKII wrote:

Compression ratio is 10.5:1. Plugs are on the rich side for sure, but hard to tell just from idling with the occasional rev.

Is it a lean condition that causes the blueing or can being rich also cause it? I had always heard that a properly tuned engine will not blue the pipes. Maybe that's just not true?

I had a 1229 kit previously with same C/R and this pipe blued more in 5 minutes than that one did in 10 years. Have different carbs and major headwork this time. I guess it could be the high performance engine that creates more heat also??

Am unfamilar with excessive richness causing overheating or blueing.

Trouble shooting guides point to causes for overheating such as blocked main jet, too low float heights, air leaks, or no air filter (all related to mixture being too lean), and to faulty ignition items such as plugs (dirty, damaged, maladjusted, incorrect heat range), incorrect ignition timing, too high compression due to carbon build-up, and other possible causes such as incorrect oil level or viscosity, clutch slippage, and brakes dragging. But nothing as to overheating due to excessive richness.

As to a properly tuned engine not bluing the pipes -- it would be more accurate imo to say that a properly tuned engine is a little less likely to blue the pipes. Recall the factories resorted to using double-walled pipes to help prevent bluing. And the characteristics of the particular pipe itself and amount/style of baffling may lend some brands to bluing more readily than others. Most advertising for aftermarket chrome exhaust systems seem quick to mention likely bluing as a natural phenomenon and disclaim any responsibility for it.

Meanwhile, would verify ignition timing and keep an ear out for any pinging. And be very sensitive to any sensation of power loss during break-in which could result from possible onset of seizing due to overheating.

Good Luck!

Retarded ignition timing will for sure blue the pipes, I actually had a turbo glowing red at idle one time, simply because I accidentally retarded the timing when I meant to advance it.

79MKII wrote:

Is it a lean condition that causes the blueing or can being rich also cause it? I had always heard that a properly tuned engine will not blue the pipes. Maybe that's just not true?

Definitely not true. Mine are deep blue and it's always running just a shade rich. Single wall pipes will blue at the turn, it's just a matter of how much.