Need help on '82 YZ80

I'm having a few issues on my YZ80. First thing when I get into the power band in 2nd gear the motor starts cutting out(not exactly sure if this is the best description) and in the final gear I have to keep the throttle in a certain position to keep it in the power band.

Also I've been seeing some sort of dark fluid coming out of the exhaust.(where the pipe connects to the motor) Is that something I should be worried about?? The other issues are suspension related. I think the fork seal is blown, how do I know for sure? How can I tell what type of forks I have? How can I stiffen the suspension on it? Any help will be greatly appreciated!

My '83 yz80 had the same issue of cutting out but in 3rd gear not 2nd but, it was because when the bike is in the powerband, it is using a lot of fuel. My carb was not set properly, so while the bike was screaming, it would not be getting enough fuel, causing it to cut out. I ended up bringing it to someone who knew how to tune them well. I don't know what is going on with the final gear, though. The dark fluid coming out of the exhaust is normal buildup of oil because it is burnt in the cylinder and leaves in the exhaust. But, not all of it escapes, and overtime it starts to get pushed out. As for the forks, check the air pressure after every ride and if there are little rings of fork oil on the shiny tubes. If there is oil or lost air pressure, your seals are bad. You can stiffen the forks with air pressure, but I don't know about the shock. Hope this helps.

My '83 yz80 had the same issue of cutting out but in 3rd gear not 2nd but, it was because when the bike is in the powerband, it is using a lot of fuel. My carb was not set properly, so while the bike was screaming, it would not be getting enough fuel, causing it to cut out. I ended up bringing it to someone who knew how to tune them well. I don't know what is going on with the final gear, though. The dark fluid coming out of the exhaust is normal buildup of oil because it is burnt in the cylinder and leaves in the exhaust. But, not all of it escapes, and overtime it starts to get pushed out. As for the forks, check the air pressure after every ride and if there are little rings of fork oil on the shiny tubes. If there is oil or lost air pressure, your seals are bad. You can stiffen the forks with air pressure, but I don't know about the shock. Hope this helps.

Thanks for all the information. I didn't mean to say it was cutting out, what I meant was at lower rpms it'll run great, the power band won't kick in.. As for the fork seals I pull the dust covers off and compressed the forks a couple times there was no oil just little dirt( I cleaned the shiny part of the forks before I did this). The rear spring I made an adjustment on the top and it raised the bike and stiffened it. Back the the power band issue I ended up ordering a top end kit. I'm also getting the cylinder bored out to 47.50. I removed the expansion chamber and found that there was no gasket. ImageUploadedByThumper Talk1459395532.792080.jpgImageUploadedByThumper Talk1459395532.792080.jpg

Oh ok glad you found out your suspension problems. However, these bikes will run well In the powerband till the top end fails. When you get the bike together, break it in properly and tell me how it runs in the powerband. Did you use Wiseco parts for the top end?

I'm not sure if it had a Wiseco piston before. But I ordered a Wiseco top end kit

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