Took chain off to remove wheel and am unable to get chain back on correctly. 2001 Magna oasis 26" 7 digit shifting speed. Unablew to locate manual...can you help?

Ask a local Bike Shop. Derailleurs for that bike are cheap. Evaluating the bike for a bent derailleur hanger and fixing it is a job for the pros. Word to the wise. Never pedal backward or roll the bicycle backward if it is the rear derailleur is not precisely aligned with a gear. It WILL rip bend or the derailleur right off.

The situation that you describe does sound like a rake based issue. Low tire pressure makes it much worse. Aside from lower speed annoyances, this design will be much more stable on the road, as speeds increase. Unlikely that something is wrong, or you would have lots more issues.

http://www.parktool.com/blog/repair-help/categories/derailleur-systems

http://www.bicyclinglife.com/howto/changeachain.htm

Before you go tearing everything apart it might help to understand how multi-speed derailleur shifting systems work.

Derailleur Adjustment: (likely cause of your problem)
http://sheldonbrown.com/derailer-adjustment.html

Shifting:
http://www.sheldonbrown.com/gears.html

Cassettes and Freehubs:
http://sheldonbrown.com/k7.html

Chains: (which also covers worn gear teeth, another possible cause)
http://sheldonbrown.com/chains.html

Of course everything requires special tools and procedures.

http://www.parktool.com/blog/repair-help
http://www.parktool.com/blog/repair-help/categories/cassette-and-freewheel-service
http://www.parktool.com/blog/repair-help/categories/derailleur-systems

Have fun.

LOOSEN THE 2 BOLTS HOLD WHEEL ON PULL BACK ON WHEEL WHILE TIGTHEN BOLTS BACK UP. CHAIN DONT HAVE TO BE SUPER TIGTH . ABOUT 3/4 OF SLACK IN CHAIN.

With the wheel off remove the two pins which locate the guide wheels on the deraileur. Take off the guide wheels and the guide plate. Now straighten the chain and unwind the snarled area. Locate the chain around the smallest cog wheel on the back wheel and mount the wheel to the bike. The chain will hang slack. Now mount the upper guide wheel and guide plate to the deraileur making sure that the chain feeds off the rear cog and passes around the guide wheel towards the front of the bike. Push the deraileur forwards relative to the chain and slip the lower guide wheel in between the guide plates and pushing the chain back in the guides & fasten with the pin. As you reassemble the plates and wheels on the deraileur be sure to observe carefully which way the chain is running. It is quite logical and this should prevent mistakes being made

you need to put chain back on and move the back wheel back so the chain is tight tighten the nuts up and should be okay

Does the rear wheel go on such that you can adjust it to take any play out of the chain? If so, turn the bike upside down or put it on a bike stand. Loosen the back wheel and pull it so that the chain is tighter and then tighten the wheel. There are other possible causes but I suspect this since you recently removed the wheel. Also I'm not sure how often the chain falls off. If this doesn't work, ask again and let us know how often its coming off. Good luck!

MAGNA 1996 TE you have to pull down all covers of front of motor remove rh wheel and inner plastic protecters to access crank wheel remove crank wheel. rh engine mount and two outer belts lower/lift engine to remove timing belt pulleys ect.remove timing belt to access waterpump lots of labour can email photos if any one needs an idea .of whats involved when replacing water pump. best get a timing belt kit and replace belt ,pulleys as well. then good for 100.0000 kms and plugs as well platium ones by doing on your own can save 800 to 1000 dollars just be carful not to move pulleys on timing belt . good luck i posted this after i had no response .a desiel mechanic guided me though the ordeal a lot of labour for a waterpump it took me 8 hrs straight to do . hope this is useful i didnt need timing kit just belt total cost if you do job $350.00 i got quoted $1500 by mechanic
$25 COOLANT
$300 TIMING BELT KIT OR $100 FOR BELT ALONE
$95( WATER PUMP NON GEN SUPERCHEAP AUTO)( GENUINE MITS $300 TOO MUCH$$$)
$90 PLUGS PLATIUM
$30 OIL
$7 OIL FILTER
$10 GASKET GLUE