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something simple?

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1994 xr650l just had the head re-done and installed. when I start it up I have to choke it and I get a puff of smoke. I have to hold the choke for 1-2 min. to let it warm up or it wont idle. Even if I take off riding I have to hold the choke in about half way or it will spit and sputer until it warms up. Then after warm up while riding no smoke and runs fine. but if I stop and set and idle for a few seconds and then rev up the engine pretty high it will smoke not heavly but bad enough. Then take off and ride, not smoke. whats up with this?

thanks for any help.

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Smoke... black of blue? Did your carb get gummed up while sitting waiting for the head to get finished?

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Dang it I can't remember what the deal is when the bike only runs with the choke on...The choke is giving it more fuel right? So I would think if you had to hold the choke ON for the bike to run, then that bike is very very lean and it's hurting the motor. That very well could be your issue with the smoke as well. I remember hearing that if the left side crank seal is bad you'll get a ton of smoke. I hope someone else can come in and verify some of this. I'm still real new to my 2 stroke and learning, so take my words with a grain of salt (more people on here need to be honest like this), but just my .02

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ThumpNRed-smoke was blue.

BlackCR25098-ya I was thinking to lean but I am not a carb guy so thats were I need the help if thats the problem.

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Well. Blue smoke isn't a fuel issue. Somewhere, oil is getting in to the cylinder. That may explain the extra warming up for it to run right. It's needing that heat to burn off the oil getting in to the cylinder. ANC until it does, it needs the extra fuel to keep running...hence the choke issue.

I will only guess that when you put the head back on that maybe it wasn't torques down properly. This is only a question so do not be offended as we are only trying to help. Bt did you reuse the old head gasket? If it is the old one, there may be some by-pass there. Where the valves cut and seated properly.

I guess what we really need to know are the specifics for the head job. Give the details on what was done, parts used, etc. Also, what did the bike run like bfefore the head job?

I have been there brother. Be patient. Someone will figure it out.

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torque was 26lbs on the head bolts. Yes I did re-use the head gasket it seemed to be in good shape. The head work was only new valve seals, one valve seat was out the guy at the shop put it back in. The valves were lapped when put back in. The valves were in good shape, guides were good to go. I adjusted the valves just before starting it up. I am thinking I should have put in new rings while I had it apart but I put new ones in about 1 1/2 years ago. cleaned the carb before I put it back on to and new air filter.

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Its good practice to use new gaskets when reassembling an engine, however the metal gaskets can be reused if you use a sealer. I think if it were rings the bike would be smoking all the time not randomly.

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I thought they could be re-used I uesd hi temp silicon (red) on it. the bike was runnig great before it just had some top end noise and an oil leak around the head cover. The noise I figure was the loose valve seat and I replaced the cover gasket and fixed 2 striped bolt holes.

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Your rings\piston and\or bore is shot.Also,, The carb is simply slightly plugged on the pilot jet. Leaness,,(especially on the main jet) will destory that motor.

These are very picky on the wear of the oil rings for end gap. Should of done the piston area too...

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Your rings\piston and\or bore is shot.Also,, The carb is simply slightly plugged on the pilot jet. Leaness,,(especially on the main jet) will destory that motor.

These are very picky on the wear of the oil rings for end gap. Should of done the piston area too...

So I am guessing rings. Piston. New head gasket and go through the carbon again, right?

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Did you take the jug off? If it was running fine without smoking before, and you didn't take off the cylinder, then I am not sure a piston/ring job is needed.

Pull the plug and look at it to see howit is running. You know the deal about how to check it for running lean or rich.

I just did the same thing not too long ago when I replaced the cam chain. I also reused the gasket, but only the tappit cover. For the head I bought a new OEM gasket.

In any case, I really feel you need to pull the head off. Double check the retainers for the valve springs. If those do not seat like they should, it can push the valve to one side adding extra preessure to the seal. However, if that was the case, the smoke would be constant.

Does the bike pop or sputter on deceleration? Or when it finally gets nice and warmed up does it bog when you whack the throttle? Some times that can clue you in to running rich or lean.

Just some ideas. Keep the symptoms coming. Something you mention will trigger the cause.

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I was afraid it would be another tear down. After it gets warmed up the throttle responce is good and plenty of power. I can get the front end off the ground in 2nd gear. No smoke. It only smokes when I stop at an idle for a few and Rev it up high. A low Rev will give little if any smoke

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Have a shop do a leak down test,it's the simple way to be sure..

But having done many many rebuilds...i stand by my previous post.

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took the carb off and cleaned it again some junk in it but nothing big. took it on several short rides (2-3 miles each). smoking has cleared up and almost gone. Maybe the valve seals need to breakin? starts better after the carb cleaning also set the gas mix screw -turned it in until slightly snug and then back out 2.5 turns. throttle is " snappier".idles better too. Engine sounds better too not as much rallte as before the head was done.

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might be as simple as valve steam seals...

maybe some oil got past and into the stems and burning...

I once had this happen when I got really really hot on a tight singletrack ride...

maybe the oil thinned so much it got past the seals...

Hasnt done it since...changed oil imediately after.

heres hoping this is your issue!

cheers

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