220 psi Compression reading. Is this safe?

[StrontiumEthics]

I ending up getting a new jug and piston, replaced the crappy wrist pin bearing, and upgraded to a Push high compression head. So say the least, I am very impressed with the performance increase. However, today I got my compression tester in the mail and upon testing, after about 4 separate readings I was getting about 220 psi. I did notice that the compression on this engine had increased. These are my main concerns

1. Is this safe? (im in the process of taking temperature readings)
2. I'm currently using 87 octane gasoline (normal grade) after using 93 and noticing a big drop in performance.
3. Spark plug is a light tan color with some oil around the threads.

Let me know what you guys think. Thanks!

 

[motorbikemike45]

You will have to look up the compression your engine should be putting out. 220 sounds a little high to me. Most auto engines run in the 160-200psi range. I would try running it on the 87 octane gas you have been using, but be careful. If you hear predetonation when the engine is under a heavy load, IE pinging, stop immediatly and switch to higher octane fuel. The ping sound is actually a super high pressure wave hitting the inner surfaces of the engine and is very damaging. It is caused when the mixture self-ignites early during the compression stroke, like a diesel from hot temps caused by the high compression, before the spark plug ignites the mixture at the right time. You would notice the pinging most when accelerating hard or climbing a long/steep hill. Hot weather will also make it worse.

 

[Al.Fisherman]

I ending up getting a new jug and piston, replaced the crappy wrist pin bearing, and upgraded to a Push high compression head. So say the least, I am very impressed with the performance increase. However, today I got my compression tester in the mail and upon testing, after about 4 separate readings I was getting about 220 psi. I did notice that the compression on this engine had increased. These are my main concerns

1. Is this safe? (im in the process of taking temperature readings)
2. I'm currently using 87 octane gasoline (normal grade) after using 93 and noticing a big drop in performance.
3. Spark plug is a light tan color with some oil around the threads.

Let me know what you guys think. Thanks!

Depends on what engine you have...if a HT, yes it's too much.

 

[Deleted member 12676]

I doubt that tester is reading correctly. If I bring mine close to 150psi then its hard to get enough traction to turn the engine over when starting.

Those cheap testers are affected by temperature. Best to have the tester between 70 and 80 degrees inside then bring it outside to quickly do the test.

Does the gauge show 0psi when not hooked up to engine?

 

[geebt48cc]

I even wil say that over 150psi is WOW, for these little china engines............

Gosh.............! Hello, wrist pin bearing..................

 

[Deleted member 12676]

yeah, even with a replacement wrist pin bearing I don't recommend more than 130psi.

 

[StrontiumEthics]

I think the engine temps were running super high so I decided to put another gasket on it which dropped my compression psi to 170.

 

[StrontiumEthics]

Thanks for the recommendation. I didn't know that temperature affects them. Now I know. But I actually do my testing inside where the temperature is definitely between 60-75 fah.

 

[Deleted member 12676]

170, eh? Mark your mileage now and let us know how many miles it lasts before it starts making clunking noises from play in the bearings. that is, of course, if the reading is accurate. you might take the bike to an auto mechanic and pay him $10 to check the pressure with his more expensive gauge.

 

[StrontiumEthics]

yikes. I actually heard some rattling after today's test run. Does this mean it has messed up my new roller bearings?

The rattle noise I heard is only when im idling. It smoothness out and goes away when by the time I get low-mid throttle.