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1981 XV920RH front cylinder issues

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1981 XV920RH front cylinder issues

PostAuthor: Danoxv » Thu Jul 19, 2018 7:20 am

Hi All, I am having issues with the front cylinder its an 81 920RH .Its driving me crazy for I have been around this bike since 81 it has 40000 km on her. Ill try to make this short, one day I noticed it was starting to act up so figured carb issue , Well still would'nt work after cleaning .I am getting fire but it seems fuel is on and off with the plug.I did a compression test and getting nothing .The rear has 150 so all good there.
Here's what I've done

cleaned Carbs multiple times
set valves
new rings
oversized the jets (see if I could get more fuel)
Checked coil
I dont know what to do any recomendations would be great

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Re: 1981 XV920RH front cylinder issues

PostAuthor: bstig60 » Thu Jul 19, 2018 7:52 am

If you are not getting any compression on that cylinder, you either have a burnt valve, blown head gasket or a hole in a piston. Could be bad rings, but usually you will get some compression if you add a little motor oil into the plug hole.... Try adding a few ounces of oil into that cylinder and run the compression test again. If it still fails, its time to pull the head....
Bill
"It´s a friggen motorcycle, it´s not supposed to be comfortable, quiet or safe. The wind noise is supposed to hurt your ears, the seat should be hard and riding it should make you s**t your pants every now and then. "

Please take the time to edit your profile to show your location. City, State/Province and Country. It is easier to help you if we know where you are.

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Re: 1981 XV920RH front cylinder issues

PostAuthor: Danoxv » Thu Jul 19, 2018 11:19 am

Thank You for the responce I forgot too mention new headgasket also new valve seals cleaned valves and no hole in piston, if I put oil down the plug I get compression.This is the biggest mystery !!!! Electrical??? Although coils are fine!

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Re: 1981 XV920RH front cylinder issues

PostAuthor: Hexrod » Sun Jul 22, 2018 4:34 pm

The electrical system can't make you have compression or not. I wonder if your compression testing is accurate and consistent. I would try to check that first. if you conclude that you have no compression on the front cylinder, then the options listed above need to be investigated, which means you will pull the motor and remove the front head, at the least. If you find that you consistently have compression, then you can look into electrical or fuel systems. You can test the coil with a multi-meter. Personally, when I have intermittent spark problems, I look at the spark plug and spark plug cap... Both are cheap to replace and can produce intermittent problems. Good luck!

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Re: 1981 XV920RH front cylinder issues

PostAuthor: Hexrod » Sun Jul 22, 2018 4:36 pm

Also, since you recently did head work on the bike, are you sure that the timing on the front cylinder is right? If the valves are opening at the wrong time, it's hard to have compression. :-)

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Re: 1981 XV920RH front cylinder issues

PostAuthor: Danoxv » Tue Jul 31, 2018 12:43 pm

Thank You for the help Hexrod, I have 2 of these and fairly familiar with them, although im stumped ugh! I did the valves on the front cylinder many times (Just put to the i mark and gauge the valves to 10 and 15 also making sure I was TDC with a screwdriver in the plug hole ) I checked the camshaft and it lines up with the notch in the casing.Everything appears mechanically ok, I put new rings gaskets on the rebuild. the back cylinder runs great I just dont get it.Ive tested the coils even put other ones in Ive checked for broken wires through the harness but cant find an issue other than Im scratching my head....The 4 relays under the seat seem ok and Ive done the carbs and its getting fuel and fire any other ideas would be greatly appreciated??

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Re: 1981 XV920RH front cylinder issues

PostAuthor: bstig60 » Wed Aug 01, 2018 7:40 am

If you are sure the cam timing is correct, and you get no compression on that cylinder unless you add motor oil to it, you have a problem with the rings. You are going to have to pull the head and at least check the ring to cylinder clearances. I would also pull the jug and check to make sure the rings are installed correctly.....
Bill
"It´s a friggen motorcycle, it´s not supposed to be comfortable, quiet or safe. The wind noise is supposed to hurt your ears, the seat should be hard and riding it should make you s**t your pants every now and then. "

Please take the time to edit your profile to show your location. City, State/Province and Country. It is easier to help you if we know where you are.

SERVICE MANUAL DOWNLOAD LINK
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Re: 1981 XV920RH front cylinder issues

PostAuthor: nanno » Wed Aug 01, 2018 8:37 am

Driving you crazy, eh? I had the very same issue on an engine many, many years ago.

Make sure you have the rings facing up in the right direction. (The lettering has to be visible from the top.)

Additionally it could quite easily be, that you broke a ring and with a bit of heavy oil even the most worn out piston will seal again.
http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

http://greasygreg.blogspot.co.at (My blog - Greasygreg.blogspot.co.at)
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Re: 1981 XV920RH front cylinder issues

PostAuthor: Danoxv » Sun Aug 05, 2018 10:28 am

sorry for the late reply YES its driving me crazy ugh, I did check and the rings are in properly Im just at a loss lol it makes no sense, Im no expert but have been wrenching for many many years, Now my starter cut out relay fried, not sure if I can bypass that or not to at least get the moter to turn again, for I dont want to cross the solonoid and wreck that

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