Author Topic: 750K2 Hot Rod Revival - Early Christmas  (Read 43184 times)

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Offline PeWe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #150 on: August 30, 2019, 08:08:02 AM »
My Hindle 4-2-1 is really loud too, like a race exhaust when twisting. It has the longer and more silent baffle! :)
I hope that a Dyno can be done this year + video.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline MRieck

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #151 on: August 30, 2019, 10:07:44 AM »
Flat slides are noisy at low rpm idle! I prefer idle to be +1200 rpm.
Like spanish castanets ;)

I had also thoughts about something wrong so I searched about it and found several threads about clattering flat slides.

Do your carbs whistle when giving some throttle?
My TMR32's do. RS34 should also, right?
RS's don't whistle Per. The FCR's on my FJ do whistle.
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Offline PeWe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #152 on: August 30, 2019, 11:55:40 AM »
Aha, thanks Mike for extending my knowledge ;)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Bankerdanny

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #153 on: August 30, 2019, 12:22:23 PM »

Just found out is was the Dyna2000 box that took a #$%* on me. They won't cover it but are willing to give me a good discount. 137 miles.  ::)
Jerry, don't you have a new-in-the-box Gerex? ;) ;) ;)

Yes, yes he does, I've seen it. LOL. The problem with the Gerex (as you know) is where to put that giant controller box.
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #154 on: August 30, 2019, 12:30:13 PM »
Scott, yes. Wonder what it would sell for?! No more experimenting for me.

Joe, Bonneville was fun as usual but anti-climatic this year. The replacement 2000 is on it's way. Plug and play at this point. At least I hope so (again) haha
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline CBJoe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #155 on: August 30, 2019, 02:38:32 PM »
Safe to say the 115 Mains are too lean.  I did a lot of constant high speed on the test ride.  Probably gonna go back to 120s and see what the Dyno Says tomorrow.

I also have 122.5s and 125s to try.

Of note...these plugs are older and were not changed when I installed the Mikunis




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« Last Edit: August 30, 2019, 02:42:48 PM by CBJoe »
'07 Bonneville Black
'15 Moto Guzzi California 1400
CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #156 on: August 30, 2019, 02:53:40 PM »
How's the sync?
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline CBJoe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #157 on: August 30, 2019, 02:58:14 PM »
How's the sync?

To be honest Jerry I checked the bench sync'd but didn't check with gauges.  Now that the tank is on and time short I won't be able to check them tonight. 

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CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
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Offline scottly

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #158 on: August 30, 2019, 07:48:21 PM »
Something odd going on with #4 plug: looks like it had carbon buildup that later got baked to a crisp?
I think I'd throw in a new set of plugs if you have time.
Don't fix it if it ain't broke!
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Offline scottly

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #159 on: August 30, 2019, 08:00:12 PM »
Scott, yes. Wonder what it would sell for?! No more experimenting for me.

I paid $100 for one, but it wasn't new in the box. I might be interested? Danny, how much do I have left in my account, after all charges including the standard forum donation?
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Offline CBJoe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #160 on: August 30, 2019, 08:05:09 PM »
Something odd going on with #4 plug: looks like it had carbon buildup that later got baked to a crisp?
I think I'd throw in a new set of plugs if you have time.

New plugs installed and upped the mains this afternoon


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'07 Bonneville Black
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CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
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Offline scottly

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #161 on: August 30, 2019, 08:15:11 PM »
Looking forward to seeing the dyno charts for your bike and Ron's!! ;D ;D
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Offline CBJoe

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Re: 750K2 Hot Rod Revival - RS34s Tuning
« Reply #162 on: August 31, 2019, 12:11:42 PM »
Back from the Dyno...unfortunately wasn't able to get Ron's bike transported there for different reasons.   Dyno Charts attached...the chart with 3 runs they had something called SAE Correction enabled on the Dyno whereas they normally run with a standard correction.  So they re-printed 2 of the runs with Standard Correction and its attached as well.

79HP and 54ft-lbs Torque (EDIT: 91 Super Ethanol Free Fuel)

Was actually a bit less than what I was hoping for as I would love to have seen 85 or higher.  The shop says that their Dyno runs about 6% lower than dyno's from other shops they've done comparison runs with same bikes, but who knows.



My starter issue has reared it's ugly head again...though now it's not chattering and clacking.  See below video.  Almost sounds like the starter itself is going as opposed to the starter clutch. Luckily I have another good condition starter clutch gear i can install with new rollers and springs.


