Author Topic: Jetting?  (Read 852 times)

Offline Allington

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Re: Jetting?
« Reply #15 on: April 17, 2019, 05:09:31 AM »
Find somebody with a dyno and an interest in classic bikes and book a couple of hours dyno time.... well worth it for a non std set up, the only way to get it right. You wont find anybody who can tell you what jets to use over the internet, maybe some can give you a rough starting point but thats all. Good luck with it.

If anywhere near Grantham Roy at RP Motorsport is excellent. Dyno, tons of knowledge and old school too.
"A little bit of knowledge is a dangerous thing..."

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Offline Arch stanton

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Re: Jetting?
« Reply #16 on: April 17, 2019, 06:33:33 AM »
I'm not near Lincolnshire. But I am 1 mile away from Frank Wrathall. So maybe I'll see if I can book it in with him.
But ultimately. All I want is the bike to be as pleasant as possible to ride, in its present form.

Offline Allington

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Re: Jetting?
« Reply #17 on: April 20, 2019, 05:11:23 AM »
I'm not near Lincolnshire. But I am 1 mile away from Frank Wrathall. So maybe I'll see if I can book it in with him.
But ultimately. All I want is the bike to be as pleasant as possible to ride, in its present form.

Frank is excellent and really knows his stuff. Tunes some of the fastest production bikes in the world.
"A little bit of knowledge is a dangerous thing..."

FS1E - RD200 - CB500 - Norton Commando - Z900

Offline Arch stanton

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Re: Jetting?
« Reply #18 on: April 20, 2019, 07:23:57 AM »
Indeed he does.
At the moment the bike is on the bench of one of the best Honda mechanics there is. John Carr. Formerly of Bill Head Motorcycles.

Offline Arch stanton

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Re: Jetting?
« Reply #19 on: May 12, 2019, 07:32:33 AM »
The answer to my original question is..
130 mains & 1&1/2 turns of the air screw.
I don't have a standard K1 to compare it with. But it feels fine to me. Fine enough to go to the TT on anyway.

Offline Jamesh_sussex

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Jetting?
« Reply #20 on: May 12, 2019, 10:59:07 AM »
So to clarify, you’ve fitted 130 mains, adjusted the idle screws and all is well on your K1 running open bell-mouths? Did you get someone to set the bike up for you on the dyno in the end..?

Offline Arch stanton

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Re: Jetting?
« Reply #21 on: May 12, 2019, 09:58:07 PM »
No. I just got my Mechanic John Carr to go through everything. In order to give it a final set up after building the bike over winter. I didn't open the engine as it appears to be a very good one.
I was pleasantly surprised how easy to set up it was.
The differences between the F1 & K1 have been pointed out to me.
But from what I remember. The K1 is riding quite similar the the F1 I did 50,000 miles on many years ago. With the very same set up. Though the F had a 3/4 Rickman fairing.
I think I will be quite satisfied with it.
By the way.
John Carr built the Honda that Alan Jackson won the first 3
World formula 2 World Championships on. + was awarded the Shell oils Mechanic of the year award at the TT around 1982. He knows his stuff.

Offline MarkCR750

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Re: Jetting?
« Reply #22 on: May 13, 2019, 05:59:04 PM »
I had my 750 sohc dynoed a couple of years back, K6 engine we think!, fuelling was good above 3k revs but a bit lean below, I have a 4 into one (piper pipes and generic reverse cone silencer) and pod filters that I grafted onto the original velocity stacks from the Honda air box, I fitted 135 main jets and left the original pilot jets in,  the dyno guy (Sam Ermolenko, google him) said at the time that the silencer was stifling it a bit, at the weekend during a bored moment I drilled some bigger holes in the baffle plate, the result?, it’s gone very lean, like white plug tips lean , oops!, so I just ordered some #40 pilots, this is with PD41A carbs by the way, now I know when I fit them that everything is going to be absolutely perfect and anyone saying different is just plain wrong :), one thing I noticed when setting the float heights is that even if you set them carefully you get variance in the fuel levels across the carbs so I will be using the clear pipe on the drains method to make sure I get them all correct and the same, I have never removed pressed in pilot jets before, does anyone have any tips?, bit of heat?, pull with pliers?, new ones in the freezer before fitting?, all advice greatfully received:)
Here’s mine on the dyno
https://youtu.be/dzyp3A1TQBY
« Last Edit: May 13, 2019, 06:21:45 PM by MarkCR750 »
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1977 K7 CR750 (lookalike, what of I’m not sure)
Ducati 900SS (Soul & Speed)
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James Captain 197 (pure adrenaline, i.e. no brakes!)
"Eff yir gitten awvestear yir gooin te farst"
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Offline SteveD CB500K0

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Re: Jetting?
« Reply #23 on: May 13, 2019, 07:08:32 PM »
I hope you had a set of ear defenders on as well!


