350 500 motor conversion

Maestro, SEI-V
brianh0_4
Posts: 64
Joined: 02 Nov 2011 12:59
Location: Graulhet France
Location: Graulhet, France

350 500 motor conversion

Post by brianh0_4 »

Hi ,
Just been going back through the search box on this subject but sometimes it goes a little off track.
So please can you, who have done the conversion of fitting a 501 to a 75 strada frame, give me some tips and pit-falls to avoid?
I would like to make it look as original (ie stock) as possible.
Do you or can you use the 350 transducer/pick ups, and generator, or is it best to use what is fitted? Can i use the 350 air filter box? And what about the exhaust?, try to get standard 500??

I have received a 501 Camel and a 501 Excaliber, neither run, there are no sparks on the cruiser and the camel doesn't like to turn over, but not looked any further.
Am i right in thinking that there is no advantage to either engine??

Thanks for any pointers
Brian
PS i did put a post on the 350 board, as i didn't expect to receive a 500.....
EVguru
Posts: 1528
Joined: 01 Aug 2006 11:13
Location: Luton
Contact:

Re: 350 500 motor conversion

Post by EVguru »

I'll presume you've got Kokusan electrics and a front mounted starter motor.

To convert these engines to the original styling, you need to replace the clutch side case with an earlier one and use the Ducati alternator.

You would have to add the locating flats to the camshaft for the ignition rotor too, or use another cam.

A 350 airbox can be used.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: 350 500 motor conversion

Post by julianharty »

My 501 engined K1 framed bike currently has the more traditional clutch cover on the left side and no front mounted starter and retains the Kokusan generator and ignition with the coils mounted quite well under the tank similar to where the strada has the older coils. The wiring needs modifying for the ignition switch and the kill switch if you do something similar (otherwise I'd be interested in obtaining your kokusan parts as long-term spares for mine - I do have various spares I could trade that would help you convert yours).

BTW I do have a long-term cunning plan to get the front mounted starter motor back on my bike, the K frames run closer to the front of the engine and the standard front starter motor cannot fit in the space (it can just fit in the older pre K frames from what I've seen and read, including a particularly detailed article in German on the modifications that person did to make everything fit).

As I mentioned in a PM I also managed to get the excalibur / new york exhausts to fit with some small yet vital modifications (including shortening the rear header by about 8mm about 5cm from the cylinder head end, and creating a shorter exhaust castellated nut with much of the inside removed to allow it to bite despite the sharp curve of the pipe). Perhaps it'd be useful for me to write up the mods and post them here. I'll gauge the interest from whoever asks me to do so :)
julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: 350 500 motor conversion

Post by julianharty »

An important detail, the kokusan ignition system needs 12V to power the ignition, so a good healthy battery (and ideally the charging system working) are vital to getting them to spark and run.

As a general tip I've recently bought 4 of spark gap test tools similar to these https://www.ebay.co.uk/itm/Ignition-Spa ... 0011.m1850

They enable me to check the sparks on my bikes practically and with the spark plugs removed from the cylinder head (so easier to turn over). I have some old Honda VFR400 NC24's as projects and needed 4 for these :)

As mentioned in my PM you're welcome to call for a chat about the many details and options. There are several other active forum members who've done something similar in the past few years.
simonnorthroad
Posts: 388
Joined: 16 May 2017 10:57
Location: Bath, UK

Re: 350 500 motor conversion

Post by simonnorthroad »

How do they work? Plug into the cap then the crocc clip earthed?
You really donrt want to have the Transducer sparks not going to earth....
julianharty
Posts: 478
Joined: 15 May 2016 16:34
Location: High Wycombe
Location: High Wycombe Area (Bucks)

Re: 350 500 motor conversion

Post by julianharty »

They effectively replace the spark plug, the spark happens in the central chamber (which I don't consider to be truly a chamber as it's open along the length, but I can't think of a better way to describe it).

So one end - the brass end has a small cap that unscrews (similar to the way some spark plugs have a removable cap). The plug cap goes on this end. The clip goes to earth e.g. on an exposed bit of metal on the bike. I'd recommend removing the spark plugs just to make the bike easier to turn over. If you wish, it'd also be good to do compression tests at the same time (I bought these devices so I could safely protect the HT circuits on my VFR400's while doing compression checks).
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 Paul/Julian

No nether engine is Kokosan, the Camel is 86 and the Ex 88. the engine letters are C and R.
Both with Nikasil barrels.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 350 500 motor conversion

Post by norbert »

You should take the R motor of the Camel because of the L5 camshaft. It works fine with the 28 Dellortos and the normal 350 filterbox if you connect them with the 500 rubber manifolds. I would begin with a 130 mainjet then.

norbert
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: 350 500 motor conversion

Post by harrymuffin »

I had a spare pair of unused 507 barrels and heads and after reducing the barrel spigot fitted them to a 5speed bottom end. I do not like the rubber inlets so made up metal curved inlet tracts which screw into the head, so the inlet duct is 28mm all the way down to just before the valve head which tapers to increase gas velocity. As you cannot get the head and barrel off the back cylinder once fitted, should the matter arrise, I shortened the return loop tubes to the under side of the seat tubes and moved them rearwards as on the 500 frames and re welded. This also give, you more room for the rear exhaust even though the frame is narrower than the 500 frame. If you do not do this mod then you have to spend 1/2 an hour whipping the engine out to take the back head off. It is also less fiddly checking valve clearances.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 350 500 motor conversion

Post by norbert »

harrymuffin wrote: I do not like the rubber inlets so made up metal curved inlet tracts which screw into the head,
That´s what I´m dreaming of since years (not able to do this job :cry: ) If you still have a pair of them, let me know :wink:

norbert
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: 350 500 motor conversion

