Topic: Keihin CR, Dyna 2000, 836, ported head- Tuning

[scondon]

   It seems that the number of members with these performance mods is growing. This is my first time through with the CR's and Dyna 2000 so I figured it might be good to start a thread of the tuning so far.

Wiseco 836
Webcam 63a
Mrieck ported head with oversize intake valves
CR 29mm
Dyna 2000
Dyna 3.0 coils
Kerker exhaust/ no baffle, just the end cap

   Initially I had some trouble with the CR's and it took me a bit to figure out. I had bought them "slightly" used and fuel had dried on the starter circuit seats(http://www.sohc4.us/forums/index.php?topic=25833.0 ) . Fixed that and it was on to trying out different ignition/carb settings.

   Getting the main jets figured on the CR's has been a bit of a challenge. I can't do a plug chop and have been road testing much like I would road test stock carbs i.e.  get the bike rolling around 5000rpm and whack open the throttle. These carbs just don't seem to work that way and after initially jetting up to compensate, which didn't work, I've ended up with 120 mains, needles 2nd from top, 62 pilots w/ 1 turn out. Just to note, my needles are not the YY8 needles spec'd for 29mm carbs.

     The Dyna 2000 has 5 settings of advance curves. #'s 4 and 5 are spec'd for 2 valve motors and the manual states that 40 degrees of total advance timing is average. With the port work and oversize intakes my motor is burning pretty efficiantly and I have retarded timing to 35 degrees on the #4 setting. My mpg  went up slightly and the power stayed the same. I still get a little rattle at 3/4 throttle(pre-ignition) when the bike is very hot and will either retard the ignition some more or shim the needles a 1/2 step to see if I can't tune it out.

     My local shop is changing out their dyno at the moment, but it looks like I will be able to take the bike in for a run in early October. I'll get a good read of how it's burning fuel and where it makes power then.

     Since I understand better now just how these carbs work and have adjusted my throttle hand accordingly the bike is super fun to ride


EDIT:   posting final tuning results here, in case anyone searches this topic and doesn't feel like wading through to find them.

 Bike is now tuned as well as I'm going to get it before taking it to dyno. I've managed to tune out any rich "blubbering" and lean "rattling" at all throttle ranges, though I can still experience lean "rattle" if I lug the engine when it is really hot. Really nice to be able to experience the full throttle range without having to baby it through certain transitions

 Keihin CR 29mm-

115 main

needle clip- 2nd from top(lean)

62 pilot- 3/4 turns out

 Dyna 2000-

#4 advance curve

33.5 degrees total advance

[Heironymous Josh]

So long as the money's flowin' I intend to tear my bike down for a full resto and 836 engine build this winter.  I hope you don't mind if I look to you for a couple of questions.  If it makes you feel any better, I'll probably try buggin' Sparty too!

[scondon]

  No worries,H. Josch, most of what i've learned started with other peoples experience here on the forum. Happy to pass it on

[750essess]

I am also getting some pinging at half to 3/4 throttle under a high load, like climbing a mountain. I have tried anywhere from 32 to 35 degrees and position 4 and 5 on the dyna 2000. I am going to try raising the needles next. Im afraid the pump gas nowadays just isnt what it used to be.

[scondon]

I am also getting some pinging at half to 3/4 throttle under a high load, like climbing a mountain. I have tried anywhere from 32 to 35 degrees and position 4 and 5 on the dyna 2000. I am going to try raising the needles next. Im afraid the pump gas nowadays just isnt what it used to be.

   Thanks 750essess, those are the same conditions that I experience the pinging. Yesterday it happened on flat freeway, but that was only after heading home from 8 hours of high rpm riding.

    My other bike is also 836 but has the stock F2 "pumper" carbs and Dyna S fitted. With the extra squirt of gas I was able to tune out the 1/2-3/4 pinging, but the #35 pilot jets had me pinging just off idle.

     Currently I am able to just roll on to WOT, past the pinging point, then let the engine catch up before rolling back down to 3/4. Instead of trying to "lug" up and have the engine rattling away as I try to get beyond it.

