Author Topic: Euro vs USA spec carbs.  (Read 546 times)

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Offline Montoya

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Euro vs USA spec carbs.
« on: September 10, 2019, 04:41:13 PM »
HI guys

I'm scratching my head, still. Some say the US RD350 -73 shall have 140 main jet, 5DP-4 needle 15mm float hight and 2.5 cutaway, 1 3/4 turn on the pilot screw. Other say 130 main jet with 5J6-3 needle, (unknown float hight), 1.5 cutaway and 1 1/4 on the pilot screw.

I'm wondering if there is different spec on a Euro vs USA models?
My bike is new in Norway. Carb set up as a us model. As far as I know all of them have reeds.
« Last Edit: September 10, 2019, 04:46:29 PM by Montoya »

Online 5port

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Re: Euro vs USA spec carbs.
« Reply #1 on: September 10, 2019, 07:07:57 PM »
HI guys

I'm scratching my head, still. Some say the US RD350 -73 shall have 140 main jet, 5DP-4 needle 15mm float hight and 2.5 cutaway, 1 3/4 turn on the pilot screw. Other say 130 main jet with 5J6-3 needle, (unknown float hight), 1.5 cutaway and 1 1/4 on the pilot screw.

I'm wondering if there is different spec on a Euro vs USA models?
My bike is new in Norway. Carb set up as a us model. As far as I know all of them have reeds.

Hi, who "says" these specs to you?  The figures you give there are sort-of in the Clymer manual.  The first set are an inaccurate set, similar to an R5.  The second set are an incomplete set of the setup quoted in a Clymer manual table.  However, that set is complete rubbish, as far as known production models go!  ::)
Can you tell us what your "Carb set up as a us model" is?   This is what it might be....
Carb body number 360 A2, Slide 2.5, Needle 5I4, Clip 4th groove down, Needle jet #175 O-8, Main jet 140 (for unbaffled filter), Pilot jet 25, Idle air screw 1.75 turns out from lightly seated, Float lever 15mm.  How does that compare?

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Offline Barnett

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Re: Euro vs USA spec carbs.
« Reply #2 on: September 10, 2019, 07:47:59 PM »
HI guys

I'm scratching my head, still. Some say the US RD350 -73 shall have 140 main jet, 5DP-4 needle 15mm float hight and 2.5 cutaway, 1 3/4 turn on the pilot screw. Other say 130 main jet with 5J6-3 needle, (unknown float hight), 1.5 cutaway and 1 1/4 on the pilot screw.

I'm wondering if there is different spec on a Euro vs USA models?
My bike is new in Norway. Carb set up as a us model. As far as I know all of them have reeds.

Hi, who "says" these specs to you?  The figures you give there are sort-of in the Clymer manual.  The first set are an inaccurate set, similar to an R5.  The second set are an incomplete set of the setup quoted in a Clymer manual table.  However, that set is complete rubbish, as far as known production models go!  ::)
Can you tell us what your "Carb set up as a us model" is?   This is what it might be....
Carb body number 360 A2, Slide 2.5, Needle 5I4, Clip 4th groove down, Needle jet #175 O-8, Main jet 140 (for unbaffled filter), Pilot jet 25, Idle air screw 1.75 turns out from lightly seated, Float lever 15mm.  How does that compare?

5port
 

+1 for that, not much 5port dosnt know about rd  carbs.
Yamaha 1974 RD125 (AS3) fully restored 2018 on road
Kawasaki 1977 z650 B1 on road
Yamaha 1972/3 U.S. early RD350 ongoing project.

Offline Montoya

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Re: Euro vs USA spec carbs.
« Reply #3 on: September 10, 2019, 08:49:23 PM »
Lots of different set ups apparently. This is the set up in my carbs today: 140 main (baffled) 25 pilot, 5DP-4 needle, 2.5 slide, idle screw 1 3/4 turn out and 15mm float hight.
Though it has some issues from 0-1/2 throttle and between 5k - 7k rpm. sputtering and hesitating.From 7k rpm and above it runs fine again.
Barely react to adjustment of idle air screw, but runs slightly better when air pilot screw is almost closed. approx. 1/4 turn out.

