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Author Topic: Comet 125 unhealthy engine noise. Advice?  (Read 797 times)

MightJustGoJap

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Comet 125 unhealthy engine noise. Advice?
« on: March 16, 2017, 10:38:10 AM »

I've researched every related top regarding this, however I've never come across some solid information to fix this problem, or found a definite answer - however I was advised that korider is the place to be.

It seems to be a "similar" issue occurring on 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.


My other concern is the bike starts fine (GT 125's in general do tend to need a good warming up to tick-over smoothly) it starts, idols, warms up and never stalls. however when it's idoling if I pull the choke slowly to around half way it revs up to 6000 7000 RPM, if I pull it all the way down the bike cuts out.

Definitive advice on this would be massively appreciated.
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BikeBandit.com

Re: Comet 125 unhealthy engine noise. Advice?
« Reply #1 on: March 16, 2017, 12:19:03 PM »

Strange noise = investigate cam chain tensioner. Known failing point on these bikes.

Choke should only be used for starting and warming the bike. No need to use it if the bike is already idling.
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MightJustGoJap

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #2 on: March 16, 2017, 03:19:55 PM »

[quote author=̮̐͋͋ͅȋ̙̬̱̬ͨ͜͞n̴̞͚ͫ̓͒̑̆̕͞j̧̡̖̩͓̱̖͆̑̾ͫ͊́a̅ͣ͌͛ link=topic=28568.msg254228#msg254228 date=1489663143]
Strange noise = investigate cam chain tensioner. Known failing point on these bikes.

Choke should only be used for starting and warming the bike. No need to use it if the bike is already idling.
[/quote]

I was hoping it would be the Cam Chain Tensioner.

However shortly after I discovered that particular part is located on the east of the bike towards the rear of the back cylinder, where as my noise seems to be coming from the west of the bike towards the top of the cylnders or carbs
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Dojy_biker

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #3 on: March 16, 2017, 07:47:17 PM »

take the cam cover off and look to see if the cam sprocket bolts are loose on the sprocket

and drop the oil out to see if its machining parts inside the engine (sparkles and small shavings would suggest that)
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Joss

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #4 on: March 17, 2017, 09:37:26 AM »

take the cam cover off and look to see if the cam sprocket bolts are loose on the sprocket

and drop the oil out to see if its machining parts inside the engine (sparkles and small shavings would suggest that)

I agree with inspecting the oil too. If this is your first oil change (which it shouldn't be) then you will get filings in there from a new engine, its normal. If its not your first oil change, you don't want much.
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MightJustGoJap

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #5 on: March 17, 2017, 03:56:38 PM »

Something bugging me is that just doing a couple of internet searches it's easy to find people describing the same & very similar problems, there's all kinds of suggestions as to what the issue might be.

But there's no definitive answer to say what causes it.

When there's a common issue on other bikes, everybody seems to know... "I have x-issue", "Hi yes that's because your xxxx is xxxx and you need xxxx to fix the xxxx and job is a gooden"...

Yet it seems for this issue there's a whole lot of speculation and no definitive answers.

I guess I'll have to pay a local mech a years insurance to look and tell me what the issue is... then after that hopefully I won't have to pay the actual value of the bike to get it fixed.
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Cloud

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #6 on: March 17, 2017, 09:58:39 PM »

Yet it seems for this issue there's a whole lot of speculation and no definitive answers.

Your float levels are set too low.
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Joss

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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #7 on: March 17, 2017, 10:53:38 PM »

Something bugging me is that just doing a couple of internet searches it's easy to find people describing the same & very similar problems, there's all kinds of suggestions as to what the issue might be.

But there's no definitive answer to say what causes it.

When there's a common issue on other bikes, everybody seems to know... "I have x-issue", "Hi yes that's because your xxxx is xxxx and you need xxxx to fix the xxxx and job is a gooden"...

Yet it seems for this issue there's a whole lot of speculation and no definitive answers.

I guess I'll have to pay a local mech a years insurance to look and tell me what the issue is... then after that hopefully I won't have to pay the actual value of the bike to get it fixed.

Youve been given the answer, it just wasnt the easy fix you wanted to hear. You've decided you dont want to inspect the engine and take it to a mechanic who will inspect the engine.

I hope the bill doesnt hurt too much too.
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Re: Comet 125 unhealthy engine noise. Advice?
« Reply #8 on: March 18, 2017, 11:09:57 AM »

A video would do wonders in this case.

Very difficult to get a forum of people to tell you what the solution to the problem is with a couple of sentences about vague clanking.
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