Topic: Andys CB810 K2 -updated 14 Oct 2024 - missing link!

[MRieck]

Happy to say the broken pilot jet has been extracted and Andy should have the carbs back very soon.

Thank you Mike!!!!   

My pleasure brother.

[knowsnothing]

Are the felts on the throttle shafts lubed? That can cause a slow return to idle.

Hey Raf, thanks for thr tip.  I dont want to steal Andy's thread,  but i dont think its that.  I recently rebuilt the carbs and they snap back closed nicely. It also doesnt do anything when i try to twist the throttle forward, so the carbs seem to be all the way closed and not hanging.

[andy750]

Thank you Treeve! I was over in your neck of the woods on Saturday morning at 8am....did the Blue Hills-Wollaston Beach loop from mine and back to test ride the K2. Passed with flying colours! Next time Ill shoot you a text before I head over. I was back home by 8:30 before the heat hit.

How is your bike coming along? Running yet? Need any parts? 

Let me know next time for sure. 

The bike is finally running.  I still need to finish the tank and seat, but I have a stock tank and seat on it for now so I can get a few miles on it while i finish.

 Right now i am working on tuning.  It has a hanging idle issue I think is likely due to a lean condition, so I am working on that.  Still need to open it up on a highway, but its nice and peppy so far. I am just pumped it didn't grenade on first start up since i did do most of the work      .

Congratulations!! Its a great feeling when it dosent explode and actually runs . Both my K4 and K2 had hanging idle issues after rebuild - especially the K4. For me it was find adjustment of the air screws (after running bike for x miles) and changing the spark plugs made a big difference. Looking forward to coming over and seeing it! Maybe a Wednesday night or one of these weekends.

[andy750]

Just an update on the K2:

MikeR did an amazing job on the carbs and extracted the broken pilot jet in his sleep. He also sorted out all the uneven floats (how it ran so well before is a complete mystery) and put in shiny new 112 mains; I had already transferred the 120 mains to the spare carbs I had as thats what the 810cc likes. Thank you Mike now I have the best set of spare carbs!

Last weekend I took the K2 for a test ride: a 280 mile round-trip to Chester, Vermont for lunch at the Scottish pub for double haggis, tatties and neeps. The K2, after the carb change, after the DynaS install (and timed by me), after the plugs were all changed ran like a top and got me to VT with a big smile on my face. The way back was no difference with a very satisfying high speed run down Rt2 in 90+F heat. I had left at 9am and was back by 6pm  . What a great day for riding!

Love this bike and thanks as always to MikeR for keeping me on the road! At 62,000 miles this bike is only just warming up (the K4 has 92,000 miles  ).

What a great summer for riding so far....
cheers
Andy

[PeWe]

Good news Andy!
We have hopefully 2 months left for rides and restaurant/cafe pit stops.

You run with Keihin 112.5 jets?
I have always seen them in steps of 5 only.
I saw a seller that sold them in 2.5 steps as Mikuni.

It can differ a lot between 2.5 sizes. If only using 5, result can be to choose between too lean or too rich.
My K6 Mikuni carbs run fine on 145.
147.5 is too rich. At high speed 160-190kmh, reduce a little, WOT again, reduce. I hear how engine get too much.
142.5, loss of torque when twisting from 100kmh (60mph), big difference.

This must be the truth for Keihin std carbs too.
My stock K2 has 115 since 120 was too rich, 110 gave less response.

When google "keihin 112.5", I get plenty of hits.
I need to look for a set of new main jets

[scottly]

Andy, I already knew what haggis is, and I'm guessing tatties are mashed potatoes, but what are neeps?
Per, Keihin does make jets in steps of 2.5, but they are usually marked as 2 or 3, like 112, or 118, IIRC. Once you get past a certain size, each step is 5.

[PeWe]

Thanks, good to know.
I have gaps to fill in my bag with jets

[andy750]

Andy, I already knew what haggis is, and I'm guessing tatties are mashed potatoes, but what are neeps?
Per, Keihin does make jets in steps of 2.5, but they are usually marked as 2 or 3, like 112, or 118, IIRC. Once you get past a certain size, each step is 5.

.
Neeps are turnip (usually yellow once cooked). Pic attached of the Haggis lovers special 

Per, my 810cc K2 runs best with 120s, stock airbox, HM300 pipes (need to replace baffles as quite the drone at the moment when zipping along the highway). I went from 110s to 112s to 115 to 120s. Did this a number of years ago and stuck with the 120s. Based it on riding, popping out the exhaust on decel and plug colour.

My 836 K4 will get the new MikeR carbs with the 112s as currently it has 110s on there. Maybe a Fall project.

Your are correct though only a few more months of riding. Hoping to get to December this year but all depends on the Fall weather (my favourite time of year is Fall although have to say its been a great summer so far.

Andy

[PeWe]

Andy,
"my 810cc K2 runs best with 120s, stock airbox, HM300 pipes"
- Is that with needles at 4th notch from top?

[andy750]

Good question Per but to be honest I cannot remember _ been a few years since carbs were opened up

[PeWe]

My stock K2 with stock airbox, Yamiya no numbers (HM300 type) without wool has:
Stock pilots, air screws 1 turn out, needles at 4th notch, 115 mains. (Tried leaner needles wirh different main jets before)

[andy750]

The K2 gets new tires:

http://forums.sohc4.net/index.php/topic,186278.msg2164170.html#msg2164170

Mounted and balanced them myself 
Looking forward to seeing if they outperform the Accolades that were on there - they should!

