What mph should I expect?

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purple_pill67
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Wed Jul 11, 2012 3:20 pm

I have an SR type kit bored out to 66mm, Asso piston, Med weight flywheel, new sloped AF clubman, open mouth PHBH30(still needs a fine tune), im guessing a spanish LI150 gearbox(as its that casing) and guess GP crank.
The kit looked to have been tidied up a little but not perfect.
(It was a complete engine fitted to the bike when I got it)
What sort of MPH should I realistically be expecting??
Trying a free gps app on my phone in my trouser pocket, so not ideal, I was only showing about 46-48mph, which seems abit poor?!?

(Eventually I want to get a standard 200 engine, would they be much difference in mph/mpg over what I have-assuming I use the same carb/pipe)

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Doom Patrol
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Wed Jul 11, 2012 3:35 pm

I think you're carb is too large and wasted on something like a Clubman set up, which will be the bottleneck and probably restrict your top speed. Come down to something like a 25mm. Even so I reckon you're looking at a realistic top speed of something like 55 - 60 MPH.

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purple_pill67
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Wed Jul 11, 2012 3:54 pm

Abit late now Nev, cant afford to change it again lol, I need to get up to John to set it up anyway, was just curious really.
(You out on the rideout next week? I hope to be)

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Special X
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Thu Jul 12, 2012 1:14 pm

I've got a tuned 230cc cast iron with a clubman and a 26 PHBH on it. I've got a 30 PHBH carb which I've tried on it and it gives a considerable increase over the 26mm carb so the clubman is letting it breathe. The last 2 clubmans I've had (42mm AF) let the engine rev out to at least 7,500 rpm although they don't give as much power as a decent expansion.

The 25mm PHBL will give considerably less power than a 26 PHBH . . . only a small lift over a jetex 22 really.

camel
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Thu Jul 12, 2012 10:39 pm

the gearbox your using is the let down,altho with the clubman you may get away with the big gap between ratios.altho the front sprocket will need upping to obtain a usable final drive ratio

joey
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Thu Jul 12, 2012 11:59 pm

...sounds like a good improvement on a standard sx/gp 150.....? bin the sr kit, bin the worst gear box ever made and you might start to gain some speed....

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purple_pill67
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Fri Jul 13, 2012 8:25 am

joey wrote:...sounds like a good improvement on a standard sx/gp 150.....? bin the sr kit, bin the worst gear box ever made and you might start to gain some speed....
Until I get my insurance compo I wont be able to do too much, certainly not change the kit sadly, esp as something better than an SR kit is starting to get to 200 block money.
What'd be the best sprocket or gearbox if I tried that?
Something thatd be good for a 200 block further down the line would be ideal.

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coaster
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Fri Jul 13, 2012 9:09 am

I think binning the kit is a bit extreme at this point, SR Kits are capable of putting out decent power so long as the porting has been looked at. Your low top speed could be down to a number of factors, let us know some more details of you kit and set up such as:
What the jetting is in the carb?
What the timing is set to?
Have the ports been re-worked and if so by whom?
What does it run like through the gears?

At the end of the day though, as I think Camel said, 65mph is about all you can realistically expect and that will require factors like gradient and wind to be favourable 8-)

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purple_pill67
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Fri Jul 13, 2012 9:22 am

coaster wrote:I think binning the kit is a bit extreme at this point, SR Kits are capable of putting out decent power so long as the porting has been looked at. Your low top speed could be down to a number of factors, let us know some more details of you kit and set up such as:
What the jetting is in the carb?
What the timing is set to?
Have the ports been re-worked and if so by whom?
What does it run like through the gears?

At the end of the day though, as I think Camel said, 65mph is about all you can realistically expect and that will require factors like gradient and wind to be favourable 8-)
The jetting still needs fine tuning but is as it came jetted for 200 from AF.
Not sure on timing until I speak to my mate...18/19 BTDC.
The engine came via a guy in beverley on ebay that the previous owner bought and fitted. The kit had to come off for rebore so noticed it had been worked on a little but not properly.
1st and 2nd gear is nice and nippy. 3rd isnt quite as good and 4th seems a litle flat. I have moved the clip up to the top from 2nd which helped on the boggyness 4th had.

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coaster
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Fri Jul 13, 2012 9:29 am

Ok, if you hold it flat out for say 2 miles in 4th then cut the engine and coast to stop, what colour is the plug? It's possible it's a bit over jetted, the needle only affects from 1/4 to 3/4 (give or take) throttle, after that it's mainly the main jet.

Do you know what front and rear sprockets you have, standard or larger front?

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