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Old 09-21-2024, 07:54 PM   #526
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Edit 42P 135M was the winter tune.


I have installed 38P 138M jets. still 4th needle clip.


 
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Old 10-03-2024, 09:33 PM   #527
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Might be the nail in the coffin for the this CG250...




 
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Old 10-03-2024, 09:56 PM   #528
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Engine swaping alternatives

So the OG $80aud basket case used CG seems to be on the way out...


The blown headgasket ordeal might have been to much for it and it's giving up.


Oil is sweating out of it and the clacky bottom end is knocking on heavens door.


So I have some options...I while back I picked up a few used chonda engines after my catastrophic head gasket fail...


I used some parts of a Dukar CG250 to save the OG engine...So I have the option of using the Dukar core and bottom end and swapping parts over from the OG....However the Dukar looks about as abused so its a toss up how long that will hold up...


I also have some smaller displament 200cc CB/CG chondas...unknown quality.


And finally the gem being the 169FMM CB250 that appears newish* and I got to turn over after finding all that was wrong was a stuck intake valve...The issue being the valve/cam cover fouls on my modified XL350 fuel tank...


But it might be possible to dent some clearance...


Not what I had planned for the weekend as I am now in a position where all my vehicles are pit stopped for some reason.


I will try the 169FMM first...
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Last edited by XLsior; 10-04-2024 at 04:32 PM.
 
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Old 10-04-2024, 04:25 PM   #529
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CB250 and tank fit check

Got the 81 frame out for a test fit before committing to installing the CB250 into the 92 frame.


Would appear to fit no issue but looking under the tank the CDI and inner tank wall are likely kissing, but its close enough that I'm ok shaving 1 side or love tapping the other to call it doable.


With that information I proceeded to rip out the tired old heart 'again' and bolt in the 169FMM


Got it in before sun down.
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Old 10-04-2024, 08:40 PM   #530
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169MM runs but also issues

So I got the 169FMM running...


Good news is that it runs and all gears work...


Bad news is that the clutch is stuck and there is significant blow by...


So its seen some action.



It hot starts pretty well so I'd say the compression is fair and the blowby might improve with more use as I suspect the cylinder and rings might be rough from neglect/sitting.


However Is it worth investing more time and effort into?



I am inclined to use the Dukar CG250 core and swap all the bits over from the busted bigend CG250 OG...


Sorry for thumb in vid shot...Honestly all the gears shift and there is neutral...





 
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Old 10-04-2024, 10:01 PM   #531
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Comparing Rods

So now I had to establish if indeed the bottom end was bad...


after removing the top end on the clacker and comparing it to the Ducar...


I came to the conclusion that they are about the same...


Nothing jumped out suggesting the crank or rod was bad...


So with that piece of insight I have elected to keep running the OG.


Seeing as I went this far I opted to install the 70mm DYNOP flat top piston and send it...


it's just gotta last 6 months of small errand work...and maybe a 700km return trip at Christmas.


Then it can keep leaking oil and collect dust under the house...


The 169FMM will likely go into the 81 frame. As i would have to modify the tank and header pipe to make it fit in the 92 road bike.
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Old Today, 07:31 AM   #532
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Delving deeper

Pulled of the flywheel cover to see if there was any signs of contact wear or loose items...all looked ok.


rocking the flywheel by hand the clack felt like it might be coming from the other side...


So off came the clutch cover. things looked clean but feeling around there was noticeable slop in the clutch basket...


I took the clutch cover of the Ducar parts engine to cross reference...


And well this is what happened




 
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Old Today, 07:40 AM   #533
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Some More upgrades while at it...

While I had the top end deconstructed, Seemed like a last hoorah upgrade opportunity with some parts I had...


New valves and springs.



and grinding a little more clearance on the flat top piston seeing as I had shaved the head and was using a metal head gasket.


Also discovered the AN fitting I had used to shorten the oil cooler lines had failed, So potential major oil leak remedied with a spare long cooler pipe...
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Old Today, 07:54 AM   #534
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Comparinng Baskets and slingers

So the Zongshen turns out to be a 7 plate clutch with a small oil filter slinger. The basket is shot.



the Ducar has a 6plate clutch with a large slinger.



I have installed the 6 plate clutch and larger oil slinger into the Zongshen engine without issue, All the gasket kits I have only support the larger slinger.


I do not want to spend money on a new 7 plate clutch basket.



Cleaning the Ducar clutch cover to install as it fits on the case no problem but is required to engage with te 6 plate and clear the larger oil slinger...


So the take away is, not all CG250 engines use the same clutch and slinger configuration.


But the friction disks are the same so no harm in buying 7 if you're unsure.


Though if your clutch cover has a bulge around the slinger its likely a 6 plate.


Fingers crossed this sorts out the clacky clacky pop pops
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