Cylinder head boring

[VaDeerHunter]

Looks like I may be doing a top end overhaul. I see pistons on sale and kits and some offer head boring. If you were going to get it done locally or via shipping who would you use? Can a regular auto machine shop do the work?

Thanks,

Pat

 

[richardpr]

A regular machine shop can do it. Just be sure to leave them the pistons so they can do the clearance on them

 

[VaDeerHunter]

Thanks, so I should buy pistons a bit over or take the head in first and have them tell me how far over they are going to bore.

Thanks, again..

Pat

 

[richardpr]

depends on how scored the walls are

 

[Mekanix]

What size are they now? If you can't measure it, take the cylinder to the shop and ask them if you need .25 or 0.50mm over.

Then buy a kit that size.

Take it all to the shop and they will bore the cylinder s to match the pistons.

Takes a good scratch to need a 0.50mm but you need to see what they say first.

 

[VaDeerHunter]

Thanks guys, got to finish up the shaft replacement in the 787 first then going after the 951.

Pat

 

[Minnetonka4me]

It you are talking cylinder head...not any shop will do. They must understand the squish clearance and mill that edge accordingly. I would recommend Group K.

 

[Sportster-2001-951C-Stock]

It's unclear to me why you decided the 951 needs a top end, wasn't the compression in both north of 120psi? I think ~120psi STONE COLD isn't that bad, unless maybe you saw scoring or something.

 

[VaDeerHunter]

Its my understanding it should be more like 135-150. I get plug fouling in one cylinder too. I have a feeling one of the rings in the one cylinder is bad and not having enough compression is causing a bad combustion. Just some thoughts, I have to pull it to fix the starter Bendix and starter anyway.

Pat

 

[AdamXP800]

Pull the motor to fix the starter? Not that I'm aware of

 

[VaDeerHunter]

Both the starter and the bendix need to be changed out and possible the flywheel based on what I am hearing. The Bendix is in the Flywheel housing.

Pat

 

[AdamXP800]

I could be wrong, but the bendix is on the starter and engages the flywheel

 

[Sportster-2001-951C-Stock]

119/120 - This is the same compression between the two cyls, so plug condition should be the same all else equal. Hate seeing somebody waste their money if it can be avoided.

 

[VaDeerHunter]

On a 951 it is in two pieces, the starter goes into the Bendix and the Bendix is engaged with fly wheel. Yeah its easy to change the starter out but the Bendix assembly is only accessed by removing the stator cover. At least that is what the book says.

Pat

 

[VaDeerHunter]

I am going to get a better compression tester and see if the cheap one is right. But I expect one of two things, the oil ring is cracked letting oil in the cylinder along with the oil in the gas or the coil for that cylinder is bad or the wire. The forward cylinder plug is a nice golden brown. I appreciate your helping me not go overboard

Pat

 

[Jetskigoodies]

I think the guys think you are referring to your 787, if you are referring to your 951 the compression is different that the 150. You should be in the 130 range and the bendix is in the housing and not on the starter. After reading the thread you never clearly stated what motor you are working on. If you get the jugs bored and order pistons just do a one stop shop like fullboreonline.com just send your jugs to them and they will measure bore and send you the complete top end kit for around $300 and they will even cover return shipping.

 

[Jetskigoodies]

Lol you posted the last two comments while i was replying.

 

[AdamXP800]

Sorry, I overlooked the 951 part:facepalm: