Topic: jets were changed?

[beaniam]

Haven't calculated mileage yet but I have a feeling I'm getting about 25mpg range in my 78 750k.  I bought it with pod filters and a 4 into 1 exhaust and a dyna ignition.  It smells like it's running rich and you see some puffs of black smoke under hard acceleration.  I replaced the accelerator pump diaphragm.  I have the mix screws 3/4 out each.  I can go further in but from what I've gathered they don't make any difference past 1/8 throttle anyway.  I just cleaned the uni foam filters.  I have spark plugs on order, D8EA's.  Just changed the oil.  Idle is stable and it runs great.  Is it likely my jets were changed out to too large of one?  I've had the bowls off and cleaned the bottom half of the carb but I haven't had the top half apart yet.

[BobbyR]

I have a K8 also. The size is stamped on the bottom of the jets. I am the second owner and I have 120 which is larger than the stock 110. I am having no real issues. These bikes may smell rich since we are used to today's cars. The new plugs should tell you the story. 

[beaniam]

Yeah I'll know for sure with the new plugs and when I fill up on this tank.  I don't think I got over 100 miles on the first tank of gas when I got the bike but it idled a lot and sat for about a month while I was working on it.  I'll check my jets for a stamp.  I'm about 25 miles into the second tank and the fuel looks over 2" down from full.  The needles aren't adjustable on these are they?

[BobbyR]

On the K8 the needles are not adjustable. There is some way to shim them, since we have accel pumps we do pretty well when we crack the throttle open. 

[beaniam]

Much to my surprise they are 110's.  Is it possible to tell if they have been drilled out?

[TwoTired]

Much to my surprise they are 110's.  Is it possible to tell if they have been drilled out?

Of course.  If the actual holes are bigger than 1.10mm, then they've been drilled.

[beaniam]

Oh duh that makes sense.  I'll check with the micrometer tomorrow night.

[beaniam]

Finally got a chance to check it out.  Jets are marked 110 however a 115 drill bit fits smoothly in the hole.  Not snug.



Could even be a 120 possibly, I didn't have that size bit to check.  Would it be a good idea for me to pick up some 105 and actual 110 jets to give a try?  Bike has a 4-1 exhaust and pods.

[beaniam]

Ordered a set of 105, 110, 115 jets from Z1. 

[beaniam]

Put the 110's in and changed the plugs.  PO had 2 8's and 2 7's in.  I replaced them all with D8EA's.  Ran new fuel like with a filter from the petcock.  Mixture screws are all 1 turn out.  I lost some low end but everything else feels the same and overall smooth.  Haven't rode far enough yet to see if the mileage has improved.  The mains are really the only things in the carb that would effect mileage for the most part right?  It's a 78 carb so the needle can't be adjusted.  Not sure what else to try if my mileage is still horrible after this.  Brakes don't drag, I haven't adjusted the cam chain tension or valves yet but I wouldn't have thought they could be the cause of nearly a 20mpg loss.

I made sure while the pods were off to see that the choke fully opens which it does and the accelerator pump also works.  Strong streams of fuel shoot out of each one when I crank the throttle.

[GammaFlat]

You may want to change from pods to an airbox.  The main reason to do this is so you don't get beat up around here .  Many will say (and I believe them) that running pods makes it difficult to get get the bike running correctly.  Others will argue that getting the bike to run correctly with pods is not bad.  That may be true but there are probably more folks around here that will be willing to help you through your issues if your setup is more "standard". 

If you need an airbox, they're relatively easy to get and cheap.  Even if you want to run pods, it may be helpful to get it running correctly with an airbox so you have a base line. 

[beaniam]

I suppose it could be worth a try but is an airbox going to net me an additional 20mpg?  I picked up a spare complete set of carbs off ebay which are stock so I guess I'll rip into mine again and check things side by side for reference.