Low power, Brand new Engines?

[gary55]

200 is way up there for a stock engine. I would be curious what your other engines read with that gauge. Here is one reading in that range, but it had .030" decked off the jug. It ran strong so anyways it doesn't appear that compression is the issue. Could be jetting, but if you try a carb off a good running engine with no improvement then that's eliminated. What do the weak engines have in blow down? MM's from top of exhaust to top of transfers. Got a pic. of the piston at tdc?
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[gary55]

No when at TDC the piston crown is above the cylinder a little.

It don't look like their is any marks that would indicate piston bounce. I assume the outer edge of the piston is slightly below the top of the jug? Your post says 50psi, but it's 200psi right?

 

[Street Ryderz]

200 is way up there for a stock engine. I would be curious what your other engines read with that gauge. Here is one reading in that range, but it had .030" decked off the jug. It ran strong so anyways it doesn't appear that compression is the issue. Could be jetting, but if you try a carb off a good running engine with no improvement then that's eliminated. What do the weak engines have in blow down? MM's from top of exhaust to top of transfers. Got a pic. of the piston at tdc?
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That's pretty tight eh brother!LOL seriously 205 is getting up there.Looks like your putting some heat in the pipe too!

 

[Jason Kotchey]

I redid the compression test at a lower rpm. it built to 70psi then leveled out (photo enclosed). I think thats more accurate than the video attempt. . Also pics of the piston at tdc.

 

[crassius]

70 is too low

piston arrow markings can go either way, but locating pins for rings must be on back where intake is

some older H2 cylinders (that sometimes get used on other bottom ends) have about 2mm more deck height than normal cylinders - compare distance from base gasket deck to head gasket deck among your other motors

no fix for that but to sand down top of cylinder

if cylinders are same height, check walls to see if rings are seating well (may need just a VERY light hone)

last option is live with some a bit slower

 

[gary55]

That's pretty tight eh brother!LOL seriously 205 is getting up there.Looks like your putting some heat in the pipe too!

This is a buddy of mine's bike. To some extent he Don't care how long they last as long as the run strong. I told him about all the wrap, but some folks just have a mind of their own. That being said you would be hard pressed to find a nicer person.

 

[gary55]

I redid the compression test at a lower rpm. it built to 70psi then leveled out (photo enclosed). I think thats more accurate than the video attempt. . Also pics of the piston at tdc.

Piston looks like it's where it needs to be at TDC. Comp. is low at 70. Since you say they are new engines my guess is a new head gasket and proper torque. Might wana check the head for warping. Could do some port work to soup it up a bit. A good pipe couldn't hurt.

 

[Jason Kotchey]

 

[gary55]

Move c clip to top notch. Is this the one that reads 70 psi on the compression. If so that is the problem. 70 is to low. A engine may run and idle at 70ish, but will be gutless under a load.

 

[Jason Kotchey]

Okay Ill give it a shot!