E: Engine Blind jetting

greg brillus

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Well you really need to sort out if it is either rich or lean............If you are not running the air corrector set up, you might be able to ride it to the point of missfire/ stutter and perhaps mute the bellmouth with your left hand to see if this makes it better or worse, not block off the air all together, just a couple of fingers across to restrict the air flow. My Eso/Norton was not coming back on the power cleanly out of the corners, this with a 36 mm Mk 2 concentric on methanol, the slide was a number 3 from memory, way too rich. I modified the slide to a number 5 and now the engine is as clean as possible out of corners now.
 

Bill Thomas

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I got John Kinley going once, He said it was hard to find slides for his L/ning, I said just file a bit out, He said what if I take too much out, I said well then take a bit off the bottom !, He said so it was YOU, He had some that had been got at !. All Good Fun. Cheers Bill.
 

vibrac

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The thing to remember about filing slides is that its not a parallel cut the cut has to end at the bottom in the same place as the original but start higher at the apex and a do little at a time you cant put it back!
really an emergency job in the paddock or wait a day or so for a delivery
 

Bill Thomas

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I have always done it, Must admit I took too much out of the Mk2 s the other day, But the slow running screw affects much higher up on these, And I have managed to get myself back on track, Had a few rides and am well pleased with the plug readings.
I am going to try and make a notch on the choke lever, So I can use a bit of choke, For warmish starting Standard they are all or nothing. Cheers Bill.
 

ClassicBiker

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I did a set of Mikuni slides awhile back. Decided that the guide pin slot center plane was perpendicular to the center line of the cut away and was on center of the slide. Worked out where the bottom plane of the guide slot was compare to the center of the slide, that became my rotation stop. Then measured where the cut away plane crossed the end of slide plane. Measured how far down the current cut was from the end and how much more I needed to be to make a 3 from a 2.5. Trigged out how much I needed to angle the sine plate such that a flat cut would cross the end at the same point. Zeroed on the high point at center of the slide and took very shallow cuts. Deburred with a swiss file and checked by sliding an imperial drill under the cut way, just a light drag and no lift. Unfortunately the clamping ever so lightly distorted the slides from round so I gave a few gentle taps with a raw hide while I held them in my hand. Then they slid down the bores under their own weight. If I were to do this again I would make a holding that retained them either through the needle hole or a finger on the back side.
Reason I did it was, Mikuni VM28 round slides only go to 2.5 cut away. Mikuni would make me 3's on special order at $40 a slide, minimum order 10 slides.
Showed all this to Dave Matson one evening at our monthly section meet. He looked at me and said "I just mark them with a pencil and file 'em."
Steven

#2.5 Slide now #3 Slide.JPG
Set Up 1.JPG
Set Up 2.JPG
 

greg brillus

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VOC Member
I just use a surface plate, a sheet of thick glass with some sheets of emery paper glued on, I use it all the time and have modified many slides on it. To take some off the bottom, I slide an alloy spigot inside the slide to stop it collapsing and trim off in the lathe. You can take a couple of cuts before the slide is ruined but I have never had that happen yet.
 

Martyn Goodwin

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Non-VOC Member
This is a summary of dyno runs with a 10TT9 32 mm, No. 7 slide, needle in middle slot and a two inch straight pipe. Started at 44".
View attachment 22547
I found the bike did not like the long pipes that are usually recommended and that 28" was the best with this set-up. On a bike that made 35 BHP stock, it was nice to get almost 5 more BHP just by cutting the pipe.

David

Bit of blind faith here. My std C Comet with a 30mm Mk1 and std pipe. Std pipe from head to exit to atmosphere was 60 inches. Just sliced 7 1/2 inches off the outlet from my 'old' 'silencer' - it was all I could remove without cutting into the silencer body - so now the exhaust end is just forward of the rear axle. Road testing this weekend. If its no good/better then my new , longer silencer will go back on.

Martyn
 

Bill Thomas

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VOC Member
The Racing bug bites !, I bet it goes better, But you might need to make it richer, And wear ear plugs !.
They always said, End at the wheel spindle, Worked for me.
I know they can go better even shorter, But no good for the road.
Have Fun. Bill.
 
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