HS6 mixture locknut wrench

[hans2]

Can someone post a pic or link to the style of wrench used to loosen the carb (HS6) jet locknut? Thanks much ....

[Ron Kwas]

Hans;

There's nothing special about the wrench...an open end wrench (or spanner, as they would prefer to call it on this forum) will do it, after removing Air-Filter for access...by my measurement, 15mm for the lower mixture adjustment nut, 18mm for the jet securing nut (this is the one which will need to be loosened for centering jet).

Picture Source: http://www.sw-em.com/checkchoke.htm
Cheers from Connecticut!

[Derek UK]

What do you mean by "jet lock-nut"? The jet holder is hard fixed into the carb body but the jet adjuster can be turned by hand, with the spring acting as a lock. i.e. it won't move after adjustment. SU dealers can supply a short angled spanner made from thin plate, but most people can do the job with fingers.
I'm sure Tom won't mind me posting this link which shows all of the various parts. The jet holder nut is done up TIGHT, so can be hard to shift but that's a bench job with a vice being helpful.

http://thosbryant.wordpress.com/2014...building-hs-6/

Ron beat me to it. As you can see, the jet holder nut is very thin and tucked away, hence my comment about doing it on the bench.

[arcturus]

A little "copper-ease" on the jet adjustment nut makes life easier!

[Ron Kwas]

Derek;

That's the first thing I noticed in Hans's post...the title "...mixture locknut..." refers to the the bottom nut...but text of post refers to "...jet locknut..." which would be the top one...that's what I tried to clarify also...do you follow, Hans?

Cheers

[hans2]

Appreciate quick replies ... first time adjusting an HS6, I presumed the locknut required loosening in order to adjust 15mm lower mixture nut (should be non-metric, right?). I see the spring and will just turn the lower nut with more force, ignoring the top locknut. My 18mm crowsfoot couldn't get around it anyway. Thanks.

[Ron Kwas]

hans;

Reiterating...adjust mixture with bottom nut (it is "locked in place" by preload from the spring, to prevent moving on its own!).

DO NOT LOOSEN top nut for mixture adjustment! Top nut is strictly for locking Jet centering position, and you don't want to mess with that if you don't need to!

Cheers

PS. I have just visited the Tom Bryant article linked by Derek... THANKS!...article is IMO excellent(!) in its content and presentation...

[Tom Bryant]

Originally Posted by Ron Kwas

PS. I have just visited the Tom Bryant article linked by Derek... THANKS!...article is IMO excellent(!) in its content and presentation...

Thanks Ron. Now I know why your name was so familiar to me; I had seen it often on this site.

The Jet adjustment nut is actually 5/8" (or 16mm). The jet bearing "locknut" is 18mm, and as several have indicated, you just don't want to mess with that nut, unless your jet needs centering, and that should never happen unless whoever assembled your carbs didn't do the job correctly. In fact, when rebuilding carbs, I usually do not even loosen the jet bearing; rather, I leave it in place, hoping that I won't have to center the jet. Only if the jet needle drags do I loosen the jet bearing and center it properly.

As for all those jet centering tools that can either be purchased or fabricated, forget them. They do not, and cannot, work. That's because, in general, both the jet itself and the needle can be, and usually are, slightly eccentric, so each jet and each needle must be centered as a pair. At any rate, it's not one whit more difficult to center using the needle itself, rather than some "centering tool". Actually, it's easier because you don't have to take the carb back apart and re-install the needle after "finishing" the centering.

Tom