Flat slide blues but getting there...

Sad to here you might miss an event Fred, because of something probably simple, but hard to find.
Hope it turns out OK in the end.
I have had the same trouble with the Gaskets from day one, and have had the Carbs to bits many
times now, more than I like, as the screws are a little loose from new.
I fill the groove in the Bowl with grease so the gasket will stay in place, it works if
you act quickly.
I guess we all knew when we bought this setup that they were incredibly well priced as far as
Flat slide Carb Kits go, and in my case, (being a staunch Mik man) only decided to try them
after reading many reports from happy customers. Unfortunately for me, after reading the debate
re these Carbs being made by Kiehin, as genuine PWKs are, I thought the debate was settled.
Living in Australia, means 10-14 days wait for anything from overseas, except N.Z. so I decided to
go to my local Kiehin dealer, (a 15 min drive) to buy a pair of Slides with less Cuttaway, and or
a pair of Needles with a slightly steeper secondary taper.
Unfortunately, the Parts are not the same, don't look the same, and the part numbers are not the same.
The jets might be, but not sure, when I tried different ones, in a jump of one size, things were radically different.
Jim doesn't have other slides, there are none avaliable.
I don't see different slides on the Mikes XS page.
For the $500.00 delivered price, to my door, I am happy, but need to eliminate a spit back at small throttle openings.
It's Winter, cold and wet, at the moment so productivity is low.
Jim has sent me a pair of altered Needles, but initial testing was thwarted by a Boyer problem.
We'll get it right I'm sure, hopefully.
AC.

Sanket, I am in 24 and 14 - my mistake.

My carbs idle fine and the mid range is good. I haven't had any issues with the float bowl gasket as they fit when dried out. The needles are closing. What are those seals on the jet block doing?

FastFred said:

Sanket, I am in 24 and 14 - my mistake.

My carbs idle fine and the mid range is good. I haven't had any issues with the float bowl gasket as they fit when dried out. The needles are closing. What are those seals on the jet block doing?

Click to expand...

You won't have any trouble with jet blocks or needle binding. I now check & take care that there is no needle binding on every carb set I send out. The instructions warn that you must dry out the bowl gaskets before assembling so they shrink back down (if they swell up from gasoline exposure).

For awhile I used to ask customers who had trouble to return the carbs to me so I could test them on my street bike. They all needed idle mix & speed adjustments - a couple needed the needle clips to be raised leaner. I made videos showing that they worked perfectly when adjusted correctly. After about 5 customers I got tired of it. It takes me 2 or 3 hours by the time I've made the tests & processed the video etc. So now I ask $95 for that service (there have been no takers). Some customers still couldn't get it right even after I tuned the carbs on my street bike and recorded the settings. Its not a perfect world. There is a small percentage of flatslide customers who have problems because adjustments are required with all carb installations. I cannot adjust them myself for everyone - but for the record - the majority of flatlside owners find them easy to adjust and like them very much.

See adjustment carb video at:

http://youtu.be/6j2nMv9TQb4

Jim thanks, That carb tuning video is very basic. I don't think it is the carbs. . They tickover fine and the mid range is good. I have tried everything I can to cure the misfire so have decided to go to Mallory on the Beemer, sh*t happens, I'll fix it later...

Forgot to mention I found two huge cracks in the downpipes today! They won't be helping things...

Fred,

All I can offer, from past experiences with EI boyer and now Pazon. Very carefully check the wire connections on the trigger plate. I have seen symptoms of a engine misfire at mid to high RPM and only really found out the cause when it got worse from poor contact. Another time on the Pazon the engine was running like a clock, rode mils out to a bike rally, started and ran for a couple of minutes the next day and then just stopped and would not start again. It was the wire connections at the trigger, these are very critical!

HTH

Richard

There's something else going on . . . some kind of air leak, one side or the other, intake or exhaust. Maybe ignition . . .

You found two cracks it the down pipes - maybe they were there all along?

Well today me and my mate spent another wonderful afternoon trying to rid my bike of the high speed misfire with these carbs that have had me Commandoless since March. Reset slide heights before fitting vacuum gauges to fine tune and then set mixtures with Colortune. Tickover beautiful.

My mate brought his new Wassell power module which we wired up as this was my only remaining idea of a possible 'solution' (thought that my boyer powerbox may be producing excess volts at high rpm, over 16V can also cause boyer ignition issues).

Went out to road test and all seemed well but then misfire at 90mph still. Came back home and put 160mainjets back in. Same again. Plug colours seem perfect.

Have got to the point now where it's either a dyno job or sell the carbs. Shame as it goes like a train until the misfire kicks in.

I had a similar problem on a bog standard 850. As rebuilt it ran great, and I started getting high-speed misfiring similar to what you describe, but it coincided with changing the tinware from Interstate to Roadster, so the only change was the volume of fuel in the tank - or so I thought until I remembered changing the fuel taps as well.

It simply wasn't able to draw enough fuel because one of the brand new petrol taps was partially blocked. - with both taps on it miraculously cured itself....

Have you checked for good fuel flow? With standard Amals with ticklers you'd notice it taking a while to flood, but with chokes... :roll:

Could it be something simple like a bad contact somewhere, ie ignition switch? This was the problem with my 650SS, overlooked by numerous Norton experts and also by me for some time.

Glen

It's not the ignition switch and I have been testing it with both fuel taps on, these have been checked for fuel flow Thanks for suggestions.

You might want to take a look at the cast inlet manifolds. The first two Jim sent me were porous, you could see the blemishes in the bores of the casting and petrol would piss straight through the walls. The second two were better but still not brilliant. I drilled and tapped the casting and fitted brass stubs from my Morgan Carb balancers, then capped the stub. The manifolds were made by Quaife apparently. Quality british product? Hmmmm No

I'll look at that thanks, one of my carbs has a casting hole (porosity) in the main venturi (!)but it is blind (not a through hole) and would therefore only cause a very small disruption of air flow. I tapped for Morgan's as well.