The Sensible Twin

[peewee]

Right, I've got a working ignition. But an odd one. The new 2KR ignitor ex China has all the right colour wires but one don't work...

There's a blue wire which when power is switched on to the box is supposed to send power to the fuel pump relay. Turning the pump on.
It doesn't..I can live with this as it does at least spark. Means rewiring the fuel pump to eliminate the relay.

All the bells and whistles work - neutral and oil lights - even the temp gauge twitches.

So there's still the tank and fittings to do.....Then the carbs......

The ex NSR carbs are semi downdrafts. I've got to make the jet positions look like the pic in order to make them work in full downdraft mode.
I have some ideas. Subject to change without notice, LOL.

would 28mm mikuni downdrafts work better than what you already have ?

[speedpro]

The blue fuel pump wire isn't switching ground instead of 12v is it? You don't have the standard carbs to try? What about a normal sidedraught feeding a plenum on the top of a couple of velocity stacks. Sort of like what I have but instead of the turbo feeding it have a carb. If it pops back it shouldn't be too big a bang.

[husaberg]

The blue fuel pump wire isn't switching ground instead of 12v is it? You don't have the standard carbs to try? What about a normal sidedraught feeding a plenum on the top of a couple of velocity stacks. Sort of like what I have but instead of the turbo feeding it have a carb. If it pops back it shouldn't be too big a bang.

He could just use a curved inlet.

He fixed the crank by making a pressed up version

[Grumph]

I'm sure that what you put up is interesting Husa, please remember I can't see any youtube shit you post.

28mm Mikunis ? they'd have to be CV's - and no I won't even try CV's thanks. I'm actually quite experienced at setting them up - which means I don't want to. Which rules out stock carbs too - even if I have enough bits to build a pair. "Someone" - on the west coast i think - took a full set apart to see how they worked and I doubt I've got all the bits.

Ideally, I'd win lotto and order up a set of 4 keihins and split them. Don't like the odds of that.

To be honest, It'd probably be easier to convert a pair of Mk1 Amal concentrics to downdraft than these keihin semi downdraft flatslides.
The Dutch do it with Dellortos.

I'll check that the blue wire isn't switching ground as you suggest - but one of the dud boxes I have here will run the pump if you jiggle the exposed guts so i'm fairly confident i've got it right.

[husaberg]

I'm sure that what you put up is interesting Husa, please remember I can't see any youtube shit you post.

28mm Mikunis ? they'd have to be CV's - and no I won't even try CV's thanks. I'm actually quite experienced at setting them up - which means I don't want to. Which rules out stock carbs too - even if I have enough bits to build a pair. "Someone" - on the west coast i think - took a full set apart to see how they worked and I doubt I've got all the bits.
t.

Nah not here, one engine was from CHCH and the other from Dunedin way. one was $5 and the other $20 on trademe.
I had a third one on trademe in gisy but the guy refused to send it wheni got it for $1 on a no res Auction
All the carb and engine bits from me are how they were delivered. other than some rolling arround in my misses car.
The only thing removed was a conrod and a head and cover which either Neil or The hillbillies got, and a mag with Mike got. and odd bolts were robbed.
I looked at the carb box one day most of the bits seemed there.
from memory the two different engines had two sizes of intake ports.

Why cant you see videos Grumph
What the video is is Millyards engne with slightly curved intakes and PWK copy carbs.

[Grumph]

I can't see videos because i'm on dialup. What life I have left isn't long enough to download anything.

Again, curved manifold are something I'm very familiar with - Aermacchis can be made to go very well with them.
If I can avoid it, I don't want to use tham here. I'm not just trying to get it running, it's a race engine.
As we all know, they're never easy...

[husaberg]

I can't see videos because i'm on dialup. What life I have left isn't long enough to download anything.

Again, curved manifold are something I'm very familiar with - Aermacchis can be made to go very well with them.
If I can avoid it, I don't want to use tham here. I'm not just trying to get it running, it's a race engine.
As we all know, they're never easy...

We all know the answer is then either Fi or TDM28mm mikunis FCR28's or Yoshimura 28 downdrafts.

