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ghbrown125 |
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ghbrown125 L Plate Warrior
Joined: 24 Apr 2009 Karma :
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Posted: 12:24 - 26 May 2009 Post subject: |
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it would pull that kind of gearin cos mine used to have 14 front and 41 rear, it now has 17 front and 36 rear, pull perfectly fine, if u have a racing cdi box pefrformance air filter and exhaust. |
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Newbiker0507 |
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Newbiker0507 Crazy Courier
Joined: 30 Oct 2007 Karma :
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honda nutter |
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honda nutter L Plate Warrior
Joined: 18 Nov 2009 Karma :
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unitybiker |
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unitybiker Nova Slayer
Joined: 28 Nov 2009 Karma :
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Posted: 22:47 - 04 Dec 2009 Post subject: |
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CG's after the early 80's used a twin wall exhaust ,changing to a single wall non standard one and a k n N should boost 2hp just remember to adjust mixture .Although a carb swap is a good boost carbs from early 80's onwards have an accelerator pump on the side .I think the concept was ....weak mixture/jetting and richer mixture when accelerating for 11 hp traction.
I would'nt focus too much on top speed ,they just get knackerd valves and springs at top wack all day and you can quickly wear the motor out in 5,000 miles . whats special about the symetrical one cam valve timing is the amount of low down chug in 4th and 5th, by modding the exhaust and air filter they stomp along at low revs,this extra power can be geared in for 5-6mph at the higher range of use ,,,,i,e, 50 -60 mph
remember if your cg's got an enclosed chaingaurd then look after it it's a fiddly fkkkr but it will make it worth buying a decent chain because of the much longer chain life. |
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markrolls88 |
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markrolls88 Renault 5 Driver
Joined: 30 Nov 2009 Karma :
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johnsmith222 |
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johnsmith222 World Chat Champion
Joined: 26 Dec 2008 Karma :
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The Shaggy D.A. |
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The Shaggy D.A. Super Spammer
Joined: 12 Sep 2008 Karma :
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Posted: 18:39 - 10 Dec 2009 Post subject: |
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1. Put a screen on.
2. Rebump in another 6 months to make it a 6 year old thread. ____________________ Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5 |
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Ben35 |
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Ben35 L Plate Warrior
Joined: 28 Feb 2010 Karma :
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mrr1 |
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mrr1 Traffic Copper
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mrr1 |
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mrr1 Traffic Copper
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smegballs |
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smegballs World Chat Champion
Joined: 28 Oct 2007 Karma :
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mrr1 |
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mrr1 Traffic Copper
Joined: 24 May 2009 Karma :
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Posted: 20:37 - 26 Mar 2010 Post subject: |
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errr.....jesting, oh yes, of course - I was jesting, ha, ha ____________________ TRX850, TDM900, ST1300, CB650SC Nighthawk, ragtop Saab, gym membership, messy divorce, large chested blonde fiance
Damn, I'm loving my midlife crisis. |
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markrolls88 |
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markrolls88 Renault 5 Driver
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Howling Terror |
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Howling Terror Super Spammer
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N cee thirty |
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N cee thirty Banned
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Frost |
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Frost World Chat Champion
Joined: 26 May 2004 Karma :
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The Shaggy D.A. |
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The Shaggy D.A. Super Spammer
Joined: 12 Sep 2008 Karma :
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Posted: 19:53 - 05 Jun 2010 Post subject: |
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\o/ ____________________ Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5 |
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Old Thread Alert!
There is a gap of 2 years, 56 days between these two posts... |
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v6413 |
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v6413 L Plate Warrior
Joined: 30 Jul 2012 Karma :
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DMCpro |
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DMCpro Traffic Copper
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Alpha-9 |
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Alpha-9 Super Spammer
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tahrey |
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tahrey World Chat Champion
Joined: 07 Jul 2010 Karma :
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Posted: 17:11 - 08 Oct 2012 Post subject: |
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Mild thread necromancy (on a truly ancient original post)!
I ended up at this after somehow being inspired to look at TL150s etc (I think I was looking for XR gear ratio lists or something? weird how the internet works)... a "Miller conversion"?
