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Author Topic: CR Flatslide jetting  (Read 4885 times)
4laf
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« on: December 06, 2014, 09:37:01 PM »

I have acquired a 1990 CB-1 that is fitted with  CR flatslide carbs. It has good compression, good spark and will run.
I have been through the carbs installing new Sudco kits. No one at Sudco remembers nor does their data base support this application. Here is the known jetting that is installed. Main 130 long hex, pilot 50, Needle jet (no number visible)
Float height 9mm, Needle  Huh set screws for needle will not unscrew., mixture screw 2 1/2 turns out. For any of you with CR flat slides how does this set up compare with what you run at sea level? thanks,  Laf
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knee-dragger777
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« Reply #1 on: December 06, 2014, 10:11:52 PM »

This is sort of new territory, cause I just don't know of any people that have fitted CR's and gone through this process. 

However, I will say, based upon stock and even "jetted, and aftermarket exhaust" bikes, that have been modified with success on the stock carbs., you sound VERY rich. on your jets. You might want to get a set of jets, and start smaller.
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ptlcb1
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« Reply #2 on: December 07, 2014, 02:29:55 PM »

Sounds to me like you will need some dyno time to get it tuned right.
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a_morti
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« Reply #3 on: December 07, 2014, 03:54:12 PM »

If someone fitted flatslides, they may have got hold of the old cb-1 from heck article for ideas. That may in turn mean your bike has an uprated cam. I suppose it has a full exhaust and modified air intake. Then you're definitely into dyno time.

With CBR400 cam but stock carbs ISTR 116 dynojet main jets being within one size of correct on my old bike, but I never really finished tuning it.
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ptlcb1
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« Reply #4 on: December 07, 2014, 05:01:10 PM »

Love that article, "The CB-1 from Heck!"  It one point I think i had that whole article memorized!  lol
 
I was thinking the same thing a_morti, about what his bike may also have...

4laf,   Whats the story on how you acquired that CB-1?
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4laf
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« Reply #5 on: December 07, 2014, 06:54:32 PM »

Thanks fellows for the responses. How does one access "The CB-1 from Heck" article? Is it part of the sites archives?
After this posting I will make another attempt at finding a part number on the needle jet and I will try to remove a needle to get a part number. Armed with the additional info I will call Sudco tomorrow and see if they can unravel what I have against what I need.
The only CR flatslide package that they still offer is for the Honda CBR600F2. Perhaps I will gain some insight if they will reveal the jetting package used for this model.

Here is the history of the bike. It was purchased new in Honolulu, Hawaii in 1990. The last known registration was in Honolulu in 1998. At that time it had 13,990 miles on the speedo. The modifications at the time included a 4 into 1 Kerker racing exhaust and the four downdraft CR Flatslide carbs.  It was stored and resold as a non-runner several times over the ensuing decades. It ended up here on Maui about 3 years ago. It changed hands again and the new owner removed the head to have a look. He then decided he was in over his head and offered me the bike for $275.00.

I removed the cylinder and carefully cleaned and made sure the rings were all free. I gave the bore a light hone and stated the reassembly with new gaskets. I gave each valve and seat a clean lapping and continued the reassembly. I verified the thermostat was functioning, replaced a few hoses and dismantled the water pump to remove the decades of congealed crude. I added fresh coolant, oil and oil filter. I replaced the fuel filter and cleaned out the gas tank. I quickly discovered that two of the plug caps failed the resistance test. I sourced replacements from a modern Honda 919.

The airbox was removed long ago to fit the CR carbs. Blue velocity stacks, no air cleaner(s). Easy to spray ether starting fluid.
But first I went through the carbs with new needle and seats and other rubber bits that are exclusive to the CR type carbs. After a bit more sorting it started up but was rich. The new plugs fouled in short order. Everything was too rich across the board.  I suspect that the bike was put away those many years ago because the carbs were never jetted for a 400cc engine. I'll post the results of the Sudco conversation tomorrow.  Laf
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a_morti
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« Reply #6 on: December 08, 2014, 10:56:15 AM »

Enjoy Smiley

http://www.hondacb1.org/reviews-cycle1090.shtml

I think you may be right about the jetting never having been right. It wouldn't go from fine through to massively rich by being stored.

While you're busy in the engine, could be a good time to fit that CBR400 cam. There's a lot more duration on them, so you can make significantly more top end power. IIRC the stock power quotes are 45 vs 63hp, and most of that is from the cams and the exhaust. There's more in that article. Seems a shame to have flatslides but the engine held back by the cam.

If you do go for the camshaft then don't start jetting yet. I had to go from 105 stock to 116 DJ (IIRC) after changing the cams.

