Struggling to keep a low idle

[bcware]

I run an free flow 2-1 with mikesxs large oval pods and I run 42.5 pilots Are you sure you don't have the vm pilot jets instead of the cv stile ones? I have had people sell me the wrong ones before they almost look the same but the bike won't idle right with them.

You know, I was considering your setup and drewpy's; you both run much small jets than I do.

I am going to try and lower the jets for giggles.

How can I tell the VM from the CV pilots? The pictures on MikesXS show a very similar design. I intended to buy the CV ones and I am pretty sure I did, but it is possible I scrolled down on accident since they are on the same page. Also I guess I could have been sent the wrong ones. On hand I have 42.5, 45, 47.5, and 50 pilots. That leaves me a lot to compare. I also have every main jet from 137.5 to 160.

What are you running for a main jet?

 

[bcware]

There is a diagram on MikesXS that compares the vm and cv pilot jet internals. The pilots I have are definitely the correct, cv, type.

 

[xschris]

I run 142.5 in both of my bikes as well as x-4 needle jet and 5Z1 needle set on the middle or third clip. Both bikes run at the same temp.

 

[bcware]

Spark plugs:

Maybe someone can help me read them? The crappy looking one is from the right cylinder. I tried to get clear shots, but my camera does not want to focus well on anything that close.

Left plug:

Looks quite rich at idle (big surprise)
Threads look good (1 - 3 threads dark, rest clean)
Color changes on ground strap at the bend (good)

Right plug:

Looks rich at idle
Threads look bad (very spread out dark area)
Color changes on the ground strap at the bend (good)
Showing signs that this plug may be too hot? White glazed spots

 

[xschris]

They don't look rich if anything a little lean. How may miles on them?

 

[bcware]

Less than 1000, maybe less than 500. I changed them recently. You think they both look lean? I thought the left looked acceptable, but the right one has me concerned. Keep in mind, these plugs are with 50 pilots and 150 mains!

 

[bcware]

I had an idea just now that might explain why the right plug appear to need a colder type. I did sleeve the plug threads in the past on the right side only. Perhaps the sleeve is not allowing that plug to lose heat as well as direct contact with the head would.

I may try going one step colder (bp8es) on the right and seeing what happens.

 

[xschris]

Here is the set out of my modded 80 they have 1300 miles on them. The head temps at the exhaust side of the plug is 270f or so after a 60 mile run at 60mph and 85f outside. I use a 0 ohm cap with a ngk bpr7EIX resister plug 93 octane fuel with yamaha fuel stabilizer and conditioner for alcohol containing gas.

 

[xs400neophite]

I also have this problem of wich you speak!(....puhpuhpuhpuhpuhpuhpuh____papuhpuphpuhpuhpuhpuh) and if she isnt tuned up and 3 turns out on idle screws, she will stall. I read some of houghmades stuff and he advance the timing according to Dan the mechanics suggestion for older bikes
http://www.xs400.com/forum/showthread.php?t=5435
Dont know if it will rectify the problem but at some point I may try it. Maybe hough can comment on this and if his bike is still "ignition/miss/idle problem" free?
keeping my eye on this thread. Thanks BC

 

[domains]

Going to be funny if just a burnt plug... start bike get it running and pull a plug off to see if theres a difference from side to side. if diff change spark plugs... that black one looks burnt

it will run with just one piston, twist trottle a bit more to keep running

 

[bcware]

The right side (lighter plug) also definitely has a glazed appearance. This is another sign of overheating.

Picking up a few bp8es plugs in the afternoon.


Common cause of overheating:

Spark plug heat range too hot (bp7es is correct, so this can't be the problem)
Insufficient torque and/or no gasket (plausible because the sleeve may be preventing correct contact)
Insufficient engine cooling or lubrication (air cooled, no problems with engine lubrication)
Excessively lean air/fuel mixture (if anything I should be too rich)
Over-advanced ignition timing. (statically set very recently)


The most likely cause of overheating is poor plug contact with the engine due to the sleeve insert leading to high temperatures. Everything else seems like a stretch.

 

[xschris]

Do you do a lot of red line riding?

 

[xs400neophite]

busted hehehe

 

[bcware]

I don't hit red line a lot, but I will say that I do ride the bike pretty hard. I hit the upper rev range quite often. I am fairly liberal with the throttle as well. I stay in the power band and accelerate through the turns, etc. Most of my riding is "performance" oriented. I don't do a lot of slow, casual trips. I get my knee down on most turns...

 

[xschris]

Could be why at idle its flooding out and you don't notice the over jet with the hard riding

 

[drewpy]

I'd tweek on the mix screws as your pretty much there.

had to open my mix screws with 50 pilots, may even raise needle just to see if there is a difference although WOT is amazing and lifted a wheel on the tracker (light bike I admit)

 

[bcware]

I didn't touch the jets (150/50), but I did close the idle screws a bit. They were pretty far out; just past 2.5 turns when I pulled the plugs shown. I set them to 1.5 turns. The left cylinder is getting a new bp7es plug and the right is getting a bp8es plug. New coils arrive Thursday. I am going to wait for them before I do a test run. Hopefully my intermittent missing is alleviated.

I added a photo of the threaded insert for reference. It looks as though it may protrude into the spark plug gasket seating area slightly. I also wonder if lateral heat transfer through the threaded area is significant.

 

[63-Coupe]

Hard to tell from just a picture but have you had a real close look where the arrows I added are to make sure they are not cracks that go right through. I am thinking they probably are not or else you would likely see some discoloration or carbon deposits.

 

[bcware]

I didn't even notice that; I will go out and take a closer look.

 

[bcware]

Weird; it's just the photo. In person I cannot even see these "cracks." There is very faint surface dirt and such, but that's all. I reduced the photo size by 80% in photo shop and saved as a jpeg. The lossy format and dramatic size reduction probably created the effect.