Topic: brandEn's K4

[brandEn]

Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

[brandEn]

float level should be 3 or 4 mm below the gasket...that looks too low

Really? Hmmm, I though I  had the 26mm set good. Maybe I measured from the wrong spot. I measured from the bottom of the little notch of the carb body casting.

setting the float to 26mm is supposed to result in the fuel level being 3 or 4 mm below the gasket.  I have found that it often does not.  So much so, that I don't even measure the float position anymore.  I just adjust the float until it results in the actual fuel level being 3 or 4 mm below the gasket.  No idea how much of this really has to do with your idle problems, but it has worked for me.

I'm gonna keep that in mind. Pretty sure I can do that without pulling the carbs. It would make a mess with fuel though.

[seanbarney41]

yep, that snap wire float bowl retainer thingy is my favorite thing about these carbs

[Jerry Rxman Griffin aka MuthaF'er]

float level should be 3 or 4 mm below the gasket...that looks too low

Really? Hmmm, I though I  had the 26mm set good. Maybe I measured from the wrong spot. I measured from the bottom of the little notch of the carb body casting.

I've done my measuring from the cut out notch right below the hole for the bowl retainer clip. None of the pictures in any of my 4 manuals are good but the one I'm looking at now in my CycleServ manual shows a float tool being used that has a fat base that fits right into that notch and is the same width as the notch.

[brandEn]

Thanks man. I read on another site that was the right spot, good to have some more confirmation. I'm gonna try and raise the fuel level a bit like suggested.

Now about those vent lines Chef mentioned. Those need hoses for proper operation?

[lucky]

Comment: Lucky-

"I adjusted my floats to 26mm before installing them. One thing I  noticed is that the float valve springs would not compress under the weight of the float when it was resting on the tang. Not sure if that would cause problems or not."

That is right. The float tang should just touch the needle it should not depress the spring. The spring does NOT shut anything on or off.
It is just sort of a shock dampener. Look at it closely and you will see that.

If you take a float needle and look at it closely you will see that the little pin that pushes up and down does not open or close ANYTHING and does not OPEN
If you installed new float needles and seats and adjusted them the way the book tells you there is NOTHING else you have to do.
They do not control the way the engine runs.
All they do is supply gas for the carb to run thats it.

Hopefully you did not use that clear tube method to set your floats.

Are all of the mixture screws set to the same EXACT number of turns open??
Very important.

And remember DO NOT touch the mixture screws to sync the carbs !

[lucky]

Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

You have to have those vent lines on the carbs!
If not, they can spill over and start a fire when the engine gets hot.

[brandEn]

Thanks, I will get some installed ASAP.

[brandEn]

Comment: Lucky-

"I adjusted my floats to 26mm before installing them. One thing I  noticed is that the float valve springs would not compress under the weight of the float when it was resting on the tang. Not sure if that would cause problems or not."

That is right. The float tang should just touch the needle it should not depress the spring. The spring does NOT shut anything on or off.
It is just sort of a shock dampener. Look at it closely and you will see that.

If you take a float needle and look at it closely you will see that the little pin that pushes up and down does not open or close ANYTHING and does not OPEN
If you installed new float needles and seats and adjusted them the way the book tells you there is NOTHING else you have to do.
They do not control the way the engine runs.
All they do is supply gas for the carb to run thats it.

Hopefully you did not use that clear tube method to set your floats.

Are all of the mixture screws set to the same EXACT number of turns open??
Very important.

And remember DO NOT touch the mixture screws to sync the carbs !

Thanks lucky!
My screws are at one turn open each. When I synced my carbs I did not touch the screws. I got a great sync on the carbs now and adjusted the slide adjustments only. 

I used the clear tube method to see where the fuel was and to double check my work on the bench. All levels are even but seem to be 2-3 mm low.

[flybox1]

I used the clear tube method to see where the fuel was and to double check my work on the bench. Which is the right way to do it. All levels are even but seem to be 2-3 mm low.

...and this can be caused by those new float valves with new/heavier internal springs.  make that float height 25mm as I mentioned yesterday.  1mm float height makes +/-2mm fuel level change.  should be good to go. 
get that exhaust leak figured out?

[brandEn]

Exhaust leak is fixed. The #1 copper gasket was leaking for some reason. Replaced all four. Good to go. Gonna try adjusting the floats later today.

[Jerry Rxman Griffin aka MuthaF'er]

Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

You have to have those vent lines on the carbs!
If not, they can spill over and start a fire when the engine gets hot.

Did we not notice the bike's name? 

[brandEn]

Got the idle issue ironed out I think.
I raised the float levels a couple mm's and it definitely idled better. But once I richened up the air screw from 1 turn out to only 1/2 turn it ran even better.
Went and got some fresh 92 and better yet. Pretty happy with the way it idles now.


I can pull the airbox, carbs, and adjust the floats then put it all back together including adjusting the cable in under 30 minutes....
Not to bad.
 




Now.... I need to try and remove some of that dampening fluid out of the tach. I overdid it and it moves SLOW. I also need to fiddle with the neutral switch as it is always on even if I put it in gear.




IDLE FIXED and Rosco is confused at the end
CB750 idle fixed

[cheftuskey121]

very glad to hear it Branden! super jealous of that tone. I am hoping my next bike will have a motogp pipe on it

[brandEn]

very glad to hear it Branden! super jealous of that tone. I am hoping my next bike will have a motogp pipe on it

Thanks!
This pipe sounds completely different than my Yamiya. Way throatier. I know that's not a word but it fits the description well I think.

[cheftuskey121]

do you have video of the yamiya pipe? how much is that one?

[andy750]

Well done! It's great to get all these updates and then you solve the issue. Can you post another video when you get the chance as curious to hear the difference. Thank you! Glad to hear you have become a carb expert - it's much easier when everything is new!

Enjoy the ride and all your hard work!
Cheers
Andy

[brandEn]

Thanks Andy. I have some riding videos of TAO with the Yamiya pipe in the build thread and my You Tube page. I can get a garage idle vid if you guys would like.
 
http://www.youtube.com/channel/UCjNgibJ82CxNiAj_V_KA4rw

[cheftuskey121]

Thanks Andy. I have some riding videos of TAO with the Yamiya pipe in the build thread and my You Tube page. I can get a garage idle vid if you guys would like.
 
http://www.youtube.com/channel/UCjNgibJ82CxNiAj_V_KA4rw

oh yes of course! lovely sound. I would like to hear both of them idling and rev'ing. I am narrowing my search for a pipe down....too many choices. even considering a Benjie 4-4 for a retro racer look...

[Stev-o]

Great news, glad you found it relatively quick. Rosco did look totally confused!

[brandEn]

Anybody have some advancer springs they can rob/sell off an old advancer for me ?

[flybox1]

Anybody have some advancer springs they can rob/sell off an old advancer for me ?

yep...

[brandEn]

Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.

[MCRider]

Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.

That's a good price. I've seen them go for $50, being as they are NLA. If you need one there's no alternative.

[brandEn]

Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.

That's a good price. I've seen them go for $50, being as they are NLA. If you need one there's no alternative.

Yes it is a good price. Lucky for me it was one of the cheapest and best condition advancers.