Does radical porting equal radical carby changes needed?

[Husabergpete]

Gents,

In the process of restoration of a Husky CR 125 1981. All original, including the small Bing carby. The original barrell was stuffed so it has been replaced by a highly ported Paul Rooney barrell.

The question is will the port changes (huge transfer ports for example) require a larger carb or at the least jets or not?

Many thanks for any info or advice.

Pete

[matcho mick]

shit yeah!!

[Slakewell]

I had an 84 husky 125 and ran 36mm which I think was a little large but might be right for a Ronny barrel.

[JohnnyO]

A 32 or 34mm carb would probably be better on a 125. Bigger carby= less bottom end. You may have to go up in main jet size for the ported barrel but could still run the standard carby if you want, depends on how much power you want.

[Husabergpete]

Boys,

Thanks for the info. As far as the power, I think for this unit the more the better as it really a 250/430 frame and running gear with a dinky little 125 stuck in it. I just didn't want to run it as a new motor, run it lean and stuff if using the original carb. A mate with some knowledge just said to run a larger than main from standard and work back from that just to get it running then see how it goes.

Quite temped to buy a new 34 mm mikuni - The 82 CR 125 had a blue tank and a 38mm  Mikuni. I thought that was a bit of overkill.

Pete
Heaven #100

[Slakewell]

I remember my 84 had 36 Mikuni and it had huge jets which didn't make sense then I work out it didn't suck ( flowed so little air) that it needed the huge jets to get enough fuel.
Given you can buy a new Mikuni for as little as $150.00 on ebay IMO I go for the 34mm. Jetting is far more than just main jets people don't seem to want to change needles and tubes.

[Lozza]

Depends what you term 'radical'? Do the transfer dividers have knife edges? Anything 'huge' in ports went out with Darryl Eastlake. It all comes back to the pipe as the pipe does all the work and sets the rpm the engine comes into phase.

[Husabergpete]

Lozza,

Going from recent memory (barrell bolted up on motor now) The transfer ports have been enlarged by about 40 to 50% more. The cases had metal taken out about the size of a 5 cent piece +++ to get the barrell to match.

He has added an additional gallery within each transfer port back to a new opening between the barrell and the sleeve (inlet side I think) then all that work has been smoothed and polished like glass. Signed and dated. Not sure what has been done to port height etc. but all in all it looks like a work of art compared to original barrell that someone had a go with a drill on years ago.

The pipe has been modified in the day. Appears to have had a section added to the UP section.

Mahle piston went in as standard. Original Bing is in good condition and ready for testing once the electrics go back on.

Thats what I have at the moment

Pete

[Nathan S]

Anything 'huge' in ports went out with Darryl Eastlake.

What? Darryl Eastlake isn't cool now?!
 

FWIW, Paul Rooney was apparently the only bloke in the world who could get those Husky 125s to go properly (fast, rideable and reliable). According to an ADB article at the time, the Husky guys took a lot of photos of Jeff Dawson's Rooney Tuned barrel at an ISDE in the early-mid 80s after Dawson's bike blew away the 'works' Husky 125s and didn't blow up.

[Husabergpete]

From looking at this barrell I could believe that Nathan.

I have consulted with Paul Rooney some months ago and he was very accommodating. He said I on the right track with the original Bing but not limited to. He also said the changed the pipe in the up section back in the day. I put this post up to see if anyone else has their own experience with this sort of barrell mod. I didn't want to bug the crap out of Paul given he did this work in 1981 for someone other than me.

Info so far is very helpfull so thanks

Pete

[bigk]

I have a P.R  Husky 125 cylinder here, but the sleeve is missing. Anyone have his contact deatils?
Cheers,
K

[JohnnyO]

Anything 'huge' in ports went out with Darryl Eastlake.

What? Darryl Eastlake isn't cool now?!
 

FWIW, Paul Rooney was apparently the only bloke in the world who could get those Husky 125s to go properly (fast, rideable and reliable). According to an ADB article at the time, the Husky guys took a lot of photos of Jeff Dawson's Rooney Tuned barrel at an ISDE in the early-mid 80s after Dawson's bike blew away the 'works' Husky 125s and didn't blow up.

I'll ask Jeff about his 125, i see him all the time. I'll also quiz him about Paul Rooney and if he still does engine work..

[Lozza]

Lozza,

Going from recent memory (barrell bolted up on motor now) The transfer ports have been enlarged by about 40 to 50% more. The cases had metal taken out about the size of a 5 cent piece +++ to get the barrell to match.

He has added an additional gallery within each transfer port back to a new opening between the barrell and the sleeve (inlet side I think) then all that work has been smoothed and polished like glass. Signed and dated. Not sure what has been done to port height etc. but all in all it looks like a work of art compared to original barrell that someone had a go with a drill on years ago.

The pipe has been modified in the day. Appears to have had a section added to the UP section.

Mahle piston went in as standard. Original Bing is in good condition and ready for testing once the electrics go back on.

Thats what I have at the moment

Pete

Sounds just like a simple boost port added.