In/Outlet port cleaning/polishing

In the next few months ( once all the parts are acquired) I will be changing the mufflers, and air filter, adding a 1200cc big bore kit, CVP carb tuner kit and V-Ductor.

While I have the heads off, I have been wondering about the internal finish of the inside of the ports on a stock 883 Sportster head.

Do they need much (or any) work? is it just a light polishing or is it a job of removing a good bit of material, rought edges, casting marks etc with a die grinder..

I have an air die grinder, but no tools small enough for this sort of job. Any recommendations with regard to the type(s) (material/size/shape) of grinding heads for the die grinder?

Neil

Neil IMHO headporting ia an Art and a Science thats best left to the pro's, you can take a good set of heads and a die-grinder and make an expensive set of paperweights.
With your bike plans....pipes,breather and 1200 conversion, a good street port(stock valves) for the heads, don't forget the manifold either, with stock cams ....you'll have one Sporty Sportster.

True, I was not looking to go mad on the job and max out the ports, as this can often be counter productive.....too big a port, reduced velocity of the air flow and poorer fuel/air mixing etc.

Was more after an idea of what the overall finish inside the ports is like and if its worth doing at all. As you say probably not, but worth asking just the same.
Last time I did any work on ports was on my 2 stroke 50cc Yamaha RD50 when I was 14...so 26 years ago. and doing a 2stroke is a totally different ball game...changing timing by lengthening the ports

Here a bit of info on running 883 heads on a 1200 big bore kit. Art's(Bike Talks Sportster Guru) post#5 and #6 explains a lot

http://bike-talk.com/forum/motorcycle-tech-talk/8243-883-1200-vss-nrhs-1250-upgrade-kit.html

Yes, that is certainly informative.
Where I ride, stop/go riding and small winding lane performance is what I need. We only have small roads, and the speed limit is only 40 mph, so looks like leaving the heads as 883 is going to be good for me

Cheers

For what you want to accomplish, the 883 heads will work fine with "reverse dome" pistons made for an 883>1200 conversion. Standard 1200 flat-top pistons will make the compression ratio way too high.

If you want to have the heads worked a bit, but not go crazy or spend a lot, this is what I do - measure the intake & exhaust ports, find the larger of the each & clean it up, removing any casting flash & rough spots, but NOT polishing the port - that's for top-end only engines & hurts street/road performance. Then make the port in the other head match.

Do the same thing with the combustion chambers - you don't want to open them up as that'll drop the CR, but a little clean-up work & making sure both combustion chambers are exactly the same size helps.

One more thing when you're putting it all back together is to match the intake manifold to the intake ports & you'll probably have to remove a bit of material - you want to make the joints fade away so there's no lip or step on the inside where the manifold meets the heads. But again, don't polish the inside of the manifold, as a rougher surface breaks up "laminar flow" & helps the incoming air & fuel mix better. Ideally you want the surface of inside of the manifold & intake ports to be identical & slightly rough - there are some long, flexible, cylindrical wire brushes made that you can use in a drill to run down the inside & leave a surface similar to a cylinder that's just been honed.

That work will improve efficiency from idle to redline & any good head shop can do it without breaking the bank. You can do it yourself, but if you haven't done it before you run the risk of removing too much material & obviously you can't put it back :witsend: Any more work on the heads such as making the ports and/or combustion chambers bigger changes & narrows the powerband & will also require different valves & pistons.

Thanks for that. I'll have a look once I get them off. Looks like that will not be until well into the New Year now. I have just received a new headlining for the '82 Landcruiser, have been waiting 6 months for it..the vehicle has been off the road since October 08, so I need to get it finished. Doing the Sporty is a whole new project...another one

definitely have your heads done by a pro. i have seen quit a few ruined heads from doityourself port jobs. the price of a good headwork is well worth it and will be the larget hp gain per dollar you will ever do to your bike. im basing this on my last 40 some odd years wrenchin scoots. we are a performance head and engine shop,but i would suggest you spend some time talking to who ever reworks your heads. if you have any questions i would be glad to help any way i could. tony m. dabbs Dabbs Engineering And Design, D.E.A.D.

