Author Topic: C15 ss Max speed  (Read 2809 times)

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MICKREEVES

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Re: C15 ss Max speed
« Reply #15 on: 21 April, 2017, 14:13:01 »
My standard 175 Bantam was faster. 65 mph normal, and with with the wind , 69.8 mph for 2 miles!
Only good news on the C15  is - one kick start every time, from dead cold, no choke, no tickle, no throttle.
Just with throttle stop set right.
Mick

STAR TWIN

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Re: C15 ss Max speed
« Reply #16 on: 21 April, 2017, 15:37:12 »
If it starts first kick from cold, no choke, no tickle, your tickover and possibly cutaway are set far too rich. Set them when the engine is at operating temperature and you will notice the difference in smoother running and better mpg.

MICKREEVES

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Re: C15 ss Max speed
« Reply #17 on: 25 April, 2017, 18:46:42 »
I bought a pressure gauge to check if my C/R was really 10/1.
After a number of kicks, the gauge reached 134 PSI.
So, with atmosphere at 15 PSI the ratio would be 8.93/1.
Atmosphere at 14.7 PSI ratio would be 9.12/1 ??
My bike accelerates well, pulls away lustily from 30 mph in (overgeared) top.
Now reaches 65 MPH, on satellite speedo, at 5500 Rpm, or 7750 rpm in third.
Mick

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Re: C15 ss Max speed
« Reply #18 on: 26 April, 2017, 20:36:30 »
I would hesitate to rev it to 7,750 rpm too often. Bravery or cruelty to old engines?

MICKREEVES

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Re: C15 ss Max speed
« Reply #19 on: 07 May, 2017, 11:53:01 »
Latest test this morning. Windy.
67 mph in one direction, 76 mph the other way.
Revs about 6600 with 2 teeth oversize sprocket.
I dont want to use the smaller sprocket. I prefer low revs on the engine.
This will greatly reduce stresses and (hopefully) stop it failing.
Mick

MICKREEVES

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Re: C15 ss Max speed
« Reply #20 on: 07 May, 2017, 11:59:31 »
PS.
I also have a Virago V  250 twin. This easily reaches 80 mph.
I have no liking for this 'cruiser' style bike, but it is one of the few bikes weighing about 300 lbs.
I have not the strength for anything heavier. Many of the 250 bikes are 350 lbs or more.
I will sell it soon.
Mick

MICKREEVES

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Re: C15 ss Max speed
« Reply #21 on: 24 May, 2017, 18:34:53 »
I just sold my 250 Jap bike (Easily reached 85). It did not have the appeal and nostalgic feel for the old British bikes.
My C15 Now manages about 70 MPH, perhaps  a bit more.
I measured the head volume. - 35 cc. This works out at just over 8/1 compression ratio. The piston part number makes it 10/1 ?
I find the brakes are very effective.
Mick

MICKREEVES

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Re: C15 ss Max speed
« Reply #22 on: 29 May, 2017, 14:32:51 »
I have now reverted to the original absorption silencer.With a few short runs, I find that the top speed is 70 MPH, or a little more,
measured by satellite. Speedo reads 10 mph fast. (80 top speed!). Rpm reaches 5150 at 60.That should be 5956 rpm at 70.
, and 7940 at 80. isnt that about right??
I do not want go down on gearing. I dont like to run at high revs. At 50 mph, I would prefer to gear  UP! But that would mean using third for higher speed, No.
I really aught to increase engine size for result I want, but engines are expensive and one does not know if they will perform without renovation.
Mick

MICKREEVES

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Re: C15 ss Max speed
« Reply #23 on: 29 May, 2017, 15:39:11 »
My figures were wrong. Tried again and got
6008 @ 70
6866 @ 80
So ,its about 1000 rpm too slow at 80 (if it could reach that.)

MICKREEVES

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Re: C15 ss Max speed
« Reply #24 on: 24 June, 2017, 13:31:30 »
My C15 SS came with 15 tooth sprocket. As used on C15T
the standard for C12 SS, is 16 tooth.
For C15, 17 tooth.
I have now changed to 18 tooth.
I like it!
More relaxed at higher speeds. It still moves away from rest easily, and has lusty acceleration with a handful of throttle.
And that nice bang bang sound of a big single.
Mick

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Re: C15 ss Max speed
« Reply #25 on: 01 July, 2017, 14:06:52 »
This morning I changed my rocker box gasket. Bad leaks from top end.
I tested my top speed. Now 66 mph at only 5300 rpm, not the 8000 rpm
'red line' for this engine. Much more pleasant.
Mick

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Re: C15 ss Max speed
« Reply #26 on: 25 July, 2017, 09:22:18 »
I think I have reached a plateau with my C15 SS.
With the 18 tooth sprocket, it needs clutch slip at take-off, or in slow traffic.
Did a flat out speed run. 66 mph one way. 71 mph coming back.
With the previous low gearing, it was no faster.
At only about 5400 rpm, it is more pleasant and less strain on the engine.
At full speed on full throttle, when I ease the throttle back ,there is no loss of speed until nearly down to half throttle!
This suggests that the 1 1/16" carb is bigger than needed. It would be interesting to try a 7/8" if I had one.

8.5/1 comp ratio, scrambles cam, bigger inlet valve.
Mick

MICKREEVES

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Re: C15 ss Max speed
« Reply #27 on: 25 July, 2017, 10:35:11 »
PS
80 mpg
Mick

Mark

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Re: C15 ss Max speed
« Reply #28 on: 25 July, 2017, 19:24:25 »
I really can't understand what you are trying to achieve these bikes are made to enjoy & not to thrash the arse off them & probably destroy them.

SIMPLE SOLUTION IF YOU WANT MORE SPEED BUY A BIGGER BIKE! ???

Regards Mark.


TIGERJ

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Re: C15 ss Max speed
« Reply #29 on: 29 July, 2017, 22:34:35 »
Mick your C15 seems to go really well I however am struggling with a 375 carb.
Am I correct in thinking you are on a 376 with 200 main jet ?
Regards
           Tim