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DR 350 No compression

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This is my first 4 strike and I need some help. I bought a 92 DR 350. I started it prior to buying it and it had a leak from the valve cover. I took the valve cover off and resealed with liquid gasket. Followed all the rules for letting cure. I didn’t mess with the valves or any internals. I put it back together and when I went to kick it over there was no compression. It feels like the decompression lever is engaged but it’s not. Also weird is that there is a port on the right side of the carb and every time i kick air shoots out of that port. Any thoughts what is going on?

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First thing I'd do is get a service manual. Then get the right valve cover gaskets, o rings iirc, and adjust the valves to spec. If still no good make sure the cam is timed right and didn't jump a tooth. As for the carb, the manual should tell you what the port does. It's either fuel inlet or vent, either way air shouldn't blow out of it.

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On 9/14/2018 at 7:12 AM, nobade said:

First thing I'd do is get a service manual. Then get the right valve cover gaskets, o rings iirc, and adjust the valves to spec. If still no good make sure the cam is timed right and didn't jump a tooth. As for the carb, the manual should tell you what the port does. It's either fuel inlet or vent, either way air shouldn't blow out of it.

Go to ThisOldTractor.com for a service manual.

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I find that if I leave my DR sitting for two-three weeks completely untouched, it'll "loose" compression. I can turn it over by hand, which makes starting a bit trickier.

 

I'll usually kick it over with the decompression lever open as fast as I can about 10 times, and then, with the choke fully open, it should build enough compression to start.

 

If I leave for a month or so, I just end up bump starting it. A smooth hill, neutral, decompression lever clicked in and then put it into second while rolling. Even if it just sputters it'll usually be enough to do the usual starting procedure.

 

I always found this weird, because the bike has good power, doesn't smoke and after starting has enough compression for me to stand on the kick lever.

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Yeah....I’ve noticed that too. With my 1990 DR350S if I let it sit awhile it really acts as if it has no compression at first when I try to start it. More than my other bikes.

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Check the decompressor lever on the cylinder head is "loose"  - the cable should have a small amount of free play and the lever on the head should move a few mm freely. Otherwise it will be permanently opening one of the valves.

 

A more serious problem can occur if the engine has been burning oil for a while - carbon can build up on the valve seats and prevent them sealing properly (from experience with one of my DR's).

 

 

 

Edited by thedktor

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