Dan Hodges Bang for your Buck Engine Mods

[AussiXS11G]

all that is very good, but the best "bang for the buck", I reckon - assuming the engine/exhaust is generally OK, and
with an OK bottom end, would be a set of BS36 carbs, Ignitech ignition system, new coils, and TPS -
prob. get out of it for less than a $grand - retain the airbox -

start adding on for head work, rings, bearings if needed, rebore if it's necessary -

[makzy]

Great reading! Loved it, probably beyond most, not everyone would be even care but to the 2 percent that do, magic!!
It’s got me thinking, I have an early 1179 wiesco piston kit , an 80 head that’s been tickled a bit on the inlet side with polished exhaust ports, just need to be able to retire so as to have the time to build it!!!! Ahh well, one day.

[BrettS]

Jonesy ya old fella, it’s called copy n paste

Jeff, no tripe there it’s pure gold, I’ve read it several times just needed to put it all together.

[excess.11]

Surely you jest grasshopper...who the phuck is gonna read all that tripe?
We are but simple mortals ....not literary geniuses.

[Jonesy :-)]

No wonder we haven't heard from you in a while Brett, would've taken me several sittings to put all that down in print

[BrettS]

Starting this thread to get all Dan Hodges advice in one spot for my easy reference and contemplation. Also so you guys can help me not make any silly mistakes as I put the engine together.
Parts I have or will have on hand shortly.
1 police bike motor 5H4 Oceania broken starter gear and best guess at moment worn gearbox bearings. In parts.
1 3X1 Oceania in bike going strong with good compression.
No known differences in these engines same as early model American small valves low dome pistons.
Mikuni RS36's Flatsides installed, noticeable power increase but believe they are running too rich.
XJR 1300 4-2 exhaust modified to fit. Removed at the moment to trial 4-2 Xpipe borrowed from Christian.
4-1 of unknown origin, similar to the Kerker but no dogleg near the collector. Rusted out but have booked in to be remade for $300
1196 wiseco bigbore kit with barrels machined to suit, bought from a PO with no guarantee so I'll need to learn how to check it.
1 Hopefully late model American head with large valves in the post due early October.

In researching getting the best Bang for your Buck power increase in the XS1100 engine Dan's name kept popping up. He has spent extensive time trying many different things in taking the motor to the extreme and comparing many different options including the simplicity of wiseco big bore kits and standard head piston options with a dyno and was nice enough to explain a lot of what he learnt. He seems to have a good grasp on taking the engine to the extreme as well as what standard combinations work well for your desired want from the engine in street use.

In no specific order this is some of what he has to say.

The late head, 80-81 will give you about 5% more power from 5,000 rpm up vs a 78-79 head if you maintain the same compression however the combustion chambers in the early head are smaller/tighter because of the smaller valves and the piston domes of the 78-79 pistons are smaller to match this head. If you use the stock 78-79 piston in conjunction with a late head you will lose about a half point of compression which is worth about 2% of hp. The late head will flow about 10% more air than the early one however to properly utilize it you will need to reduce the chamber volumn by cutting it (.012 = .23 of compression) or going to an aftermarket piston. The late head not only has bigger valves but the valve bowls and ports are also bigger. If you insist on using the stock early pistons I would not mess with it. If you use the late pistons with the early heads you will gain about 1/2 point of compression because of the larger domes and this might be a low buck way to pick up a couple of percent over what you have. The early cams are designed on a 101 degree centerline and advancing them 4 degrees is probably not a good idea. The hot set up is the late head cut .012 and a set of Wiseco pistons which have a 6.6 cc dome and in this configeration will fetch an honest 9.5 to 1 static compression. Mention is made that a used head with over 40,000 miles on it will have valve guide wear not withstanding the fact the valve stems are worn and the exhaust valve head and seat is worn out. The factory doesn't sell these valves anymore but a few dealers still have them and Kibble /White will make them to order. If it were me and I had it apart, I would put a 1179 kit in it and a nice pristine big valve head with new valve springs and valve stem seals. You could port match the intake runner to the intake boot and lap the valves per the factory manual and you would have a sweet piece. Remember, early head, small chambers & small piston domes, late head, large chambers and large piston domes. Good luck. Dan

There are several piston manufactures that will build you a set of custom pistons.
All you have to do is send them a stock one so they can profile the dome or a head but the spare piston deal is easier. Both Ross and J&E are two companies that are out there that have good stuff and I believe J&E is associated with Wiseco and I might add that the latest Wiseco design was the ultimate deal because of the ring package and the way that the ring lands were designed.
I was under the impression that Wiseco still offered the 1179 kit but had discontinued the 1196 (74.5mm) kit but I could be wrong but no matter, Ross will make you a set for the same price that a set from Wiseco cost.

