Help Find A Cure for Crazcnuk's bike?

[egsols]

Here's an interesting page.....http://www.motorcyclecarbs.com/Mikun...e_Jets_W92.cfm

Says that the 266 has 16 holes, used in the 79 sf for carbs 2 and 3
300 has 6 holes and is used in 80/81/83 XJ/XS 1100
301 has 10 holes and is used in 78/79 1100's e and f and also in 79 sf but only for carbs 1 and 4.

Psyco, you sure you got 300's and not 301's?

When I check the part no.s on the needles for the 266 and 301's they are the same but have are different for the 300's

[3Phase]

Jet Needles

From Carburetors.com:

Series 266 Size X2 Type P
Holes from bottom 4,4,4,4
Application BS34 1979 XS1100SF Carb #2 & #3
Yamaha Part# 3H3-14941-02 

Series 300 Size X2 Type P
Holes from bottom 0,0,4,2
Application BS34III 1980/81/82 XJ/XS 1100
Yamaha Part# 3H5-14941-02

Series 301 Size X2 Type P
Holes from bottom 4,4,0,2
Application BS34 1978/79 XS1100E/F All and 1979 XS1100SF Carb #1 & #4
Yamaha Part# 2H7-14941-02

Because they're practically next door, I drove over to Mikuni USA in Northridge, CA. No one there knew anything about old CV carburetors except that they don't make them any more. I was referred to http://www.carburetors.com for obsolete parts and information.

Are the 266 and 301 jets reversed in the list at carburetors.com or is it correct?


psyco: I copied the information for the jet needles out of a MS Excel spreadsheet from Hungary, then pasted it into a message and surrounded it with 'CODE' tags to preserve the formatting. I added 'COLOR' tags to make it easier to read. The link to the spreadsheet is earlier in this thread and there are 1852 needles listed. There is no real explaination of what the fields mean, just a small graphic image of a jet needle and the data.


Regards,

Scott

[egsols]

Hey 3phase,

They're correct, 300's are the 3H5 part no. while the 301's are the 2H7 part no.

The part no. for the 650's is 2F3-14941-92-00 or 2F3-14941-90-00 so it doesn't look like they are exactly the same.

BTW Craz, I used to get 160 km out of a tank on my 79 special...15 litres (had 80 carbs on it)

[Crazcnuk]

100 miles for 3.9 gallons of gas is only ~ 25mpg....

Derwat was getting ~ 118 miles to a tank on his 79SF when he went to Vancouver this spring, that's 190km. (36mpg imp). He is usually going onto reserve not long after 160km.

Yesterday, when we went on that cruise he was getting 32mpg, I was getting 39.9. His was down from normal, mine was way up.

Oh, one other thing, I didn't use any oil that trip!

Up until now a trip of that length (240kms) I would have used a liter of oil or so... I didn't check that until today, as it was dark when we got home.

I got my LED lights, today, so I put them in, lubed up the speedo and put the new speedo cable on, so I have a trip odometer now.

Unfortunately, the cable they sent me was for a Virago, so I had to put the Virago speedo drive on as well.

As for the tubes and needles, where does that leave the 366 Y0's that I have here? They have 9 holes (or 18 depending on how you count them...) 4-4-4-2

[Crazcnuk]

The needle info is cool, if I knew what it meant.

My needles are .5 shorter, all through the range, than the ones the carbs call for, what does that mean to us in real word terms?

[prometheus578]

shorter....
If I follow you correctly... that would mean that the taper comes into effect sooner. Using more fuel sooner... or using more fuel than you need at a particular RPM.
What do the plugs look like?

[Crazcnuk]

Which time? I've worn out the sparkplug holes doing this, been through several sets of plugs. Other than when I had the 120's in, they all look the same.

Nice tan color and using double the fuel, and 50x the oil, it should, and no power in the high end.

The BEST it's done is after I dropped the needles 1 notch.

