Hyosung GT 125 Comet - Unhealthy Engine Noise

[MightJustGoJa...]

I've researched high and low regarding this, however I've never come across some solid information on what this issue actually is.

It's strange, because tt seems to be a "similar" issue occurring on a lot of Hyosung bikes. My Bike is a 2014 (non-digital-dash) model of the GT 125 Comet, the body is immaculate and has done less than 3000 miles.

The bike starts perfectly, it does idol. I haven't ridden it much to test power/speeds etc etc.

The main thing bugging me is - when the bike is in idol, itermittently the engine (seems to be on the West of the engine, towards the top of a cylinder (not sure which) or -the carbs, seperate from the natural sound of the engine is a cranking / grinding / scraping noise, it's noticable but doesn't quote overwhelm the natural sound of the bike, it happens very intermittently, twice in 20 seconds, once every 4 minutes, 3 times in 136 seconds.... lasts for around 5 - 10 seconds, so it's not constant.

I was hoping it is the cam chain tensioner, but that is located toward the east side of the bike, to the rear of the back cylinder, and as I said, my noise comes from the west side of the bike, towards to top of the cylinders, maybe the cams.

Definitive advice on this would be massively appreciated.

[jaffa90]

Does holding the clutch in make any difference?

[MightJustGoJa...]

[Evil Hans]

Starter motor not disengaging?
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Triumph Sprint ST 1050. And it's Red.

[MightJustGoJa...]

[Evil Hans]

That's what I was asking you

It should disengage once it stops spinning and the bike is started.
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Triumph Sprint ST 1050. And it's Red.

[MightJustGoJa...]

[Teflon-Mike]

I have never laid spanners on one, but ISTR that the comet is a bit of a parts bin special, built essentially from a Suzuki 125 Savage V-Twin engine mounted in a GS500 frame, to make a physically large, is somewhat heavy learner legal of rather dubiously over complicated and under performing mechanics, before they added a lot of added cost cutting and 'anti-tamper' measures, that conspir with poor parts support t make them something of a nightmare to live with, for not a lot of good reason.

That appraisal aside; most common engine related rattle, would be the exhaust gasket, and on the Hyasinth, ISTR that is rather aggravated by the V-Twin layout and complex header routing, that's rather rot prone, and confounded by an anti-tamper sleeve in the flange that's rivotd to the head rather than bolted.

Given propensity for header rot, and for owners to try removing supposed 'restriction washers', or just try ad get more niose, THAT would be my fist area of invstigation, and not one I would aproach wth much optimism, if the exhaust rotted or just the gasket 'gone', it could be an expensive fix to get round the anti-tamper rivot and find or have made suitable replacement 'zorst.....

Next area of investigation would be the Cam Chain tensioner, and I'm pretty sure that the Savage 125 twin has a single Overhead cam in each head ad a pair of cam-chains and a pair of semi-automatc hydraulic adjusters, that aren't completely maintenence free, oil pressure does tweek the tension, but they are supposed to be server adjusted periodically; ignoing oil changes or manual adjustment would make the Cam Chan rattle, which can be intermittent. Both likely on a more obscure and less common 'big' 125. Tappet adjustment can also cause erroniouse top end rattles, that can compound or confuse either exhaust header 'blow' or presumed CCT errors.

A FEW areas for investigatio to ponder....

Start with a dam good service, eliminate tappets and CCT issues with oil change and FULL service making all adjustments n the book including tappets and CCT.

For exhaust header / flange issues, get it running and get down on the floor next to the front end, and look closely at the pipe-work, whilst some-one else revs the throttle, looking for any 'blow' smoke, and listening for where noises happen, after (when still cold!) looking closely at the pipe work ad tugging headers for any looseness in mounting etc. Also look for pin holes in the pipes when running.

Bottom line, its old fashioned hands on mechanics that will sort this one; we cant do it by ESP.
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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?'