Topic: 76 F1,small cams,4 into 1,pod,836 kit.. Ball park main jet and needle position?

[1976cb750f836]

I've pulled. My bike out of the basement,where it sat 3-4 years in limbo.
I built it bout 12 years ago,836 mod and cams. Owned it over 20 years.
Trying to get all bugs out, I've messed with it in spare time all summer,almost Done?
My last modified was a different exhaust canister and baffle.
Got tired of the almost open header with insert baffle.
I'm nit picking the carbs now, in search of that FI tune?
The baffle I installed flows better than my old setup.
I'm up to 130 mains, and I've leaned the needle from 2ND to 3rd to 4th from bottom+ shim , now
As the mains went up I had to lower the needle to get good roll Ons!
Just wondering what main and needle setting most other 836 bikes were using,mine is still improving?
Stock 76 Fcarbs.

[Jerry Rxman Griffin aka MuthaF'er]

Sounds like you richened the needles if you are lowering the clip from the top?

My F0 812 with Yoshimura full race Daytona cam, stock head and Kerker at 7000' elevation was slightly rich (below WFO) with 115s and clip lowered 1 notch to 4th from the top.

Stock needle position is 3rd/middle.

[1976cb750f836]

My bad, I changed it,it was from bottom not top, I was leaning it (needle) When richen ing the main!

[1976cb750f836]

63 degree hear today, I rushed the carbs back on,after work today,left they partially done last night,after work.

By sundown I test drove, Best it's ever benn, with 130s, and clip in 4th from top with shim [3-1/2].
It now pulls hard from 4k to 9.5k. Like jerk u r arms Off! Below 4k it's slugish.(the cams I bet]
I might be done, I might try 132s? this summer,low Temps and low humidity now.
In East tn Temps will be high and high humidity in summer?
It kinda doesn't. Idle Well?
I've messed with air screws, set on bout 1 turn out,does that seem Close?
Am I mabe going to have to up my pilot? It's stock now?
Ps- it's Way better than before with my old baffle setup?
Thanks all!

[seanbarney41]

If you been messin' about with the needles, you are gonna have re-do your vacuum sync before it will idle nice.  Maybe it's just me, but I have always found the vacuum sync process seems to richen up the idle just a bit too.

[Jerry Rxman Griffin aka MuthaF'er]

Pilots should be fine @ 40. Fine tune with screws. Definitely sync!

[Don R]

 I could be incorrect but it sounds like you went to fat on the main jet and are correcting by going lean in the needles?

[Jerry Rxman Griffin aka MuthaF'er]

Kinda my take too Don.

[1976cb750f836]

I've read 2 different carb tuning manuals, they both say set the main first for best Performance!
While ignoring all other circuits of the carb.
Then set the needle for best roll ons.
Then set air screw,and adjust float for low Speed?
I also Web searched 836 jetting,a bunch of different settings came Up?
My plugs are still tanish,with no signs of too Rich?
With anything smaller than 127,it revs slowly front 8k up,with the 130s it revs and pulls hard to 9.5k.
Ps- these are the easiest  carbs I've ever changed mains in,I do it with carbs on bike,but those damn needles are the hardest I've ever done,and the carbs are the hardest to get off and on I've ever done?
I replaced my rubber intake when I did the 836,old ones were hard,now these seem hard,no cracks though.
I really love this bike,draws lots of attention at gas pumps.
I even took it to a HD show once,feared for my life [lol], but lots of HD riders started riding on Hondas?
It drew more attention than many custom HD bikes!
Thanks all.

[PeWe]

I caused lean at WOT on carb 1-2 by adjusting the floats.
I checked all 4 levels (clear tube) and saw that 1-2 were higher then the other and adjusted. (no other reason)
2 years after I remembered what I have done when the dyno run showed much leaner on carb 1-2 compared with 3-4. Should I really jet 2 carbs richer (main)?  I have earlier blamed fuel supply and routed fuel hose to 1-2 better.