[andy750]

Thanks to Dick in Southwick, MA for putting me onto these HM300s for sale - covered in grime they are in remarkably good shape once cleaned. And I got to see Dicks beautifully restored K1.

cheers
Andy

[MRieck]

Thanks to Dick in Southwick, MA for putting me onto these HM300s for sale - covered in grime they are in remarkably good shape once cleaned. And I got to see Dicks beautifully restored K1.

cheers
Andy

Looks like you found the Holy Grail brother.

[PeWe]

Look really fine! Still Christmas!
So finds like that still out there...
Thick layer of dirt has protected them!

[Stev-o]

Thanks to Dick in Southwick, MA for putting me onto these HM300s for sale - covered in grime they are in remarkably good shape once cleaned. And I got to see Dicks beautifully restored K1.

cheers
Andy

Looks like you found the Holy Grail brother.

+1!   Just what I need for my upcoming K1 project

[andy750]

I replaced the wiring harness (Yamiya K0-K2 replica harness) 140 miles ago as mentioned in this thread:

http://forums.sohc4.net/index.php/topic,190819.msg2220274.html#msg2220274

Bike ran great after harness install with no issues.
Battery had been in bike since 2020 and kept on Batter tender when not being used.

Went for a Sunday ride heading west and got about 15 miles from home when bike died at a junction. Pushed it to the side of the road and discovered battery was only reading 8volts. Bummer! No kick start on this bike. Managed to jump start it after a few tries and rode it back towards home - decided to take the highway to make it quicker and had a blast up I-95/Rt128 for 2 exits coming off at Kendrick St...running fine....until the second traffic light when it died again....pushed it off to the side and eventually ended up in an industrial/office car park with a gentle slope for a bump start....after several attempts no luck this time...battery was probably too low...6 miles from home 

Took letf sidecover off and discovered one of the rectifier plug wires had melted and had separated...bugger!....called help and got a ride home where I got my K4 battery, jumped in the car with tools and went back to the bike. Took old battery out and discovered it was swollen.....

Replaced battery, twisted the melted rectifier wires together, got geared up and hoped for the best...rode the bike home....amazingly it made it with no issues reading 12.9v at the end 

So...why did the new harness get fried after 140 miles since install? Nothing else had been changed once I installed the new harness...had I connected a wrong wire somewhere? Was it the old battery? Did I connect new harness up incorrectly?  I need help!!

See photos below for closeups...no other part of the harness was damaged only by the white plug as shown in the photo.

Thank you!
Andy

[andy750]

There was some burn through here as well....where the oem sticker is on the frame

The twisted bare wires was me AFTER I discovered it was broken and thats how I rode it home (last pic).

[Godffery]

Due to the battery being swollen like that; My first thought would be a possible over charge issue.
If so, that would lead me to suspect that the voltage regulator stuck in the charge mode? Or perhaps a failure of the rectifier?
 In ether case, this might be a good time to update those components with one of Rick's Reg/Rec units to eliminate those as a possibility. 
 https://ricksmotorsportelectrics.com/l/honda-regulator-rectifier

[Kevin D]

Andy,

In the aftermath, your bike ran without issue with a different/decent battery, yes?
Even with the twisted wire roadside repair it ran!
Did you start it with the electric starter?
Have you checked the voltage with the bike running? 2000rpm, 4000? Lights on? lights off?

Was it the old battery?

I wonder what it looks like under that bulge?
A short?

[scottly]

Andy, the wire with the insulation burnt off appears to be touching the rectifier fin in this pic, perhaps causing a short circuit if the fin cut through the insulation?
edit: Check the diodes in the rectifier itself. Shorted diodes may be the cause of the melted insulation. It's a fairly simple test with a meter that has a diode test function, usually represented with a symbol like ->l- .

[andy750]

Thank you all who replied you have given me something to work on and test. Ordering a replacement harness, test the rectifier (potentially replace it).

Kevin, yes ran it with new battery and yes it ran fine with 12.9v at end of 6 mile ride home. I am more worried by long term damage but I take your point. Ill very carefully wire the new harness making sure no short contact points. Will do as you suggest and do a more thorough check of voltage at varying rpms.

Ill update here with progress but with winter approaching may take a while.

Much appreciated,
Andy

[scottly]

So...why did the new harness get fried after 140 miles since install? Nothing else had been changed once I installed the new harness...had I connected a wrong wire somewhere? Was it the old battery?

I now believe it was a shorted cell in the old battery. The charging system was trying to shove 14 volts into what is now a 10 volt battery, which overheated the wire, as well as the battery case.

[scottly]

Battery had been in bike since 2020 and kept on Batter tender when not being used.

This would not be the first reported case of batterycide by battery tender.

[Godffery]

Battery had been in bike since 2020 and kept on Batter tender when not being used.

This would not be the first reported case of batterycide by battery tender.

I have seen that some batteries are more temperamental on the type of charger / tender or setting. ( AGM, Gel, flooded, Lithium, Etc. )