JS Motorsports Carbs

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Awesome is all I can say after testing the bile with my slightly worm stock Amals and then fitting JS flatslides and running comaprison rides one up and two up along the same piece of high hilly freeway. If anyone has been over the Wairoa River Road (between Te Puna and Lower Kaimais) for any Kiwis who may know the area, then over the range twice for my tests. Sunday sports bikes and riders were in awe!!!!
Thanks Jim, they are as good , if not better than advertised and has totally transformed my bike. Now just have to watch the rear tyre wear !!!
Will post pics of fit up and a couple minor issues I came across once I have uploaded my pics.
Regards Mike
 
One big advantage of the PWKs is the fact that the jetting/set up used is relevant to use with modern ethanol bearing fuels, unlike the Amals which retain the same settings commonly used with 5 star leaded fuel. Seems weird that the people who sell the Amal carbs are unaware of the fact that different settings are required for modern fuels?
 
Greetings,
I'll play the Devils advocate for a moment.
We know that the chief problem with the old Amals was the use of like metals in both slide and body. Furthermore, regarding their use on a Commando we can not discount the fact that they were rigidly mounted and subjected to a thorough drubbing each and every second the engine was running. If the Commando was as smooth as a Goldwing for example I'd wager no one would have deemed it necessary to seek out alternative carburetors. Now regarding the PWK carbs, I don't know for sure, but I don't think there are any of us who have run them 10,000+ miles or more. So will they hold up in the long run (I'm sure they will), but just asking?

GB
 
geo46er said:
Greetings,
I'll play the Devils advocate for a moment.
We know that the chief problem with the old Amals was the use of like metals in both slide and body. Furthermore, regarding their use on a Commando we can not discount the fact that they were rigidly mounted and subjected to a thorough drubbing each and every second the engine was running. If the Commando was as smooth as a Goldwing for example I'd wager no one would have deemed it necessary to seek out alternative carburetors. Now regarding the PWK carbs, I don't know for sure, but I don't think there are any of us who have run them 10,000+ miles or more. So will they hold up in the long run (I'm sure they will), but just asking?

GB
Click to expand...

well not PWK's but my mikui flatslide (TM) has about 12K on the norton now - works perfectly still -of course unlike the PWKs (which i have on my triumph, but with limited mileage ) it is mounted to a rubber flange
 
geo46er said:
Greetings,
I'll play the Devils advocate for a moment.
We know that the chief problem with the old Amals was the use of like metals in both slide and body. Furthermore, regarding their use on a Commando we can not discount the fact that they were rigidly mounted and subjected to a thorough drubbing each and every second the engine was running. If the Commando was as smooth as a Goldwing for example I'd wager no one would have deemed it necessary to seek out alternative carburetors. Now regarding the PWK carbs, I don't know for sure, but I don't think there are any of us who have run them 10,000+ miles or more. So will they hold up in the long run (I'm sure they will), but just asking?

GB
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The fact that Amal carbs wear out very quickly on just about every bike they are fitted to, and the jetting is inappropriate for any bike running on modern day fuels, rather than leaded 5 star, are things worth thinking about if you intend to fit new ones.
 
It look`s like I also have to by JS- flat slide cabs. But I have one question.
Do you have to tickel the flatslides cab before you start, or can you just start and drive.?
Vidar
 
vidar hjelm johansen said:
It look`s like I also have to by JS- flat slide cabs. But I have one question.
Do you have to tickel the flatslides cab before you start, or can you just start and drive.?
Vidar
Click to expand...

no tickle - choke is a pull-type - look at picture you'll see it -
 
I have had JSmotorsport's flat slides for 18 months now.

From a cold start, pull up the two "choke" levers and kick it over strongly with also giving it a little throttle.

The trick is get enough fuel drawing.

Immediately after it fires up, push down the choke levers and hold the idle with the throttle for a minute and take off

When starting with an already warm engine I find that you do have to give it about one quarter throttle to fire up.

Nothing that unusual about all this, and these flat slides warm up quickly and idle stead in just a few minutes.
 
The right choke is a little obscured. I seem to only have to pull the left to start (1 or 2 kicks), then close at start and and warm with the throttle. I have one of those throttle controls on the grip and can regulate the warm up in this manner.
 
