KZ250 Muffler Options

Glowing red is not so unusual on a 1000hp turbo motor at full load on a dyno, but a KZ250 single running around, not so much. That suggests the exhaust gas is too hot which we tend to think means mixtures are too lean, but if it's too rich, it could be burning in the pipe. Retarded ignition also causes that effect, as does a muffler that is too small.
 
Here's a picture of the bike with the original (rusted and cracked) muffler installed:
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Here it is yesterday with the CX500 muffler installed:
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And a pretty crappy nighttime photo with the Emgo muffler installed:
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Khaos said:
If you go back to the old filter, does the engine still run hot?

I haven't been able to work on the bike in a few days, but I'll try swapping back to the non-OEM filter within the next couple days and see how it runs.


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Today I pulled the left side engine cover to get to the starter motor for replacement since the part came in a couple days ago and I finally have a little daylight time to do some work. Found out the alternator rotor is cracked and needs replacement also:
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After a little bit of searching, it seems this part is going to be hard to find...


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It looks like we're in the same boat - we've both bought bikes that are 10 miles of bad road! But - nothing's impossible. I guess it's time to hit the breakers yards for ya. Good luck, and keep the faith - that bike needs you ;)
 
Khaos said:
It looks like we're in the same boat - we've both bought bikes that are 10 miles of bad road! But - nothing's impossible. I guess it's time to hit the breakers yards for ya. Good luck, and keep the faith - that bike needs you ;)
Haha, yeah keeping the faith for sure. Just wish I had all the parts I needed right here with me whenever I realize I need a new one.

I was able to find the part on eBay. Turns out the same part was used in a KLT250 3 wheeler. Good find at $72 on eBay since it would've been just a few bucks shy of $300 from partzilla Says it came off a 1982 KLT250a, but engine number is for a KZ250D.


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eBay has been my saviour. I got a stator, reg/rectifier, 2 x cdi, 1 x clutch for about $40 delivered, a lithium ion battery at 75% off rrp (about $30 delivered), a chain guard (about $6 delivered) and so on. Loads more on the way as well, I've got a LOT of making good to do. Last owner's bro and dad were enthusiast, but had low to no standards for quality of work. Before I can make changes the bike needs to be safe and reliable.

You can start yours. I'm jealous!
 
Well it won't be starting back up for a couple weeks at least now. Just ordered the rotor, about to go change out the starter clutch, but I might as well check the cam chain, valves, etc. while it's sitting.

Are you working on the GPZ305 or a different bike?


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citizendeck said:
Are you working on the GPZ305 or a different bike?

I'm working on the GPZ305 - the green bike that's my avatar. Lots to do :( The big target for me is April, when the next MOT (annual safety certification) is due. By that time I want her ready for any safety inspection. Hell, I want her to be a bike that I'm going to be proud to have someone look over, not one where I'm ashamed of any part. Right now she'd fail on the way the battery was fitted - not housed or secured properly at all.

When I've got all the ingredients in place for the battery/charging solution, I'm going to start a thread in the build thread area, although it's more like a rescue mission.

Shit, that makes me sound like some sort of goddamned saint. That I'm not. BUT - my grandfather rode a Black Shadow around parts of Brazil as a missionary. My father used to ride around on a Douglas Dragonfly, amongst other bikes. I'm a third generation biker. My grandfather is dead, but at some point my father's going to be seeing this bike, and it's going to be right by that time. If I can get a quiet nod from him, I'll know she's ok.

Then I'll have to try and keep him out of the saddle.
 
Best of luck on the deadline, Khaos. I don't really have a deadline on this build. Sooner is better than later though. Building it up for a cousin who's looking to learn to ride so there won't be too much custom about it besides new standard handlebars (got rid of the cruiser style buck horns and put a scrambler style set on), a flattened out seat, and a working engine. I've got a second KZ250 that I've got to do a top end rebuild on for myself to get a nice little city bike out of. Hopefully this first bike won't need much more than that new rotor and starter clutch. Already changed out and adjusted a few things to get it road ready. Once the rotor and starter clutch are fitted in, cam chain and valves checked, and fresh oil put in I'll be able to see if it's still running hot on the header. That problem's on the back burner for now.


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Hope it gets fixed soon - I'm just waiting for bits for my starting/battery box fix to turn up. Should be next couple of days. Hopefully I'll have good weather on the weekend, and I'll get the bike cleaned properly. A thorough bike clean and polish is a 2 day job, for sure :(
 
Well, I replaced the starter clutch and rotor. Started her up and the cam chain is making a racket. Looks like I'll be tearing into that tomorrow. Anyone got any tips on cam chain adjustment? Or should I just replace the sucker? The KZ250 has an automatic cam chain tensioner on it.

I did just see some manual cam chain adjusters for the bike selling on eBay. How does changing the automatic adjuster for a manual adjuster work/compare?


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My old gs850 had an auto cam chain tensioner - only thing that the PO didn't get ticking like a Swiss watch. A gentle tap with a rubber mallet once a month did the trick :)
 
Khaos said:
My old gs850 had an auto cam chain tensioner - only thing that the PO didn't get ticking like a Swiss watch. A gentle tap with a rubber mallet once a month did the trick :)

Really? Hope this works on my bike too! Do you just give it a tap at the adjuster?


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yes, but this was done regularly. Your experience may not be the same. Proceed carefully. Every now and then mine went GLOING, which was quite scary.
 
Cam chain sounds fine now and got the new rotor and starter clutch fitted but I'm still hearing a clunking sound coming from the left side of the engine. Now I'm wondering if a loose starter motor chain is the culprit. In the pictures below you can see that it's resting against the inside of the engine case. Could this be the culprit?
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This thread is months old now, but finally got back around to working on the KZ today (busy 7 months I suppose, ha).

Replaced that loose starter motor chain and sprocket, adjusted the clutch lever response, fitted a new fuel line & put some fresh fuel in the tank... I'm still hearing a loud clunking sound from the engine and it (the engine and bike since it's so small) seem to be shaking from whatever is going on in there. Any ideas from the gurus -- what do I check next?

Khaos, how's that GPZ build coming?? Did you pass inspection??


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