Topic: My CB750K2

[willbird]

17 or 18t makes only ca:250rpm difference at 100kmh, 60mph.

My K6 with plenty of torque had no problem with 18, but got 17 to release some stress on the clutch
It has 130/80-18 rear tire, diameter between 4.0 and 120/90.

Rear tire size/profile make a difference.

Bigger 120/90-18 change rather much compared to 4.0-18.  (Lower rpm at a certain speed with 120/90)

The old style modification with 16" rear made more revs. 43t rear needed.

When I installed new tires recently I got 110/90-18 rear, the choice I made has zero wet traction so I could see an upgrade there this winter maybe. A 120 in the same tire would be 3.6% bigger circumference. I would not choose that tire tho ;-).

[Stev-o]

17 or 18t makes only ca:250rpm difference at 100kmh, 60mph.

My K6 with plenty of torque had no problem with 18, but got 17 to release some stress on the clutch
It has 130/80-18 rear tire, diameter between 4.0 and 120/90.

Rear tire size/profile make a difference.

Bigger 120/90-18 change rather much compared to 4.0-18.  (Lower rpm at a certain speed with 120/90)

The old style modification with 16" rear made more revs. 43t rear needed.

When I installed new tires recently I got 110/90-18 rear, the choice I made has zero wet traction...

What brand tire?  A softer compound tire with lower pressure will improve wet traction.  120 is what I run, it is .39" wider that a 110mm.

[willbird]

17 or 18t makes only ca:250rpm difference at 100kmh, 60mph.

My K6 with plenty of torque had no problem with 18, but got 17 to release some stress on the clutch
It has 130/80-18 rear tire, diameter between 4.0 and 120/90.

Rear tire size/profile make a difference.

Bigger 120/90-18 change rather much compared to 4.0-18.  (Lower rpm at a certain speed with 120/90)

The old style modification with 16" rear made more revs. 43t rear needed.

When I installed new tires recently I got 110/90-18 rear, the choice I made has zero wet traction...

What brand tire?  A softer compound tire with lower pressure will improve wet traction.  120 is what I run, it is .39" wider that a 110mm.

It is a Dunlop. The whole process of taking the bike from sitting around for 30 years, 5 of that in my outdoor shed to running and ridding was all about order of operations and focus on what needed to be done to make the bike run and ride. So ordering 2 tires, tubes, and rim strips from one supplier as a package deal helped that process along.

I looked at what I took off and originally I did have a 120 on it so that should fit fine, I'll work on finding the perfect tire this winter :-).

Put the Hondaman ignition on yesterday when I got home from my normal 315am-1115 am Saturday OT shift. Found out that my 25 year old self somehow has the wire colors swapped up so that blue and yellow cross under the RH side cover. Minor issue there, will resolve that easily, I had totally forgotten that. Thinking on fire up it would not run way back then and I just swapped wires there.

Bike had been running kinda crappy 2k to 3k rpm under power...idle screws have been out one turn for this whole resurrection.....took a ride with a screw driver starting at 3/4 turn, that made it worse, took them out to 1-1/4 turn and that made it great :-).

New spark advancer from 4:1 showed up yesterday....might fiddle with installing that next week.

Bill

Bill

[willbird]

Removed, cleaned, lubed, and reinstalled stock advancer. did not pay attention to where the cam was aligned when I took it apart, used repro advancer from 4:1 as reference to reassemble, hmm bike does not run. Swap blue and yellow back to blue-blue yellow yellow and it fired right up. So sometime in the past between my dad and my 25 year old self the points cam was assembled 180 degrees out :-). 

Mystery solved on why one of us needed to swap wires many years ago anyway :-).

Will verify points  gap and timing later this week.

The cam on the 4:1 advancer has a "weird" spot on it's profile.

Bill

[willbird]

One set of points the gap was a little large, adjusted that, checked timing, timing was good.

Bill

[HondaMan]

Softer tires today are the Metzlers and the Bridgestone in the BattleAx (spelling?) type. Avoid the "Conti Twins" from China. The Continentals from Germany are good, if hard to find. My all-time favorites are going out of business (Avon).

[willbird]

Fighting a lean issue at cruise speeds. Felt like a lean issue, pulled plugs #1 and #4 after a ride and they are indeed white. Replacing crappy OEM "replacement" carb boot clamps with the Oetiker clamps as a start. I had them so went ahead with installing them.  Double checked that Pilot jets are clean the other day. Petcock strainer is totally clean, no debris in fuel bowl or carb bowls.

Have struggled a bit with this since installing initial awakening when I installed a supposedly NOS Honda petcock. Have proper 5.5mm fuel lines routed correctly. Popping tank lid does not resolve issue so that eliminates tank venting as cause.

Need to proceed with making a way to do clear tube method and confirm flat levels.

Spotted a set of new OEM #45 pilot jets on Ebay and grabbed them to hedge my bets on final solution. I have a set of non Honda mains that I could work into if need be. I raised the needles one notch back in the 90's and jetted up when I added the pods. Could be that with todays nearly universal E10 that I am just on the edge of too lean maybe. Left pilots alone back then. Dug back through some posts and found that bike presently has #130 main jets in it. has been getting 45mpg cruising 60 mph.