I have found that the bike will start without choke in our warmer weather(southern hemisphere ) and warm the engine on the throttle a little and then back to idle.
I had to drillout the supplied manifold holes a very slight amount, have let Jim know, as the standard SHCS bolts didn't fit through the holes due to some casting defect. Also I cannot get the supplied air filters on due to the the lack of room between the bell mouth and the backing plate of the original air cleaner. looking at modifying my original(as did another forum member) by chopping down the depth of the original perforated surround and putting in a shallower element.
Other than that easy to fit, have used the T's from the Amal fuel line set up so I ca still run the reserve petcock/fuel tap.
Well worth the wait to get them and a huge change in performance.
Regards Mike
 
Brooking 850 said:
Also I cannot get the supplied air filters on due to the the lack of room between the bell mouth and the backing plate of the original air cleaner.
Click to expand...

I think you're suppose to remove the backing plate.
 
rpatton said:
Guido said:
I will miss the look of the stock air filter though.
Click to expand...

You might still be able to keep it. I've been running a single Mikuni with a shortened airfilter element from K&N. I cut down the perforated surround and got a single hole front cover for the aircleaner. Just from looking at the pictures on Jim's site, it looks like they might fit by going back to the original two hole cover.

JS Motorsports Carbs
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So let's say that the front air box plate will fit up to the carbs, where would one find a filter which would fit the space between the two plates?
Go to a auto parts store and ask to open all the filter boxes to try to match one up?
Where did you find yours and how?
 
I got it out of the K&N catalog. It's been so long ago that I can't recall the dimensions of the one I used, but there are a lot of options. I got an oval and flattened it at the top. If I ever get a relplacement, I'd get a rectangular one and give away a little surface area at the bottom.

http://www.knfilters.com/search/universal.aspx
 
rpatton said:
I got it out of the K&N catalog. It's been so long ago that I can't recall the dimensions of the one I used, but there are a lot of options. I got an oval and flattened it at the top. If I ever get a relplacement, I'd get a rectangular one and give away a little surface area at the bottom.

http://www.knfilters.com/search/universal.aspx
Click to expand...

They sell one for the stock airbox. Get the dimensions of that one and then find one that is thinner.
 
I must've been tired and not thinking out side of the box, as I revisted the supplied filters this m'ing and after talking to jim, he assured me you can do the fit up without removing the original backing plate. I did chop my perforated surround and will eventually get an element to fit same as pics show in this thread , in the meantime, pulled the carbs off, leaving the hard alloy inlet manifolds on the head, fitted the airfliters and then slid the carbs back into the rubber boots.
I did put a selfadhesive clear anti scuff on the ends of the conical airfilters though, just so they didn't scuff against the backing plate.
All good!!! Rode to Ngaruwahia (no not a new Indaian nation in the NW!!!)to see Paul Bryant at Viking Exhausts, 3 hour return trip, bike runs sweet , so good the law dedollared (-$$$$) me $80 NZD and 20 demerit points for my troubles
Regards Mike
 
An update on the fit up of the JS carbs. Wasn't totally happy with the way the filters were still rubbing on the original air fliter backing plate, so removed the carbs from the manifold, found that i had over tightened the supplied Jubilee clamp/worm drive clamp at the carb side and had totally distorted(which lessened the diameter) of the square O ring, in formed Jim of this , he mentioned you dont really need them as they are only agap filler, but i backed off the clamp and the o ring sprang back to its original size.
I then cut 5 mm off the rubber boot at the filter side, used some narrower clamps, I thinks off a TL Suzuki!!!, and fitted all on the inlet manifold. This gave me the clearance on the backing plate.
Jim mentioned that his latest manifolds were slightly different than earlier models and this why they made the filters contact the backing plate.
Eventually will get the K&N narrower filter no. and fit up the slightly modified original. have tested the replacement Norton filter boots, and it will fit nice.
What ever filter I use, the carbs are the best investment yet, no regrets!!!
Regards Mike
 
Just for something different, I am trying a set of Amal's new "premier model" 932 carbs built to suit a 73/74 850. These units can be ordered for a small extra amount over standard issue carbs, about $450 delivered to Australia. I prefer to keep the original airbox set up.

These carbs feature...

More precise castings on the bodies, with a passivated finish.
Relocated pilot jets, that can be replaced and or cleaned.
Annodised billet slide
Stay up float

So when they arrive and I fit them I will let you know how they run.

Cheers Richard
 
well these new Amals cant be anything but an improvement over the crap ones they been making up till now, I've bought the pre Premier versions , total rubbish, I await your report, maybe I'll buy some also, for restoration only otherwise it would be the JS carbs for sure, these new Amals certainly look much better.
 
Why on earth are customers for Amal carbs being asked to pay extra for a product which seems slightly more fit for purpose intended? This seems to be a bit of joke, as it suggests that products still being sold for a little less money are not fit for purpose, and shouldnt be considered by anyone wanting to actually use them on a bike?
 
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