All points considered but for me the overall problem is that I live on an island of 80,000 people, and there are certainly not a dyno over here, at least not at a garage, maybe one in private hands but not the i know of.

Same problem with getting the heads done at a pro shop, there is not one...so anything that needs to be done either has to be done by myself or sent over to mainland England....or I take it over myself...so a 4 or 500 US dollar boat crossing or flight, before I even consider the cost of the job.

I will only be able to decide if I will do anything or not when the heads finally come off. If I do any work it would be only the very mildest of work, any huge obvious casting marks/slag.

I want to improve low to mid range grunt and am not too interested in top end performance. I am thinking of towing a small trailer when I go over to Europe touring around and camping. So 40-50-60 mph speeds max, country and 'B' roads rather than main highways.

Yep, that is what I am doing. I have a 1200 big bore kit
1200 SILVER BIG BORE CONVERSION HARLEY SPORTSTER 04-09, and that is good for using the 883 heads. I do have a question about that and the headgasket, but will start a new thread about that.

Yep, carb tuning, and Kens kit arrived yesterday, with jets and needles for both 883 and 1200cc, plus the brass carb fuel feed elbow, a V-Ductor and EZ-Just idle adjuster.

Will be leaving the cams until some more money turns up, had not even considered a cam change. If I think about that I will post a new thread when the time comes. Don't want to confuse this thread with a cam discussion now

From what I have read in a few books and from this thread, that looks about as much as i will be able to safely do.

Had read that too. IF I do anything to them it will just be as much as Art_NJr and you have said

This is all still a few months off, but doing as much research and getting questions answered before I start.

Thanks for your all your advice.

Just a note there - the stock cams have virtually -0- overlap, make a smooth, wide powerband & work just fine for what you want. If you decide to go with more cam later, don't go with any more than the "W" grind - standard in 1200's as of 2004. The reason is 883 heads have smaller valves & won't flow enough to utilize more cam like SE .497's or Andrews N4's & all you'd do is give away low-end torque for a minimal gain in top-end HP. You'd lose a little bit on the low end with the W's too, but not much & they'll work very well in the midrange (3000-4500 rpm), which is probably where you spend most of your time anyway.

One more thing - I'm not personally familiar with the 1200 kit mentioned & given the fact that you do not have machine shop services readily available, you need to ask the seller if the cylinders have been honed on torque plates to match the new pistons. If they have, fine & that's a good price, but if not, don't buy that kit & get one where the precision work has been done. There are some shops who's work I do know personally & one of 'em is NRHS, which sells a 1250 kit for $700:
NRHS - High Performance for your Harley Twin Cam, Evolution, Sportster or Buell!

The #1 problem with 883>1200 conversions is off-the-shelf cylinders & pistons which have not been matched to each other by a qualified machinist. Torque plates bolted onto the cylinders before honing duplicate the forces on the cylinders when installed. Just sitting on the workbench they'll be out-of-round but you don't care about that - all you care about is what the dimensions are when they're on the engine & the only way to know that is to use torque plates. I've seen cylinders change shape by as much as .004" & that might as well be a mile.

Especially when using forged pistons which "grow" as they heat up, the piston-to-wall clearance is absolutely crucial - it's either 100% right or 100% wrong & the new parts will wear way too fast. I've seen 883>1200 conversions (BT kits too) that had to be done over again in 6 months, others still going strong after 60,000 miles & the only difference was whether or not the cylinders were properly prepared for the new pistons / rings & the PTW clearance was right or not. Be off .001" & you've got problems - the best shops stay within +/- .0005" & you need special (expensive) tools to do that.

