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Discussion Starter #1
Hello and thank you for taking the time to read and hopefully respond to this post.
I bought a 1980 yamaha dt175 last year, my very first motorbike. I have experience wrenching on cars and stuff so im pretty confident in my mechanical abilities, but 2 stroke engine troubleshooting is new to me.
It was always hard to start but it would always eventually start. little by little it got harder and harder so start, i did leave it outside the winter before last, and maybe that started this problem, but last winter i garaged it.
In any case, I have the repair manual and have gone through everything except a leak down test.
It has fresh gas, clean petcock filter, no obstructions from fuel tank to carb. Carb has been inspected and cleaned and is all good. spark test outside cylinder shows good blue spark, new reed valves, battery is probably totally dead but i figure that probably doesnt matter. i ohm metered everything i could and found little problems here and there and replaced or cleaned up parts as needed. i metered ignition coil, spark plug boot and cable, source coil, stator coil, everything checks out according to my manual.
There are a few things, I did a compression test after rebuilding the top end and it reads 120 psi, which seems ok to me but idk. but I can hear a little hissing noise coming from somewhere around the head or where it meets the engine case.
I replaced left hand side crank seal or maybe it was the rh side. cant remember.
The other thing im wondering it could be is the CDI box or whatever, the computer part. i gave it a look over and aside from dusty seems fine. but could that be failing?
should i just try to do a leakdown test? im affraid ill have to rebuild the engine which ive never done...
Anyway, im feeling pretty lost and my feet are sore from kicking this thing over and over. any help would be great.
Thank you again.


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