Rob priced the yoshi carbs
I emailed you the pic of Millyards its pretty short considering
I found a Chinese copy of the Yoshi downdraft carb but i cant find it now or for the last year.
https://wholesaler.alibaba.com/produ...783090638.html
there you go $68 USD each

the Downdrafts of the small TZR250 ikt would allow them to be shorter than the pwks plus they have all the 4T Mikuni stuff fits.
You coukd do the same with the Ta10's you have keep them at std angle and do a slight curved intake.
All Engines are compromises somewhere
that one one fires once every 4 strokes on each cylinder

[Grumph]

thank you for the Millyard pic. I'm pretty sure he's a mate of Allens the Mikuni agents in the UK. While they list Keihin sets for the FZR, they're much dearer than the Mikunis - and Allens primarily sell Mikunis. He's interested in simply getting it running properly, not racing it.

The Yosh carbs are again semi- downdrafts. I've looked hard at them to see what's different. It's the fuelling arrangements - not the mounting angles. 45 deg is apparently the max - and dellortos will do that.


I checked to see if the box was switching ground for the relay - no it's not. Nothing off that pin whatsoever. May not even be connected...

[peewee]

ive got a set of the mikunis but have no use for them pretty sure they were from some type of suzuki. rgv250 maybe but i dont know. if someone needs the them just pay the postage and theyre yours

[Grumph]

ive got a set of the mikunis but have no use for them pretty sure they were from some type of suzuki. rgv250 maybe but i dont know. if someone needs the them just pay the postage and theyre yours

Thanks for the offer. They're semi downdrafts like the Keihins I have. Between what I have here already in Amal, Dellorto and Keihin carbs - and what a mate has stashed away - I'm pretty sure I'll come up with something.

[husaberg]

Thanks for the offer. They're semi downdrafts like the Keihins I have. Between what I have here already in Amal, Dellorto and Keihin carbs - and what a mate has stashed away - I'm pretty sure I'll come up with something.

One of the GPs had no pilot jet at all didn't it?
How much angle do you need?
Suzuki Stinger like downdraft

[Grumph]

One of the GPs had no pilot jet at all didn't it?
How much angle do you need?
Suzuki Stinger like downdraft

No - the GP2 had the pilot relocated to the intake side so it's good for steep angles.

How much angle ? Measures up at 15 deg off vertical.

Funnily enough I have a pair of 90cc stinger downdraft carbs here...Bought years ago for pennies to see what the layout was.
No room to bore them though.

[husaberg]

No - the GP2 had the pilot relocated to the intake side so it's good for steep angles.

How much angle ? Measures up at 15 deg off vertical.

Funnily enough I have a pair of 90cc stinger downdraft carbs here...Bought years ago for pennies to see what the layout was.
No room to bore them though.

Yeah they were pretty tiny 18mm and 20mm or something the wolf was same casting but even smaller. wolf 90cc stinger 125 even same cylinders with thinner bores
IDA Weber is all i could think of unless you went smalll car like bambina or Ford MOCO escort. etc
the SP FZR400 had FCR carbs not sure what the inlets manifolds look like but i cant imagine they were steeper than 45 degrees

[Grumph]

Ok, still working...I'm going to give the keihins a try with this adapter. It's 15 degrees - which is 15 less than I'd like but 15 more than they are on the NSR. So 60 deg downdraft. I set the carbs up on the bench and worked out where the fuel level was at different angles. I think this will work.
Interesting to make. I'd made a parallel one in Tufnol and from that realised that I needed something I could tap into...
Got a mate to mill a chunk of alloy to a 15 deg wedge and basically hand cut it from there.
The carb rubbers are GS1000. Rock hard and useless until an overnight soak in Xylene. Magic.

Won't be able to try a fireup until a large item of UK origin leaves my work table.

[husaberg]

Ok, still working...I'm going to give the keihins a try with this adapter. It's 15 degrees - which is 15 less than I'd like but 15 more than they are on the NSR. So 60 deg downdraft. I set the carbs up on the bench and worked out where the fuel level was at different angles. I think this will work.
Interesting to make. I'd made a parallel one in Tufnol and from that realised that I needed something I could tap into...
Got a mate to mill a chunk of alloy to a 15 deg wedge and basically hand cut it from there.
The carb rubbers are GS1000. Rock hard and useless until an overnight soak in Xylene. Magic.

Won't be able to try a fireup until a large item of UK origin leaves my work table.

Paint thinners aye i thought thy would turn into a gooey mess?