Pipe temperatures

[Scud]

1980 GS750E with CV carbs

All this talk of pipe temps makes me wonder. Number 1 and 4 are cooler to the touch for a nitceable amount of time as compared to 2 and 3, I thought that it was due to the fact that they are the two inside cylinders and they just warm up faster. But all of the plugs are white but are still within the 'lean but not bad' category. I raised my float levels from 20mm to 24mm, would this make them all run lean?, I have great acceleration in all RPM's in all gears, and what is the significance of the cooler pipes? I did a thorough cleaning and put in all new o'rings and original jets. I also recently synched the carbs with a carbtune II this made for much better idling, the mixture screws are all out 2.5 to 3 turns.

Thoughts??

Scud O

[earlfor]

Re: Pipe temperatures

Changing the float levels from 20 mm to 24 mm will lean the carbs through the entire operating range. If all your plugs are burning white, that is not good. Why did you change to lean float settings in the first place? Cylinders 1 and 4 are cooler because there is not a combustible mixture in the cylinder available to burn during the idle range of operation of the carbs. I would richen the float level settings, then test ride and check the plug colors. If the cool pipes on 1 and 4 at idle situation continues, I would open the mixture screws on those carbs.

Earl

1980 GS750E with CV carbs

All this talk of pipe temps makes me wonder. Number 1 and 4 are cooler to the touch for a nitceable amount of time as compared to 2 and 3, I thought that it was due to the fact that they are the two inside cylinders and they just warm up faster. But all of the plugs are white but are still within the 'lean but not bad' category. I raised my float levels from 20mm to 24mm, would this make them all run lean?, I have great acceleration in all RPM's in all gears, and what is the significance of the cooler pipes? I did a thorough cleaning and put in all new o'rings and original jets. I also recently synched the carbs with a carbtune II this made for much better idling, the mixture screws are all out 2.5 to 3 turns.

Thoughts??

Scud O

[Scud]

Hi Earl,

The reason I changed to lean float settings in the first place was because my plugs were sooty and black, this condition came about after I did a thorough cleaning and installed a K and L replacement carb kit (and Robert Barr o'ring kit). The pilot jets it turned out in the replacement kits were larger then the originals (two holes perpendicular to each other running through the jet opposed to two holes and one hole perpendicular on the original) and this made for a rich running bike. I tried to compensate by increasing the float level and then when I discovered that the pilot jets were larger I replaced them with the originals (nothing was wrong with them just gummed up), then the plugs were white. I have a feeling that you are going to inform me to reset the float level to the previous setting and see what that does :roll: . If you recall from an earlier post I submitted, I increased them from 20mm to 24mm with the gasket removed). At that time you said that 20mm was to low ( it is not within the Clymer manuals range).., assuming that I should decrease them where should I set them this time for a baseline? Also, should I reset the mixture screws to 2.5 turns on each?


Thanks in advance

Scud

[earlfor]

Let me see if I have this right. Your pilot jets were too large (but you didnt know that at first), so you lowered the floats to get a lower fuel level in the bowls to lean it out. It still ran rich with the large jets. Then you discovered the jet size was wrong, so you installed the original smaller jets, but you did not reset the float bowls to the original height, so now they are too lean for the correct pilot jets that are installed.

Hmmmmmm, well you said it first. :-) The thing to do is set the float levels to the correct height for the jets you are using. :-) :-) The correct float height for your bike using stock jet size is 23 mm (that would be about 29/32 of an inch) 2 1/2 turns out is a good baseline setting for the mixture screws.

