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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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Old 10-15-2016, 03:25 PM
vhatley vhatley is offline
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Join Date: Sep 2010
Location: Oklahoma City, Ok. 73118
Posts: 27
Question Port Matching Questions And A Good Word About A Supplier

It's been a while, but I am back on a bike...sort of. But do have a few minor, (I think,) questions about the port matching as outlined by BarelyAwake here: http://motorbicycling.com/showthread.php?t=16646

Flipping AWESOME thread BTW, Barely, and as a 30 year drag-strip trained mechanic I can say it is one EVERY owner needs to read.

First, Thanks for any and all advice I get here, (or anywhere else for that matter,) I used to work on V-8 4 stroke HORSEPOWER, and these little 2 smokers are just too cool to leave alone.

Now, the GREAT word on a supplier: The engine I am working on was purchased on Amazon in a kit from the seller BHTEC-Motor, and while I wasn't initially happy as the kit didn't include a Large Frame Mount Adapter, (my bad, I didn't read the details,) but determined, I started building on a used Raleigh I had. The build went well, (I've done a 40-50 of these for other people,) But on initial start-up I noticed a bad vibration. After inspecting I found The rear right motor mount stud broken...even with the case thread still in the hole. I contacted BHTEC.

After sending him some pics, (link below,) he agreed to "send an engine block." I ASSUME that it will not include the top end components. So I read Barely's tut, (about 10 times, all 10 pages,) and got to work tearing the engine down...I NEED those parts anyways, right? What follows are pics of the components with about 1 hour run time on them with the questions/statements/opinions that I need answers to...

Sorry bout the pics being on FB, BUT I don't use Photobucket, and have damn few alternatives I liked...

First, the broken stud in the hole...(sniffs slightly, wipes a tear.)
https://www.facebook.com/photo.php?f...type=3&theater

Real B&*thch, huh? If he lets me keep the "engine block" I see a bunch of spare parts, (nice,) OR tap and helicoil, then balance crank and upgrade clutch/gearing system in the near future...now to the show and tell/ask.

I was pleased to find the wrist pin and lower rod bearing are needle bearings. The pic here is the piston intake side and a (faint) scratch at the bottom. The scratch is the upper wall of the intake runner with the piston at TDC. Will removing this aid in intake fuel flow? It would seem so. AND, in Barelys' post someone said it could help...

Pic here: https://www.facebook.com/photo.php?f...type=3&theater

On the subject of the piston, what about removing material from the exhaust side. Here's a pic of the lower exhaust wall with the piston at BDC. The KILLER here is with the amount of material I would have to remove would make it dangerously thin for the top piston skirt...I'm really starting to wish I had a Micrometer or dial calipers...Piston Ex. Side Pic:
https://www.facebook.com/photo.php?f...type=3&theater

For the most part, the work on the exhaust and intake ports will be easy. Only a minimal of dremel work and both will be as good as our Dennis Pirranio funny car Hemi heads. Maybe I got lucky and got a good casting, I dunno, but you can't tell it from the outside of the jug. Here's a good pic of the intake: https://www.facebook.com/photo.php?f...type=3&theater
And 1 more for good measure: https://www.facebook.com/photo.php?f...type=3&theater

Now the Exhaust, it's pretty good too, but could use a little work: https://www.facebook.com/photo.php?f...type=3&theater
And 1 more: https://www.facebook.com/photo.php?f...type=3&theater

X-Fer Runners are nice, I won't include pics here but they are all in the FB album I've been using for these. I'll do a dam little work on them, but I will work 'em.

Manifolds are a different matter...LOTS of work required here, but I understand this and am already on it. The head, (slant plug, :P ) is an all-together different beast.

The material seems sufficient, but the squish ring is a little f^&ked and the casting is much rougher. I guess my real question here is: Can I salvage this without the aid of welders and lathe? After seeing the head inside I didn't even bother checking the squish ring clearance. BUT then this brings another question into play... Here's the head (Problem w/squish ring seen at lower center, sorry bout the pic quality: https://www.facebook.com/photo.php?f...type=3&theater

More of the head, with the head gasket showing, (note gasket thickness,): https://www.facebook.com/photo.php?f...type=3&theater

There's not much angle at all to the squish ring, and on the exhaust side it's a little messed up, (pitting that LOOKS like casting deficiencies,) but (apparently) this engine relies on the head gasket for the squish ring clearance. My questions here are this:

A) The piston doesn't clear the top of the cyl at TDC, AND there's 3 (THREE?) gaskets on the bottom of the jug...Pardon my inexperience, but doesn't the piston come MUCH closer to the top of the cyl? and can I adjust the position by removing 1 or 2 (all?) bottom gaskets? And would this increase the compression too much?

B) Would it be better to reduce the squish ring clearance via the head gasket or plane the top of the jug...my head MAY already need surfaced, but that is no problem, just effort. IF the jug is better, I have a machine shop (buddy) I can "borrow" long enough to reface the jug top.

C) I didn't include pics here, but really, how important are the transfers? Mine (interior) look as good as the pics (again stock interior) of the intake runner, MAYBE a little work here, but I'll reserve it UNLESS someone here says that's it's THAT important.

AND IN CONCLUSION, I would like to thank you for just taking the time to get this far. Most especially if you respond with good advice or encouragement. You can get all the pics I have so far (of this build) in the same FB album I've been sending you to. There are more, I have pics and albums of some of the builds I've done, and others I repaired...You may not be able to believe some of the bikes people have brought me to fix. Send a request and you can even be my newest FB friend, I have about 300, all kinds of topics and discussions...

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