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Discussion Starter #1
Hello.
Please forgive me if I aren't using correct terms and if this is posted in the wrong place, I'm new to motorcycling and these forums :)
So I recently replaced my head gasket on my bike, and was told I needed some exhaust paste, so I visited my local garage and they supplied me with some high temperature exhaust paste. When I got home I fitted the new gasket and put the paste on and went out on it the next day.
All was well until I rode half way down a main road I got to about 55mph and I lost revs (I'm not sure if that is the correct term), which made my bike slow down and a loud pop or bang out the exhaust. I pulled over, waited a bit and set off to my desination and everything was fine as I took it slow.
Unfortunately due to wet weather conditons, as I arrived at my destination and set off again to go for lunch I slipped and my bike crashed and the bike needed a new chain and sprockets but that's a different story.
Anyway I picked up my bike from my garage yesterday, I set off and forgot about this problem altogether as it has been two weeks. The same thing happened again as I got down the road, the loud bang and my bike slowed down. I managed to get it home and I've had a think and I thought I may have put too much paste on my head gasket so I had another look, took the gasket out and sort of cleaned out all the silicon type gunk that was in there. Put the exhaust back on and rode down the road at a high speed. The exact same thing happened.
Has anybody got any ideas? Could some of this paste have gotten into the exhaust somehow? The exhaust is a new exhaust too and it never had this problem at high speeds before. It never happened before I put the paste on. I have a Sinnis Max 125 which I am told is a cheap version of a GS 125 as parts are interchangeable.
Sorry if some of it didn't make any sense and I'd be happy to assist with any part that didn't make sense. Thanks in advance!
-Dan :)
 

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Dan, I've never heard the word 'exhaust paste' in my life and I've worked on my own and others bikes since 1962.

There is something called gasket cement that is put sparingly on some gaskets. Head gasket normally do not use gasket cement at all.

Your popping and banging is probably due to a leak in the intake system or maybe a leak at the exhaust.

Check to make sure the carb is tight in the intake manifold and make sure the intake manifold is tight and not leaking.

Good luck.

Sam (Porter):coffeescreen:
 

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Where do you put the exhaust paste?
What you describe sounds like the ignition shut off and came back on causing a back fire.
 

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Could he mean "valve cover gasket" instead of "head gasket?"

Maybe he's talking about an intake manifold gasket? That could explain the backfire if he's got an intake leak.
 

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Ghost in the machine
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The top speed on that bike is approx 60mph. Is it possible that the bike is hitting a rev limiter?
 

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Discussion Starter #7
Hi All and thanks for the replies :))
Porky, I was told by the local garage that it was needed for the gasket to be seated correctly, and I will check the other things you said next time I get the chance and get back to you :)
Muggs, The paste was put on the head gasket to stop it falling out when I was trying to fit the exhaust back in.
Eye_m_no_angel, Like I said I'm not too good with techincal terms ahah but where I am talknig about is where the exhaust goes into the engine.
Jag13 and murphyshuman, before I put the new head gasket on with this paste it was fine, I could reach 60mph no problem and nothing would. Now I can't get past I think it's 7000 RPM without my exhaust making this popping sound and my engine feeling like its sort of cutting out.
Thanks for your help! :)
 

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This posting is amazing due to the OP's lack of credible descriptive terms that make sense:confused:

I believe that any one of us that responded could diagnose the problem with simply looking at the bike/ scooter (?) and listening to it run.

Sam:coffeescreen:
 

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Discussion Starter #13
Hi all, and thanks for your help.
I did mention in my first post that I am sorry if I wasn't using correct terms.
Anyway, I've tightend up the bolts where I was told there may have been a leak at the exhaust and I took it out again, got to about 30mph and the same thing happened, the bike lost revs and made one single loud popping noise. As I continued further down the road the same happened again but there were multiple 'pops' so I turned around and returned home.
I read on another forum that replacing the spark plug may address the issue, I bought another spark plug and the issue still hasn't been solved.
Thanks in advance :)
 

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Ghost in the machine
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You should start by doing a compression test. I doubt that the exhaust head pipe gasket is your problem. Did you replace the head gasket yourself? Was the valve cover gasket also replaced?
 

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Discussion Starter #15
Yeah I did replace the gasket myself. I'm not too sure what a valve cover gasket is aha so no it was not replaced.
Thanks for the reply :)
 

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Ghost in the machine
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Are you sure you lined up the timing marks when you re-installed the timing chain? Are you sure what you replaced was even the head gasket? Do a compression test!
 

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Discussion Starter #17
I don't remember touching any timing chain and it was definitely the head gasket as I have replaced it before. What is a compression test?
 

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Ghost in the machine
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The timing (cam) chain is what operates the valves. My guess is that what you replaced was in fact NOT the head gasket. Maybe the valve cover gasket or the header crush washer (gasket), but not the head gasket.

Now I'm curious, if this problem didn't exist before you replaced (what you thought was) the head gasket, why did you think it needed to be done? Did a shop or previous owner tell you it needed to be replaced? If so, it still needs to be replaced because IMHO you never replaced it.
 

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By "head gasket" I think he means exhaust manifold gasket. It is on the engine head, but the head gasket is actually between the head and cylinders.

It sounds to me like it could be a problem with the ignition system. Moving along, loss of power, gasoline exploding in the exhaust pipe. It could be that the plugs stop firing intermittently, pumping fuel out the exhaust, then when they start sparking again, boom.

Is a theory, anyway.
 

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Discussion Starter #20
I replaced my exhaust but kept the current gasket, and I was told by a friend that I should have really put a new gasket on, and then a family member said I should use some sort of paste, which I thought was correct because the first time the gasket was replaced I took it to a mechanic, and it wouldn't stay in for him to re fit the exhaust, so some sort of silicon type paste was used. So I replaced my gasket and put some paste I bought from a shop which they informed me was designed for gaskets. I fit the gasket with the paste, and the next day when I set off I went to overtake a bus on a dual carriageway, and as I sped up the bike lost revs, made a loud bang, and I had to pull back behind the bus and pull to the side of the road.

Since this, I've put a new gasket on because I bought two and it is still happening.

In my head, when I'm riding it feels as if something is blocking the exhaust as the engine is trying to push emissions out. As if some of this paste or whatever it was is stuck in the exhaust. Probably wrong but just my guess. I was thinking, should I try my old exhaust? The baffles were bad on it but it's worth a shot to see if the noises continue if it's just for 10 mins down the road and back?
 
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