Hot Pipes!

[Phaseman]

OK... So I just finished my first carb rebuild. Everything is shiny and clean with fresh new O-rings!

Here's what happened next!
I got everything reinstalled clamped down and buttoned up (note that for this first start up I had no air filter in place.). Outside air temp was at about 40deg.

After about 40-60 seconds of cranking at high choke setting I gave it a blast of starter fluid. A few more seconds turning over and she sparked up! Woot!

Sounds great, a little popping on decelerate but smooth and nice even before any adjustments.

Here's where it goes hinky... I walk away from the bike as it's idling to call a buddy and tell him my success story. The bike is sounding fine in the background, no answer to my phone call so i head back over to the smoothly idling GS.

It was well into dusk and the bike was sitting in an unlit carport. As I round the corner to see my idling bike, I thought that I had wandered into that Nicholas Cage movie where he rides the flaming chopper! Well, there were not actually any flames... But... I'm looking at my bike head on and what I'm seeing are four toaster element red header tubes. It was kind of surreal and took a second to sink in. I immediately shut down the bike.

Too rich? Too lean? Should I make adjustments before i restart and do the screw adjustments for high idle? Should I change the oil before going any further?

I estimate the total run time from start up to shut down at about 10 minutes for this event. Anyone have any feedback?

[first timer]

It is running lean because you have no filter installed. Install filter and see if it starts up quicker and runs better. Should run a bit cooler too.

These stock exhaust pipes or after market?

Also to help the bike start quicker I also switch the petcock to prime for a few seconds to make sure the carb bowls are full of gas before i start cranking it over.

[Larry D]

Doesn't matter what the temp is outside. If you're going to be running the bike at idle for a length of time. Tuning, etc...... Get a regular 20" fan and blow air across the engine.
And the bike is sucking to much air. +1 on installing the filter.

[Steve]

I think the only thing that's scarier than seeing four glowing red pipes is seeing only TWO glowing red pipes.



This was right after we got the bike last year. It has been completely gone through now, and is running very nicely.

.

[Phaseman]

first timer-It is running lean because you have no filter installed. Install filter and see if it starts up quicker and runs better. Should run a bit cooler too.

These stock exhaust pipes or after market?

Also to help the bike start quicker I also switch the petcock to prime for a few seconds to make sure the carb bowls are full of gas before i start cranking it over.

Filter on does make a huge diff. Pipes are aftermarket 4 into 1 but I'm not sure which brand. I've tried that with the primer, this bike is cold blooded as H#$%. Before the rebuild I would typically have to hook it up to the battery charger to make it through to a start. Looks like I'm headed that way even after the rebuild.

Larry D- Doesn't matter what the temp is outside. If you're going to be running the bike at idle for a length of time. Tuning, etc...... Get a regular 20" fan and blow air across the engine.
And the bike is sucking to much air. +1 on installing the filter

Copy that on the house fan, will do it next time around.

Steve- I think the only thing that's scarier than seeing four glowing red pipes is seeing only TWO glowing red pipes.

True about two glowing pipes. I did pay enough attention to notice that they were all glowing and that they were all the same color and all glowing from top to bottom.

Next question is... Now that I've got it running, I can't seem to get it to idle below 2000rpm. The throttle shaft seems to be moving full travel from stop to stop and I have the idle screw just barely making contact.

Any more ideas? As for the rest.some popping and missing from 3 -5000 rpms (pre-adjustment).

[first timer]

your carb boots look like this?


if so time to replace them. High idle is an indication of an air leak or vm style carbs having improperly adjusted slides. Take the carb off and re adjust the slides so they are almost fully closed with the idle screw all the way out. You can use a narrow drill bit as a gauge to staticaly synce all the slide heights the same.

These bikes aren't cold blooded, that is an excuse for a problem unfixed.

How new are you spark plugs? if old replace they are cheap to replace

did you follow the carb clean series exactly?

take your plugs out and ground them so you can see the spark plug spark, is it a nice bright blue or weak yellow? You can stick a flat head screw driver up the boot with the bike off and unscrew the leed, take some sand paper and clean up all the ends of the pieces that drop out and reinstall.

have you checked you timing/points?

The aftermarket pipes are thined walled and will glow red pretty easy.