      Thankfully there are many ways to approach tuning away the pinging with the Dyna 2000 and CR carbs. Raising the needle is certainly the easiest and most immediate approach. We have 91 octane supreme here in California and I'm with ya in believing that these motors would like a tad more than that

[nippon]

just my experiences with the following setup for my CB750K1:

Wiseco 836ccm
Webcam 63a
Ttianium retainers
Harder valve springs
head work by nippon
stock carbs, jets #120
Dyna coils 3.0
Dyna S
stock valves
Hm300 exhaust

There are no power leaks between 1000 and 8000 rpm. It pulls strong the whole way.
At 5000 rpm the engine is pushing forward great, at 7000 rpm,...the inferno is starting.
No pinging at any time, no wonder, I'm using the horrible expensive European 100 octane gasoline.

nippon

[scondon]

just my experiences with the following setup for my CB750K1:

Wiseco 836ccm
Webcam 63a
Ttianium retainers
Harder valve springs
head work by nippon
stock carbs, jets #120
Dyna coils 3.0
Dyna S
stock valves
Hm300 exhaust

There are no power leaks between 1000 and 8000 rpm. It pulls strong the whole way.
At 5000 rpm the engine is pushing forward great, at 7000 rpm,...the inferno is starting.
No pinging at any time, no wonder, I'm using the horrible expensive European 100 octane gasoline.

nippon

  Sweeeet!!!

   Are you using pods or stock airbox with your set-up?

[nippon]

stock airbox

[scondon]

stock airbox

   Definitely the way to go when possible. Much less troublesome and nice action through the throttle range compared to pods. I would have to mod something up for the CR's though, can't fit the airbox in with them and the Dyna 2000 ignition module mounted.

[Sam Green Racing]

Use the bellmouths, let the sum#$%* breath

Sam.

[sparty]

Guys,

I'll be running the CR carbs as well.  My local Shell station sells the V-Power fuel it is rated at 98 octane.  I'll use that in my tank.  Do you think I will experience any pinging with that fuel?

Art

[scondon]

Use the bellmouths, let the sum#$%* breath

Sam.

   You guys are just full throttle happy over there ain't ya   I know it's against the WOT Club rules, but maybe you could drop a needle clip or twist a idle screw to clean up Chris's plugs

[Sam Green Racing]

Guys,

I'll be running the CR carbs as well.  My local Shell station sells the V-Power fuel it is rated at 98 octane.  I'll use that in my tank.  Do you think I will experience any pinging with that fuel?

Art

That's what we run the CR on, should be just fine Art.

The only down side to it is, it smells fishy 

Sam.

[Sam Green Racing]

Use the bellmouths, let the sum#$%* breath

Sam.

   You guys are just full throttle happy over there ain't ya   I know it's against the WOT Club rules, but maybe you could drop a needle clip or twist a idle screw to clean up Chris's plugs

Now we know whats causing the problem we can sort it.

I spoke to the dyno guy this evening and he recons it can be controled on the mixture screws.

Sam.

[scondon]

Guys,

I'll be running the CR carbs as well.  My local Shell station sells the V-Power fuel it is rated at 98 octane.  I'll use that in my tank.  Do you think I will experience any pinging with that fuel?

Art

That's what we run the CR on, should be just fine Art.

The only down side to it is, it smells fishy 

Sam.

  I'm with Sam on that one,Sparty. With 91 octane the pinging comes only when lugging the engine in 5th,sometimes 4th, gear. I can richen up the 3/4 range to get rid of it, but usually at the expense of over rich 1/4-1/2 throttle. If I could get 96 out of a pump ANYWHERE in CA I'd be a happy camper. Where do I have to move to get 98? 

Use the bellmouths, let the sum#$%* breath

Sam.

   You guys are just full throttle happy over there ain't ya   I know it's against the WOT Club rules, but maybe you could drop a needle clip or twist a idle screw to clean up Chris's plugs

Now we know whats causing the problem we can sort it.

I spoke to the dyno guy this evening and he recons it can be controled on the mixture screws.

Sam.

