#6

[Grumph]

You'll notice the camshafts have been flipped over as the locating discs are now on the right. Happily Mr Yamaha put suitable slots in both sides of the head and the lobes are symmetrical so it doesn't matter which way the cams rotate. It did my head in trying to figure if it was possible considering lobe sequences and then the cam timing as you can't use the marks to line it up.

Ha - mirror image. Firing order doesn't matter if you've got a crank triggered ignition firing every revolution.
More than once i confess I've timed up VFR400's wrong - doesn't matter, just turns them into a big bang motor, LOL

Thanks. food for thought.

[TZ350]

Cam re timing can be pretty easy, particularly with cam timing overlap that is symmetrical at TDC. Simply rock the piston at TDC and the cams should rock the valves evenly back and forth between the inlet and exhaust valve.



Commonly the center of the overlap is dead on TDC, in real race engines this may not be strictly true but will be usefully close for positioning the cams.

[husaberg]

You'll notice the camshafts have been flipped over as the locating discs are now on the right. Happily Mr Yamaha put suitable slots in both sides of the head and the lobes are symmetrical so it doesn't matter which way the cams rotate. It did my head in trying to figure if it was possible considering lobe sequences and then the cam timing as you can't use the marks to line it up.

I can't remember for sure but I think the earlier (2kr) and later (3ln) cams have different cams and timing. The carbs on one model are bigger as well (3ln I think)

[speedpro]

IIRC the 2KR & 3LN cams are the same lobe height. I couldn't tell you which ones I ended up using as I had boxes of bits and just used whatever came to hand. Primarily the 3LN has 2mm longer rods but 2mm shorter pistons. The 3LN also has a different sump with the oil filter now a cartridge mounted to the left side. The sumps are interchangeable. The longer rods must have allowed the higher redline. Max power was at 14,000 I think but they revved to 18,500. We saw 19,000 on the tacho on the dyno early on but I suspect that was more likely only 17,000rpm or so.

[husaberg]

IIRC the 2KR & 3LN cams are the same lobe height. I couldn't tell you which ones I ended up using as I had boxes of bits and just used whatever came to hand. Primarily the 3LN has 2mm longer rods but 2mm shorter pistons. The 3LN also has a different sump with the oil filter now a cartridge mounted to the left side. The sumps are interchangeable. The longer rods must have allowed the higher redline. Max power was at 14,000 I think but they revved to 18,500. We saw 19,000 on the tacho on the dyno early on but I suspect that was more likely only 17,000rpm or so.

http://www.fzrarchives.com/ipb/index...ded&show=&st=0


From what I found on the net The first 3ln gave its claimed output I think at about 2000rpm higher 16000RPM vs the earlier 2kr and the later 3ln models
But that only what they claimed, they changed the 250 class rules at one stage to 40HP rather than 45HP (Again this is only claimed outputs)
My thoughts are by rights would be that the first model Exup equipped 3ln should have the more racy cam timing.than the later 40HP models
Then they went back to the same 2KR cams
These post kind of fits my theory.
http://www.fzrarchives.com/ipb/index...howtopic=58568
http://my-x15.net/FZR_INFO.html

Carbs
2KRs are 26mm BDST26
3LNs are 28mm BDST28
http://2fiftycc.com/index.php?thread...erchange.8271/

Pretty sure all the specs are on the FZR250.com page

[speedpro]

Jeez it's been a while.

So little time now with work but starting to get interested again. As well as it ran before, but with not much power and limited revs, combined with niggles with the Ecotrons system, I've bitten the bullet and bought a Link G4+ Atom ECU. I had a good talk to the local guys down south who are confident it'll be good for 20,000rpm which is a few more than I ever intend. Now the fun begins all over. I need a 6T trigger disc on the crank and a 1T trigger disc on a cam, plus I need to fit new inlet temp, water temp, MAP sensor, crank and cam sensors, etc etc. I've also pretty much decided to keep the Ecotrons throttle bodies but remove the throttles and run a separate throttle body between the turbo and plenum, probably about 28mm, with the TPS on it. the idea is to use the Ecotrons injectors and fuel rail but possibly add overhead injectors and run a staged setup for higher revs. With injectors small enough not to run rich at low revs once I start revving it out properly with a bit of load I run out of time to inject enough fuel. The Link ECU allows a staged setup where the secondary injectors can be larger so hopefully problem solved. I also need to run an ignition amplifier. I have one lying around but I need to use low resistance coils. A quick check finds them at $165ea, or I could run the dual post ones on my other bike and just ground one lead. Plus there's relays for ignition 12v and the fuel pump. My bench is covered with computers and wires and sensors and relays which I will have to find a place for on the bike.

