Suzuki NZ250 that has me beat...

[nudemetalz]

Have you had the CDI and or regulator tested ?
Suzuki's of that era had some issues there.
Saying that, my old NZ250 was very reliable.

[Conquiztador]

Have replaced CDI. And as stated, placed motor in a frame with all electrics that worked perfectly before old motor blew up.

Spent some more hours on her today. The "not enuf air" got me searching. But after taking off aircleaner and fiddling with carbi (carbies) no change. She starts, she idles, but when going up in revs she shoots out the xhaust. Then suddenly she snaps outta it and there is like no problems ever existed. Almost like the xhaust cam jumps a tooth or two. But it cant be. I am sure it is a mechanical problem. Just have to suss out what.

[riffer]

still waiting for the answer ...

[MSTRS:Me]

You haven't mentioned fuel. Or whether your second bike had it's own fuel and tank....

[riffer]

still waiting for the answer ...

[nudemetalz]

Maybe the NZ fixed itself and no more problems exist !!

[Conquiztador]

Sadly none of my bikes have ever fixed them self.

I took time out from the NZ. Only so much hair pulling one can stand before one goes bold.

Now spent the evening working on her again. Need valve shims for the second motor to be completed. And there is not many around for the NZ in our country. So will have the old ones machined down.

So spent the evening triple checking (and quad checking some bits) But no matter what I do, she still acts the same.

Once the other motor is completed and in the frame and I have taken the faulty one out and apart I will inform re what I have found.

[FROSTY:Me]

just one thought here--fire her up and squirt crc all round/over the rubber inlet manifold. See if there is a sudden change.

[cowpoos]

Sadly none of my bikes have ever fixed them self.

I took time out from the NZ. Only so much hair pulling one can stand before one goes bold.

Now spent the evening working on her again. Need valve shims for the second motor to be completed. And there is not many around for the NZ in our country. So will have the old ones machined down.

So spent the evening triple checking (and quad checking some bits) But no matter what I do, she still acts the same.

Once the other motor is completed and in the frame and I have taken the faulty one out and apart I will inform re what I have found.

the valve shims in the NZ250 motors are pretty generic suzuki items...check the tolerence's and then go see your suz dealer...they should have some to you pretty quick...if needed that is.

the root of your problem is air,fuel or ignition/timing...nothing that hasn't been mooted here yet...I would check the cam chain ain't poked or too slack..and camshaft timing...and ingnition timing...then move to air leaks after the carburator...and since you have check the carb to death it shouldn't be that I would imagine...ya need know though...

[onearmedbandit]

The most interesting piece of information is that the bike comes fine after a short period.

[cowpoos]

The most interesting piece of information is that the bike comes fine after a short period.

hmm...good point bro...maybe a valve not seating and after the engine heats up metal expand causing the valve to seal better or something along these lines??

[onearmedbandit]

I was thinking similar but surely the valve clearances etc were checked when the engine was both hot and cold.

[cowpoos]

I was thinking similar but surely the valve clearances etc were checked when the engine was both hot and cold.

wheres motu when ya need him!!

[Conquiztador]

The shims for the NZ250 is a size that the NZ Suzuki dealers do not carry. When comparing to all they have in stock they are bigger then most. They are about a old 5 cent size. Also went to the other jap shops and nothing. So have now had the old ones machined down. (When I give the local Suzuki shop the frame and motor number when trying to get shims, the NZ agent comes back saying that they do not stock parts for her...)

That is for the spare motor that will go in the frame this w/e.

The one with the problem has precise valve clearances. This has been double and quad checked. Hot and cold.

The carbi has been swapped against two other working carbies. Same problem.

The inlet manifold and aircleaner rubber has been swapped. Have also run the carbies without aircleaner. Same problem.

The cam chain is inside tolerances and the tensioner is working well. I was thinking that it was a problem with the chain. But after spending time checking it I came to the conclusion that it is OK. I did run the motor for a very short while without rocker cover as it was the only way I was able to really see what was happening. And could not fault it. (But there was a bloody mess left after from all the squirting oil...)

So will update after I have fitted other motor this w/e.

Thanks for all help!!!

[JimO]

would another suzi engine fit??