[egsols]

Hey Craz,

I've read in a few places, on here, where someone found out their clips where either high or low on their needles....resulting in bike not going past 6000rpm....when clips set on middle...they had to hold on.

It would appear that the position of the clip severely effects performance. I would assume that if you are running the wrong needles and or tubes, it would be extremely difficult, if not impossible to get the carbs right.

As prom said, if the needles are shorter, you would be effecting a richer mixture.

I'm reading through my Haynes and it mentions the fact that the needle is fixed on the G(US). So I go looking further and find specs on the G(UK), needle position 3rd groove. Okay, so maybe they used the adjustable needles on the G's, for UK and possibley Can, but that would be the type II carbs not the type III's. I always assumed the easiest way to tell the types II's was by the drain plug in the bowl versus the type III have the taps.

Type II diaphragm and needle....

So if you have the adjustable needles in type III carbs, I would think that getting them set up right would be a supremely, major, PITA.

I'm not sure about the 366's but they may be richer then the 300's

Rather then screw around with them anymore, do you know anyone out there that can lend you a full set of carbs to test out?


This link shows the different specs.....http://members.tripod.com/xs11/carbspec.htm

[psycoreefer]

sorry for the confusion, I've got 301's not 300's. Thats what I get for going from memory and not getting off my butt and walking out to the garage to check.

[psycoreefer]

Re: Jet Needles

Originally posted by 3Phase

Mark	Slots	Length	Dist.1	Dia 1	Dia2	K1	K2	K3	K4	K5	K6	A1	A2	A3


5GLZ18	5	50.500	3.000	3.000	0.000	16.300	20.300	34.300	0.000	0.000	0.000	1.45	3.00	7.00 

5IZ7	1	51.800	3.000	3.000	0.000	16.800	34.800	0.000	0.000	0.000	0.000	2.15	8.00    0.00 

Crazcnuk    = 5GLZ18 
1980 G      = 5IZ7 

SO what does it all mean. Well according to Motorcyclecarbs.com

Often we are asked what needle to use when an OEM needle is no longer available. The way Mikuni Needle numberings work is:

The first number is the length series.

The second and sometimes third characters being letters describe the taper from the clip end in 15minute (1/4th of a degree) increments. For example "B" is 30 seconds, and "E" is 1 degree, 15 seconds.

The last digit be it one or two characters is the number in that configuration shown in the previous characters that has been created. Example. 4D3, and 4D8 are similar in length and taper. However the taper may begin higher up on the needle than the other. This would make a smaller tip diameter. If shims, or clip positions were incorporated on one needle it is possible that it may effectively perform like the other. For this reason we sometimes suggest ordering a 4D3 for example if an OEM application calls for a 4D5 which is not available.

Lastly there is sometimes a number designated by OEM's and this designates the clip position. Example: 5DP3-4. However this "-#" designation is not part of the needed part number.

That means each letter is a different tapper, 5IZ = two tappers on the needle, 5GLZ = Three tappers on the needle

Going from this I can say that A1, A2 and A3 is the tapper in [Degrees].[Seconds] that begins at point K1, K2 or K3 respectfully. This makes sense because according to the quote G = 1 degree 45 seconds or 1.45. Likewise I = 2 degrees 15 seconds or 2.15.


K1 ect is then the measurement from some point to the beginning of each tapper. The drawing make it look like the measurement is taken from the clip position on the needle but doesn't say or depict what happens to needles with multiple clip positions. I'm guessing that they would measure from the center clip position as that would allow adjustment either direction. This is also supported by the fact that on the whole table comparing needles with the same number identifier but different number of clip positions yields the same measurements for the K's.

All this makes sense because it gives you all the points you need to tailor a needle to your needs such as how the mixture changes and at what point that change begins.