The design of the original stock pistons is light years behind what can be had today as far as piston material, rings and so forth goes and if you are going to go through all the time and effort to rebuild a classic bike like the XS why in the world would you want to use junk pistons.....beats me.

I sent my cylinder block to Advanced Sleeves in Ohio for special sleeves, boring and honing to match my pistons and you can find them on the internet.

This is not rocket science but good parts don't come cheap and God only knows what you will find on flea bay.

Quote:
Originally Posted by xs650man View Post
Thanks Dan
As I'm in NewZealand sending a sample piston half way round the world may be out of the question but the idea of getting some made has crossed my mind, there used to be a company here called Denco Engineering that made 500 cc single Speedway Bike motors, sort of like your Flat Track. I'm about to do some research to see if they're still around. The Wiseco 1179cc kit has popped up again on Ebay for $667.68 plus shipping to NZ ( ouch ! ) but at the moment that's my only option.

Mark

Hi Mark

If it were me I would call Wiseco and get the 1179 kit and be done with it.
The 1196 kit is no longer available except by special order which is more expensive. A lot of the stuff you find on e-bay is old stock as Wiseco updated the pistons for the XS around Y2K.I've bought a couple sets of Wiseco pistons for the XS over the years and the latest ones have different skirts, lands and ring design than the original ones had. Mention is also made that a lot of dealers still have the original design and probably don't know the difference themself which is why I would get them directly from Wiseco.....if you can. In a worst case scenario you can get Ross or J&E to build you a set,they ship all over the world.

Good luck.

Dan
Quote:
Originally Posted by tcoop View Post
Well I did the compression 150 across the board. this was with WOT and engine cold. That didn't seem to be any big increase. IIRC the last time I checked compression on this bike it was at 140 to 145.


As far as the centrifugal advance unit I'm going to hold off on that. The bike is running better than ever right now. I may look into it this winter.

I did set all the valves clearances to the loose side. she sounds like a well oiled sowing machine.

There are no clearence issues when using the early cams with the late pistons or when putting the early heads & cams on a 80-82 motor. You can safely set the valve lash on the early cams using the late pistons per stock specs but do keep an eye on the cam chain adjustment.

You can determine your running compression ratio by dividing the pumping compression by 14.7 (atmospheric pressure)-----hot battery, good starter with carbs fully open required. This number is not the same as the mechanical static compression ratio which is based on swept volumn.

Pumping compression has everything to do with the intake valve closing in that the quicker the intake valve closes the more pumping compression you will have with a given amount of static compression.

A smaller cam will pump more while a more radical cam will pump less all other factors being equal.

The late pistons have a dome volumn of 6 cc's and the early pistons are about half that. The Wiseco 74 mm piston for the XS measures 6.6 cc's.
Using the late head with the early pistons is a no, no for two reasons. One, you would have very little compression due to the loss in piston dome volumn and two, the valve reliefs in the early pistons will not provide sufficient clearence for the big valve late heads.

Mention is made that a point of static compression is worth about 4% more power untill you reach about 11 to 1 and then the gains begin to diminish.

The late head is worth about 5% more power than the early head all other factors being equal.

A set of late pistons with the early heads will fetch about 3% more power.

The ignition advance can be easily changed on the 78-79 and the 81 doesn't need to be changed because it's already at 40 degrees at WOT.
One can study the advance curves in the Yamaha shop manual and see for him/herself.

Gas isn't what it once was however 93 octane BP gas is pretty good stuff and works well even in motors with 200 pounds of pumping compression.

Some pump gas is better than others but it all goes bad in a hurry and it's all very corrosive because of the 10% added ethanol and of course ethanol leans out the motor slightly however E-85 gas should be avoided, period.

