How to tighten chain on mopeds - 2008 Derbi Senda XRace 50 SM

Their is a vacumn pipe from carb to the valve on the bottom of the fuel tank ,,,check it out is pipe split is there a vacumn ? has the valve jammed .

you have to use the tension screw to move the cutter bar to tighten the chain then you do up the bar mounting nut to keep it tight

Tighten the adjusting screw with the two nuts loose but snugon the middle of the chain on the top of the bar. Tighten the chain screw until the chain is loose enough to raise the chain up about 1/2 inch then tighten the mounting nuts tight. Then see if it is ok.
Terry

Remove cover on the chain side of the saw. Loosen the two hex nuts that hold the bar onto the saw. You will need to loosen the tightener screw also. Place chain back onto the bar making sure the chain is positioned properly in the sprocket at the rear of the bar and just reverse the directions. Tighten the tightener screw until the chain is tightened leaving a little slack, then tighten the two hex nut. Replace the side cover. When you pull the chain down away from the bar, it should have just a bit of slack not tight. This allows the chain to turn without a lot of friction. I hope this helps.

Usually the cable breaks at the very end where the barrel is attached. if so there are cable repair barrels sold at bicycle shops that you can insert the broken cable end into and tighten a small set screw in the side to clamp down on the cable. I've had to drill the hole a little bigger for some larger cables.
Picture reference: http://t1.gstatic.com/images?q=tbn:ANd9GcTWl_KhEmoSJ8pfIqp0Dnj-_7EUayYvprBbJQF_aHC3NwBEhR2B

Between the chain bar and the body there is an adjusting screw, if the adjusting screw is stripped it will not pull on the chain bar to tighten the chain.
procedure for tightening chain. loosen the chain guard nuts, tighten the bar adjusting screw by turning to the right or clockwise, the chain has to roll freely around the bar but not bind. check with gloves or rag, don't use bare hands to avoid accidents. once chain is adjusted, tighten the chain guard nuts. good luck!

Thanks for contacting FixYa. I was just reviewing some of the old unsolved problems and wanted to make sure your question gets resolved.

Chain can be correctly tightened by loosening the axle nut so the axle floats. Then tighten the chain tensioning nuts on either side evenly so they tighten the chain. When the chain is properly tensioned you will have 3/8th - 1/2" of slack between the chain and the swing arm. Then re-torque the axle nuts and lubercate the chain. Should be ready to go.

TF

There are usually two 7/16" nuts on the side of the chain saw. Loosen those a little first, then turn the screw to tighten the chain - not too tight or you'll stretch out the chain when you use it. Don't forget to re-tighten the two nuts before using the chainsaw.

Remove the water trap bowl at the bottom of the petcock, (gas valve). Any water or trash in the bowl? Drain a cup of gas from the tank. Any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Turn off the gas. Drain the carburetor> There is probably a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. Remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the two screws on the outside throat of the carb and spray into the screw holes as well.
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Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the carb back together, clean the air filter and install the carb. Be sure the mounting bolts are tight on the carb AND on the manifold attached to the cylinder. Tighten down the cylinder head bolts and put in a new spark plug. Turn on the gas and let the float bowl fill then start the engine. Set the idle speed with the idle screw. This process should fix the engine and probably eliminate the 'feathery' sound..

The oil leak can probably be fixed by just tightening up the case screws. The only other place for an oil leak is the shifter seal and the chain sprocket seal. Replace them if they are bad.


If the 'feathery' sound is still there then tighten down the exhaust mounting bolts. If it is still there then learn to love it....
Get a new battery Daniel, your'e hurting my head!

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( 4 diamonds would be nice ) >Thanks Daniel!