Triumphrat

dkreidel · 08-24-2007

I was at the airport today working on cleaning up the hangar, when I discovered an old Alcor EGT gage and a couple of EGT probes. I decided to do some experimenting, and removed the two ports on the Bonnie's header pipes and machined a couple of adaptors to allow an EGT probe to mount in each header, and ran the leads to a switch to allow me to change between LH and RH cylinder readings. I ty-wrapped the EGT gage to the handlebars, and rode around to see what I could learn. What I discovered was that the RH cylinder exhaust temps at full song are about 100F hotter than the left side. Just to make sure it wasn't the probes, I switched everything around but the right side is still hotter EGT at full tilt than the left. Just for yucks, I put a 115 main jet in the RH carb and now the EGT's are pretty much equal across the RPM range. I did not check the left carb; but I'm assuming it still has the stock 110 main jet. I'll have to do a plug chop to see if I'm all wet here. I did spray ether around the RH intake to see if there was an air leak in the RH manifold somehwere, but it seems to be fine.

This is my Montana bike - which is dead stock. It may be the EGT gage is a good tool for carb tuning. I certainly use the EGT gage a lot when flying, as aircraft carbs have cockpit adjustable mixture controls. I'm at 3,000 MSL altitude here in Montana.

Dick

webonnielad · 08-24-2007

I don't know if you saw my thread about this last week

Does your engine run hotter on the right side than the left, or similar to that anyway, well thankyou, someone finally gave me a scientific answer that I feel I can trust.
I now know I'm not nuts.

But can anyone offer as to why this is so?

Anyway now I can sleep nights.

Jon (UK)

sweatmachine · 08-24-2007

an EGT probe may be good at sensing exhaust temps, but a wideband llambda sensor is what you need to see what your a/f ratio is. You can get kits for under $300 that include the sensor, the computer, and an attracive a/f ratio gauge. I plan on getting one soon.

I'll only get one sensor, but I will switch it between carbs from time to time when tuning to check for variations.

ohiorider · 08-24-2007

Sweat - is this something you could install on the bike, perhaps at the test points in the headers, and check mixture in an actual riding situation? Man, would that be cool, especially if somehow, one could capture engine rpm and throttle position, and link that info to the a/f numbers.

Bob

dkreidel · 08-24-2007

I can not correlate a/f ratio to EGT, but I do know that on air cooled airplane engines that fuel inejctor nozzles are swapped around until the EGT's are equal on all cylinders. Head temps are a different matter, as there is no tight correlation between EGT and CHT readings if everything is working nominally. What is a lambda sensor?

My plane has EGT readings within 20F of each other - all 4 cylinders - and it has a single carburetor.

dick

greyplague · 08-24-2007

Quote:

Originally Posted by sweatmachine

an EGT probe may be good at sensing exhaust temps, but a wideband llambda sensor is what you need to see what your a/f ratio is. You can get kits for under $300 that include the sensor, the computer, and an attracive a/f ratio gauge. I plan on getting one soon.

I'll only get one sensor, but I will switch it between carbs from time to time when tuning to check for variations.

Check this out, Sweat:
http://www.markvanderkwaak.com/dbbp/tech-tips/mm.html
Looks nice.

sweatmachine · 08-24-2007

Quote:

Originally Posted by ohiorider

Sweat - is this something you could install on the bike, perhaps at the test points in the headers, and check mixture in an actual riding situation? Man, would that be cool, especially if somehow, one could capture engine rpm and throttle position, and link that info to the a/f numbers.

Bob

It sure is Bob! That's exactly what it's for! You can even get a model to hook it up to your computer and download your history!!!

here's the company's website:

http://www.innovatemotorsports.com/products.php

and here's the kit I'm going to get:

http://www.innovatemotorsports.com/p...s/g2_gauge.php