Front and rear cylinder differences?
 

Was looking at a few sets of twin cam take off cylinders to have bored down the road and noted some had an “A” and others had a “B”.

I’m referring to the upper right numbers. Not the part numbers.

is there a difference between the two?


https://cimg0.ibsrv.net/gimg/www.hdf...4eeb2ec2c.jpeg

Unless those have been bored, they are standard bore (3.750") cylinders.

Yep. They were in a pair of Screaming Eagle boxes. Guy said they were takeoffs from when the engine was upgraded to 95ci. My main concern is that I was looking at several sets of cylinders today and wasn't sure if there are any differences between the front and rear cylinders or if they are interchangeable? Here's a better picture to illustrate what I was asking. If you see the number "A95", some cylinders had a "B" instead of the "A". That made me wary if they were specific front and rear and if the ones I was looking at were mixed up. I don't know, but trying to learn before ignorance gets expensive! LoL.

https://cimg9.ibsrv.net/gimg/www.hdf...86aee6bc65.jpg
Notice the "A95"? Some cylinders had a "B" with the number. Does this designate front or rear? Do you NEED both an "A" and a "B"? I pulled this image from the 'net. This is not one of the cylinders I was looking at today. FYI.


They'll be bored and matched to pistons by likely one of the very helpful guys who are on this board. My main thought was to have the cylinders bored and pistons/gaskets ready to do the job when I pull the engine down. I'm not in a hurry to do it, since we're getting into our nice riding season. Plus, the engine runs really well (I think) so there's no reason to muck with it. But, just thinking down the road. Guys were asking between $75-$100 for the set with pistons, but the pistons obviously wouldn't be used.

That obviously would be on top of the machine work, and I'm wondering if I should just wait, be patient, and have the work done to my cylinders? Thoughts? I had also thought of having a shop *cough (Kirby!)* do some street head work while it's all torn down. That said, it would make sense to just send 'em all at the same time.

I'm kinda working through the process as I type I guess. But would still like to know what I can about these engines.

Talk to Kirby. He used to offer "specials" for various services that were reasonabley priced. I don't know what your budget will allow but boring to 98" with Stage I head work and whatever cam you and Kirby come up with is the way to go, so wait, save the $$ and do it right the first time. Of course you will need to upgrade inner cam bearings and tensioner shoes but that's not expensive. Talk to Kirby, he might be able to do the work on an "exchange" basis where he provides the parts/service and you pay a core charge which he will refund when he receives your cylinders and heads in good condition; no down time. You didn't say of the bike in question is EFI or carbed but if EFI, fuel management will have to be addressed, i.e. a tuner and dyno tune but if carbed, a simple re-jet. Get the service manual and plan on having some fun "bonding" with your bike; a great DIY project.:icon_wink"

Personally, as long as the gasket surfaces and PC are good and the bore hasn't taken anything like a broke piston, I'd use take off cylinders and have them bored. Have the base and top surfaces check for flatness.

There isn't any difference between from and rear on the, 88, 96 ci models. 103 no difference except for the bore. Less to take out if you are going 4.927 - 4.937 bore.

Update, and thanks for the info
 

Lots to update to this thread.

First, the basics for @djl and some info for both he, and @Max Headflow. I need to update my sig so this info is always at hand. The engine currently has Andrews 21 cams, a Screaming Eagle hydraulic cam plate and oil pump, updated inner bearings, a ThunderMax ECU, V&H true duals, and Arlen Ness air filter housing. The bike also has an Andrews 34-tooth trans sprocket, which changed the bike for the better- considerably, IMHO. big bore is just the natural progression! :icon_banana:

I would like to keep the Andrews 21 cams (at least for now) and I assume that if I kept the compression under 10:1, that should be fine, right? I like the way the bike runs right now, but when it's time to look at the top end or I simply start looking for more, I'd hope the Andrews cams should still treat me right on a larger cube engine? I know there are other, better-suited cams for a larger cube engine with certain compression ratios. Would I be at a crossroads where the Andrews cams would dictate components, or if I went with another cam for more power, should I choose items that would NOT work with the A21 cams? The only thing I can think of would be compression? Currently, the Andrews A21 cams suit my riding style very well. I've also heard about Minton's Big Bore stories in older magazines. He liked the A21, right? (Definitely seeking advice/thoughts, and will be speaking with Kirby when the time comes).

Now, for the update

So, I went back over to Biketoberfest in Daytona. I looked at a few sets of cylinders again. My brother-in-law and I discussed a bit about them. Then, we walk over to a big, blue tarp. There's a sign with "Everything $1!!!!" And, wouldn't ya know it, there's a set of "A" and "B" twin-cam jugs sittin' right on the tarp!!!! I looked at my BIL and we both said, "These CAN'T be a buck!"

I scuttled my butt over to the guy sittin' in a chair under the tent and asked if the twin-cam jugs on the blue tarp were $1. He said, "yep, a buck apiece!" Of course, I paid him before I even walked back over!

I looked at them and they have a little rust on them, but not as bad as some I was looking at just minutes earlier. I haven't measured them, or really inspected them thoroughly, but I couldn't see any faults with them. I'll do a quick clean-up and then post pics. If they pass my uneducated eye, I'll definitely have them inspected before any machining. But, I feel REALLY fortunate at this point to have checked out the stuff on a blue tarp. If they check out, they'll be my new cylinders when I do the swap. If not, those two dollars put my day on a positive note for the rest of the day. Cheap happiness, I'd say. I also bought a couple of exhaust hanger plates for a buck each, so, if things go south, I paid $4 for two exhaust hangers. :icon_shrug:

I figured that two bux is exactly what I tipped the server at Golden Corral for my breakfast, so if they turn out to be trashed somehow, I still didn't get hurt.

Until you settle in on performance goals and budget, there is little I have to offer aside from what I have already posted. The Andrews 21 as well as similar cams are often referred to as "mouse" cams. If you want more displacement and more power, you shoud probably plan to drop the A21 cams for something more suitable. IMHO, 10:1 static is pushing the envelope for those cams and unless you have access to a tunner that is "expert" with the TMax, tuning could be an issue.

This is where I repeat what I posted in #4; talk to Kirby.:icon_wink:

Agreed djl.

and appreciate the info so far. SO much reading on this subject on this forum. Main thing right now is getting these cylinders checked out. It seems they are good to go. I cleaned them up a bit today and there appear to be no issues. I'm in no hurry but glad I found these so when I'm ready and have all my ducks in a row, I can get these checked, done, and ready for the swap.


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