xingyue 260t-4 problem By jenningsjosh (Read 9,275 times)

[jenningsjosh]

ok.. i will replace the belt.. i hope it fixes my issue

[jenningsjosh]

Hey I got a compression gauge.. what should it measure? I think the yp250 manual says 160psi...

Actually it says 1400 kpa? Which converts to 203 psi...

Opinions?

[Alleyoop]

Well you know something is not right if the manual says 160psi and you get a reading of 203.
If you have 203 psi You would have a hard time turning it over with your hand and even the starter would grunt turning it over.
So my opinion is the gauge is a cheap gauge which are known not to register correctly.
my .02
Alleyoop

[jenningsjosh]

No no no.. the manual says 1400kpa... doesn't give a psi.... I haven't done it yet....

Just asking if that is correct

[Alleyoop]

That is a good question IF THE MANUAL IS CORRECT, CHINA MANUALS are known to NOT be correct. But since you have a gauge take the compression and see what you get.
Alleyoop

[vansmack2]

Your belt is about 873 or 874 and definitely too long. I would also check the compression like Alley said too be sure you cover all the bases. I totally understand your frustration, but check all that is suggested. None of us are there with you to see, or check things for ourselves, so we have to make educated guesses. Take care.

I checked the Honda Helix 250 manual I have in PDF form. It says the 244cc Honda engine has 10.0:1 compression, and should be 213 psi at 6oo rpm. See the picture below.

[jenningsjosh]

I have the 257cc motor... and the only way I know how to check the conpression is by letting it warm up for a few minutes... kill it.. ppull the spark plug... hook up gauge.. and try to crank it over and get compression reading that way... if there is another way... pls do tell

[bhinch]

That is the only way I know of....warm or cold....what reading did you get? Since you had compression at the shop, I don't think that is your prob. Not sure about the rpm....that is a first for me. I am a Licensed A&P tech and have yrs of experience with internal combustion engines. The ones that leave the ground, where you can not pull off on the shoulder. Keep working on it and you will get it back in shape. Enjoy the ride....

[jenningsjosh]

Yeah i was reading on another forum that uou were into aircraft... i appriciate the help...just stick with me and give me all the help you can pls... i am willing to try any kind of test or order anythkng that might be wrong.. i just want it fixed...I have class all day today... I will get you the readings tonight... thanks

[jenningsjosh]

I got busy tonight.. its friday.. enjoy guys

[vansmack2]

I don't know what the 600 rpm is either. I only know cars. You just remove a plug, attached the gauge, crank the engine, then check the pressure.

I read a few forums to try to figure out the compression number. It sounds like the 213 psi should be in the ballpark of a good 10 to 1 compression engine. There are other factors that effect compression readings besides just the compression ratio though, such as how long the valves are open, and at what point in the stroke they open and close.

[bhinch]

All an engine is an air pump..intake-compression-power-exhaust...called a four stroke. In the aircraft industry, you use a differential compression tester. A two gauge tester, one gauge is for supply, 80 psi into the cylinder and the other gauge is what the cylinder is holding. Anything under 70 psi is reason to pull a cylinder. The piston is placed at TDC (Top Dead Center) on compression stroke and the air enters the cylinder and the prop should not move. When done correctly you can hear the air excaping and where it is. In the exhaust it is the exhaust valve...intake the intake valve. In the engine case (crank case) it is the rings. Kinda different from the direct engine start procedure, but you get the idea. Just remove plug and install tester and windmill the engine for the reading.

[jenningsjosh]

Ok so I did the compression check.. looks like 165psi.. Is that decent enough or does it show my problem? While i have it hooked up... i keep reading about adding oil... then rechecking... Do i add oil where i adjusted the valves?(NEWB) Lemme know what you think pls

[vansmack2]

I have been reading trying to find a definite answer and have not found one. I think that 165 reading is fine. There is not a definitive answer because it depends on when the intake and exhaust valves close, but 165 is a good number. Others can chime in with their opinion. If I have a compression gauge around I can compare mine.

[jenningsjosh]

That would be nice.. just for anyone else that might come across same issue.. just to have a running good bikes actual compression reading for this motor... thanks vans