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fuel flows thorugh carb wrong way

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Yeah I know it sounds weird. While trying to get this old 82 xr200r to fire for the first time since I got it, I ran into numerous problems. Since the bike wouldn't start and I have absolutely no clue what I am doing I decided to start messing with stuff. I unhooked the air box off of the bike and started kicking it over. I was doing this to see if it would suck on my hand. My hand started getting wet. I smelled it and odley enough it smelled like gas. Does this mean my timing is off by 180*? I did not tear into the motor, but my compression seems poor. It won't blow my thumb off the spark plug hole. Any idea's on what I should check, where it is located, how I get to it and what should it be set at? I am goign to try an order a manual on Thursday after I get paid. I was hopign to get it running with out having to buy a manual yet. Also i do not have the compression release hooked up, it just rests against the cylinder head fins.

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Since no one has replied to you yet, I guess I'll give it a go. I'm not real sure if I'm deciphering your posting correctly, but here goes....

I think what you mean by gas flowing the wrong way is, instead of feeling a suction on the carb inlet, you are feeling slight pressure? Combine that with little to no felt compression at the spark plug hole.

No, it's not the timing. The first thing that came to my mind is a bent / cracked / worn out intake valve.

I'd suggest, at the least, getting a Clymer manual for the model of bike you're working on before you go any further. If you still are uncomfortable with what you are doing, find someone that has over hauled motorcycle engines that can help you. Or you can take it to a shop, but that costs big money. If it's a bad intake valve, you'll have to take the head to a shop anyhow.

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I to thought bent valve but i would still check the timing before pulling it apart.

Im surprised you didnt pull the head to check things out when you had the engine off the frame.

On my 87 xr100r ............ i found a bent valve (but mine was exhaust) ........... When i pulled the head and looked into the exhaust port ....... i could see daylight shining through.

If you dont notice anything right away visually ................. pour some kerosene or squirt some WD-40 into the port to see if any leaks past the valve.

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I didn't pull the head because I didn't have a manual yet and also I was the told the bike ran great when it was parked. I did put carb cleaner in the port and let it sit for about a minute too see if if leaked past the intake valve. It didn't. I assuming do to that test I do not have a bent valve. I feel completely confident in working on this dirtbike motor. I can build any automobile motor from a 4 cylinder all the way to alcohol and top fuel V8s. I have also completely rebuilt a couple of harley Davidsons to include the motors on them. My thing is I do not know torque specs or tolerances on this motor. Obviously getting the manual will tell me these things. I just figured if I could get the info else where and save that money right now it would be to my benefit. My wife is about to have our second child with in the next few weeks.

I offer tech help on a couple different mustang forums and we actualyl tell all the info people need in order to do what efer they are doing. We offer up torque specs tolerances and methods of accomplishing what needs to be accomplished. I do notice a trend on this and another dirtbike forums that more peopel temnd to say get the maual it tells you how. I am not sayng I disagree with that, it is just not what I am used to. On the mustang, and well now that I think of it the chevy 4x4 forums I belong too as well, the tech sections go so deep you can do a quick search and find all the info on completely rebuilding a motor with all the specs that will be needed and most of the proccess you will have to go through. I have n oproblem buying the manual but right now my money is limited. Spending $30 on this manual right now means I won't be buying the levers I need. Once the baby is born I am out of time and money for a while. I have yet to also buy tires, rear brake shoes, a rear fender and right side plastic before I can ride this bike. Now Add a $30 manual and what ever parts I may need to get this motor running properly. I don't want this to sound like a rant against these forums because it is not. It is actually me trying to accomplish my goal with les time and money that it should require. I just want to make sure it is done intime so I can be takign my daughter out to ride her quad when we spend out special time together. My wife and I want to make sure we each get to sdpend somr quality time with our older daughter as she will not be the only child anymore. We want to make sure she knows she is still loved and just as important.

I will say this has been a very exciting time for me. My daughter spends a lot of time with me working on this bike waiting for it to run so we can go riding. Teaching her to ride her quad on a dirt lot next to our house was one of the poudest moments of my life. I just can't wait to take her out on a real ride. Sorry this post turned so long.

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If you have no reason to believe there is anything wrong internally with the engine, don't tear it apart yet. I would tear down the carb and give it a good cleaning first. Check to make sure its getting spark too.

As for the carb appearing to flow in reverse, valve overlap can easily cause enough backflow to get some fuel vapor on your hand at that slow of rotation. I wouldnt think too much into it.

If you cant get it running with a clean carb, fresh gas and a new plug then start to think about tearing into the engine.

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I completely rebuilt the carb. Soaked it in chem-dip for 2 days, bought new jets, sprayed compressed air(from my air compressor) through it. I am getting spark. I am not only getting fuel vapor through the carb, but lots of it. 3 kicks and my hand is soaked. I also have very low compression. The low compression tell sme something is wrong somewhere. The gas flowing backwards through teh carb at that amount tell sme maybee my valve timing has jumped a tooth or something. Now mind yu oI am going at this with out a manual and on my own thinking. I have the rocker box loose but it will not come all the way off becaus eof the 4 cylinder studs. It is loose enough to see inside. The tiny inspection hole cover will not com eloose so I am revign the entire side cover in order to loosen it. Then I can make sure I am perfectly at top dead center. Then I just have to figure out how the cam is supposed to line up. Also should there have been a gasket between the rocker box and the head? There was not one there on my bike. If so i need to go get one so I can put it back on. Which means I have to pull the motor to get it on because of those 4 studs.

