Uneven Header Temps??

[Darin Jordan]

As part of my carb-tuning-with-pods adventure, I decided to keep check the temps at the header after a ride to see what affect the jetting changes might have on this.

According to both of my infrared temp checkers (Yes, I've read the previous threads which diverged into the accuracy of these things, so we don't need to go there again... more interested in relative temps for now ), the temps this morning were as follows:

1, 2, and 3 were around 400-420
4 was 235

Not focusing on the actual temps, which seem high to me, I'm a little curious as to what might lead #4 to consistently be 100-degrees or more lower than 1, 2, and 3??

Normally, I'd think that 1, 2 and 3 were running too lean, while #4 was slightly rich, but are there other things on these bikes that might cause this that I should look at??

Also, about what "should" the temps be? I realize that this may be subjective, dependent on riding conditions, etc... Temp was about 50-degrees out this morning, and I had just finished riding into work, then about 3/4 of a mile through the plant in 1st gear around 15-20 mph or so...

[Big T]

I don't think anyone has really recorded what the temps should be on the pipes

But, you are correct, you have an issue with #4

What do your spark plugs look like?

[Guest]

depends on the RPM's, but if you are reading on the same place on each pipe and the surface is consistent, they should all be close.

[Darin Jordan]

Pulled the plugs today while tearing down to do a valve adjustment. #4 was totally black. The others look good. Obviously it's not firing properely. First thing that came to mind was the plug wire ends/caps, but the valves, both intake and exhaust, were pretty tight. Couldn't fit a .05mm shim under them, so the clearances were at the minimum end of the range, at best. Have shims on the way to get everything within spec.

Question about the cap ends... Is the the cap ends that actually go up in resistance when they age, or is it the connection to the wire? I pulled the cap off and cut the wire back 1/4" to get to some fresh core and re-assembled it. Not sure how to check the overall resistance in the wire, since they appear to be premenantly sealed into the coils at that end.

Anyhow, I'll see if that helps, once I get the valve adjustment completed. If it does, I may be looking into an upgrade for the ignition system.

I also received my Carbtune on Friday, so once everything is buttoned back up, I'll be balancing the carbs as well.

Really looking forward to riding this thing once all of these maintenance details are taken care of.

[four_shot]

I think you're on track with the valve adjustment and carb synch. I'm subscribing to see where this goes.

My $.02 the #4 pilot screw is dialed in too rich.

[Darin Jordan]

My $.02 the #4 pilot screw is dialed in too rich.

I'm doubting that... All of the pilots were adjusted the same... right where DynoJet recommended them originally, and about 1/2 turn out since then, since the recommendations were too lean and I was getting popping and fluttering at 1/8th throttle or so and under decell.

I too, thought that perhaps #4 might be adjusted wrong, so I tried altering it seperately of the others, and it made no difference.

From the looks of the plug, I'd say either the ignition system has issues and the plug isn't firing consistently or hot enough, or that the valves were too tight and it wasn't building compression. Based on the valve adjustment I'm doing, I'm certain the later was part of the problem, as I couldn't even get a .03mm shim under the cam.

As for the ignition, I removed the plug cap, cut back the wire 1/4" or so to get to fresh conductor, and have reinstalled, so we'll see if that helps at all.

At least with the valves adjusted and the carbs sychn'd, I can check those possibilities off my list.

I'll report back on the rest, as soon as my shims and breather gasket get here so I can button this thing back up and give it another ride to test.

[Darin Jordan]

My $.02 the #4 pilot screw is dialed in too rich.

On second thought...

I got my shims last night and wrapped up the valve adjustment, getting the valve cover back in place. Still waiting for the breather gasket to get here... Not sure why Z1 Ent. sells the valve cover gasket, but not the breather gasket (had to get from Bike Bandit), but whatever....

After buttoning all that up, I decided to go back through and check all of the pilot screws... DynoJet recommended 4 1/2 turns to start for their Stage III kit. I think the #4 was out something like 6-turns. I KNOW that I originally set it at 4 1/2. In fact, I set them a couple of times, just to make sure. I'm thinking that "lightly seated" may have turned out to be "lightly dragging in the threads??

Anyhow, I redid them all last night back to 4 1/2, and we'll see how that works out.

Question: The pilot screw needles looked like they could possibly be getting worn down. Does this happen with these? Are these screws something that should be replaced when the carb is rebuilt? They don't look like they are broken or anything. I should look at them under a magnifying glass and get a closer look.

[niclpnut]

On second thought...

I got my shims last night and wrapped up the valve adjustment, getting the valve cover back in place. Still waiting for the breather gasket to get here... Not sure why Z1 Ent. sells the valve cover gasket, but not the breather gasket (had to get from Bike Bandit), but whatever....

After buttoning all that up, I decided to go back through and check all of the pilot screws... DynoJet recommended 4 1/2 turns to start for their Stage III kit. I think the #4 was out something like 6-turns. I KNOW that I originally set it at 4 1/2. In fact, I set them a couple of times, just to make sure. I'm thinking that "lightly seated" may have turned out to be "lightly dragging in the threads??

Anyhow, I redid them all last night back to 4 1/2, and we'll see how that works out.

Question: The pilot screw needles looked like they could possibly be getting worn down. Does this happen with these? Are these screws something that should be replaced when the carb is rebuilt? They don't look like they are broken or anything. I should look at them under a magnifying glass and get a closer look.

Typically don't need to replace these. Sometimes a tip will break if they are turned in too tightly. The O rings and sometimes the springs are they only things that are usually worn.

[Darin Jordan]

Typically don't need to replace these. Sometimes a tip will break if they are turned in too tightly. The O rings and sometimes the springs are they only things that are usually worn.

Right on. I have replaced the o-rings, and the springs seem OK, and none of the tops are broken, so I'll just leave be for now.

Hopefully the #4 issue WAS just a mis-adjusted pilot screw and everything will be better now. We'll find out once the gasket for the breather arrives.

Then, it'll be time to perform the carb sync with my new CarbTune...

[Darin Jordan]

OK... Finished up the valve adjustment... #1, #2, and #4 were all less than .05mm (smallest feeler gauge I had), and #3 was .06mm... I now have the others in the .06-.07mm range.

Put everything back together, adjusted all the Pilot Screws to the recommended 4 1/2 turns (DynoJet, Stage III) and ran some long fuel and vacuum lines over to the gas tank, which I had setting on a table next to the bike. Ran it for a few minutes to get it warmed up, then hooked up the CarbTune and put a fan in front of the motor.

Here is what the CarbTune looked like going in....

[Darin Jordan]

And HERE is what it looks like now....

You guys were right... Feels VERY smooth, with very little vibration in the bars. Starts up nicely. No more popping with the choke on, or on decell. Even sounds better.

I STILL have the bad stumble at around 5500 RPM at 1/2 throttle or more... I have GOT to figure out what that is!

But, everywhere else, it feels good, and I feel better knowing that this general maintenance has been carried out. Should be a reliable ride for awhile, I hope.

[Darin Jordan]

OH, and the header temps are now dead even!

[dr_fosg8]

Good job on getting that sorted. Now that the header temps are even how does number 4 plug look? Just curious.

[Darin Jordan]

Good job on getting that sorted. Now that the header temps are even how does number 4 plug look? Just curious.

I'll check it out after I ride it a bit more. I'm guessing it should be looking a lot more like the other ones!

NOW, if I could JUST get rid of that stumble!

[dr_fosg8]

I think I have read in other posts that a stumble in that area could be cured by raising the needle a bit. Is your bike running stock airbox and exhaust?