Depressing Engine (It's a pun)

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Hello everyone, basically I've posted here before a few times, I have a TZR125 (Here's the album of chronological pictures)

https://www.facebook.com/album.php?aid=120336&id=584260891&l=daf708567f

Recently I decided to take the engine out, clean it, put it back in.

I ended up just draining all fluids, replacing them, taking the head gasket off, gazing in amazment at the head of my piston, then putting it back together again Razz

Now it's all back together and I'm having... Well, Issues.

For one I can't find neutral anymore. Literally, the light won't come on ever and I can't feel it anywhere either, and I know you're sposed to move the bike around a bit to move the engine so you can change gears a bit, but I have no rear wheel at the minute (getting a new valve, it's leaky) so I've tried pumping the kickstart to move the sprocket, even then, no neutral to be found

Second problem and more serious is that it won't start.

Fresh fuel, fresh two stroke. I'm sure I put the carb back together right and all the lines go where they should, so as far as I'm concerned the bike has the fuel and air (And after a particularly hard session of trying to kick life into it, black liquid that stinks like petrol starts seeping through the gap between the exhaust port on the engine and the exhaust connection.) Next thing I checked was Spark plug: I took the plug out, plugged it into the HT lead and there's a spark, so I have a spark. Thirdly I've checked for compression by putting my thumb over where the spark plug goes and I feel the compression as it kinda farts through my thumb Razz

So I'm stumped, if I hold the choke on and kick it a few times, I hear the engine turn over about 6 times, the exhaust lets out smoke, but it just dies down... It's like it can't sustain the reaction.

And it's really annoying cause I set out to understand my bike and breathe new life into it Razz

Even more annoying now that I can afford to insure, MOT and tax it Razz

Any advice will be muchly appreciated, I'm happy to do any kinda diagnostic you can think of and I dunno, record the results and post a video on the internet or something.

I'm that desperate for this to work.

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Well, I think it's fair to say you messed something up when you took it apart. So I'd limit myself to whatever you did there.

My first thought is did you use a new headgasket, and did you torque the head down properly. Otherwise you'd lose compression and it'll never start.

Gaz

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

That might be possible, I mean I did use all the old parts. Thing is I did check compression with my thumb and it's working, it pushes against and past me... Still, I was expecting it to suck on the way down, which it did not.

I've got some time off college coming up tomorrow so I might just take it apart again back to where I was before but put it together again with a better idea of what to do right.

ms51ves3 · Super Spammer Joined: 07 Jun 2007 Karma :

iooi · Super Spammer Joined: 14 Jan 2007 Karma :

Take plug out and get a spanner on end of crank. That should allow you to get down to 1st by rotating enging back and forth a bit. Once 1st is found netural should not be hard to find.
As to the light. Have you connected all the wires up to the switch and in the right order.
This could also be why it wont start if it has anything like a side stand or clutch switch and its not connected up correctly.
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Just because my bike was A DIVVY, does not mean i am......

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

richbike · Two Stroke Sniffer Joined: 29 Mar 2010 Karma :

Hi,

make sure its defo kicked all the way down to first before hunting for neutral.

My TZR really doesnt like changing gear when its stationary.

cheers

Gazdaman · I did a trackday!!! Joined: 12 Aug 2004 Karma :

Yeah, I wouldn't panic about not finding neutral until the engine's running. And if you haven't had the gearbox apart, it's unlikely you've fudged anything in there.

Gaz

Vincent · Banned Joined: 16 Oct 2006 Karma :

Aleks · Two Stroke Sniffer Joined: 09 Feb 2008 Karma :

Re-reading everything Gaz has said is pretty much pointing towards the head gasket needing a change, the only thing that's making me doubt that is the compression I feel when I put my thumb over the spark plug hole.

Then again, thinking about it, the compression from me turning the engine over slowly with the kickstart is nothing really, compared to the pressure going on in there when the kaboom happens.

My money is now on Head Gasket Fail. Thanks Gaz Smile