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1978 Yamaha RD 250 Questions & Answers
What is gap on sparkplug on 1978 Yamaha 250 snowmobile?
Hi nana
Leaving the plug set to what it came as is as good as set correctly, unless you have dropped the plug already:). Attempts to adjust the gap are often done wrong, and potentially damage the plug. Unless you are race prepping the engine/indexing it also, it will be fine straight out of the box. Good likely hood that the old 2stroker will need a new plug long before the gap becomes and issue:) Hope this helps.
regards
robotek
Yammy rd 200 1978 inconsistent running
check the neddle valve seats under the float bowls,may find that theseats are not sealing,to test,take the carbs off the bike,remove the bowls ,compress the floats untill they are all the way up(simulates full bowl of fuel)then blow through the fuel inlet pipe,you should not be able to hear air passing throgh the valve if you can replace the valve seat and the needle valve,sorry cant remember point settings,long time ago since i worked on one of these
No spark, when it was running it would rev funny
Not as much info in the posting as I would like so I will provide a broad answer.
First thing> install a new set of the stock NGK spark plugs for your bike. Check for spark before installing. Still no spark?
How good is the battery? Is the battery nearly full of water as it should be? Are the battery wires clean an tight? Is the kill switch on? Is the side stand up? It should be up when starting. Is the bike in neutral? Check the fuses. Check the wiring connections, are they tight?
If spark is present, is the gas turned on? How clean is the air filter? Clean or replace the air filter.If the bike still will not start go ahead and drain the carbs. There should be a screw on the lower side of each carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carbs to fill with gas. If the bike doesn't start properly then shut off the gas and remove the carburetors from the engine.
For both carbs > 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 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.
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. Remount the carbs.
Next, remove the water trap bowl at the bottom of the petcock, (gas valve). Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ). Turn the gas back on to let the float bowls fill then start the engine. Be sure to balance and sync the carbs when finished. If you don't know how to balance and sync the carbs, get back to me after you do the stuff mentioned above. This process should get you back on the road.
Please rate this solution as " FixYa " if all goes well. Thanks!
Oil pressure loss -
He must have had some other failure. A motor can go for longer than 10 minutes at idle with no recirculating oil. Had an old xr200 that made it about 4 hours with no oil, and we weren't being kind to it.
How to connect wiring to the battery
Under the seat / possibly behind a side panel. You should find 2 heavy wires. One coloured RED and one BLACK. Presuming the bike is a negative earth. Means the black lead is attached to the frame at the other end, this will got to the negative side of the battery. The red lead, that will got to the starter solenoid, if it has one and possibly a regulator rectifier box?. So in essence one wire BLACK will go to the frame. So thats the BLACK.
The other the RED wire, will go to some kind of electronic device a solenoid, a box or a finned box, maybe all of them, maybe just one, but RED will go to something electrical. so RED from the battery to something electrical. BUT NOT TO THE FRAME
Thats about it you should also find a fuse in there, but who knows if people have been it meddling. A 1970's Yamaha RD 250 in fair condition brings around UK pounds 2000 in the UK that's dollars 3000 plus. I am thinking you are new to motorcycles. If you was thinking of ragging it round a field or something destructive like commuting, you could maybe sell it and buy something more suited to a new rider. Oh also its a 2 stroke bike that means you need to have oil and petrol/gas mixed together else you will ruin the engine. Ask at a bike shop, they will sell you some and show you where to pour it. It needs this every time you use it, not just once in a while. Oh yes they are a jolly dam quick, fast, bike! DO!!! Wear a helmet, as they like to deposit you on the tarmac at any opportunity. Not very forgiving, but really good fun. enjoy your bike.
I have just aquired a
There might be a key number on the switch itself but even if not a competent locksmith can make a new key for you in a short time for less than the factory will likely charge you for a replacement. I would suspect it should cost less than $25 if you take it to the locksmith, more if he comes to you.
Compression problems
If its a 2 Stroke engine you need new rings on piston if its 4 Stroke you could have A valve stuck open it also could need rings on piston
I may buy a 1976
Hi,,,the major things,as it has sat for so long will be,,gummed up carbs,,hardened crank seals and rust in the tank..
You can jump start it but i dont reccomend it.
Price will vary with condition,,both external and engine wise.
They are a great bike,,,good luck with it.
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