What does this mean for CrazCnuk...
It means your going to come into the first tapper sooner by about 1/2 mm. It also means that your current needles (G < I) will be leaner then stock from off idle till 1/4 throttle or so. Could explain why the PO put in larger idle jets to compensate for the lean condition caused by the needles.

above that you'll be richer then stock (L > I) untill around 3/4 throttle, could explain the black smoke and poor mileage.

From 3/4 up both are marked 'Z' however the measurement from the table differs by 1 full degree. Maybe mikuni used Z to denote anything more then 6.30 or maybe the last number in combination with the Z somehow encodes the actual tapper. Either way your needles are leaner (7 < 8 ) at the top end. Could explain why you had to go up on the main jets to get a good looking plug.

Also your needles are 1.3mm shorter overall then the stockers. That means you'd be getting onto the main jets sooner. In my mind that makes the mixture to rich, WOT gas flow at less then WOT, possibly why you can't get to redline.

If your still against getting new needles I'd try lowering your needles - possibly all the way to the top clip position - and then try a red-line run. It might run like crap below WOT but if you can get to redline then I'd think it proves your too rich cuz of the short needles.

You could also try the mikes needles instead, they are a closer match to the stock needles then what you've got now. Maybe try the #2 clip position as they are a bit shorter then stock, and the tapper starts earlier.

[Crazcnuk]

No, mine are the type IIIs: 3J6 model for the '80SG, as in your list.


The only differences are: Mine have the different needles and #45 pilots.

The needles were all in the middle position, but, so far, the bike has had the best economy with the needles one position down (clip up one groove)

Psyco: I have 5GLZ18 needles, but SHOULD have 5GL16, not 5IZ7, so the 5-G-L is the same, we just don't know what the 'Z' and the last number mean. According to the chart mine are 0.5 shorter than the stock ones.

I had good looking plugs with the stock jets. They also look fine with the 115's, which is odd considering it was using nearly twice the fuel it needed.

If my last fuel run was not a fluke, then dropping the needles one notch brought the economy from 28-29mpg, to 35.5mpg (US). Even more interesting (if possible) is the oil consumption dropped to near 0!

Saddletramp has offered to lend me his set of stock 80G carbs. I may have to take him up on it.

[psycoreefer]

Somehow I got it in my head that you had a G instead of an SG. Sorry.

The table doesn't seem to make sense, according to what I've read a 5GL needle should only have two tappers, yet the table lists three. I wonder if anyone has a stock GL needle out and can confirm it has three different tappers.

If the table data is correct then your better results from dropping the needle's makes sense.

Are you able to make it to red line now? Maybe I missed it.

[egsols]

Sounds like you're getting close.

As for changing needles, I haven't tried it but can the type II needles fit in the type III slides (or vice-versa)? I'd send you out a set of needles and slides but the spare ones I have, have one bent needle and all the diaphragms are toast.

The fact that you aren't using oil, all of a sudden, is real wierd. Do you think maybe a ring was stuck?

I would definitely try out a spare set of carbs, if possible. Also like pysco suggestion of raising the clip to test at top end. If your needles are that much shorter, raising the clip may make them closer to stock and give you an indication of the true problem.

BTW, glad to see that the "two weeks" has been and gone.

[3Phase]

Originally posted by Crazcnuk
No, mine are the type IIIs: 3J6 model for the '80SG, as in your list.

Erm, your profile says you have a 1980 G. So, you have SG carbs on a Standard or? I've think I've lost the plot somewhere.

Whatever it is it sounds like it's running better than it was and it's not using so much oil that you need the rare 'Oil Derrick by Vetter' to get out of your own driveway!



Regards,

Scott

[Crazcnuk]

Yes, my bike is an '80G with an '81 SH motor and '80SG carbs!

This was one of the issues when I first started out. Identifying which carbs were on the old Junkyard Dog.

I am in the process of rebuilding the 80G motor, but, with my alzheimer's progressing, I am not sure how long that will take. My cylinder head has been out for rebuild for nearly 2 years....