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RED LINE

3K views 13 replies 8 participants last post by  jzeiler 
#1 ·
Why does the red line on a 1999 K1200LT go to 8500 RPM when later models red go to 8000 RPM even 2004 and later with higher HP only go to 8000 RPM just curious?
 
#2 ·
That may have been the original setting in the ECU but for some reason they changed it. You can always check yours to see if the rev limiter kicks in at 8,500.

OK I looked at the service manual for the pre 05 bikes and it does state 8,500 as maximum permissible RPM. I also checked the 05 + manual and it also states 8,500 is the max. I need to go out and see where my limiter kicks in and see if it is 8,000 or 8,500. Maybe they just got a good deal on red paint for the dash.

OK I looked at both dashes and they both have 8,000 where the red line is.
 

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#3 ·
I suspect it is to accommodate the lag in the tach. Most tachs lag a little when you are revving the engine quickly as in the lower gears. Back before rev limiters, the tach was often marked a few hundred RPM lower than what the engine could actually withstand so that if the driver shifted when the tack read say 6,000 RPM the engine would actually stay below say 6,500 RPM. At least that was the case on many of the 60s and 70s muscle cars.
 
#4 · (Edited)
Gary, John, Matt,

See attached image taken from the owners manual (technical handbook) of a USA market K1200LT of 2005-2009.
This is page 68 toward the end with all the specs:
- I have indicated with a GREEN block the RPM at max power: 8000
- I have indicated with a RED block the MAX allowed RPM: 8500

This might explain the confusion between various values - the RPM at which an engine attain its max power is not necessarely the same as the max allowed RPM (mechanical limits). I do not have a copy of the same owners manual for 1999-2004 to compare.

BY THE WAY, on the K1200RS having the same internal mechanical engine components (valve train, crankshafts ....), plus higher compression pistons, the MAX allowed RPM in the specs is 9400 but the Red line on the Tach is at 9000. So, I would NOT worry that anyone will blow up anything at 8500 on a K1200LT ;-)
 

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#6 ·
Gary, John, Matt,

See attached image taken from the owners manual (technical handbook) of a USA market K1200LT of 2005-2009.
This is page 68 toward the end with all the specs:
- I have indicated with a GREEN block the RPM at max power: 8000
- I have indicated with a RED block the MAX allowed RPM: 8500

This might explain the confusion between various values - the RPM at which an engine attain its max power is not necessarely the same as the max allowed RPM (mechanical limits). I do not have a copy of the same owners manual for 1999-2004 to compare.

BY THE WAY, on the K1200RS having the same internal mechanical engine components (valve train, crankshafts ....), plus highwer compression pistons, the MAX alowed RPM in the specs is 9400 but the Red line on the Tach is at 9000. So, I would NOT worry that anyone will blow up anyting at 8500 on a K1200LT ;-)
I was interested to see the maximum oil consumption of 2,300 MPG or 575 miles per quart. Probably just a metric for denying warranty claims, but a pretty high consumption to still be considered normal.

I still suspect the 500 RPM difference between the published redline and the indicated redline is to allow for lag between tach and engine. If the tach was marked at 8,500, I suspect that when the rev limiter kicked in at 8,500 the tach might only show 8,000 and the owner would complain to the dealer than the engine wasn’t performing properly.

It is sort of like the temp gauge on many modern cars (my 2015 Chevy truck has this) which is computer controlled and does not show the actual engine temp. My truck goes smoothly to 215 degrees and then never wavers. Doesn’t change whether I am plowing snow, towing a trailer or coasting down a long hill. My prior 1994 Chevy truck had a real temp gauge that moved around based on the engine load. I thought 215 was awful high, but when I asked the dealer he said it was normal and “they all run that hight.” Well, after I bought a BluDriver (think GS-911), I checked and the trucks typically runs 192 or so and the temp does vary with engine load as expected, but the gauge never varies from straight up which is 215 degrees. What a stupid decision to waste money on an indicator that is completely meaningless.
 
#5 ·
The LT & the RS both have the same valve spring and valve springs have a lot to do with max rpm. I have run my LT on the rev limiter a lot in the mountains but have never looked at the needle when it was on the limiter.
 
#9 ·
The red line on my 2000 LT starts at 8,000 RPM. Note the photo of my tachometer which indicates the red line starting at "8" (8,000). The third fine black line (note attached photo) in the middle between the "8" and "9" probably represents 8,500 RPM. I personally don't like to push my bike anywhere near the "red line", the LT is pretty quick enough for me to enjoy at more moderate RPM's.
 

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#10 ·
I had an 85 k100rs
redline was 8700
Manual listed max continuous RPM 8600.
Man I loved that bike! had it for 17 years
There heard there was a chip that would increase redline to 11,000
I have had rpm to 9200, the injectors shut off.

Sold it, ran great, 350k+ smiles

I have only ran the LT to redline once (5th gear)
 
#11 · (Edited)
You must have been going down a really long hill as my LT won’t even come close to getting to redline in 5th on the level. It actually goes faster in 4th than in 5th.

Although, when my clutch was oiled I could hit redline in both 4th and 5th. :grin:
 
#12 ·
The RS has a lot less wind resistance, which is a killer for the LT. Remember double the speed quadruple the wind resistance.
 
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