I had to open the float bowls and adjust carb 1-2 back how they were. Next dyno showed better. All 4 now more equal.
Maybe carb model related. This is Mikuni TMR32

My recent experience is how the dyno is performed. The last dyno runs which gave the correct jetting were done to read the A/F ratio during cruising speed.
- Slowly increase throttle from 2000 to 6000 rpm on 5:th gear. This revealed really reach needles on my carbs. This is the most important reading for a street bike.

WOT done too of course to check full power HP vs Torque, main jets and the reason for lean I have caused, float levels.
Dyno is well worth the money to read the actual A/F ratio.

My K6 carbs with 836, ported head + cam + pods + 4-1 + leaded real fuel on the 80's 
Needles 1 step richer (4:th notch from top
Pilots 40
Air screws were opened only 1/2 turn

Mains were really big, 147.5!  This is strange, 130-135 is more understandable.
No dyno check, practical tests to and on full speed, release throttle a little at around 170-200 kph. If it ran better then, bigger mains.

[1976cb750f836]

The 2 center Cylinders do run hotter,might need a different setting, my stock suzuki gt550 2 stroke came from factory with different main in center cylinder, it's a thought?

[1976cb750f836]

I went up again to 132s, removed needle shim,now in 4th from bottom.
Damn thing is still getting better,and the shim out improved my off idle.
I thought it ran good before I started messing with carbs, now from 6k up its like a different bike,pulls hard,6 to 9.5k.
Might try to vac synk carbs this weekend,if time permits,still pitting up tree and Christmas Stuff!
Back before the 836 mod, I had a friend with a 81 gs750,16 valve, he could pull away from me.
After the 836,I could pull him, now it blows him away? Never thougot  a 8valve could run this good?
And it still lugs around,3-4k, at part throttle if need be without loading up.
Thanks all.

[1976cb750f836]

What is the max safe Redline?
I've not benn past 9k much, 9.5k occasionally?
Thanks

[MRieck]

What is the max safe Redline?
I've not benn past 9k much, 9.5k occasionally?
Thanks

In general you will not find any more power after 9,000RPM

[Jerry Rxman Griffin aka MuthaF'er]

Not any safer than the valve springs you are using.

[PeWe]

What is the max safe Redline?
I've not benn past 9k much, 9.5k occasionally?
Thanks

In general you will not find any more power after 9,000RPM

Yes, you are right Mike, it flatten out a little after 9000!  


Here another gang, screamers that seems to have CB750 performance up to around 7500-8000 rpm!
But they just continue, that's not fair!! What to do prolong the willingness to continue to at least  10.000 strong ones?

[1976cb750f836]

I put springs in when 836 kit and new cam, recomended  by cam mfg.
So 9-9.5 k is Safe?
Thanks.

[PeWe]

I put springs in when 836 kit and new cam, recomended  by cam mfg.
So 9-9.5 k is Safe?
Thanks.

Yes, my bike has seen that area very often. I did not have a tacho from 1982, but I switched sometimes to fourth gear at 100mph (160kph) when giving full until it flattened out. Front sprocket 17 that give around 9500 rpm. From 4 to 5 at around 185 kph (9000rpm)
You'll feel if getting much more after 8000-8500 rpm. Maybe not that much and you'll avoid wear. Important with a good oil.

[Jerry Rxman Griffin aka MuthaF'er]

I put springs in when 836 kit and new cam, recomended  by cam mfg.
So 9-9.5 k is Safe?
Thanks.

My 812F often saw WFO shifting at the top end of the of the 8500 - 9600 redline. JUST DON'T MISS A SHIFT THERE  The HD springs are engine savers. You should see the hole in the top of #2 piston when I missed 1-2 when it was stock. Mine has also seen 100mph in 3rd many times.

[PeWe]

Revving that high is mostly not for the power, its the sound and adrenaline kick!