Has anyone actually tried some of the TL125 capacity increasing tricks and found if they also work on CGs / XRs / CRXs etc? Assuming the engines are at least vaguely related?
Seeing as I will hopefully have a bottom end to play with soon (indeed, one that NEEDS the crank taking apart to repair - in which case I can look into stroking it a little), and top ends aren't anywhere near as hard to get hold of. It's not so much of a problem if you knacker one trying to bore it out if it's not actually vital to the continued running of your everyday bike...
They don't say explicitly on the site I looked at what the stroker comes out as, just that it's "about 150cc". The additional stroke is 9.5mm, which I assume is overall (so 4.75mm additional radius, and a 4.75mm shorter rod) ... 56.5 x 49.5 goes up to 56.5 x 59.0 = 124.1cc goes up to 147.9cc.
Which is pretty good as far as I'm concerned, so long as the crank and rod adjustment work isn't too involved or expensive, the big end still has enough clearance in the block (and the rod has clearance in the casing mouth/barrel), and the gasket/pushrods/valves/carb can be adjusted to suit. Saves all the messy reboring business, is larger at the end of the day than the "146cc" big bore kit using CB550 / CB750 parts (liner and piston) plus some risky modification of the barrel, and just seems simpler and cheaper overall. And it still stays within the £16 tax band!
As well as being something different. No-one tends to make strokers any more :p
All things being equal it'd be a potential 19% torque and power increase (vs 17% for the rebore). Or an extra 2hp and 1.8NM (10.8 -> 12.8 and 9.8 -> 11.6), and probably 5mph on the top end, with hill climbing power increased by and cruising revs reduced by about 9% each (the gearing would have to be lengthened, but not by the full 19%... though this also means it could be lengthened 10-11% whilst still enjoying improved acceleration/climbing).
(IE I could likely regear it for a sustained 70 at 8500 instead of the near-9400 at present, and see a very strong 60ish cruise at a little over 7000. That would be just dandy for my purposes.)
Fuel economy might also drop 9 ~ 19%, but I somehow doubt it, given the amount of time the bike spends at full chat or very wide throttle, vs low-fractional throttle or idle - plus there's the altered gearing (124 x 9375 = 112.5k ; 148 x 8500 = 125.8k ; 125.8 / 112.5 = 111% overall airflow). It'll still use more almost certainly, but maybe more in the perfectly acceptable 5% range except when going flat-out. May even depend on jetting etc.
And of course for those just going for all out capacity on a death weapon esque project, both together would be 174cc (+40%, 15.1hp and 13.7NM, could be another 10mph there...) just with these mods, ignoring the possible 185~200cc (16~17.4hp. woo.) increases with the more exotic and risky rebores. Though one wonders why, if you were then thinking of going higher to the "theoretical 223cc maximum", you wouldn't just upgrade to an already more sophisticated 250 :p |
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Jamie S |
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Jamie S World Chat Champion
Joined: 28 Dec 2006 Karma :
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tahrey |
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tahrey World Chat Champion
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kramdra |
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kramdra World Chat Champion
Joined: 28 Oct 2010 Karma :
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Teflon-Mike |
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Teflon-Mike tl;dr
Joined: 01 Jun 2010 Karma :
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Posted: 03:25 - 09 Oct 2012 Post subject: |
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kramdra wrote: | wonder if you could chop a 600cc...no. CBR250RR IL4 engine in half to a 125? would be a LOT of work, if its even possible. but rev to 19k, half of 45 horses... but probably lose a few in the hackery. |
Honda CB125Twin engine in full power guise offered 17bhp... bit under the 22.5 half of a CBR250R.... but close enough and not bad from a thirty five year old, two valve per cylinder air-cooled motor!
Be easier to tune one of them up, rather than cut a 250 in half and work backwards..... but, ultimately? 125 Four-Stroke? anything over 12bhp is good going, and little engine, never going to find big gains. ____________________ My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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Old Thread Alert!
The last post was made 11 years, 253 days ago. Instead of replying here, would creating a new thread be more useful? |
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