Bill

[willbird]

Ok was able to get all 8 cl Oetiker clamps installed :-).

Got a plain vanilla points cover. $23 shipped, it will do for now. My OEM was damaged due to a small accident I had in 1990's when somebody did a U turn in front of me.

[willbird]

Messed up and ordered the wrong pilot jets. Saw email and realized part number was wrong.

Ordered 99124-286-0450 Fits Honda CB350K CL350K CB360T CB450K

Need 99124-076-0450


Bill

[willbird]

Ok got a clear tube device made up, translucent tube in this case I guess LOL.

Had some 6061T6 kicking around. Thread is supposed to be M6x.75. Set lathe up and cut that thread, ran nice into a K3 float bowl, fits my K2 bowls too. There had been a few questions about this thread and this answers it for for K2 and K3 anyway.






As Bike has been since new IMHO.


Made an adjustment to all 4 to raise float level a couple mm.

[RAFster122s]

Nice work!

[BenelliSEI]

Very nice! You could sell those on here, for sure!

[willbird]

Very nice! You could sell those on here, for sure!

Yea I'd have to make a couple more to refine the process a little. Aluminum is not the best choice but it was what I had. Anodized aluminum might be OK.

Free machining steel or even 416 stainless would be a better choice.

Bill

[willbird]

Moved idle screws from 1-1/4 out to 1 turn out. Runs as it should at cruise now, feels a little rich just off idle though. I'm strongly considering buying a wideband fuel air setup.

Not sure if main jets need to go up a size or if needles need raised one notch, the main jet swap would be a lot simpler to try.

Needles are raised one notch from middle now, have been since 1992.

Need to do another carb synch too and see where things are in that dept.

Bill

[BenelliSEI]

Bill ….. sync the carbs first. Sounds like you are getting close.

[willbird]

Bill ….. sync the carbs first. Sounds like you are getting close.

I think sync would be good. But I have had those Kehin 130 in there since the 90's, I'd like to try a bit richer up top. Of course the conventional wisdom is that it will be clearly inferior without stock airbox anyway ;-). As it sits now it runs pretty good at 60mph where is where I like to be anyway, just a little blubbery around town, but the way I like to ride, around town is strictly temporary anyway :-).

I also have a couple sets of Denso plugs coming too, and it may be they work better around town.


Bill

[willbird]

I put float levels back to original. Have not ridden yet. Bought a wideband fuel air ratio setup. Need to find a way to mount the gauge. Not really intending to use the system full time with carbs. Just use it ti tune. I have aspirations to setup a MicroSquirt ECU to handle spark and fuel and will need the wideband for that. Need improved charging system to do that.

But for today the wideband should provide interesting data. Thinking to add a TPS to allow logging fuel air and throttle position using a raspberry pi. Quick and easy stuff will allow logging 5 times a second. More neckbeard solutions will be able to log way faster.

https://pi-plates.com/product/daqcplate/?gclid=EAIaIQobChMIp47Oq7K5gAMVRt3jBx3vewXGEAAYASAAEgLtWPD_BwE

PIPLATEelogger is a simple ap that allows logging 5x a second.

Of course a microsquirt would log but not prepared to throw down the $ for that quite yet.

[PeWe]

If carbs are floading due to float level, spark plugs will tell.
Pitch black, velvet surface
I have some like that

[willbird]

If carbs are floading due to float level, spark plugs will tell.
Pitch black, velvet surface
I have some like that

It just ran like crap period :-). Apparently where they were since 1972 was correct

[PeWe]

Floats can suddenly be stucked inside float bowl or dirt making float valves to not close completely.

Old dried fuel residues when parked.

[willbird]

Floats can suddenly be stucked inside float bowl or dirt making float valves to not close completely.

Old dried fuel residues when parked.

that can happen and does happen :-), but this is all minty fresh. it ran and IO could ride it but setting the float levels 2mm higher was an experiment, and my evaluation is "that sucks" so I set them back to where they have been since it was new :-).

[PeWe]

OK, so the higher fuel level on photo above gave sooty plugs, rich running at idle, lower throttle lift?

[willbird]

OK, so the higher fuel level on photo above gave sooty plugs, rich running at idle, lower throttle lift?

Worst was just off idle, I did not do a plug chop riding it around in that zone of throttle opening :-).

Bill

[PeWe]

OK, so the higher fuel level on photo above gave sooty plugs, rich running at idle, lower throttle lift?

Worst was just off idle, I did not do a plug chop riding it around in that zone of throttle opening :-).

Bill

Now back as the other photo with lower fuel level and it runs not rich anymore?

Good photos of verified rich and OK.

[willbird]

OK, so the higher fuel level on photo above gave sooty plugs, rich running at idle, lower throttle lift?

Worst was just off idle, I did not do a plug chop riding it around in that zone of throttle opening :-).

Bill

Now back as the other photo with lower fuel level and it runs not rich anymore?

Still need to give it a spin around the mile square :-). It was less than perfect before that. I might need to raise needles another notch. Will see once I get the wideband hooked up.

Bill

Good photos of verified rich and OK.