350 500 motor conversion

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brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

Re: 350 500 motor conversion

Post by brianh0_4 »

OK, got the 501 pre Kokasan, engine in the 350 frame now.
I have a 2 in 1 exhaust with a GPR type silencer ( one chicane type removable baffle) standard 28mm carbs and standard air box and filters.
It now has 128 main jets and 42 idle jets, needle fully up. The engine is a 'C' excalibur one. Black pick up and grey tranducers, straight from the donor bike ( which i never rode before hand!)
So first 'problem' is that at 2000 rpm it is almost on the 30°advance setting (with the strobe) and moves to just about the 350 34° position at 6000 rpm. the pick up is as retarded as possible. It is the same on the rear cylinder. Would this over advancement cause any rear problems??
When i start it, it goes easily with no choke or throttle, it idles perfectly at 1500, the compression is really good and equal and carb balancing was very easy, with idle, pick up off idle, and twisting the throttle spot on. Plugs are NGK 6ES's and colour after a shortish run is medium brown.
Pick up and initial riding is good, give it a good handful and it really moves..., but pull the throttle back to a cruise position, and it feels like it is going to run out of fuel, but doesn't, and will go well again if i give a big handful again. If i ride at a constant throttle setting it is all over the place power/no power/power/no power, it is not really rideable, it is that bad.
( i did change to another black pick up, but no difference) (And both fuel taps ON)
So please any suggestions??
Thanks, Brian
hendre
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Joined: 11 Aug 2007 06:51
Location: The Netherlands

Re: 350 500 motor conversion

Post by hendre »

do you have a extra thick ground wire running from the engine (cranckcase bolt next to the breather) to your battery?
I suspect there are some ground connections not connecting properly, that gives al kinds of freaky behaviour of your ignition
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72degrees
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Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: 350 500 motor conversion

Post by 72degrees »

What atomisers and needles?

Mid range carburation with PHBH28s and a 2:1 on my L5 cam 350 has been tricky to get right in 'steady state' conditions.

Symptoms very much as you describe. Easy to ride through but very 'flat spot' around 5000 rpm on about 1/3 to 1/2 throttle under load.

I'm now running X8 needles (with 262T atomisers and 132 mains - but S&B pod filters) which has made a big improvement - certainly won't be an issue once installed in the hill climber.

How does it react to dropping the needles down a notch or two?
brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

Re: 350 500 motor conversion

Post by brianh0_4 »

Hi
I have the carbs like this
Idle 42 Main 128 264BC Choke 50 Needle X18

Ok i will try the main earth lead, that i have not connected. If no change i will get needles and atomisers. Moving the needles hasn't changed a lot. Put some other grey tranducers on, no change. I think i will go up on the main jets also.

Thanks, Brian
norbert
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Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 350 500 motor conversion

Post by norbert »

If you use NGK I´d suggest B7ES rather than 6
EVguru
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Re: 350 500 motor conversion

Post by EVguru »

norbert wrote:If you use NGK I´d suggest B7ES rather than 6
BP7ES, projected nose variant, otherwise the electrode is recessed up into the head.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 350 500 motor conversion

Post by norbert »

Of cause Paul is absolutely right, it´s the BP7ES

Since a couple of years I´m very pleased with the NGK BP7EVX (Platin, not Iridium!). They help starting and last much longer. I changed mine after more than 30.000km and still there was no wear visible, no readjusting the gap in al that time. As far as I know they are not produced anymore, what is a pity. If you still can get some ... :wink:

Some people seam to use 8 plugs in the 500/501, but I think a 7 willdo as well as long as you don´t fry the engine

norbert
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72degrees
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Location: West Midlands

Re: 350 500 motor conversion

Post by 72degrees »

The EVX plugs were indeed the bee's knees. I'm now running BPR7EIX on both Morinis and despite also having 5K ohm NGK caps they seem to work very well with both starting very easily. They do both have NLM ignition modules though (with OEM type 2 red pickups). I finally had to change the Iridium plugs in my Mazda MX5 - after 10 years and 20,000 miles (it doesn't get used much, but when it does it is required to "make good progress").
brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

Re: 350 500 motor conversion

Post by brianh0_4 »

OK put in the suggested X8 needles with 262T atomisers and 132 mains . It wouldn't run past 4000 rpm....
Put the standard needles and atomisers back but left the 132's in. it is a bit better, but contant speed running is still very erratic, with it popping and backfiring occasionally. Wonderful under power, peaky like a good 350 sport, but with much more go.... so much fun to ride, even some clutch slip with full throttle..
I have managed to get the timing correct now, but any other suggestions to get in smooth in the cruise would be very welcome.

Thanks, brian
simonnorthroad
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Joined: 16 May 2017 10:57
Location: Bath, UK

Re: 350 500 motor conversion

Post by simonnorthroad »

Brian I'm on virtually identical spec engine, jetting, plugs and experiences to you with my 507 engined 350. I have dynoed it. Pilot and main jets are same as yours and spot-on but midrange was "off the scale" rich. I was raising the needles to cure spitting back at 4000rpm on a steady or trailing throttle, so theyre now on lowest/weakest setting, still spitting back and a bit wooly at 4k but I can live with it.
brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

Re: 350 500 motor conversion

Post by brianh0_4 »

Hi Simon,
OK thanks for that, what sort of air filters are you using? Sadly just took the engine out due to knocking big end, but will be fixed soon.

Brian
simonnorthroad
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Re: 350 500 motor conversion

Post by simonnorthroad »

No airbox, but I have soft foam ramair filters pushed into the ends of the carb-to-airbox rubbers, ie up under the tank, out of the rain and sucking in (hopefully) still-ish air. Ive used a couple of self tappers through the rubbers and into the airfilter (neck) to keep them in place, which is probably unnecessary

K&Ns are good. Avoid S&Bs and other cheap No-Name airfilters
3potjohn
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Joined: 02 Jun 2007 13:58
Location: Devon

Re: 350 500 motor conversion

Post by 3potjohn »

Did anyone fix this? I have pretty much identical problems with a 507.
Sent a couple of pms yesterday evening as well.
John
simonnorthroad
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Joined: 16 May 2017 10:57
Location: Bath, UK

Re: 350 500 motor conversion

Post by simonnorthroad »

PMed you a reply. An empty airbox "plenum-chsmber' seems to have improved my running further
brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

Re: 350 500 motor conversion

Post by brianh0_4 »

Hi, I PM'd a reply too, but it doesn't really help others, but nor does my reply :shock:
Never did cure it, but putting the engine back in the Excalibur it came from, as totally standard made it run perfectly......???
So 350 strada was also rebuilt and back to standardish....375 pistons..
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