Is this set up way out?

Online 5port

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Re: Euro vs USA spec carbs.
« Reply #4 on: September 10, 2019, 09:51:26 PM »
Lots of different set ups apparently. This is the set up in my carbs today: 140 main (baffled) 25 pilot, 5DP-4 needle, 2.5 slide, idle screw 1 3/4 turn out and 15mm float hight.
Though it has some issues from 0-1/2 throttle and between 5k - 7k rpm. sputtering and hesitating.From 7k rpm and above it runs fine again.
Barely react to adjustment of idle air screw, but runs slightly better when air pilot screw is almost closed. approx. 1/4 turn out.

Is this set up way out?

Yes, it is far-out man!  ;)
So, there are NOT really lots of different standard set ups.  However, there are lots of modified bikes, modified carbs and misquoted set ups! ;)
  The set up I wrote before was not just to waste my time, it IS the standard set up for a standard USA '73 RD350.
You need to tell me what your bike has standard?  You say "baffled" so, does that mean you have a metal airbox with lid and a paper filter with the two metal tubes in it?  Do you have  standard reeds and intakes, with no X-over or boost bottle?  Is your bike tuned?  Do you have standard exhausts?
Cheers

5port   
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Offline Montoya

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Re: Euro vs USA spec carbs.
« Reply #5 on: September 11, 2019, 04:27:40 AM »
Yes, the air filter is of paper, in a metal box and y-boot. No crossover between carbs, standard exhaust. Standard reeds and no tunes.
Slide 2.5, main jet 140, pilot jet 25, 5DP-4 needle, 15mm float hight. New intake boots.
(Ignition timing 2mm btdc)

Could it be slightly different due to the law of emission in US in the 70`s?
However, I really don't mind the emission anyway, I just need the bike to run properly.

Offline stukey

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Re: Euro vs USA spec carbs.
« Reply #6 on: September 11, 2019, 07:47:28 AM »
on the carb bodies there is a number stamped on the flat part by the top cap.What is it
Rd 350 special can we get more than 70bnp?
Silver-dust 350b now with new owner
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and not forgetting the r6 streefighter
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Online 5port

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Re: Euro vs USA spec carbs.
« Reply #7 on: September 11, 2019, 08:47:04 AM »
Yes, the air filter is of paper, in a metal box and y-boot. No crossover between carbs, standard exhaust. Standard reeds and no tunes.
Slide 2.5, main jet 140, pilot jet 25, 5DP-4 needle, 15mm float hight. New intake boots.
(Ignition timing 2mm btdc)

Could it be slightly different due to the law of emission in US in the 70`s?
However, I really don't mind the emission anyway, I just need the bike to run properly.

No, it is nothing to do with emissions, California or anything like that. Your carbs are very specific devices that have to be set exactly right for your bike.  I have given you the correct spec for a 1973 USA RD350 but, the details you are saying are mixed-up.  You possibly have the wrong or modified carbs but, you have not said what the carb ID numbers stamped on them are?  Please say what they are.  ;)
You are going to have to strip the carbs further to also check the Needle jet and the pilot jet.  Also, your Needle number you quote is not complete, I suspect the number stamped on the Needle is 5DP7.
You have given some good info about your bike, basically Standard!
Here is a list of the carb details that you need to write down for us, please check off all these: :)
Carb numbers-stamped on the body by the choke housing.
Slide number.
Needle number.
Needle jet number.
Main jet number.
Pilot jet number.

Remember, the Needle jet has to be tapped out up-through the carb after you remove the Main jet and washer.  You might find it easier if you heat the bare carb body in hot water for 5mins before you do this as the Needle jet can be tight in the body and covered in dirt/muck.  When you have removed the Needle jet, you will find it's ID numbers stamped on the middle of it's body.
Cheers  :)

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Offline Montoya

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Re: Euro vs USA spec carbs.
« Reply #8 on: September 11, 2019, 02:33:23 PM »
Carbs 360 92
needle jet 750-8
needle 5DP7
slide 25
pilot jet 25
main jet 140
float valve 2.5
float level 15mm

I do also have 2 spareparts carbs. 360-G1 with 514 needles. 110 and 130 main jets also available.

