CMB Alpha carb

John Seybold · May 31, 2016

Hi,

I'm looking for a modified carb for my Alpha motor. I heard that Mark Grim and Roger Payne modify carbs. I've reached out to Grim, but haven't heard back. Anyone have Roger's info? Any other suggestions are appreciated.

John

henry velasco · May 31, 2016

cell number 714 3663358

John Seybold · May 31, 2016

Thanks, I'll give him a call

The Real Grim · May 31, 2016

John

Check your messages

Mark

BulletMaster · Jul 28, 2016

Hi Guys,

Just recently started playing with an Alpha 27... and having issues getting any decent RPM out of it.. It's in a Y6 mono. So wondering a few things... A) What is the best carby/setup to run?

what sort of mixture settings are people using? Have tried a zippkits V3 pipe and a hotpipe on it. Is everyone also getting any good result with the standard ignition, or is it a must do to go to electronic?

Thanks in advance for the replies from people actually using these - and It would be great if Stu Bar or Mark Grim could comment too?

Ray Sametz · Jul 28, 2016

It's early should get plenty of responses. I doubt if your Pee Wee Herman so add your real name to your signature.

IW rules.

Ian Inverarity · Jul 28, 2016

BulletMaster said:
Hi Guys,

Just recently started playing with an Alpha 27... and having issues getting any decent RPM out of it.. It's in a Y6 mono. So wondering a few things... A) What is the best carby/setup to run?

what sort of mixture settings are people using? Have tried a zippkits V3 pipe and a hotpipe on it. Is everyone also getting any good result with the standard ignition, or is it a must do to go to electronic?

Thanks in advance for the replies from people actually using these - and It would be great if Stu Bar or Mark Grim could comment too?

Tony, I use the original barrel carb, unmodified except for a bellmouth. Hotpipe. No idea on the stock ignition as I never tried it! No idea on the carb needle settings, I tune buy ear/look at the plug!

BulletMaster · Jul 28, 2016

Hey Ian...

Ta... but last plug I looked at on that one (from a club day) had the electrode melted away! way lean we think..

Just trying to get baseline settings from the guys in the States at this stage.. don't really want to throw money at electonic ignition until we see some signs of promise.. Actually good point - what sort of timing setup do you guys running the standard ignition use please?

Ray... I very infrequently use IW, so was unaware of the name rule.. will address..

Stuart Barr · Jul 28, 2016

Tony,

I don't have an RPM gauge on mine, but it sounds like 20m +. Using a Roger Payne 929 Walbro carb and stock ignition. Ignition is set at .064" BTDC.

Best pipes are the "Hot Pipe" or CMB steel pipe with muffler cut off. Set the IMPBA oval record last November with this.

Stu

BulletMaster · Jul 28, 2016

Thank you Stu.... that is good information.

We are currently running a wyk33 carb on the engine.. just modified to a square drive setup (due to the load failures that some had been reporting?).

How do you normally go about setting the ignition point - being a CDi type setup, it's difficult to see the turn on point? As we have been running internally muffled pipes, just wondering if this might be causing our issues? Has anyone had success with them on this engine? Lastly, the engine we got was modified already, so we are not sure of the exhaust port standard timings ... but it has now been opened to 185 degrees.

cheers

Tony

Stuart Barr · Jul 29, 2016

Tony,

Flywheel needs to be removed to see the alignment marks on the stator and stator flywheel.

Stu

BulletMaster · Aug 1, 2016

Thanks Stu.. will be doing some testing this week hopefully.. and see if the changes have worked.. (unmuffled pipe - stinger, raised timing, square drive & checked ignition timing)..

BulletMaster · Aug 9, 2016

Well... testing saw us with better results.. still not perfect, but getting there (Thanks Stu & Dad!).. Looks like the boat hull is just a bit too heavy to maximise performance..

Stuart Barr · Aug 10, 2016

Tony,

As a reference, my hydro weighs 14 1/2 pounds race ready.

Stu

BulletMaster · Feb 3, 2017

OK.. Motor is now in a DELTAFORCE boat. Hotpipe is at 12.5 inches from header connection. Still can't get above 16.6 k rpm. Using wyk33 carbine stock. Running at 53 mph radared. Others mentioned 20k rpm... Does the pipe length sound right? Getting very frustrated with this setup. Ideas please guys?

DickJones · Feb 3, 2017

BulletMaster said:
OK.. Motor is now in a DELTAFORCE boat. Hotpipe is at 12.5 inches from header connection. Still can't get above 16.6 k rpm. Using wyk33 carbine stock. Running at 53 mph radared. Others mentioned 20k rpm... Does the pipe length sound right? Getting very frustrated with this setup. Ideas please guys?

Measure pipe from the outside of flange to the center of pipe at the widest part, should be 12 inches, if still slow got o a smaller prop like a X467, might have to raise the strut .60 thos at a time untill the engine starts to sing, if low and high jets are correct?

mobydickk .

BulletMaster · Feb 6, 2017

Thanks for the reply Dick... We have tried fitting smaller props & the revs still don't go above the 16.5K mark. Had a margin of success the other day, shortened the pipe waay up (12.5" to centre of piston) and jumped up to 17.5K rpm.. But suspect port timing might be an issue.. Oh well the development continues..

Scott Tonak · Feb 7, 2017

If you are using a bone stock wyk33 then that could be the problem with performance. The pop off pressure and diaphram distance must be reset in order for the carb to work correctly for our application. A correctly modified wyk33 is hands down the best performance carb I've ever used.

DON MAHER · Feb 8, 2017

This is just a thought, but have you had the tach in another boat, motor combination? It may be a tach that just reads low!

I have two "sendec max-tach" that read almost 1800 rpm different!!!

Don

Stuart Barr · Feb 8, 2017

BulletMaster said:
Thanks for the reply Dick... We have tried fitting smaller props & the revs still don't go above the 16.5K mark. Had a margin of success the other day, shortened the pipe waay up (12.5" to centre of piston) and jumped up to 17.5K rpm.. But suspect port timing might be an issue.. Oh well the development continues..

I have had success with raising the exhaust height. The newer liners have been raised close to .030" .823" top of exhaust to top of liner. I also over cut one liner to .788" top of exhaust to top of liner. It ran and ran extremely well. It is in my mono and runs around 62 MPH. CMB also has a new aluminum muffled pipe that is outstanding. Very quiet and performs better than the "Hot Pipe".

Stu Barr

CMB Alpha carb

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