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No gasket for the rocker cover .......... sealant is used there.

I would be more than happy to give you specs and scan pages of procedures for you ............. but im sure there is quite a bit of difference between an 82 and a 99. I also would have copied procedure info and posted it here but would be afraid of giving you bad info.

And you would be very fortunate to be able to just run to the shop when you get paid and purchase a manual for a 24 year old bike. I couldnt even find one for my 87 xr100 & 99 xr200. I ordered a factory shop manual from Helm for the 99 but was lucky enough to find the 87 manual for $6 at amazon books. You might want to check there for the 82's manual.

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I will have to order it from the local parts shop, he said he can get it for me. Will take a few days to get it to me. In the mean time I'll do the tests from the other thread. I think at this point in time that is wherte I am at and at a stand still until tjhose tests are done and I get that book. I really need one anyway. I just need to quit being a cheapskate and buck up.

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It is perfectly normal for a your bike to spit a small amount of fuel out through the back of the carb if it won't start, even more so if you have your hand over the end. Also, just b/c it doesn't have enough compression to blow your thumb off the plug hole doesn't mean it still won't run. If the compression is really really low it will still run for a bit if you put a small amount of fuel in the spark plug hole. I would suspect you may not have any spark or perhaps not enough. A good starting point would be to check the timing, I'm sure if you can rebuild top fuel engines you'll be able to figure out how to check the timing on your bike as the principle is the same just much much easier, as it's about as basic as it gets, check the valves wihile you're in there too.

Also I don't remember seeing you on any of the Mustang sites I frequent, do you have a different name?

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Same name on the mustang sites. I frequent foureyedpride and scoalhorsepower mostly these days, used to go on the corral alot, stangnet only to sell a few parts. I like to read hardcore50 ocassionally but my stang is not as fast as those guys yet so I don't bother them too much.

I have already set up the valve timing. I have a nice blue spark. After setting the valve timing up corectly I did get more compression. I could not do a correct compression test other than my thumb as I loaned out my compression guage and never got it back. I will just buy one tomorrow. But being as it is now blowing my finger off the spark plug hole and it wasn't before I definately have better compression. before I could kick the motor over 3 times and my whole entire hand would be dripping with fuel. Now if I kick over 3 times i can smell the fuel onhand but it is not dripping wet. I heard that is normal. With my luck I am trying to think to technical when it is porbably an easy solution. Maybee I put the cam backwards so it is on teh compression stroke but not firing at that point in time. Maybee it is trying to fire while the exhaust valve is open. This is just a quick thught. I need to figure out at what point on teh stator it is supposed to fire and that will give me a good answer. I am sure th ebook will tell me that once I get it.

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When you put the sprocket on the cam with the "O" at 12 o'clock and the "T" mark lined up with the index mark on the cases , are you making sure that the lobes are pointing downwards ? If not, you have the cam 180 degrees out.

I only frequent MD and Stangnet so I guess that's why I haven't seen you around.

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Probably so. My stang is an 84 so I stick with 4eyedpride mostly these days. I might hav ea total of 6 mposts on stangnet with 2 of them being parts I sold. Cool that we both stangs and XRs though. Yes, I made sure the cam lobes were pointed down. I also lined the T up. I used the mark on top of the head. I see you said the mark on the cases. That may be part of my problem. I will have to double check it tomorrow. No time to do it today.

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Probably so. My stang is an 84 so I stick with 4eyedpride mostly these days. I might hav ea total of 6 mposts on stangnet with 2 of them being parts I sold. Cool that we both stangs and XRs though. Yes, I made sure the cam lobes were pointed down. I also lined the T up. I used the mark on top of the head. I see you said the mark on the cases. That may be part of my problem. I will have to double check it tomorrow. No time to do it today.

Yup, just line the "T" up with the mark on the engine case and the "0" on the cam sprocket in the 12 o'clock position.

Take care of that Stang! :thumbsup:

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Yeah it has to be that rebel in us. I did not notice a 0 on the cam sprocket but I will look again. I am also goign to get a book ordered up to help me out some.

Pookie nice old stang ya got there. Too bad I am not in the position to buy another toy at the moment.

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If you dont see a "O" or mark on the cam gear (it should be right near the teeth) ......... flip it over ........ its on backwards.

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Yeah I will have to check that out. I ordered my manual today and it should be here tomorrow. If not I have to wait til Tues when the shop opens again. I'm going to take a break for a few days while I wait on the manual and then get back after it.

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Hey thankyou fatsurf... As far as the big three and cars go, I have GM covered with my 89 suburban that I dropoed a 502 in. I use it to haul my toys around. I have always loved suburbans. I'll check the thread out and I also got your e-mail. I'll give ya a call in a few days.

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