If anybody has suggestions for a compact 28mm throttle body, it doesn't need an injector, or ignition coils, let me know.

[Grumph]

Cut up a 3LN carb. Should be enough length in the casting to get a piece double ended out of it.
If you haven't got an old carb body in the scrap, I have...

[speedpro]

Looking for suggestions. Have more or less decided to replace the standard stator and rotor with a smaller one. Smaller physically and electrically. I have also decided that the crank trigger disc has to go on the end with the generator as getting a decent size disc on the crank inside the engine is a problem.

What are my options for a little generator? Making adaptors and even transferring the rotor to an original Yamaha rotor centre boss shouldn't be too hard. My only real concern is the revs it will be asked to do. Really don't want it coming apart at revs.

[husaberg]

Looking for suggestions. Have more or less decided to replace the standard stator and rotor with a smaller one. Smaller physically and electrically. I have also decided that the crank trigger disc has to go on the end with the generator as getting a decent size disc on the crank inside the engine is a problem.

What are my options for a little generator? Making adaptors and even transferring the rotor to an original Yamaha rotor centre boss shouldn't be too hard. My only real concern is the revs it will be asked to do. Really don't want it coming apart at revs.

I remember reading about the problems Trevor Franklin had with his mix and match FZR600 early late stator in PB in the 90's
Although TZ seems to have had success with re rivoting them though?
people have mounted two inner rotor Pitbike stators back to back on Honda twins with good effect but thats a straight mag only deal.
The smallest motobike generator set ups i can think of are the ones used on the aprilias Selcttra.
http://www.selettra-ignitioncoil.it/...s/4_poles.html

if you wanted to go real tiny there is always these.
Brushless RC motors


that said you always have the option of piggy backing the generator on the otherside much like a CBX400 or countless other four stroke multis.

[Grumph]

Looking for suggestions. Have more or less decided to replace the standard stator and rotor with a smaller one. Smaller physically and electrically. I have also decided that the crank trigger disc has to go on the end with the generator as getting a decent size disc on the crank inside the engine is a problem.

What are my options for a little generator? Making adaptors and even transferring the rotor to an original Yamaha rotor centre boss shouldn't be too hard. My only real concern is the revs it will be asked to do. Really don't want it coming apart at revs.

Can you consider separating the generating function from ignition trigger. Generator/alternator perhaps piggybacked on top of the clutch running at less than crank rpm. Gear drive would probably be a must unfortunately.
I know the Britten used a very small alternator housed behind a cam pulley - but without asking one of the guys i don't know where they sourced it.

[F5 Dave]

I remember reading about the problems Trevor Franklin had with his mix and match FZR600 early late stator in PB in the 90's
Although TZ seems to have had success with re rivoting them though?
people have mounted two inner rotor Pitbike stators back to back on Honda twins with good effect but thats a straight mag only deal.
The smallest motobike generator set ups i can think of are the ones used on the aprilias Selcttra.
http://www.selettra-ignitioncoil.it/...s/4_poles.html

if you wanted to go real tiny there is always these.
Brushless RC motors

at said you always have the option of piggy backing the generator on the otherside much like a CBX400 or countless other four stroke multis.

You mean Simon Howtowreckthemagazinetwicegreaves. they welded the flywheel and it failed.

[FastFred]

I remember reading about the problems Trevor Franklin had with his mix and match FZR600 early late stater in PB in the 90's Although TZ seems to have had success with re riveting them though?

Talking with TZ, he puts most of his success with re riveting them down to using plenty of 5 min Araldite glue. He thinks the large glued surface area takes a lot of strain off the rivets.

[F5 Dave]

So just how does that conversation work?

Is the Norton a reference to Edward Norton?

In the Pitts with TZ?

Have you been sleeping lately?

[TZ350]

So just how does that conversation work?

It works very well, when we are in the lunch room .....



I have had some success changing the flywheel carrier for another with a different taper by gluing the new carrier to the old flywheel then bolting through where the rivets were. I think the glue over the relatively large surface area between them helps a lot. It seems to have worked well for Mr Bigglesworth anyway.

[Hemi Makutu]

Is the glue really "5 min Araldite", or stronger, like 'JB Weld', or a semi-resilient 'Sika-Flex' type?