DHZ DPRO 160 Issues

[br0die]

Hey guys,

I need some serious help here!

I recently bought a DHZ DPRO 160 with a Pitster Pro z160 HO engine.

When I took it for a ride out in the bush with some mates, we did a slow run around just to check out the tracks, and unfortunately it stalled after about 10 minutes and wouldn't start back up.

Being in WA, the time difference between here and Sydney gave issues when trying to contact DHZ. Because of this, I decided to check the valve clearances after some recommendations from some mechanically minded blokes, and a well built guide on these forums.

After setting the valve clearances, it appeared to make no difference.

Finally a few days later, I managed to find the time to contact DHZ whilst I was on my lunch break at work - the mechanic there suggested checking all breathers, and suggested that there is pretty much no chance that it's going to be valve clearances, and is more than likely something else.

Tonight I decided to go out and have another crack at it. After checking the breather coming out of the back of the engine (Not entirely sure what it's called?), all appeared to be okay, so I decided to try setting the valve clearances one more time to be certain I set them correctly.

Again, no difference, and the bike would not start.

Then I decided before packing it in, to revisit the breather. After a much further inspection, it turned out there was a kink beyond my view that I could feel with my hands. After unkinking this breather, the bike roared back to life.

The problem I'm having now, though, is that the bike would not idle. I played around with the idle screw and managed to get it to idle nicely, but every now and again it will conk out.

It also will not start OR run if the choke is entirely off (there are 3 notches on the choke - off, half on, fully on). I suspect that it is going to be the valve clearances, but I am SUUURE I did them correctly! (to .003 inlet and .004 outlet)

Can anyone suggest why this might be the case, before I spend years doing pointless maintenance that makes no difference? Haha

Cheers,
br0die

 

[Carlts]

whats your air/fuel mixture looking like man, try screwing it all the way in and then unscrew it 1.5 turns out. Then start here up and adjust the idle to suit. when shes running apply a little bit of throttle and gently wind in or out the mixture screw until it reves the hardest (this will be the best mixture)

 

[br0die]

I've actually tried 1231824789 combinations with the mixture, but no matter what it's set at, it just will not run without the choke on.

Even if I keep the revs up while I take the choke off, it'll just die out.
This leads me to believe that it isn't the mixture :/

 

[rotn50]

Get your bike on TDC and check the valves for movement, even just sideways movement of the rocker arms is sufficent, but if there tight there might be a prob, did you pull the cam sprocket cover off to make sure your not 180 degrees out on the cam sprocket, can cause the bike to carry on if you adjusted them 180 out

 

[br0die]

Yup, I definitely adjusted them on the firing stroke at TDC.
I took the cam sprocket cover off and checked before I did anything.

There is the slightest bit of play on the valves, so they're not too tight.
I might have to go and re-do them one more time tomorrow afternoon to be 100% sure they're set correctly.

It's a bit late now to do them, and I've just packed up so I'll give it another go tomorrow and make sure they're set correctly.

 

[rotn50]

tomorrow even try a different plug mate, if its something like a torch plug it will fail, even the good old NGK will S#@T itself sometimes, i always run NGK CR7HIX iridium, time to eliminate the small things. keep us posted.

 

[br0die]

Yeh, a new plug was the other thing I had in mind, but unfortunately I don't have any spare around!

I'll try and get myself to the shop tomorrow to buy one, but I may not be able to until Thursday afternoon (late night shopping).

I'll try all these things and see what results I get!

Thanks for the amazing and hasty help guys, it's much appreciated!

I'll keep you in the loop

 

[Carlts]

^^^ other options include, try another carby and/or manifold from another mates working setup and also check for possible leaks?

 

[br0die]

Already checked for leaks mate!

And I'm not willing to spend the money for a whole new carby until I'm 100% sure it's nothing else.
Unfortunately I don't have any mates that have minis

 

[hman]

have you cleaned the carby jets? a blocked pilot jet will make the bike run as described.

 

[br0die]

I haven't checked the carby at all as of yet, I'm not familiar with taking apart a carby and wanted to keep on the safe side of checking small things that could be overlooked before I venture in to the learning trial/error territory!

I'll keep that in mind and have a look if the above suggestions are to no avail, however!

Thanks hman!

 

[br0die]

Okay, so..

UPDATE:

Been out tonight, re did the valve clearances and triple checked them and made sure they were tight.. THEY ARE DEFINITELY set to .003 and .004, despite my lack of confidence in myself

To check, I even tried sliding the .004 gauge in the inlet valve, and it wouldn't fit, though the .003 was a bit sticky.