Earl

Hi Earl,

The reason I changed to lean float settings in the first place was because my plugs were sooty and black, this condition came about after I did a thorough cleaning and installed a K and L replacement carb kit (and Robert Barr o'ring kit). The pilot jets it turned out in the replacement kits were larger then the originals (two holes perpendicular to each other running through the jet opposed to two holes and one hole perpendicular on the original) and this made for a rich running bike. I tried to compensate by increasing the float level and then when I discovered that the pilot jets were larger I replaced them with the originals (nothing was wrong with them just gummed up), then the plugs were white. I have a feeling that you are going to inform me to reset the float level to the previous setting and see what that does :roll: . If you recall from an earlier post I submitted, I increased them from 20mm to 24mm with the gasket removed). At that time you said that 20mm was to low ( it is not within the Clymer manuals range).., assuming that I should decrease them where should I set them this time for a baseline? Also, should I reset the mixture screws to 2.5 turns on each?


Thanks in advance

Scud

[Anonymous]

ya think those infrared temp sensor gadgets(the ones you point at something and hold trigger and it will tell you the temp of object your pointing) would be usefull for tuning?

[Scud]

Earl,

I was trying to be diplomatic and at the same time trying to look like I was not stupid...not sure if I was successful at either... This morning I will pull the carbs and reset the levels, oh by the way, is there an easy way to get the tang on the float pushed down, or oppposite of higher? I was looking at it when they were off before and was wondering how to get it flatter(yes, I know, I should have done it then 8) , sticking a screwdriver and bending down the tang to increase the height was quite easy, not sure how to go about reversing the process.

And yes... I did say it first...

Scud

[earlfor]

Knowing exhaust gas temp at the port would be useful, but the temp sensor your are talking about would only tell you the temp of the pipe and not the actual exhaust gas temp. You could probably do just about as well by licking your finger and noting the tone of the sizzle whenyou touch the pipe. :-)

Earl

ya think those infrared temp sensor gadgets(the ones you point at something and hold trigger and it will tell you the temp of object your pointing) would be usefull for tuning?

[Anonymous]

hrrmm, thats what I figured, oh well was a thought

Knowing exhaust gas temp at the port would be useful, but the temp sensor your are talking about would only tell you the temp of the pipe and not the actual exhaust gas temp. You could probably do just about as well by licking your finger and noting the tone of the sizzle whenyou touch the pipe. :-)

Earl

ya think those infrared temp sensor gadgets(the ones you point at something and hold trigger and it will tell you the temp of object your pointing) would be usefull for tuning?

[earlfor]

Uhhhh, bend the tang in the opposite direction? :-) :-)
Seriously, just remove the float pin and float and with your thumbnail press lightly to bend it the other way.

Earl

Earl,

I was trying to be diplomatic and at the same time trying to look like I was not stupid...not sure if I was successful at either... This morning I will pull the carbs and reset the levels, oh by the way, is there an easy way to get the tang on the float pushed down, or oppposite of higher? I was looking at it when they were off before and was wondering how to get it flatter(yes, I know, I should have done it then 8) , sticking a screwdriver and bending down the tang to increase the height was quite easy, not sure how to go about reversing the process.

And yes... I did say it first...

Scud

[Dink]

Uhhhh, bend the tang in the opposite direction? :-) :-)
Seriously, just remove the float pin and float and with your thumbnail press lightly to bend it the other way.

Earl

I use a set of long nose pliers , it allows a little more control, and finer adjustment.
Dink

[Scud]

I think I understand the 'bend the tang the opposite direction''...I did figure out a good way to do it without removing the float pin and float or needlenose pliers. I put a small screwdriver on opposite sides and under the tang and put even pressure down on both screwdrivers (keeping them away from the needle) bending the tang up

But I appreciate your advice Earl...ask a stupid one get a stupid one

Scud

[earlfor]

Youre rich, I cant afford pliers.

Earl :-)

I use a set of long nose pliers , it allows a little more control, and finer adjustment.
Dink

[earlfor]

I'm sorry, I never have been able to resist an easy mark. I have more "snappy" answers when youre ready. :-)

Earl

But I appreciate your advice Earl...ask a stupid one get a stupid one

Scud

[Scud]

OK... I think I'm ready..