Horsepower is where you find it.

The grooves or depressions that the valve sits in were called flow grooves by Yamaha. These grooves were employed to unshroud the valves at very low lift and did. If you simply grind/remove the grooves you will increase the volum of the chamber and ruin the head as 1 cc of volum equals .23 of a point of compression and every quarter (.25) point of compression is worth 1% more power. You can remove the valve seats and weld all of this up and then put new seats back in but the heat of the welding weakens the structual intergity of the parent aluminum of the head unless it is re-heat treated which is very costly. On the intake side of the 80-82 head, you can machine the head for a larger seat and use 39 mm intake valves which gets rid of most of the groove. Any larger valve than this and you will have valve interference problems and these 39 mm valves will only work on a 72.5 mm or larger bore. The head of the Eleven is partially hemispherical in shape as it has a north-south valve arrangement but is actually polyspheric in shape and employs 6 individual cuts. They cut spherical-section pockets for the valves and an overall spherical-section cut over the bore area (squinch-quench bands), flow grooves around the valve seats and machined a final relief where the spark plug nose enters the chamber. You will also notice that the intake ports curve as they enter the head and not straight on as in a true hemi head and they did this to create swirl. If you have access to a flow bench, you can clay up some of these grooves/crevices and the results will surprise you. If you close up the grooves in a stock head you lose flow and if you machine away the grooves you gain nothing but you lose compression. I could go on and on about this subject but basically I recommend you leave the grooves around the seat as they came from Yamaha. I am attaching a picture of a state of the art two valve motorcycle race head and if you look closely you will not see any flow grooves but that's another story.

The intake ports see wet flow and the exhaust see dry and so the intake ports should have a finish that is course, something on the order of 400 grit and the exhaust should be as slick as possible. The most important part of the port is the bowl just below the valve and the short side radius. The intake port measures about 1.35 inches at the opening and the intake valve on the late head measures 1.5 inches and the port should be funnel shaped and the guide which is huge in stock form blended and shaped favoring the entry and floor of the port and the two left ports enter the chamber differently than the two right ports. The shape is the most important and the port can easily be ruined if it's not correct and it's velocity that you are after not maximum size and flow. The port volume should be based on the displacement of the cylinder and the rpm in which the motor will be working which is not unlike camshaft timing in that the bigger the motor the bigger the port volume needs to be. The age old mod of blending the intake boot to the head (port matching) and removing the casting flash with a porting tool (400 grit tootsie roll) is all the novice porter should attempt. The chambers are slick enough to begin with and should be left alone because it's easy to take a couple cc's out of them and a couple cc's just lost you a half point of compression. A fine stainless steel rotary wire brush turned at slow speed will slick them up without removing any material. Mention is made that the late head in stock form will flow about 10% more than a stock early head and because of the larger valve in the late head the funnel shape can be more pronounced than that of the early head because the size of the entry is the same for both. The late head is much better in stock form from about .200 valve lift up than the early one and in modified form the disparity is even greater. The early head is fine for a heavy touring bike but if it's top end horsepower you are after it's not the plan. The ultimate torquer using stock parts for a Wing Ding type XS would be the early head, late pistons and late cams. If you were building a race head and using custom pistons you would do major work on the chambers but if you are using stock pistons or off the shelf Wiseco's you are fighting for compression and so leave the chambers alone. You can cut the head .016 without having to worry about cam chain problems or having to advance the cams and pick up .38 of a point of compression. You can paint the piston domes with VHT Hi Temp header paint and cook them in an oven at 300 degrees for one hour which cures and hardens the paint so it won't come off but all this really does is speed up the carbon build up on the piston dome, ditto for glass beading the piston tops and I've tried all this stuff on race car motors on the dyno and found nothing power wise. Wiseco, Venolia, J&E and others offer coating services for some of their pistons but any of this skirt coating stuff is tricky business and can do more harm than good if not applied properly. The latest generation of Wiseco pistons for our XS bikes are plenty trick and all they need is a properly finished bore to work and I might add that a properly finished bore cannot be obtained with a hand held hone especially a dry hone. My cylinders were bored and honed by Advanced Sleeves in Mentor Ohio on a Sunnen CK-10 machine and they came out perfect. See picture,

