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| neptune8 |
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 neptune8 Nova Slayer
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| NJD |
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 NJD World Chat Champion

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| neptune8 |
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 neptune8 Nova Slayer
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| Commuter_Tim |
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 Commuter_Tim World Chat Champion

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| bikenut |
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 bikenut World Chat Champion
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| Teflon-Mike |
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 Teflon-Mike tl;dr

Joined: 01 Jun 2010 Karma :    
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 Posted: 10:05 - 27 Nov 2016 Post subject: |
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Most small Honda's share a common mounting pattern.
There's two long bolts go through the back of the crank cases near the footrests. The earth strap for the battery usually attaches to the top one; which 'may' wind a little loose. Usual 'tell' is anomalous electrical faults when the earth connection rattles in and out of contact.
At the top of the engine, there's two triangular plates that attach to the frame's top tube under the petrol tank with two bolts, and to the back of the cylinder head with one. these are the most likely to be 'loose' and rattle, possibly against the wall of the petrol tank. Wires often get trapped in the plates when they are removed, too, and after a little use with the engine shaking the insulation relaxes and the plates become loose.
At the front of the engine, there is a bracket that connects the engine to the frames down tube. THIS is a noteable 'rot trap', and if any is 'broken' it's likely this one. Two bolts go through the frames down tube, to attatch the U section bracket, two more through the front of the engine. Muck chucked up off the front wheel gets caught in the bracket which can then rot out. More gets 'up' the front of the down tube, and gathers around the two tubes that the mounting bolts go through croswise to the frame tube, and in very severe cases these have been known to rot out from the inside and the tube crack above the bracket.
Most likely thing is that the top engine steady {triangular plates} have been left off, which can let the engine rock a bit; and stress the other mounts, and see the rear ones loose off.
IF anything is likely to actually 'break', and its not particularly likely, it will be the bosses on the engine that the bolts go through rather than the frame; because the engine is alloy which is softer than steel and can crack.
There is a niggle with the rear mounts, in so much as the bolts are prone to corrode solid in the engine, so it's not unknown for them to get mashed up by folk trying to bash the bolts out.
But AFAIK there's no 'common' problem with CG engine mountings, or any other of the small Hondas that use the same mountings.
The Suzuki GS125, uses a very similar bracket between its front down tube and engine, which IS a known bugbear for rotting, but on the Honda's I've never seen one 'go' there.
Lift the petrol tank; look at or for the 'head stay', then go down to teh front down tube bracket, then to the back mounts. give it ALL a thorough cleaning so you can see what's what, and then tweek the bolts up tight.
You'll find any 'real' problem far faster than asking us what may be one, and put it right, or eliminate the variable, whilst you are about it.
Go get your hands dirty! ____________________ 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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| neptune8 |
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 neptune8 Nova Slayer
Joined: 22 Nov 2016 Karma :     
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 Posted: 15:46 - 27 Nov 2016 Post subject: |
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OK, many thanks for the various replies. Today, I "got my hands dirty" and after removing the side panels, seat, and tank, I rechecked all engine mounting bolts,frame and lugs. Everything is tight, and no cracks or other damage. Whatever my original noise problem is, it must be elsewhere. The noise is a loudish rattle that appears to come from the engine. It is only there when the engine is working hard accelerating, or climbing a hill. It only appears above say 4,500 RPM, although I have no rev counter. There is a slight vibration through the footrests at all times, but no more than would be expected from a single cylinder engine. It sounds like a loose fuel tank or other metal part vibrating. I tend to cruise at 50 MPH on the open road, and after reaching that speed,the noise virtually disappears. Tappets have been double checked. there is plenty of compression, and the engine burns virtually no oil, as in about one tenth of a litre per thousand miles. 18,000 miles on the clock. An odd thing is that if I ride over a bump in the road, the noise momentarily goes away sometimes. I am out of ideas, and will probably live with it until or unless it gets worse, and then either strip it down or buy a second hand engine. Any theories please? ____________________ Enjoy yourself, its later than you think |
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| Rob Fzs |
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 Rob Fzs World Chat Champion
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| Commuter_Tim |
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 Commuter_Tim World Chat Champion

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| neptune8 |
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 neptune8 Nova Slayer
Joined: 22 Nov 2016 Karma :     
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Old Thread Alert!
The last post was made 9 years, 71 days ago. Instead of replying here, would creating a new thread be more useful? |
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