Engine Trouble Recently Rebuilt engine won't start

[gary55]

Well currently he still has compression problems, but I'd say that's a definite real possibility during the original problem that started back in June. At this point he's had it apart too much to even make that bet (but he still can be doing that wrong too.)


So any idea why crassius sees this symptom and why replacing the seal will fix the issue? I don't think either one of you are full of crap, so I can't willingly denounce either of you. And no offense, he runs a shop dealing with these and a repair service, so I'm aken to believe he's seeing a pattern here.

No offense taken. One can't help but wonder. I wonder as well. Believe me I wouldn't have went through all this not wanting to know 1 way or the other what was going on with the 2 different findings.
I still wonder if I am missing something, and if I am I would welcome a logical test to prove I'm wrong. If I am I want to know. I don't think Crassius is full of crap either, and still respect his opinions and input. I just can't duplicate his findings in this particular set of conditions.
I have been building and repairing these bikes for over 5 years so Crassius does have a little better than a 5 year head start on me, still with over 150 builds and far more repairs than that I feel competent enough in my knowledge and experience to discard any lack there of as a factor in the outcome of this test.
Usually when a bike comes in with a blown seal the symptoms ( uncontrollable high idle with poor power) will lead me to it without a comp. test, but I will be doing 1 on every one that I get in the future. If I do get one that confirms the opposite of my findings so far I will post it while scratching my head and wondering why. As far as myself being full of crap, well maybe not full but I wouldn't say the comment was entirely without some truth.

 

[gary55]

I got a crankshaft with an incorrect con rod so it'll be about a week before I can get a proper crankshaft.

Gary, I don't doubt you but at the same time I don't understand what else could be my problem. I have replaced the cylinder/piston/piston rings and gotten all new gaskets to no avail. Where else could the air be coming out of? and what else would cause a compression reading that low?

Reply # 20 warped head.

 

[gary55]

I got $100 on it that he failed to set the magneto/crank postion to tdc or put in backwards or his bowl floats off

I'm not taking that bet. It could be one of these, but if so he must have a bad compression gauge cause none of what your listing is going to cause 50 lbs, comp.. I'm still leaning on a warped head.

 

[HumanPerson]

or unlevel jug top?

 

[SpeedBoi]

I tried sanding the head a little, but maybe I should use valve grinding compound between the head and the jug, so I know they are mating well. Just worried about my squish gap, might need to use 2 head gaskets for clearance

 

[HumanPerson]

get a straight edge and check the top of your cylinder.

 

[crassius]

I haven't been commenting more here as I'm just hoping to hear what will clarify this issue - don't really care what the cause is as much as I just need to know. I have many black-weight crank, big bearing customers out there still (in fact my GF rides one), and I'm riding one of the first balanced crank motors from maybe 6 years ago, so my info may be out of date in terms of the more modern motors. I do repairs and charge by the hour, so don't spend a lot of time cataloguing all chars of the motor, but I see 30#, look and see seal hanging off crank, replace seal and motor runs good.

Might save me time to know if this has changed.

 

[Frankenstein]

I got a crankshaft with an incorrect con rod so it'll be about a week before I can get a proper crankshaft.

Gary, I don't doubt you but at the same time I don't understand what else could be my problem. I have replaced the cylinder/piston/piston rings and gotten all new gaskets to no avail. Where else could the air be coming out of? and what else would cause a compression reading that low?

A cracked head.

 

[HumanPerson]

like yours?

 

[Frankenstein]

I haven't been commenting more here as I'm just hoping to hear what will clarify this issue - don't really care what the cause is as much as I just need to know. I have many black-weight crank, big bearing customers out there still (in fact my GF rides one), and I'm riding one of the first balanced crank motors from maybe 6 years ago, so my info may be out of date in terms of the more modern motors. I do repairs and charge by the hour, so don't spend a lot of time cataloguing all chars of the motor, but I see 30#, look and see seal hanging off crank, replace seal and motor runs good.

Might save me time to know if this has changed.

Do you just happen to check the head torque off at the end with a torque wrench just out of habit after hitting the seal or do you just check that from the beginning?

Another question for speed, did you actually get the torque wrench or are you still putting that off, it's really important and the order you tighten as well. If you have had it run without using the torque wrench to tighten it equally then you very well may have opened yourself up to a warped head.

You also haven't reported if you went and checked for a leak under the head, just because the gasket is new it doesn't solve everything, clean out the space between the head and cylinder with brake clean and paper towel so no residue remains, then roll it down the street in a struggle to start it. Go over the area again with clean towels and cleaner, if you pick up something new and oil colored then you found the problem area.