 The exhaust port of a cylinder head should flow 70%-80% of what the intake port does and once it get's much over this you have too much scavenging effect. Contrary to what a lot of people think, the exhaust side of these two valve motors including the Kawasaki and Susuki's of the same era have very good exhaust flow compared to the intake side because the intake port makes a somewhat tortuous series of turns when the mixture leaves the carb throttle body on it's way to the valve. This is why a lot of guys when going to aftermarket cams change only the intake cam and leave the exhaust cam stock and achieve such good results. The biggest hinderance to air flow in the exhaust port is the size and shape of the guide boss which is huge and the valve bowl itself and not the gasket surface area where it meets the pipe and it's the shape not the size that is important. Unless you know what you are doing and have access to a flow bench to check your work you should confine your port work to removing the casting flash from the ports and a good valve job and matching the intake boots to the intake ports by blending the entry. Attached is a picture of my head's exhaust port which was ported and flowed by Nigel Patrick racing.

{Talking about a head another poster has shown}

This head was not prepared per the instructions but was turned into a full hemispherical chamber and subsquently ruined.
The Yamaha two valve polyspherical head was state of the art in the late seventies and early eighties and although it needed two plugs per cylinder it was pretty efficient, much more so than a true Hemi chamber.

A good two valve head needs squish/quench bands to create turbulance which makes for a more rapid burn but too make a long story short, a Hemi combustion chamber is and has been obsolete for sometime even though Chrysler Corporation clings to it tighter than Nancy Pelosi does to Obamacare.

Actually the current Mopar Hemi isn't a true Hemi either even though the production version uses a north/south valve arrangement with two plugs per cylinder. The Mopar Pro/Stock car stuff is actually a twisted wedge with the plugs going through the top of the valve cover so asHemi Heads to enable the Mopar guys to sleep at night believing that their beloved Hemi is still around but the truth is it's only still popular in blown fuel burning applications i.e. top fuel and funny car drag racing..........even Harley Davidsons "OMG" don't use true Hemi's any more........ Whew, I'm outta here!

A Wiseco 1179 big bore kit is worth over 10% more power all other factors equal. The latest Wiseco forgings have anti detonation groves and thinner rings (less ring drag) than the stock pistons and have a 6.6 cc dome and of course they are lighter than the stock slugs.

It's also worth mentioning that the earlier Wiseco pistons for the XS were a different design and didn't have the anti detonation groves, trick rings and some other features the current pieces have and too make a long story short, the latest Wiseco pieces are state of the art but they aren't cheap and it's up to the owner of the bike as to what he/she want's.

A head clean up with a valve job, new springs and OEM valve stem seals and the head is good to go.
You will also need to have the block bored and honed (properly) by a shop that can finish the bores with the finish prescribed by Wiseco otherwise the rings will take forever to seat properly if ever.
Again, if you are going to spend the money on trick pistons make darn sure you don't let some idiot dry hone your block.

I had Advenced Sleeves in Ohio prepare my blocks but there are other shops who are equally competent.

A set of early cams and the late head with the above parts will fetch 85 conservetive rear wheel hp with the stock carbs, Dyno Jet kit, stock air box and stock or similiar type mufflers.

If needed, rod and main bearings can be found if you really want them but you might have to polish the main bearing journals of the crank to match up the correct clearences with the available bearings.

Of course you can buy a junk motor from a junk yard and as long as it doesn't whine, jump out of gear, smoke or catch on fire you are good to go as long as you are not in a hurry.

Happy motoring!

The cam timing (duration) for these motorcycles are as follows.

78-79 models
Intake duration- 247 degrees @ .040 lift & .345 valve lift (event angle 102 degrees)
Exhaust duration- 247 degrees @ .040 lift & .327 valve lift

80-82 models

Intake duration- 235 degrees @ .040 lift & .345 valve lift (event angle 105 degrees)
Exhaust duration- 235 degrees @ .040 lift & .0345 valve lift

The early cams are worth 3-4 horsepower more than the late cams.


{talking about drilling bucket cam followers}
You certainly have an eye for detail my friend because this little trick lightens the valve train by an amount similiar to that typically seen when using titanium retainers from Kibble-White and the weight reduction from drilled buckets is free.

More to follow