I already have the kit, someone else bought it, and I got it cheap because he sold the bike. It is all new and un used parts still in sealed bags.
It appears to be one of these kits:
http://www.vtwinmfg.com/catalogs/cyr/pdf/799.pdf
And it does state that they are ready to go, no machining required. If the opioion on here turns out to be that it is a crap quality kit, then I shall bin it and just leave the bike as an 883.

I see no problem with the parts' quality, the question is, have the cylinders & pistons been matched? Kits rarely are - suppliers typically buy in large quantities & while the manufacturers hold close tolerances, there's enough variation that when you assemble 2 particular pistons with 2 particular cylinders, they need to be measured precisely & matched to each other. That's just a matter of measuring the piston diameter below the bottom ring groove all the way around (they won't be perfectly round) & measuring the inside diameter of the cylinders all the way around, top-to-bottom, finding out what the difference is & honing the cylinders as necessary to get the correct spacing, from the widest point on the piston, which should be directly across the wrist-pin hole, measured just above it.

The kit appears to have forged Wiseco pistons & their recommendation is .0025" piston-to-wall clearance. Only problem is you need precise measuring tools & the cylinder measurements will be false unless torque plates are bolted on 1st. If the tools are available to you, a local shop has them, etc., no problem, if not, you have to trust the matching was done by the company that sold the parts.

By comparison, cast KB pistons don't expand as they heat up, so the PTW clearance should be .0015" & while a thousandth of an inch difference doesn't sound like much, it is - set Wisecos that "tight" & they'll want to seize on the cylinders when they get hot. And when the heads are torqued down, the cylinders will change shape, so that's why torque plates are so important - even when the clearance appears to be right without plates, what you see a few months later is weird & inconsistent wear patterns. But when plates are used & light honing is done so the clearance is *exactly* right, then you can run the engine for years & years without worry.

Yeah, I tend to be "anal" about these things, but I remember a sign on the wall in an engine shop 40 years ago - "Why is there always enough time to do it over, but never enough time to do it right?" And since you've got time to put it all together, you should be able to find someone who has the tools to make sure your parts match up just so.

Understand what you are saying, but still I think I will just have to put it together and hope that what they say is true. Simply because there are no machine shops over here on this island that I would be able to trust with the work, and if I have to go over to England to get the job done...flights or boat, accommodation, travel etc I would not have much left out of $1500 so it is either use it as it is, or forget it.
I will still have the old 883 parts if there is a problem, so it can always go back to that if I need to.

Ouch !!

Well, all one really needs to do it themselves is to borrow an outside micrometer to measure the pistons, an inside mike to measure the cylinder bore & if you can get the material, you can make your own torque plates. They're just steel rings & here's a set (expensive) so you can see what they look like:

Torque Plates Jim's Harley Davidson® SKU # 713-97-232

All you do is bolt the plates together with the cylinder in the middle as the "meat in the sandwich" & torque the bolts to the specs the service manual says to use for the heads. That puts the same pressure on the cylinder as it'll be under when installed on the engine & your bore diameter measurements will be correct. When honing is needed, you leave the plates on while doing it, then measure again.

Obviously you can't change the piston diameter, but you can the cylinder, so all you need from the piston is the max. exact outside diameter & the manufacturer's clearance recommendation. Like the carpenter, "measure twice, cut once" & you're done.

Lacking those tools, you can @ least (gently) slide the pistons into the cylinders without the piston rings installed & have a look @ how well they fit. A feeler gauge between piston & cylinder wall won't tell you very much, but you can get a general idea as to whether the fit is "tight" or "loose" just by slipping the pistons thru the bore.

Yes, well could have a look. The pistons are inside the barrels, all in sealed bags at the moment.
Can have a look at making up a set of torque rings. I have a mate with a lathe, so it wont be a problem...just another job.

I have a mic that will do the pistons, but think my inside mic is only up to about 2 inch max, I do not think I have the other spacers to measure a greater diameter.