Someone in UK has a set for sale, you may find some on yahoo.jp, but there's next to no chance to find that part in the USA.

http://www.ebay.co.uk/itm/HONDA-CBR-CBR400-NC23-STANDARD-FIT-CAMS-AND-CARRIERS-VERY-GOOD-ORDER-/281347213035?pt=UK_Motorcycle_Parts_13&hash=item418199c6eb
« Last Edit: December 08, 2014, 11:05:53 AM by a_morti » Logged

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ptlcb1
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« Reply #7 on: December 08, 2014, 03:31:15 PM »

4laf,
     Here is the link for the article, again lol, along with our comments/conversation about this article.  There are 2 pages of comments. This may/may not help you with some more understanding about all of this...

Enjoy!  Smiley

http://www.hondacb1.org/forum/index.php?topic=6.msg8#msg8

If you really want the hotter cams but can not find a set, click on the link below.  Download the catalog, then go to Page 29...  Wink 

http://www.megacyclecams.com/
« Last Edit: December 08, 2014, 03:45:53 PM by ptlcb1 » Logged
4laf
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« Reply #8 on: December 11, 2014, 11:15:44 PM »

Gents:  Thanks for all of the input and links to the past. Sudco was of little help. The flatslide CR's were probably assemble by Ontario Moto Tech before they sold out to Sudco.  Here is how you can help.   Can anyone provide the jetting values for the entire carb circuit with stock CB-1 carbs. My OEM service manual only refers to them as VG06 carbs. No jet numbers are supplied.  And it is of most importance; are the stock carbs by Keihin or Mikuni?  And just for fun I purchase, below the ebay listed price, the NC-23 cam set that was recently spotted by one of you. I expect to see them by Christmas.  I am my own Santa!   Laf
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Sugs
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« Reply #9 on: December 11, 2014, 11:56:39 PM »

Stock carbs are Keihin, and according to servicehonda.com diagram, main jet is #105, slow jet is #35.
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4laf
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« Reply #10 on: December 13, 2014, 02:04:39 PM »

After re-reading the article on the CB-1 from Heck and reading everyones responses I elected to invest in a few OEM Keihin jets to try and bring the Flatslide CR's into some sort of beginning point to prevent the gross flooding that is presently occurring. Per the collective advice I am replacing the slojets with 38's (from 50's) and the mains at 115 from the present 130's. The parts should arrive on Monday so I hope to report soon that the bike is getting closer to rideable.  The NC-23 cams won't arrive until after Christmas so I hope to get it dialed in first and then adjust it again if the cams upset the mixture too much.  The saga continues.  LAF
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a_morti
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« Reply #11 on: December 14, 2014, 07:08:06 PM »

Of course the carbs are all different, but this might still be useful:
http://www.jetsrus.com/FAQs/FAQ_mikuni_vs_dynojet_vs_keihin_sizes.htm

with the cam, I got to about 116 DJ on the stock carbs.
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4laf
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« Reply #12 on: January 09, 2015, 07:31:06 PM »

My saga continues. With the flat slide properly jetted the bike still barely runs. A compression test and a leak down test reveal no worn or leaking valves or rings. The cams are timed perfectly. There is always a fat spark at each plug.  However I suspect that the spark maybe random and not timed to the actual TDC event. The bike came as a basket case. It has two ignition modules.  Both could be bad!  Would a fellow believer in the CB-1 be willing to test each of my modules on a known well running CB-1 to determine if either of my modules is okay.  I will pay the postage in both directions. With the seat removed and the rear plastic seat surround removed the module is easily accessible. A plug & play swap that would only take a few minutes.  It would be easiest to conduct this activity with someone from the USA or Canada.  I am located in Hawaii.  Thanks for helping me get this baby off of the bike rack!
Laf Young
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a_morti
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« Reply #13 on: January 10, 2015, 07:19:00 AM »

My saga continues. With the flat slide properly jetted the bike still barely runs. A compression test and a leak down test reveal no worn or leaking valves or rings. The cams are timed perfectly. There is always a fat spark at each plug.  However I suspect that the spark maybe random and not timed to the actual TDC event. The bike came as a basket case. It has two ignition modules.  Both could be bad!  Would a fellow believer in the CB-1 be willing to test each of my modules on a known well running CB-1 to determine if either of my modules is okay.  I will pay the postage in both directions. With the seat removed and the rear plastic seat surround removed the module is easily accessible. A plug & play swap that would only take a few minutes.  It would be easiest to conduct this activity with someone from the USA or Canada.  I am located in Hawaii.  Thanks for helping me get this baby off of the bike rack!
Laf Young
To be honest, a CDI unit will usually fail completely, or be fine. If it's starting the bike, then there's nothing seriously wrong with it.

Why do you think the bike is jetted right, if it's not running right? No one know the correct jetting so anything you have done is a guess.

I suggest better to try a stock carb rack and airbox to eliminate that first.
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knee-dragger777
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« Reply #14 on: January 13, 2015, 08:59:49 PM »

I had a problem with my CDI. It worked great, but my tachometer feed from it failed.  That was the only thing.  I recently replaced it with a used one from a guy on here looking to part out his bike, and it worked perfectly.
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86 Elite 80
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