« Last Edit: August 31, 2019, 12:19:58 PM by CBJoe »
'07 Bonneville Black
'15 Moto Guzzi California 1400
CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
'66 CM91 (C90'ish)

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #163 on: August 31, 2019, 02:34:40 PM »
120's?? The big jet is too small. 14:1 at 8k and up. A little lean. I've always heard ideal is 12.5:1?? That'll get you a little more oomph. That'll get you closer to your target number.

Also drop your needle? Barely rich in mid-range. The mid is closer than top and richening the top may affect the mid somewhat too by richening it also.
« Last Edit: August 31, 2019, 02:41:57 PM by Jerry Rxman Griffin aka MuthaF'er »
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Offline MCRider

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #164 on: August 31, 2019, 02:38:56 PM »
Boy that sounds great Joe! Hard to believe we were standing just a few feet away from that chain howling at 120+mph.
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Offline CBJoe

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #165 on: August 31, 2019, 03:19:39 PM »
120's?? The big jet is too small. 14:1 at 8k and up. A little lean. I've always heard ideal is 12.5:1?? That'll get you a little more oomph. That'll get you closer to your target number.

Also drop your needle? Barely rich in mid-range. The mid is closer than top and richening the top may affect the mid somewhat too by richening it also.

What do you think?  up it to 122.5?  More?  I agree with dropping the needle maybe....but I also need to consider if I should adjust the accelerator pump at all...I need to check again at what throttle position its engaging.

They also did a "cruze" graph while warming the bike up.  Attached here....
'07 Bonneville Black
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CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #166 on: September 03, 2019, 10:38:55 AM »
Play with it. Start with the half size 122.5 and work up. When it starts to stumble or the plugs get sooty then back off. That would be my idea??
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline CBJoe

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #167 on: September 03, 2019, 03:27:08 PM »
I'll plan to go up to a 122.5 and drop the needle a clip position.  I need to get my starter issues sorted out...kick starting is cool and everything...but I'll take a working electric start :)

So once I do that and wrap up some random things I'll test out the setup on the road and monitor plugs.  Maybe take back to dyno before winter to really dial it in.

Jerry...remind me, what setup are you running in your bike?  915Kit? 
'07 Bonneville Black
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CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #168 on: September 03, 2019, 04:01:53 PM »
On the RS34 engine - 1000. RC/DP315 cam. Stage 3 head with 33.5mm intakes. Crower rods. Doesn't get any better  ;D ;) except as noted below..

I'm using you for a gauge Joe  8) I may have to buy some bigger jets though. I'm thinking 125's are the biggest I have. There are worse problems to have.

The "other" engine is 915, megacycle 125/75, JMR stage 4 head with 34mm intakes and 5mm stems, lightened/balanced crank, carrillo rods and CR31's.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline CBJoe

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #169 on: September 03, 2019, 04:05:27 PM »
On the RS34 engine - 1000. RC/DP315 cam. Stage 3 head with 33.5mm intakes. Crower rods. Doesn't get any better  ;D ;) except as noted below..

I'm using you for a gauge Joe  8) I may have to buy some bigger jets though. I'm thinking 125's are the biggest I have. There are worse problems to have.

The "other" engine is 915, megacycle 125/75, JMR stage 4 head with 34mm intakes and 5mm stems, lightened/balanced crank, carrillo rods and CR31's.

Jerry....maybe check with Mike, but I believe his million dollar CB is a 1000Kit as well and he's running 117.5 Mains in his RS34's, not sure about needle type or clip position.

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Offline scottly

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #170 on: September 03, 2019, 07:59:57 PM »
Regarding the starter, my first thought was a loose alternator rotor bolt? How much did you tighten it?

The different HP readings weren't due to SAE vs STD correction as much as because one was plotted with engine RPM and one plotted with wheel MPH on the horizontal axis. Possibly tire slippage on the drum?

I would go straight to the 125 mains, and leave the needles alone for now. The dyno is only good for setting the main under WFO throttle. The target ratio is from 12.8 to 13.2, which is why there is a red marker at 13 on the chart. You are at 14 in the RPM range you are tuning for. Like I said before, a bigger motor sucks harder on a main jet, so needs a smaller jet.
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Offline PeWe

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #171 on: September 03, 2019, 11:46:46 PM »
A more open exhaust need more fuel too.
From Yamiya no numbers 4-4/ Lotus root 4-4 to Hindle 4-2-1 (long baffle) needed main jets increase from 135 to 140, pilots from 32.5 to 40

EDIT: Pilots were way too rich! 30 is max in the TMR 32s. It was problems with too rich needle jets all the time, from P1 to one size smaller P0. Lifted the needles to 4:th notch from 2nd which will be a better combo.
(I had compensated the too rich needle jets by leaning the needles and richer pilots, still not OK and mire visible with a better flowing exhaust.)

