Topic: K8 Carb Slow Jets + Points Arcing?

[Aux]

Having issues with my new K8 - After cleaning my carbs, I still have the same issue as previously described: I set the idle to 1200 but the bike still faulters and dies when I crack the throttle. I replaced the accelerator pump to no effect.

My question relates to the Slow Jets: the manual suggests they are press fit and cannot be removed. I didn't remove them to clean them.

Can I remove the slow jets on the K8 carbs?

In addition :

My points seem to be sparking. Is this cool?


Thanks!

[Spanner 1]

C'est possible remover les ' slow jets' et necessaire por bon marche  .. Please excuse my French.... yes the slow jets are removeable and must be cleaned to fix your problem... just grip with a pliers and twist and pull... the jet is tiny and can be opened with an 'E' guitar string... if clean you can just see light thru' it.. the emulsion holes need to be clear too.... good luck
Sparking points usually just need to be cleaned good.......

[SOHC Digger]

Spanner1 is exactly right.  I have used the guitar string method many times before with no problems, although other members here feel that it may damage the jet and brass should be used... but like I said, I've never had any problems and if you do screw them up, they are cheap enough to replace.  DO NOT try taking a small drill bit to them, as you WILL damage them then, trust me!

[BobbyR]

I should refer you to doing a search but seeing I am a K8 owner also, I will answer your question. The pilots are pressed in and they are removable. Get a good plier and gently but firmly grab the jet. Pull up gently while wiggling the jet and it will pop out. Be careful not to squeeze too hard or you will deform it, don;t wiggle too violently or you will deform the seat.

Really clean it using a strand of wire from a lamp cord or something similar. Flush it out with  carb cleaner. Here is the other important part. When you put them back in, make sure they are straight. Gently tap them back into place until they seat, don;t bang on them just taps till they bottom.

It is easier than it sounds. Most points will arc a bit, how much is too much is subjective. If they are in good shape it will be a very small blue arc, I mean really small and blue.  

[Aux]

Wow, thanks guys!

I will try this out and get back to ya'll.

And Spanner1, don't worry about your Francais... around my end of Canada no one is speaking it!

[Spanner 1]

Yeah, just messin'.... hey tho'... I know someone in Quebec that has NO English ( honest ! ).... I couldn't believe it either.....

[Aux]

Spanner1 - Oh yeah, that's totally normal.

[lrutt]

Did you actually verify the accelerator pump is working? My K8 wasn't because the gasket over the accel pump bowl didn't have a hole punched in it to allow gas up to the nozzles. Once I created that hole I had gas coming from all 4 nozzles.

Just an FYI but make sure you're getting the squirts when you twist that grip

[knowsnothing]

Also, a little piece of leather around the slow jet helps with the extraction.  You won't chew them up as bad that way.  

[Coyote13]

Hey Aux, if you go through and find that the idle jets are not dirty and therefore not the culprit, you may find that your mixture screw is a bit rich or lean. Give it a souple half turns in either direction, testing your throttle response after each adjustment (this is AFTER checking to see that your idle jets are clear of course)

[gnarlycharlie4u]

yea... you can pull the slow jets to clean them like everyone already described.
firm grip. twist and wiggle as you pull.

if they're in as bad of shape as mine were though, you may have to replace them.

Sirius is the only place to my knowledge that sells them.
#35 stockers - http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1107
#38 slightly bigger than stock - http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1805

[Skunk Stripe]

Cant add much to the idle jets but check your plugs after idling for a bit to see if fuel is loading up or if things are too lean.

As for arcing, yes it happens. Check the point faces for pits and spikes, those make it happen more. Also, your condensers, if not replaced when you did the points, may no long be working.

[TwoTired]

Everyone says to twist these pilot jets out.  But really, they were installed straight in and should be pulled out straight, too.

Twisting allows any grit between jet body and carb body to erode and enlarge the jet "socket", or reducing the outer diameter of the jet body.  Changing either dimension allows the jet to fit loose, and someday allowing the jet to fall out.

It's a minor peeve, I guess.  But still....

Cheers,

[cookindaddy]

I have a K8 also and I had exactly the same symptom after I also did not pull out the slow jets. You got good advice. Someone suggested parallel jaw pliers to help get them out without chewing them up but these are hard to come by. I think that the leather wrap and a good strong pull will get them out for you.
Three of the four of mine were completely plugged. When you do have them out and when you can see light through them, you will not believe how incredibly small the hole bored through the length of them is!
My K8 ran fantastically after I cleaned them.
And - you can see arcing at the points when the bike runs. That's normal. You also normally have the cover on so you don't see this. Some enterprising people here have made transparent covers so they can watch the points arc (go figure?).
I love my bike!
See the Ontario Section and let us know you are there in Burlington (if you haven't already)!