Post by harrymuffin »

I had a pair of bent fork stanchions 35o/d which are the right size onto one end I screw cut the correct thread, I then obtained a section tube 45deg and cut that in half to make a 221/2deg section and with the screw cut straight tube screwed into the head then tacked the bent piece to get the right angle. Removed from the head welded the tube together and then waded another short piece of for stanchion that allows the carb to be mounted into a rubber tube and rubber tube onto manifold so there is no step giving a smooth inlet down to the valve. If you want see the result let me know.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: 350 500 motor conversion

Post by norbert »

Yes ofcouse I´d like to see it, h :D hat would be nice
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: 350 500 motor conversion

Post by harrymuffin »

The first photo is close up shewing the manifold screwed into the head, the second the type of section pipe that I used. I must have used a 90deg pipe cut into two to create the correct angle for the slope of the barrels. The bend is from an engineers suppliers and is thick walled pressure piping used for high pressure factory installations, the wall thickness is about 4mm. When joining the bend and the 2 straight sections I formed 45deg chanfers on the straight sections on the lathe to obtain a good weld joint. You have to screw the threaded section into the head to get the correct position for the curved section and tacked, removed and welded up. I then had the manifolds bright zinc plated. You can see that the carb is connected using a rubber connecter, the carb spigot pushed in to mate with the manifold so that is flush to the whole tract is smooth bored down to the valve. I did intend to have a long increasing in diameter inlet before the carb but found the filter too close to my left knee cap and already having had one knee cracked whilst racing my Aermacchi at Cadwell in the sixties, opted for the short one as you see. Last photo is the bike as a whole. I could make one for you but ideally I would need the engine to set up the correct angle for the carb. If you should decide to do this improvement and have the original stubs in the head which are seized then find a local tool makers who may have a spark eroding machine that can cut the original stub out without damaging the thread in the head.
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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 »

So Harry, even if i don't do that clever modification, how does it run? A 2 into 1 and K&Ns (what jets?) does it rev well and no running faults??

Thanks for this information,
Brian
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: 350 500 motor conversion

Post by harrymuffin »

I built up the engine to deliberately provide torque in the upper mid range so left the standard 500 cam, but on hind sight think that the 350 sport cam would be the better cam with the slightly greater overlap. I did not want one of the big overlap cams in as although greater power would be gained it would narrow the power band and move it up the rev range which for a road bike is wasted. It was built to provide fast cruising and quick recovery from bends and cars in the way, without have to play the gear pedal like an organ. The problem with the standard exhaust is that the two halves the engine are not matched, one shorter than the other, so with 2-1 the pipe lengths are equalised and have the benefit of creating an extracted effect on the exhaust gases. The carbs are set up as for the standard 500, I think, without going through my note books and stripping the carbs to check.
She pulls from about 2000 revs without any hesitation with torque coming in at around 4000 with a surge building progressively to my own set max revs of 7500 owing to the number of 500 motors I have built for people over time with knackered big ends, so rarely have any need of going over 6500 if I have to. Once she is on full chime I do have to admit that the exhaust is reminiscent of the 500 Honda four that Halewood used to ride, made my hair on the back of my neck stand up when I first encountered it after a sort running in period and I do have to indulge at least once or more when out. I have generally gone up on the gearing as i do not carry passengers and if knowing that my work would be cross country then would go down o a 40 rear sprocket from the normal 44 as on the 5 speeders without any problems with cruising generally on A and B roads in the 70 to 80's and as I have said not having to change gear unless speed drops down below 50 and then only into 4th for a quick cruise recovery. K&Ns I have no problem with. I did have a SEI with K&Ns and the only problem I encountered was in very wet weather, rain dripping off the tank into the filter and draining into the float causing miss firing. This I remedied by shielding the top of the filter with S.S shields. If you mean do they affect carburation, particularly with the back pot, then the only time I did experience adverse effects was when I built this bike up and wanted to take it round the block on test with open bell mouths which caused the rear pot to eight stroke owing to the air pressure pressuring the float chamber at anything over 30ish mph in any gear.
Starting once warm on the electric start in no problem though when cold it does struggle but starts 'first kick' and settles down to a tick over at or around 1450 revs, no hesitation on opening the throttle and it starts straight to tick over without any throttle. I do run iridium plugs though, which do improve starting and general running over the standard plugs. I have these at great expense in my proper cars and I did notice an improvement in tractability and performance. Without checking I think I may have fitted 350 transducers with the pick up set to a 500 max advance at 6000. I suppose I should fit the 500 ones I have kicking about and see if it makes any difference. I did one morning spend half an hour trying to start the thing with starter motor, kick starter - had to fit the lever and bump starting to no avail. Return to the garage took the starter cover off and found that the rubber cam belt was broken. Fitted a standard industrial belt and had no problems since. If you look at the overall picture and down by the front of the drive, there is a small black canister with braided pipes leading to and from that canister to the drive side cover. It is a remote full flow oil filter, as when I stripped this engine bottom half and taking out the grub screws at the end of the crank pin, was at first puzzled at how the Italians had drilled a stepped hole. I then realised that the oil gallery was filling up with crud, owing to the centrifugal effect of the crank going round and creating a sludge trap. My origin SEI ran its big ends because of the oil feed to the bearings gets closed off. This happen before I bought it in bits from the first owner with about 30,000mile on the clock and changing the oil even 2500 miles. I did this mod on that SEI as well. This adds to the reliability and usability of the bike and this modification was first tried out by a chap in the Dutch club.
If you want anymore specific information then let me know or really want me to check the carb setting, then let me know.
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