Motorcycle Repair: Bike will not start, yamaha xt 225, harnass

Question
Falcon,

I did all the things that you said, 1st I resent the timing as per the manual.  2nd, checked and reset the valve gap as per the manual. 3rd, checked compression, although I do not have a gauge for exact messuring, I hald my finger over the spark plug hole, I could feel pressure from the cylinder.  I was able to keep my fingeron the whole, is this not enough pressure?  I assume there is fuel getting to the engine, I can smell it after awhile, I can also smell it on the plug when I remove it, although it does not appear to be fouled.  There is spark, I tested the plug and conection by grounding it to the frame, I see a blue spark fire across the tip of the plug.  No spark that touches the frame though.  Is this enough spark?  Any suggestions?  I am at witts end, thanks for your help.

DJ

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Followup To
Question -
recently rebuilt the engine for a yamaha XT 225. Reassembly went smooth with no problems. I also replaced the entire electrical harnass that was damaged. When I try to start the bike, the starter turns and the piston moves. Once the cyclinder is primed with the choke, iy begins to fire but will not start. There is ample air flow, fuel appears to be flowing and I have checked for spark witch is present. Any ideas why it will not start.  Could there be a timing issue here?  If so, how do I fix?
Answer -
Hi DJ.

okay.  Let's review;

1) engine turns over.

2) Fuel flows to carb.  Does it make it to the cylinder from the carb?

3) spark plug is firing.

4) Do you have proper compression?  Check it and verify the compression from the specs in the repair manual.

5) Check the timing as per the specs in the repair manual.  Is it on the mark?

6) Is the valve timing right?

Start with those and see what you find.

Good luck and ride safe.
FALCON

Answer
Hi DJ.

You really needed a compression tester to be sure of the compression in the cylinders.  It could still be too low, but without a tester you cannot be 100% sure.

Either way, now you need to be certain that all of the carbs are pulling together.  What is done to be sure of this is a static synchro.

Basically, you will check each carb as you pull the throttle (with power off) and see if the all move together at exactly the same time.

****This is a time-consuming process****

1) Slowly turn the throttle and watch inside the carb throttle bodies.

2) When one starts to move, they should all be moving at the exact same time and rate.

3) If they do not move together, then adjust the one(s) that do not move together til they do move with the rest.

4) Repeat these steps as needed til all carbs move simultaniously.

NOTE: In theory, there is a set of instructions in the repair manual for doing a static synch as well as instructions for proper synchronization after the bike is running.

There are also the following possibilities that you should check;

1) The exhaust pipes may be loose at the head.

2) The intake manifolds could be loose at the head or carbs.

3) The intake manifolds could be leaking air.


If you are without a repair manual, then get one ASAP.

If there are no other issues with the bike, then it should start and run well enough to do a proper carb synch.

Let me know what you find.
Good luck and ride safe.
FALCON