• Hi everyone,

    As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.

    When he passed, I worked with his kids to gather the necessary credentials to keep this site running. Since then (and for however long they worked with Coffee), Woodschick and Dirtdame have been maintaining the site and covering the costs. Without their hard work and financial support, CafeHusky would have been lost.

    Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.

    Unfortunately, the new software version doesn’t support importing the old site’s styles, so for now, you’ll see the XenForo default style. This may change over time.

    Coffee didn’t document the work he did on the site, so I’ve been digging through the old setup to understand how everything was running. There may still be things I’ve missed. One known issue is that email functionality is not yet working on the new site, but I hope to resolve this over time.

    Thanks for your patience and support!

Dellorto phm 40 rejetting jetting question

johnclearysm610

johnclearysm610

Husqvarna
A Class
Recently I fitted 2 akrapovic straight through silencers to my 2000 610e. Adjusting the mixture screw smoothed out 1/4 throttle and stopped any backfiring on decel from low throttle. Getting some backfiring on decel from mid to full throttle. Is this normal with straight through pipes? And should I increase or decrease the size of the main jet to stop the backfiring on decel after full throttle? My mix screw is nearly 2.5 turns out I just kept turning it a quarter of a turn out from 1.5 until It stopped backfiring on low throttle. Also if I change the main jet will I have to change the idle jet too even though it runs fine at 1/4 throttle? Thanks
 
No experience with that specific carb but speaking to carbs in general, I wouldn't worry about a little popping at higher rpm's. Changing the main jet won't help that anyway (as soon as you let off the throttle the needle plugs the mj). Try taking the mix screw out a little more.

.
 
Back firing on decel is not necessarly a function of jetting.
It's only lighting off the unburnt gas thru the ingestion of air into the exh system either thru the head pipe mounting or thru the slip connects in the system.
Some have jetted it out but all they are doing is to add or reduce the amount of fuel so it doesn't pop off.
You jet for ride ability and performance with an open system it's just going to pop more from the lack of back pressure and free flowing exh.

Seen many many perfectly jetted bikes pop.

On excelleration the pop is either lean misfire or electrical mis fire.
Later George
 
Thanks think I'll just leave it as it is then. It's pulling well on acceleration with no misses or flat spots. Thanks dyno bob. Thanks George.
 
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