Carbs for a Monza Junior

[halfpast]

Looking to rebuild a MJ engine with a hotter cam and some head work. Any recommendations on what carbs would be a good fit? Thanks in advance.

[Samurai]

No experience of a Monza Junior specifically, but if it has the inlet stub similar to my 175TS, then I've fitted. Dellorto PHBL22 straight on to it. The Dellortos have a huge range of adjustment, but therein lies their only downfall.

If you fit any carb that is non-standard and you can't get reliable data for a starting point with the setup, you'll essentially be your own development fuelling specialist. That can take up a lot of time and money on needles and jets before you get it spot on.

Ask me how I know . . .

[halfpast]

Thank you!

[halfpast]

Samurai, if you're still out there I have a question - it seems like the PHBL series carbs do not have a 'tickler'...are there any tricks to getting the carb primed before starting the bike?

Thanks in advance.

[Bevel bob]

Lean the bike over to the opposite side (the right) to flood the float chamber.

[Samurai]

Hi, you're quite correct, the PHBL series have a 'normal' choke which you can choose to have lever or cable operated depending on the set-up ordered.

I have mine cable operated using the original air-controller handlebar lever. I find that from cold I use about 3/4 choke, about a quarter throttle and from TDC it normally fires first or second kick.

Correctly set up, I find that you'll need to let the bike warm up for a good 5 mins on slightly decreasing levels of choke till it will idle reliably without dying with the choke off.

If you look at some of my earlier posts you find the carb settings I've ended up using for my standard 175 TS, which will hopefully save you a while bunch of heartache and cash to get you in the right ballpark.

Hope this helps.

Jason.

[halfpast]

The definitely helps! Thanks very much.

[tweaky beast]

I've fitted a Amal concentric MK1 624 to mine. Jets as per Burden's STD 24 mm carb. Very close to good. Made a little manifold . What can are you hoping to use.

[ducwiz]

Hi, you're quite correct, the PHBL series have a 'normal' choke which you can choose to have lever or cable operated depending on the set-up ordered.

Contradiction - No. The modern Dell'Ortos have a tiny separate starter carb, not a 'normal' choke. Such device - a slide or butterfly valve - would mechanically restrict the air inlet. Instead, the starter carb operated by a tiny plunger or piston, and delivers an enriched mixture, independent of the main carb system. This is why one should not open the throttle during a cold start, but only lift the starter plunger.

Hans