[gnarlycharlie4u]

Also, about the arching... it's not the end of the world, in fact it's somewhat normal. Although it can wear the points down faster. Just check and make they're in good shape; no pits or wear.

[TwoTired]

The points arcing is the back EMF from the coils.  When the spark event occurs, something like 400V is generated on the coil primary and is shunted to ground through the points.  When the points are near closure, this voltage jumps the gap.  The condensers are supposed to alleviate some of the more intense arcing, were it not there, and minimize the pitting that occurs with points that carry significant current.

Faulty condensers CAN make the point arcing worse, but they don't eliminate the arcing even when they are in good condition.

Cheers,

[lrutt]

Actually regarding arcing. It's not that it's a faulty condensor, it's that it's the wrong value likely. Search the net but you will find details on reading the points to see which way the material is being transfered. One way means condensor is to low of capacitance, the other way to high of a capacitance. Check it closely, then measure condensor. I can't recall the details as it's been a long time since I researched it.

[Aux]

Thanks for all the suggestions guys.

After cleaning out the slow jets with a spare E string from my fiddle (which were very clogged), and cleaning all the passages with carb cleaner and compressed air (twice) - I had the very same problem. Bike idles fine, dies if I give it fuel, but not if its choked. Hmmmm

So i get off my butt and do the valves, change the oil, set the points (twice) and time it with an inductive timing gun.

Same problem.

So I buy a manometer from the folks at Vintage CB750 and set it up.

Ah hah! At idle I get about 17 CmHg on the vacuum for carb #2, which as I have learned is the baseline. The measurements for the rest of the carbs seem to be all over the place, as follows:

Carb#1: 21 CmHg
Carb#2: 17 CmHg
Carb#3: 14 CmHg
Carb#4: 25 CmHg

Now I've never done this before so I don't know if these measurements are significant or not, but I spend 20 minutes balancing all 4 carbs until they had the same measurement, in what was a totally simple and rather Zen process.

And guess what?

My previously sickly and impotent 750 now runs like a bat out of hell!

And sounds bloody awesome to boot.

Just wanted to add this tidbit of success to the archives for the next guy with some ill PD carbs.

[SOHC Digger]

Great news!  And thank you for giving us detailed results!  And congratulations on joining the exclusive club of people who know how to sync carbs.  You are no longer one of those "Screw it, how much can it really help?" kind of people.

[theofam]

Aux, that's AWESOME news!  My K8's carbs are in recently cleaned pieces on my workbench. I just received my main jets today to adjust for Colorado's elevation, so I'm ready to put them back together and try to start Paddy soon.  I'm glad to know if Paddy misbehaves, it may be as easy as a good carb sync.  As Digger said, thanks for keeping us updated.

My slow jets were way plugged up, too! 

[knowsnothing]

HA good to know Aux.  My K8 has similar laggy throttle response like yours.  I have been thinking i had an airleak somewhere or maybe a clogged accel pump, maybe i should just tune the carbs first  

[gnarlycharlie4u]

HA good to know Aux.  My K8 has similar laggy throttle response like yours.  I have been think i had an airleak somewhere or maybe a clogged accel pump, maybe i should just tune the carbs first   

couldn't hurt to at least pull the accel pump and (thoroughly) check it.
I yanked mine and I thought it was ok, so I just put it back without cleaning it.
I still had sluggish response so I decided to get a replacement pump/spring and clean out the passage + ball bearing
That made a HUGE difference.

Some people hate to deal with the later model carbs but I think that once you get the hang of them they're the best thing around. That accel pump makes all the difference in the world!

[TwoTired]

The accel pump has TWO ball check valves (one for in and one for out) behind square plugs.
Clean by flushing with carb cleaner (aerosol cans), and use the same can to verify they block fluid in one direction.

Cheers,

[gnarlycharlie4u]

The accel pump has TWO ball check valves (one for in and one for out) behind square plugs.
Clean by flushing with carb cleaner (aerosol cans), and use the same can to verify they block fluid in one direction.

Cheers,

The other check valve was fine in my case. It seems that those don't gunk up as frequently.

[kerryb]

Wow...thanks guys.  I had the same problem as you Aux, with the addition of plugged accel nozzles.  The only way I could reach the nozzles to clean them was from the other end of the carbs with the single strand of lamp cord held in an exacto knife handle as an extension.  I bench-syched the carbs but didn't use the real carb-synch tool yet.  Sometimes they hang at 1500 rpm too long and I thought that was carb boot leaks.  I'll try the carb synch and hope for the same good results.
Yes, Sirius is a good source for idle jets and pump parts.