Author Topic: Daytona 400/ 350LC barrels  (Read 2053 times)

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Offline Richard S

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Daytona 400/ 350LC barrels
« on: April 06, 2021, 05:46:02 PM »
Hi as promised some pictures of my project Yamaha 400 Daytona ,with 250A bottom end and a 350LC barrels.

Offline tony2stroke

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Re: Daytona 400/ 350LC barrels
« Reply #1 on: April 06, 2021, 05:56:15 PM »
 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)

Offline Admin

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Re: Daytona 400/ 350LC barrels
« Reply #2 on: April 07, 2021, 09:28:05 AM »
Loving that  :o :o :o
Just my 250 special left now !

Offline niceonept

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Re: Daytona 400/ 350LC barrels
« Reply #3 on: April 07, 2021, 09:38:05 AM »
What a great special. Loving the polished YR5/DS7 crankcase covers.
Pete in the New Forest.
Current bikes GT750, RD350 & AP50.
Previous bikes YR5 (x2), KH250, GT185, DT250, AP50 & YDS7.

Offline tore

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Re: Daytona 400/ 350LC barrels
« Reply #4 on: April 07, 2021, 12:36:48 PM »
Very nice indeed!
I like the cableless speedo  :)
Tore

Suzuki T20 1969
RD350B (Indonesia) 1975
BMW R1150GS Adv 2004
HVA Roulette 1957
NV 125 1955
https://www.youtube.com/watch?v=k85mRPqvMbE

Offline Richard S

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Re: Daytona 400/ 350LC barrels
« Reply #5 on: April 07, 2021, 02:13:37 PM »
Thanks for the nice comments, I was waiting for the rubber that goes in the mud guard, hence no speedo cable , well spotted.

Offline 5port

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Re: Daytona 400/ 350LC barrels
« Reply #6 on: May 08, 2021, 01:34:34 PM »
Yes, I was going with the tuned 350LC top end for my 350 track bike but decided to stay with aircooled.   ::)
Bit surprised to see you running without the 350LC X-over tube as you seem to have the 350LC carbs?  The jetting is a bit Whacky on the LC.
Cheers

5port
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Offline Richard S

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Re: Daytona 400/ 350LC barrels
« Reply #7 on: May 09, 2021, 07:09:23 AM »
Hi , I haven't got a cross over pipe a the moment, do they really make that much difference...

Offline 5port

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Re: Daytona 400/ 350LC barrels
« Reply #8 on: May 09, 2021, 09:56:32 AM »
Hi , I haven't got a cross over pipe a the moment, do they really make that much difference...

Well!  ???
That is an interesting question, not easily answered. 
I experimented extensively with the small RD400/250/350LC x-over on my RD250E (trying to replicate the 250LC but with 28mm carbs) and on my Aircooled 350E.
First off, I think the basic x-over allows each cylinder to "steal" a certain amount of airflow from the other carb as they intake in turns.  That makes the effect of both carbs feeding each cylinder a bit.  That makes the (low) pressure intake pulse weaker and although the air flow might increase a bit, the carbs experience a weaker and more confused airflow pulse(s).  This is probably more noticeable at low power, where the low carb airflow is always an issue and, is even lower for each carb per intake with a x-over.
On the 250E with x-over and VM28's, I found it very difficult to get a good jetting. Transition from idle to mid power was impossible to jet a smooth progression.  Not impressive. 
On the 350E with x-over, I had a load of fun!  :)  With x-over with 28's it was very difficult to jet using all sorts of combinations.  The solution was, using the weaker 5J6 Needle and the 2R9 type Needle Jet.  Running then was a bit better and good full power. 
Next I tried standard 350LC 4L0-01 VM26 Carbs with x-over, absolutely standard 4L0-01 jetting.  These were great!  Fantastic throttle response, Perfect!  However, Top end not as good as I thought it could be.  ???
Finally, I went to NO x-over with 28's jetted as the RD350B.  These are Great!  For some reason, it growls and snorts like it is keen to go!  Top end very good, better than the 4L0-01 set-up!  :)

I don't know but, I think it might be interesting to try both the x-over with  26mm 4L0-01 carbs which should work well!  You might also find individual VM28's with NO x-over jetted as 350B are very interesting!  Cheers

5port 


   
« Last Edit: May 09, 2021, 09:59:21 AM by 5port »
5port

Offline Richard S

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Re: Daytona 400/ 350LC barrels
« Reply #9 on: May 09, 2021, 05:34:11 PM »
Ok thanks for that, a lot of information there, l have about a week before it gets out on the road, I will let you know how I get on ,I have 220 main jets and 25 pilots and a k/n in a 350a/b air box, so we will see :)

Offline 5port

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Re: Daytona 400/ 350LC barrels
« Reply #10 on: May 09, 2021, 06:29:26 PM »
Ok thanks for that, a lot of information there, l have about a week before it gets out on the road, I will let you know how I get on ,I have 220 main jets and 25 pilots and a k/n in a 350a/b air box, so we will see :)

Sounds good!  Yes airbox may be a factor, the LC's had a much later (10 years) design abox that will have had different effects.  All mine were with decent C/D/E plastic abox (with 400 type middle joint) that, I think, improves low/ mid range.  It is funny but, the individual inlets (NO x-over) with the VM28's using 350B copy jetting make a great intake growl, even though the intake is the same with the other carbs.  I suspect that the carbs get a much stronger pressure pulse without the x-over but, it must also work well with the x-over and 26's, just different!
I certainly prefer the individual inlets with 350B carbs, it is just raw and eager!  :D
Cheers

5port
5port

Offline 5port

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Re: Daytona 400/ 350LC barrels
« Reply #11 on: May 09, 2021, 06:33:17 PM »
Also, my only set-up similar to yours (26mm 4L0) but was with x-over and, that was perfect civilised carburation.  Didn't try 26mm without x-over.  ???

5port
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Offline tore

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Re: Daytona 400/ 350LC barrels
« Reply #12 on: May 10, 2021, 09:26:49 AM »
x-over is a bit high tech. When the reeds close (specially with expansion chamber) there will be a distinct shutoff which causes a power wave to strike backwards through the carb. The x-over consumes that power wave. At low rev and idle the x-over will interfere with the pilot jetting. If the carbs are not 100% synchronized you will end up in an endless rejetting. The RD350A and B has a bogous throttle cabling and will often be slightly off sync at low throttle.
Tore

Suzuki T20 1969
RD350B (Indonesia) 1975
BMW R1150GS Adv 2004
HVA Roulette 1957
NV 125 1955
https://www.youtube.com/watch?v=k85mRPqvMbE

Offline 5port

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Re: Daytona 400/ 350LC barrels
« Reply #13 on: May 15, 2021, 07:12:58 AM »
Is this start-up weekend Richard?  :)

5port
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Offline Richard S

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Re: Daytona 400/ 350LC barrels
« Reply #14 on: May 15, 2021, 08:31:00 PM »
Hi ,yes it is ,probably go out tomorrow morning, weather hasn't been good today, I take it that you can put videos on here ,I will upload one hopefully tomorrow  :)