Btw carbs are just cleaned up in a ultrasonic cleaner.

Does it make any sense?
« Last Edit: September 11, 2019, 04:23:43 PM by Montoya »

Online 5port

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Re: Euro vs USA spec carbs.
« Reply #9 on: September 11, 2019, 04:25:13 PM »

Does it make any sense?

Thanks, Yes!  Coming back to you!

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Online 5port

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Re: Euro vs USA spec carbs.
« Reply #10 on: September 11, 2019, 05:18:30 PM »
Carbs 360 92
needle jet 750-8
needle 5DP7
slide 25
pilot jet 25
main jet 140
float valve 2.5
float level 15mm

I do also have 2 spareparts carbs. 360-G1 with 514 needles. 110 and 130 main jets also available.

Btw carbs are just cleaned up in a ultrasonic cleaner.

Does it make any sense?

OK.  The 5DP7 Needle is not correct for your RD350, it is a DS7 and R5 part. Also, I think your "needle jet 750-8"  is  the 175 O-8.  ;) 
  The 360-92 carbs are listed for the 1974 RD350A.
The 360-G1 is listed for 1973 RD350!   :)  So, I will go through with the set-up for these.
To start, the 1973 RD350 should have the unbaffled air filter element. This is just an oval shaped pleated paper element that has no metal tubes in it.  It has a similar effect to the K&N replacement or, the foam UNI replacement.  You have to be careful because the Main jets with the baffled filter are 105 but, with the unbaffled filter 140 so, if you have the wrong Main jets with the wrong air filter element, you could be weak by 35 or, rich by 35 on the Main jet size. Your bike as a 73 RD350 would have had unbaffled air filter.  I will include both in my list here.
So, 360-G1 carbs 1973 RD350:
Should be the "low tops" type.
Slide 2.5.
Needle 5I4. 
Needle clip in 4th groove down from top.
Needle jet 175 O-8.
Main jet 140 with unbaffled filter.  105 with baffled filter.
Pilot jet 25.
Idle air screw 1.25 turns out from lightly seated.
Float lever 15mm.

I would advise using new genuine Mikuni Main jets and Pilot jets because it is difficult to tell if they have been modified.  However, that is up to you.  These settings should work well on a standard 1973 RD350.  Cheers

5port 
 
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Offline Montoya

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Re: Euro vs USA spec carbs.
« Reply #11 on: September 11, 2019, 05:31:13 PM »
Thanks a lot 5port.
So I actually have all the parts I need. It just has to be assembled correctly.

My main jets are new mikuni 140. I`ll check if I maybe have another air filter to fit 140 mains.

Will post result

Grazie mille


Online 5port

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Re: Euro vs USA spec carbs.
« Reply #12 on: September 11, 2019, 05:40:38 PM »
OK, Good. 
Remember, you can safely test your low power and mid-range fairly safely but, when you get to use higher power, you need to do some plug checks to make sure you are not weak mixture!
Cheers

5port
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Offline Montoya

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Re: Euro vs USA spec carbs.
« Reply #13 on: September 12, 2019, 02:58:34 PM »
Well, everything assembled. Not really a huge improvement to be honest, a little bit more drivable at low rev though. But it still has that stuttering at low rev.(worse when getting warm) and hesitating at higher rev. Barely react at all to adjustment of air pilot screw.
Could a 1/10 mm opening at one of the reed valves make condition like this?

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Re: Euro vs USA spec carbs.
« Reply #14 on: September 12, 2019, 04:27:39 PM »
Now you have got the carb basics right, you have to go through everything else, inc carb problems.  I note you have changed the ignition as well so, that could be involved.  ???

5port
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