• Can't post after logging to the forum for the first time... Try Again - If you can't post in the forum, sign out of both the membership site and the forum and log in again. Make sure your COG membership is active and your browser allow cookies. If you still can't post, contact the COG IT guy at IT@Concours.org.
  • IF YOU GET 404 ERROR: This may be due to using a link in a post from prior to the web migration. Content was brought over from the old forum as is, but the links may be in error. If the link contains "cog-online.org" it is an old link and will not work.

2006 Exhaust Temperature

Piston720

Member
Member
Has anyone checked their exhaust temperatures. My cylinders 1&2 are around 500F, 3&4 are 200F.
I cannot explain the difference, but am having low speed idle and rpm issues.
I will be getting into the carbs shortly to check the low speed jets and sliders as the rpm is very slow to drop when the clutch is pulled in.
Right now I am curious why the exhaust temp is so different, and what would cause it.
I was using an infrared scanner at a similiar point on all 4 pipes.
 
never had an infra red probe, but 200*f is cold.... I suggest checking your float levels in the carbs bowls for those.. you may be flowing fuel you don't see.. it's not always jetting issues.
 
What would float levels have to do with temperature differences such as these?
I did Steve's jetting with torque cams a few years ago. I also checked the float heights 3 times when doing the change over.
It runs great, to red line, in the gears. The temperature difference after such a run still has the same discrepancies.
What are your exhaust temps when warmed up? I used an infra red laser type gun to check temperatures.By the way, I also have stick coils and all cylinders are firing.(I think)
 
500F sounds about right at idle once the engine has warmed up.

Have you deleted your PAIR valves?
These let cold air into the exhaust and if the right one was stuck open it could lead to colder exhaust temps on 3&4.

Could also be duff spark plugs or coil-packs on 3&4.
 
Check the easy things first. Are your spark plug wires correctly routed? Are the electrical wires to the primary coils correct? Left coil controls cylinder 1&4, right coil controls cylinder 2&3. Cylinder order is 1,2,3,4 left to right. If correct, then check your air gaps in pickup coils.
Sorry, didn't notice you had stick coils. Are they correctly wired?
 
Last edited:
If the float level is too high, it will seep fuel into the motor at idle and cause it to run MUCH cooler. or they just are seeping past the seat due to some debris in the needle and seat. are oveflow tubes installed?
 
I have had the block plates over the 2 valves areas, for many years now.
My bike has the "T-Crow" Stick Coils that have been on for a few years, so I know the wiring is correct, but I will change out plugs to eliminate that possible issue. What is odd is that the bike runs great after warming up but still has the temperature variation.
What do others find if they measure their exhaust temperatures?
This has me baffled, but will keep digging.
 
I only started checking temp as the bike was having an erratic idle during warm up as well as when warm.
Only started running poorly, when at very low rpm, earlier this year.
I will start removing body work, tank and tip over bars shortly.
I am still curious as to what others are reading for exhaust temperatures.
 
Id def look at the carbs. easy non invasive test is to start bike let idle and warm up on centerstand. then, clamp off fuel line. the fuel level will drop a bit in the carbs as it runs. there will be a few minutes it will idle with the fuel in the bowls, watch the temp on 3&4. i would bet it will climb up to match 1&2 for a few minutes pretty quickly after the fuel is clamped off. this will pretty much verify or debunk the carb theory.
 
Thanks, I will try clamping the fuel line when warmed up tomorrow. By the way I do have overflow tubes installed.
 
Thanks, I will try clamping the fuel line when warmed up tomorrow. By the way I do have overflow tubes installed.
I've never checked temps but every time my carbs are due for a good cleaning I have low rpm stumble and one or two of my headers are cooler . Plugged pilot jets will allow it to run ok at high rpm and crappy at low rpm .
 
I clamped off the fuel line when good and warm, 1 & 2 around 550F, 2 & 3 still around 150-180F. Stalled shortly after.
I assume that means that the float levels are pretty accurate. I remember checking them at least 3 times when I did Steve's jet upgrade along with torque cams.
Looks like it is time to get into the carbs. It has been about 4-5 years.
Thanks everyone for the feedback.
 
I have removed the carbs and dismantled them.
Cleaned them today and am waiting for the new O rings to arrive. Should me here either this friday or monday.
Keeping fingers crossed.
While plastic was partially off I thought I would check coolant level, WELL the reservoir was empty and it took about a pint till it filled the neck.
It has been about 13,000 miles since last checked.
 
All back together and float levels set.
Hit starter and away she went, idled steady BUT gas started to run from overflow. Found it was #1. Had to remove bowl and did not find anything, worked float and reassembled. Working fine now, must have been a little rough putting the carb bank back earlier. Went for a good hard run and everything is fine. Temperature around mid 200's.
Forgot to mention that I had a fouled #2 plug which was replaced.
 
All back together and float levels set.
Hit starter and away she went, idled steady BUT gas started to run from overflow. Found it was #1. Had to remove bowl and did not find anything, worked float and reassembled. Working fine now, must have been a little rough putting the carb bank back earlier. Went for a good hard run and everything is fine. Temperature around mid 200's.
Forgot to mention that I had a fouled #2 plug which was replaced.
What did you find that was plugged up in the carbs? It would help others that find themselves in the same situation.
 
After disassembly of the carbs I cleaned bowls and all jets and orifices one carb at a time. Each time the carb cleaning solution that the jets were in was cloudy/yellow and there was fine particular matter. I then used a fine piece of wire to push through all areas of the pilot jets, then blew with compressed air. This was the first time these carbs have been cleaned to this extent for 63K miles/102K kilometers. Knowing this I would probably give them a similar spa treatment every 30K miles instead of waiting for an issue.
 
I had the same problem..checked with infrared temp..stalled..started a post..checked everything..found my 3 and 4 spark wires were in the wrong spot...read Denny’s post 👆before all else..can’t tell you how many times I pulled the carbs..did post about right cylinders not working..riding now!!
 
I did not notice one cylinder to be any different to the others. They all produced small particles and discolored solution when soaked for awhile.
All I can say that the clean made a world of difference, especially on startup and idle.
 
Top