Dyno Disappointment.....

[Hadies]

mine made about 55hp and not much above standard have done alot since phil with a kiss, my chain was fucked flat spot at 5k, stupidly rich through out on 118x120s

im now on 115x118s, that is a standard size for the L & M japanese models i believe.

Is that with a full tyga system Rick? IIRC your also running a modded airbox?

[porndoguk]

mine made about 55hp and not much above standard have done alot since phil with a kiss, my chain was fucked flat spot at 5k, stupidly rich through out on 118x120s

im now on 115x118s, that is a standard size for the L & M japanese models i believe.

Is that with a full tyga system Rick? IIRC your also running a modded airbox?

Full tyga, with k&n Rick o needles, and i also got some 24 slides to chuck in.

[Hadies]

Hmmm. Perhaps I need to drop down from my 120's with RO's needles. Standard everything other than a full tyga. Dyno time!

[porndoguk]

i think the rick o jets, are Dyno jet equivilant, so will run richer than Keihin jets FYI so 120's could be 127.5 keihin equivilant in size

see here

Width------Keihin # -- DynoJets # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9
0,0870---- 222,5------- 196--------- 183,7
0,0880---- 225--------- 198--------- 185,6
0,0890---- 227,5------- 200--------- 187,5

[phil x]

I think there could be something in the different mains supplied by Rick.
The Keihins have 3.1 mm exposed, the RO jets are 4.1mm. Surely this is the same as moving the float heights from 6.8mm (stock) to 5.8 as they will sit 1mm deeper into the fuel?
I guess the only way to find out is a back to back dyno run with the same size RO & Keihin jets.......
Anyone happen to have a dyno run on a stock bike with original 110 mains?

Neo; i never thought about an air leak causing the lean tickover....., i did however spend time ensuring the carbs were correctly seated & the clamps haven't slipped (why is it always the front right that drops?!?!
Vac pipe was new (R/O) & the vac tapping screws are in place, carb rubbers look good too.

Phil

PS; When i had the tank off yesterday, i whipped one of the plugs out - they were 'very dark' in colour. Too dark imho.
Lets see how i go with stock 110s

Sent from my HTC Desire S using Tapatalk

[Hadies]

i think the rick o jets, are Dyno jet equivilant, so will run richer than Keihin jets FYI so 120's could be 127.5 keihin equivilant in size

see here

Width------Keihin # -- DynoJets # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9
0,0870---- 222,5------- 196--------- 183,7
0,0880---- 225--------- 198--------- 185,6
0,0890---- 227,5------- 200--------- 187,5

That doesn't sound too good. They are dyno jets, however in Rick O I trust. I told him my setup and he suggested this.

[porndoguk]

That doesn't sound too good. They are dyno jets, however in Rick O I trust. I told him my setup and he suggested this.

However
1 - maybe he isn't aware of the size difference between his RO/Dyno and the stock keihin?
2 - what's good for one NC30 isn't necessary the same for another ive learnt this! the hard way!

[phil x]

Without doubt, Rick O is an invaluable resource for the NC30s
Rick suggested the 115/118 mains confirming suggestions from this site, I also purchased the .5mm needle shims as these were suggested too but I decided not to fit these.
Everything else in the carbs is stock & all looks mint with no apparent wear to the needles/emulsion tubes.
To my mind, especially having seen the dark plugs & contrary to other suggestions here, 12 - 12.5 is too rich.....

I really didn't want to to go for another dyno run but feel that I'll have too just to see where I'm at with a stock setup.

Does anyone have a dyno printout of a stock 'k' model running stock (110) mains. If they run as lean as everyone says - I can't believe they go from very lean to very rich by changing from 110 - 115/118 as, In all fairness, it's not that great an increase.......

My money is on the Rick O jets not being comparable to the Keihin jets as shown in the list above
Maybe someone with more time & money than me can dyno their bike with stock 110s then ROs 110s or later model 115/118s then again with ROs 115/118s. At least any future suggestions can be based on fact not assumptions

Cheers, Phil

[amorti]

Without doubt, Rick O is an invaluable resource for the NC30s
Rick suggested the 115/118 mains confirming suggestions from this site, I also purchased the .5mm needle shims as these were suggested too but I decided not to fit these.
Everything else in the carbs is stock & all looks mint with no apparent wear to the needles/emulsion tubes.
To my mind, especially having seen the dark plugs & contrary to other suggestions here, 12 - 12.5 is too rich.....

I really didn't want to to go for another dyno run but feel that I'll have too just to see where I'm at with a stock setup.

Does anyone have a dyno printout of a stock 'k' model running stock (110) mains. If they run as lean as everyone says - I can't believe they go from very lean to very rich by changing from 110 - 115/118 as, In all fairness, it's not that great an increase.......

My money is on the Rick O jets not being comparable to the Keihin jets as shown in the list above
Maybe someone with more time & money than me can dyno their bike with stock 110s then ROs 110s or later model 115/118s then again with ROs 115/118s. At least any future suggestions can be based on fact not assumptions

Cheers, Phil

I am buried in a similar hole atm, having changed my CB-1 to nc23 carbs, free-er filter and open can I am really struggling to get the jetting even close. You wouldn't think it but going from 110-115 makes an immense difference.

Consider, the relationship between jet sizes and fuel flow is not linear but geometric. For every 0.025 step in jet sizes, the diameter of the jet goes up by Pi * R^2. As you can see by comparing 110 and 115 in my little chart below, (4.155 \ 3.801) = 1.093, so there is 9.3% more area and thus fuel. So a 115 jet has about 9% more area than a 110 jet OF THE SAME BRAND, but there are complicating factors if you now switch brands again. There seems to be no real public knowledge of exact equivalents, and indeed I don't think it's even that simple as to make a direct comparison. The relative heights of the jets' "screwheads" in particular seems to make another difference on top of the bore size, but not one which easily can be predicted. As you can imagine, that 9% is going to make more than the difference you want to your final A/F ratio, and when we consider Keihin jets are generally understood to run leaner than RO's for a given size, you can see how you will end up well under optimum on Keihin 110's.

I think that you are actually very close to the ideal A/F ratio, and what you should do is put RO's 115's in the rear cylinders, and get him to sell you some compatible same-brand 112's for the front cylinders. Then take your bike for a dyno run and see where you are again. I think it will be where you want it, but humbly I submit that it would be leaner than peak performance / responsiveness and thus not what most people here wpuld want, and so the typical advice remains valid. Particularly since most here who have bothered with jetting changes will be running aftermarket cans, which will require a little more than stock.

In the end, if 112/115 is still too rich for your tastes, you only need one more pair of jets (cheap as you like anyway) to go to 110/112, and then you're done and can still sell on the 115/118 combo for about what you paid.

Hope that makes sense?!

Diam mm.....Jet.....Area mm^2
1.000.....100.....3.142
1.025.....102.....3.301
1.050.....105.....3.464
1.075.....107.....3.631
1.100.....110.....3.801
1.125.....112.....3.976
1.150.....115.....4.155
1.175.....117.....4.337
1.200.....120.....4.524
1.225.....122.....4.714
1.250.....125.....4.909
1.275.....127.....5.107
1.300.....130.....5.309
1.325.....132.....5.515
1.350.....135.....5.726

[phil x]

Hmmm, interesting thought.
I had considered sourcing some 112s from Rick & swapping as you suggest but thought I'd go back to stock & go from there. Past experience has shown me that running a leaner than normal practice, can produce good results with far better fuel economy - sometimes without power sacrifice too!

Phil