TMR32 carbs 1000cc (71.25mm pistons, 1004.7cc)
No Dyno run on Hindle pipe yet, only butt Dyno that is not safe! I had a very close incident earlier this year testing high speed WOT!

It has RC295 that gave much more power from low to high than DP315 with various valve lashes (recommended worked best) and Megacycle 125-20).Both these other cams will most likely work better with higher comp as 12.5:1 and up.

The cheap compression tester show 190-195PSI with RC295.
I have to see the Dyno result.

One sidenote:
No numbers 4-4 gave 4hp more than the more open Lotus Root that gave much more torque from lower rpm. (This might been due to the too rich needles at that Dyno giving 4hp more top, bigger mains might given more with the latter Lotus Root)

Earlier 836 with same carbs and head with stock sized valve stems 34/28mm (now 5mm versions) and my old screaming 4-1 used 135 mains and 30 pilots verified on dyno. 81 whp with Action Fours SS-1 cam, 83hp with Megacycle 125-20 that went higher in the rpm.

No Dyno with RC295 and 836 that gave more from low, fun to twist throttle from 4000rpm on 5:th gear.

I'll fix floats on 1-2 that floading making plugs deep black and bad idle when back from vacation and hopefully a visit to a Dyno. Not same Dyno as before so numbers might differ due to that, a very experienced shop though .

I hope this can give you some ideas digging out the mist of yours, Joe!
// Per
« Last Edit: March 08, 2020, 12:48:18 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline CBJoe

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #172 on: September 07, 2019, 12:47:41 PM »
This time around those who called out loose alternator bolt get the prize.  Popped the cover off and the bolt was loose. 

Scott...I'll look to tighten and get all re-installed without touching the starter clutch so I can continue testing the one you turned down for me.

Also looks like its time for a neutral safety switch.  Pulled it and thoroughly cleaned, but bike still thinks its in neutral all the time.  wire tested fine so I know that it isn't shorted to ground anywhere.  testing between switch input and ground shows it's always grounded to chassis regardless of gear position.
« Last Edit: September 07, 2019, 01:40:07 PM by CBJoe »
'07 Bonneville Black
'15 Moto Guzzi California 1400
CB750K2 Hot Rod Revival http://forums.sohc4.net/index.php/topic,171693.0.html
'65 CB77
'66 CM91 (C90'ish)

Offline scottly

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Re: 750K2 Hot Rod Revival - Back from Dyno
« Reply #173 on: September 07, 2019, 06:47:36 PM »
This time around those who called out loose alternator bolt get the prize.
What did I win??!! ;D
IIRC, the bolt is supposed to be torqued to 75-80 ft/lbs? Last time I did mine, I could only get to 40 ft/lbs before I couldn't keep the crank from turning, so I put a mark on the head of the bolt with a felt pen and use an air impact to tighten it an additional 1/4 turn or so.
Make sure the neutral switch is fully seated; the body of the switch should be tight against the engine case.
Don't fix it if it ain't broke!
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Offline Kstuhren

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Re: 750K2 Hot Rod Revival - 5/20 it Lives :)
« Reply #174 on: September 26, 2019, 10:48:30 AM »
Are either of you Joe or Ron from Indianapolis area?? I'm in indianapolis and have been dialing CR29's for a year +. Would love to chat in person if able sometime.
Kevin Stuhrenberg
812-593-4100

So I'm trying to decide about fuel flow to the CR29s.   The tank currently has a New OEM style dual output petcock with the standard 5.5mm (ish) fuel line.  The Fuel inlet on the CR29s appears to be an 8mm (ish) inlet. 

I'm trying to decide if I'm good just plugging one of the outputs of the petcock and running a single line to the carbs, or if I should get a Y-Adapter to merge the two smaller diameter lines into a single 8mm line?

Thoughts?

Joe
Hi Joe: I had Phaedrus I plumbed with the 2 spigot tap to the CR29s. Used a T and had fuel line everywhere but it worked. Phaedrus II has a single nipple tap, and I used an in line reducer to get the hoses to work. Its a straight shot from the tap to the nipple on the carb ( a little underslung curve. The line goes up into the carb).

So you could close off one, and do the straight shot routine. But you wont have a functioning reserve, I don't think, unless you use both nips on  the tap.