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Offline MarkCR750

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Re: Jetting?
« Reply #24 on: May 13, 2019, 07:16:46 PM »
Pardon?
Ducati Scrambler 803.(Pure fun)
1977 K7 CR750 (lookalike, what of I’m not sure)
Ducati 900SS (Soul & Speed)
Ducati M900 Monster (Handling & character)
James Captain 197 (pure adrenaline, i.e. no brakes!)
"Eff yir gitten awvestear yir gooin te farst"
Sir J.Stewart.

Offline philward

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Re: Jetting?
« Reply #25 on: May 13, 2019, 08:29:42 PM »
I had my 750 sohc dynoed a couple of years back, K6 engine we think!, fuelling was good above 3k revs but a bit lean below, I have a 4 into one (piper pipes and generic reverse cone silencer) and pod filters that I grafted onto the original velocity stacks from the Honda air box, I fitted 135 main jets and left the original pilot jets in,  the dyno guy (Sam Ermolenko, google him) said at the time that the silencer was stifling it a bit, at the weekend during a bored moment I drilled some bigger holes in the baffle plate, the result?, it’s gone very lean, like white plug tips lean , oops!, so I just ordered some #40 pilots, this is with PD41A carbs by the way, now I know when I fit them that everything is going to be absolutely perfect and anyone saying different is just plain wrong :), one thing I noticed when setting the float heights is that even if you set them carefully you get variance in the fuel levels across the carbs so I will be using the clear pipe on the drains method to make sure I get them all correct and the same, I have never removed pressed in pilot jets before, does anyone have any tips?, bit of heat?, pull with pliers?, new ones in the freezer before fitting?, all advice greatfully received:)
Here’s mine on the dyno
https://youtu.be/dzyp3A1TQBY
Your CR sounds great Mark!
Current Bikes:-
Kawasaki ZZR1100D3
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Offline MarkCR750

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Re: Jetting?
« Reply #26 on: May 13, 2019, 09:08:56 PM »
Cheers Phil, it actually sounds even better when you’re on the bike, a really addictive sound that usually leads to travelling too fast!, there’s something about an 8v 4 that’s hard to beat.
Ducati Scrambler 803.(Pure fun)
1977 K7 CR750 (lookalike, what of I’m not sure)
Ducati 900SS (Soul & Speed)
Ducati M900 Monster (Handling & character)
James Captain 197 (pure adrenaline, i.e. no brakes!)
"Eff yir gitten awvestear yir gooin te farst"
Sir J.Stewart.

Offline MrDavo

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Re: Jetting?
« Reply #27 on: May 15, 2019, 03:18:31 PM »
Good luck with finding your bike's sweet spot. You're always at a compromise between power at full bananas and tractability, even at factory settings.

As a dyno related aside, at Donington once I was asked to take Michael Rutter's RC45, which had just been fitted with a new factory engine, over to a mobile dyno in the paddock. I can't remember the hp, and at the time I wouldn't have been allowed to disclose it, but the sight and sound of an RC45 race bike at full tilt on the rollers certainly made the hairs stand up on the back of the neck. No ear defenders of course, by then it was too late, I'd already seen Quo and Black Sabbath live.
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Offline Arch stanton

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Re: Jetting?
« Reply #28 on: May 15, 2019, 04:57:08 PM »
The old thing is quite nice to ride  in most scenarios.
But its an old bike. If I wanted to go quick I'd ride something
More recent. So I'll treat it with a bit of respect.
I have become Too old to die young. So I've decided to stop trying.

Offline K2-K6

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Re: Jetting?
« Reply #29 on: May 15, 2019, 06:59:26 PM »
Good luck with finding your bike's sweet spot. You're always at a compromise between power at full bananas and tractability, even at factory settings.

As a dyno related aside, at Donington once I was asked to take Michael Rutter's RC45, which had just been fitted with a new factory engine, over to a mobile dyno in the paddock. I can't remember the hp, and at the time I wouldn't have been allowed to disclose it, but the sight and sound of an RC45 race bike at full tilt on the rollers certainly made the hairs stand up on the back of the neck. No ear defenders of course, by then it was too late, I'd already seen Quo and Black Sabbath live.

I saw him on that at Brands Hatch long circuit,  seem to remember thrashing the others when it was wet that race.

They are quite scary when flat out under load like that aren't they,  probably a good job you can't hear so much when riding them.