The bike still WILL NOT run without the choke either half on, or fully on.

I tried changing the spark plug, and the old one had a black tip, so it is running too lean, right? So I replaced the plug and richened up the mixture.

It still wouldn't run without the choke!

One thing that was a huge alarm for me though, is that it backfires... A LOT! And flames out the back.

This is a sign of too much petrol, and the inlet valve being open too much, isn't it? :/

And the final thing I did was run the breather coming out of the back of the engine straight in to the open, so that I was 100% sure there was absolutely no kink.

To summarize, the bike still won't run (won't even idle) when you move the choke on to the OFF position, and it is constantly back firing.

It also loses a bit of umph and response when it starts to back fire.


I'm not the most mechanically minded guy - I'm the IT nerd - so help me out!

Haha Cheers guys,

br0die.

 

[DHZ_XR8cing]

You best bet is to pull the bowl off the carbie and see if there is anything in it that shouldnt be.

 

[motorman]

Definitely check the carby. Give it a good clean out especially the jets.

I would also double check your timing.

 

[br0die]

Just an update guys:

I was reading through some threads in regards to backfiring and what causes it while I was waiting for a response, and I found that suggested checking the manifold and seal between the exhaust and the engine...

When I went out to do this, I found that the muffler had actually come loose from the inside of the exhaust pipe itself; It's too late to be running it now, as I'll have some pissed off neighbours, but I'm guessing that's the cause of the sudden addition of backfiring.

I doubt this would cause the choke issue, though, as it was definitely sealed when I first ran it, and was having the same issues.

I will rip out the carby in an hour or so and give it a good clean and report back!

 

[twisties]

The bike still WILL NOT run without the choke either half on, or fully on.

I tried changing the spark plug, and the old one had a black tip, so it is running too lean, right? So I replaced the plug and richened up the mixture.

One thing that was a huge alarm for me though, is that it backfires... A LOT! And flames out the back.

To summarize, the bike still won't run (won't even idle) when you move the choke on to the OFF position, and it is constantly back firing.

Black spark plug and backfiring indicates too rich.

Strangely though, turning the choke on would make the mixture even richer, so it's odd that turning the choke on helps even though the bike is already running rich (black spark plug, backfiring)... Are you sure you're turning the choke OFF when you think you're turning it off?? I don't mean that in a rude way - I always forget which way is on and which was is off on my choke. If you take the air filter off you'll see the butterfly valve attached to the choke lever. When the choke is on the butterfly valve closes, when the choke is off the butterfly valve will be open. (I don't mean any of this in a rude way - you said you have little experience so I just thought I should explain every detail just in case you aren't sure )

If I were you I'd have a go at pulling the carb apart and cleaning it with some kind of aersol spray - you should be able to see light through all of the jet needs. If you don't have anything thin enough to fit through the jet, try cutting a bit of wire off a wire brush - that usually works for me. I know it sounds daunting taking it all apart but it's really easy - just take your time and take photos of everything before you take it apart.

After that maybe just reset everything to a middle zone e.g. Air/Fuel screw 2.5 turns out, needle clip in the middle, and just try and tune it from scratch. There are plenty of guides on here and on youtube that will show you how.

 

[rotn50]

whats the compression like? a black plug is rich and a whitish plug is lean, have you check that you havent spun the keyway on the magneto or a poor fitting keyway that has been bashed and worn wearing the keyway slot and flywheel key slot? Just throwing stuff at ya now mate.

 

[rotn50]

if your running a mikuni 26mm it wont have a choke butterfly just like the oko, forward on the mikuni is on and back nearly parallel with the slide tube is off

 

[br0die]

Ahhhhh.. god dammit!

I think I have the choke incorrect... when I think it's on, it's off -____-

I did check the butterfly valve, and when I think the choke is ON, the valve is fully open.. I thought this was the choke on, as it lets less air in, but then I thought the mixture would require LESS air to create a richer mixture, thus meaning it was the other way, but when I asked my dad, he confirmed my very first theory.

So ignore that one guys, sorry for my idiocy :embarrassed:

EDIT: The other reason I thought I might've had it wrong is that when I turn the choke ON (what I thought was off) it dies down as though it's bogging out.. which now makes entire sense!

 

[rotn50]

thats what the forum is about mate, just glad someone could help, does it run good now, keep us posted