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 Post subject: Re: drz troubles
PostPosted: Sun May 01, 2016 11:47 am 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Oh dear :( ,

Lets look at this current situation in two sections;

firstly the flywheel;

make sure that the new woodruff key is a good fit into the crankshaft and the flywheel
next that the taper of the shaft and inside of the flywheel are not burred, clean them up as best as you can
carefully align and refit the flywheel plus replace and torque set the securing nut

secondly the compression;

recheck valve clearances and then need to check out the compression which you can partially do using a standard compression gauge, this method will measure the compression as the engine is spun over with the throttle held wide open and the ignition coil plug lead earthed to the the frame (fully charge the battery before conducting this test as rotational speed is important)

the best method to test is with a workshop air compression tester which is; an adaptor that screws into the spark plug hole, the engine is locked into the TDC position on the compression stroke with both valves closed; compressed air is then fed from an air compressor through the adaptor into the cylinder and you check the gauges (most have two gauges - one is the line pressure and the other is a percentage leakage) but at the same time using all of your senses check for air escaping from the cylinder;

air leaking through the carburettor with petrol smell indicates that the inlet valve is not seating; air leaking down the exhaust pipe will be heard at the outlet of the silencer; air leaking past the piston and rings will be smelt by oil and air through the oil filler in the crankcase or breather pipe outlet; (on liquid cooled engines check for possible fumes and bubbles in the coolant and on multi cylinder engines listen at the other spark plug hole/s which would indicate probable head gasket failure)

Unfortunately this test is normally only carried out by a professional garage that has full workshop tools.

If you have access to an air compressor but not the gauges have somebody push an air gun or tyre connector up against the spark plug hole whilst you listen/look/sniff as previously described, might give you an idea of possible problem/s

Other than that now I can only suggest that you seek help locally from the local Group or take the bike to a repairer of trusted capability in your locality. Let us know how you get on, fingers crossed ;)

TTFN

Hugh.

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Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 8:57 am 
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125cc

Joined: Sun Nov 10, 2013 3:28 pm
Posts: 144
Location: yeovil
Well the flywheel is correctly aligned with new key and timing is fine. It runs from cold fine.....when its hot it just refuses to start.

Valve clearances are fine except 1 exhaust valve which is on the tight side. Would this cause low compression when hot? I'm guessing if it has low comp its struggling to drag enough fuel in when hot?

They have auto decompress on the cam....will check that is.not.sticking open.

I think it will need to go.to a shop with proper compression checking tools to see if the valves are leaking.

I will know this bike inside out by time I figured all this out


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 9:57 am 
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125cc

Joined: Fri Jan 08, 2016 3:37 pm
Posts: 155
Good luck mate, all I can say is that I had a major saga with my Husqvarna, so I know what you are going through. Mine started out as a simple cam chain job, then rocker arm bearing, then the pickup coil bolts came loose when I was testing the engine, overtightened, broke pickup coil, had to wait for a new one, wire it in etc. Took 3 months from start to finish, working outside in all weathers and waiting for parts, waiting for the weather to get better, so I know how it feels. You have my support.


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 12:52 pm 
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300 cc
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Joined: Wed Jul 06, 2011 4:49 pm
Posts: 535
How tight is the valve clearances if the gap become 0 or negative when hot it will hold the valve open. Low compression, poor hot starting could be symptoms of it. You want to sort this as you could burn a valve if it's not closing properly as the closed period provides cooling to the valve face to stop it getting destroyed.

Drzs are shim under bucket so you have to remove the cams to get the shims out to measure and work out the thinner shim you will need to open the gap up.

If you do it yourself take the opportunity to measure all the shims and write it down somewhere safe. If you need to adjust in the future you get the shim you need in advance.

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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 4:01 pm 
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300 cc

Joined: Fri May 04, 2012 10:06 pm
Posts: 507
Dan time to burn it and claim of the insurance, which you can put towards another bike and get back out there riding :D :D


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 4:25 pm 
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125cc

Joined: Sun Nov 10, 2013 3:28 pm
Posts: 144
Location: yeovil
Blueray wrote:
Dan time to burn it and claim of the insurance, which you can put towards another bike and get back out there riding :D :D



Soon as mortgage is in place....its shopping time :D


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 9:04 pm 
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650 cc Monster

Joined: Sun Nov 11, 2012 7:31 pm
Posts: 3512
Yeah , shims that, classic sign is the hot starting issues...piece of piss to do... Cheap fix...


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 Post subject: Re: drz troubles
PostPosted: Sun May 08, 2016 9:09 pm 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

I hope that you do get away with just a shim change, it is the cheapest option.

A professional compression loss test will be required if you are thinking of keeping the bike, sadly depending upon how long it has been running with a tight valve will depend if the valve and its seat are worn/burnt requiring a cylinder head overhaul. Depending upon your skills and finances you could remove the cylinder head and have it serviced professionally as required to return it to a serviceable state.

Good luck.

TTFN

Hugh.

_________________
Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: drz troubles
PostPosted: Tue May 10, 2016 6:44 pm 
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125cc

Joined: Sun Nov 10, 2013 3:28 pm
Posts: 144
Location: yeovil
Ok getting somewhere now.

The auto decompressor seems to the issue....or the exhaust valve it sits on.

With the decomp left alone I get 63ish psi....i Jammed some cardboard in it to keep it closed. And I got 160psi.

The valve it is on is right on the tight side of clearance tolerance. I'm going to re shim it on the looser side of tolerance. If that doesn't work then ill have to replace the entire cam...

Cheers
Dan


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 Post subject: Re: drz troubles
PostPosted: Sat May 14, 2016 4:53 pm 
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125cc

Joined: Sun Nov 10, 2013 3:28 pm
Posts: 144
Location: yeovil
ok re shimmed.

a lot better.... the compression has gone up to 90...was 63. starts cold on the button no issues. once hot will start with just a slight opening of throttle. once again jammed the de compressor and psi is 160.

going to see how it plays over the next week when I can get it out on road. if it plays up then ill be cutting the decompressor out (cant beat thumpertalk for drz information)

thanks for all advice so far

Dan


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