SKWID L Plate Warrior
Joined: 19 Jan 2022 Karma :
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Posted: 22:16 - 19 Jan 2022 Post subject: 2005 honda cg125cc with big bore 150cc upgrade, carb advice? |
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Hi all,
first time posting on here and hopefully someone can help me out with my bike.
I recently stripped my bike down completely and converted my 125cc engine to a 150cc, I'm having some issues due to this being my first project too.
I believe I need to upgrade my carb and iv not been able to find something because I'm unsure what id need exactly.
The bike is a honda cg125cc 2005
any help would be appreciated |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 22:49 - 19 Jan 2022 Post subject: |
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If you haven't ported the head, there's probably not much point fitting a bigger carb. I'd expect you might need to tweak the jetting on the standard carb.
Depends how it's running. How is it running?
Tuning bikes is a can of worms, it's never plug and play. Even if it's sold to you as if it is. Take this from someone who just had to take a rotary burr to part of his crankcases yesterday to increase tappet clearance. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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WD Forte World Chat Champion
Joined: 17 Jun 2010 Karma :
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 01:16 - 20 Jan 2022 Post subject: |
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In fairness, there is a fair chance it won't need any changes to the carb at all.
As above, you haven't altered the stroke, porting or the valve and ignition timing, just the bore. Not sure how it would play regarding compression ratio, that would depend on the new barrel and piston profile.
In any case. Going from 125 to 150cc with a simple overbore, I would expect the bike to start and run well enough on the standard jetting to act as a basis for improvement, especially at low revs. If it's not running, I doubt fueling is the problem.
If Virus sees this, I think he had a 150cc CG125 at one point so may be able to give you some pointers. I very much doubt he bought a new carb for it, he was spending most of his money on beer at that stage. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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