   Also, you can cap the starter circuit air nozzles on each carb if your not using the choke for starts. The circuits are very touchy and if one is open just a crack that's a lot of extra fuel to one carb. Of course, you guys have about 20 times the experience with these CR's than I do so I offer this info as humbly as possible

[Sam Green Racing]

Sean, thanks for any info, I certainley don't have the experience that you have.
When we got the carbs, we fitted them then took it to the dyno to have it set up.
My only experence is changing the main jets. I've done it 4 times recently and have got it down to 9 minutes for the set.

Sam.

[MRieck]

Use the bellmouths, let the sum#$%* breath

Sam.

   You guys are just full throttle happy over there ain't ya   I know it's against the WOT Club rules, but maybe you could drop a needle clip or twist a idle screw to clean up Chris's plugs

You have to remember that that idle air screws, needle height and mains all work together. The mixture screws add fuel throughout the curve. You can't think of this circuits as individual machines that turn on and off at particular throttle settings. That's called fuel injection. Even then when you start spinning an engine to 10,000, 12,000, 14,000 RPM all sorts of things start happening. Sean and I were talking about this last Friday.

Now we know whats causing the problem we can sort it.

I spoke to the Dino guy this evening and he recons it can be controlled on the mixture screws.

Sam.

[scondon]

 The needles on these carbs are easier to change than the main jets, in my opinion. All ya need is a #2 phillips to pop the caps off and you can pull the needles out with your fingers. No need to drain gas from the bowls, just have to remove the gas tank. 8 minutes, easy

  Hey Mike, are there supposed to be washers under the needle clips on the CR's ?  I couldn't find them on the parts diagram and am thinking you might have put them there as a 1/2 step shim.

[Sam Green Racing]

Thanks Mike, I wondered if that was the case, if we manage to weaken it off down the lower end of the rev range on the mixture screw, we will probably have to go to bigger mains to correct it at the top end, is that right ?

Sam.

[MRieck]

The needles on these carbs are easier to change than the main jets, in my opinion. All ya need is a #2 phillips to pop the caps off and you can pull the needles out with your fingers. No need to drain gas from the bowls, just have to remove the gas tank. 8 minutes, easy

  Hey Mike, are there supposed to be washers under the needle clips on the CR's ?  I couldn't find them on the parts diagram and am thinking you might have put them there as a 1/2 step shim.

I probably did Sean. Hard to remember.

[MRieck]

Thanks Mike, I wondered if that was the case, if we manage to weaken it off down the lower end of the rev range on the mixture screw, we will probably have to go to bigger mains to correct it at the top end, is that right ?

Sam.

I'd think so but not by much. What idle jet are you running Sam and how many turns out? Did you check the float height? Block off those starter circuits vents too to get a solid baseline. If those aren't sealing perfectly you are dragging extra fuel and screwing up the carb synch as well.

[Sam Green Racing]

I haven't a clue Mike. When the carbs were fitted, Chris took it to the dyno when I was at work.

With it not being a road legal bike, it makes it difficult to do any adjustments and testing.

Sam.

[MRieck]

I haven't a clue Mike. When the carbs were fitted, Chris took it to the dyno when I was at work.

With it not being a road legal bike, it makes it difficult to do any adjustments and testing.

Sam.

You shouldn't have any problems with the Dyno and adjustments as the WinPep program gives you the A/F ratio with the pull

[Sam Green Racing]

I hope we don't have any problems on Saturday Mike. I've only met the guy once but lots of people have recommended him.

Sam.

[scondon]

 So I'm still playing around with different tuning settings in order to rid the pinging in 5th gear(3/4 throttle going uphill/ 91 octane) and also so that I can be more familiar with things when I take it to dyno.

  Yesterday evening I raised the needles(up one notch from leanest setting) and retarded ignition from 35 degrees to 33. I know, I know, one change at a time to better map results      At 33 degrees total timing the bike did not start up very easily in the #4 Dyna curve(25 degrees total advance) so I switched to #1 Dyna curve(20 degrees total advance) which effectively advances ignition at idle by 5 degrees.

  Bike started normally and the ride in to work had no pinging no matter what I tried   The ride home will be a better test as it should be a good 30 degrees warmer and the bike will be in stop and go traffic before it hits the freeway.

   I get the feeling that I may have swung a bit to the opposite side of "ideal" with this last tuning change. But no pinging is no pinging and I like that