Head work for a 750 job

RainLand · Posted: April 11, 2006, 11:02 am Post subject: Head work for a 750 job

I'm putting in a set of 750 barrels on a '78 motor.
I'm thinking of using a MikesXS cam and valve set, with nothing else
in particular done to the head. Any other chores ( other than new guides ) I should do while I'm in there?

Steve · Posted: April 24, 2006, 2:57 pm Post subject: Re: Head work for a 750 job

Check this post out. Engine Rebuild and Big Bore Kit

RainLand · Posted: May 2, 2006, 12:11 pm Post subject: Re: Head work for a 750 job

Thanks - very interesting.
I've got someplace to start, at least.

royfisk · Posted: August 26, 2006, 7:34 pm Post subject: Re: Head work for a 750 job

Do the heads dollar for dollar it will get you more bang for the buck

royfisk · Posted: August 26, 2006, 7:36 pm Post subject: Re: Head work for a 750 job

Why would you try to force another 100cc through already restricted ports.

chapmanmd · Posted: August 27, 2006, 12:50 am Post subject: Re: Head work for a 750 job

I can handle routine maintenance, some fabrication, building my engines, etc. I am NOT a machinist. Could you recommend someone that would be willing to port 650 heads? I am in the middle of a 750 upgrade using 34mm Mikuni's. Shell #1 cam, etc.

Any place to start would be greatly appreciated.

Thanks.

royfisk · Posted: August 27, 2006, 6:55 am Post subject: Re: Head work for a 750 job

Sure try xsjack, dont know if he could right now or not but Ive been talking to him and he really knows his stuff about these bikes. Hes going to do mine.

royfisk · Posted: August 27, 2006, 6:58 am Post subject: Re: Head work for a 750 job

Mark your carb and cam set up sound like a real good start for good streetable performance, combined with the big bore and heads wow sounds real good.

chapmanmd · Posted: August 27, 2006, 6:38 pm Post subject: Re: Head work for a 750 job

Thanks Roy. Having just recently joined the ranks of the XS from the Brit Bike world (Norton and Triumph), I can say that Im having a heck of alot more fun with the XS. I'm just hoping that I can bring over some of the knowledge and tricks I have learned from the "other" twins. I know that I have alot to learn, just like everyone else. I know what works on a dirt track after close to 40 years of racing and wrenching, but still need LOTS of advice for streetable, reliable performance. I'm hoping XSJack may chime in here or IM me. I really want to get these heads done before winter and enjoy at least a couple rides with a stronger motor. Thankfully, the stocker with the 34's and exhaust is still running great. Now, where did that trackmaster chassis go... Very Happy

Thanks again for the tip, Roy

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Mark.......... I had a response but lost it through submitting and I'm not happy! I'll get back tomorrow.............Jack

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Mark...........I have tried on several occasions today to post a response but evertime it gets lost'don't ask me how it just does, I'll pm you a # to call for references to my workmanship and if your interested then contact me at xsjackheads @ yahoo.com................Jack

trailguide46 · New Member Joined: Jul 10, 2007 Posts: 3

If you want the ultimate in 650 work, go to "thomasracingservice.com".
He is top notch in 650 work, and one of the best in nitro hillclimbing. He will make it run...

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Just about anybody can port the XS head but knowing the areas to address to achieve good results is the the trick and not all Xs heads are equal in regards of having sufficient material to work with,so you either searh for a approriate head or work with what you have,it's that simple. When it come to top notch guru's porting the XS heads,Bob Bertant,Creg Hanson at Hanson Racing and Michael Morse come to mind.

ost power gains on the XS will be in the exhaust port and port volume and how the the inside turn is work will dictate the flow percentages but flow isn't eveything cuz in the end your motor respnose tells the true story wether the porting was on key to the engine application.

A decent ported XS head will show a gain of 15 to 20% on the intake,depending on the type valve used with stock head dimensions and the exhaust should show a gain of 25% or slightly more and with these flow percentage gains you should expect a 88% exhaust flow percentage of the intake flow,doesn't mean this is right for your application,just goes to show the XS head does have respectable potential,what ever the application...........................Jack

TripleKing · Posted: July 19, 2007, 5:41 pm Post subject: Re: Head work for a 750 job

Try Extrudehone for porting. You will never pick up a dremel again or pay anybody else to for that matter. unbeatable results. I'm pretty good with a Dremel but no human hand can duplicate the process they use.
Check out Gethoned.com
I can get really good pricing(much less than retail) as I use them Alot if anyone is interested.

tracker79 · Posted: July 19, 2007, 6:56 pm Post subject: Re: Head work for a 750 job

Correct me if i am wrong, but doesnt the extrudehone process just follow and hone the existing shape of the port?

TripleKing · Posted: July 20, 2007, 10:34 pm Post subject: Re: Head work for a 750 job

Extrudehone can do just or a whole lot more depending on what you want. the media comes in all differeent cocsistencioes and grits depnding on how much you want your ports hogged out. using a more fluid compound and less severe grit they can follow the original contours and relieve small restricions(casting flash for instance) while smoothing and optimizing flow along the way. on the other end with a really stiff media and harsh grit you can punch out your ports and minimize or even remove larger restrictions.
the media is going from point A to point B and depend ing on the grit, consitency and flow speed, it can be nice and flow like a lazy river around all the stock mistakes, or go class 5 and wipe out every hindrance between points A and B plus anywhere in between. All controlled by the computer and perfectly repeatable. When You get heads back they flow exactly the same from port to port whehter its a 2,4, or 6 cylinder head. they flow test test your heads not only before and after the process but also all during the work in different phases. i give them my cam specs and carb flow #'s and they optimize the port work to match the cam profile. Why go hog wil and bore out the ports for a basic street performance grind? they can work it to any cam or desired flow specs you want.
It really is the best thing since sliced bread. And for around $250 to $300 bucks, unless you are doing it yourself, nobody worth their salt works that cheap on heads(that I have found)
my dremel hasn't touched a head for years.

Shannon60 · Posted: November 12, 2007, 4:08 pm Post subject: Re: Head work for a 750 job

Hello all I am new to the site I have been racing the 650's for a number of years both dirt track and ice racing here in wisconsin I also have about 15 years building racing engines from go-karts to outlaw sprint cars my specialty is cylinder heads and porting. I am setting up shop at my home near Appleton, Wisconsin and i would graciously welcome any opportunity to provide my services, if you would have any questions please feel free to contact me. I am feeling out the ideas of making this a full time operation and would also appreciate any input that you may have.
Thank You

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Seems like everyone wants to tap this market,you're certainly not gonna get rich. Are you handy with a tig welder or mig? Cuz I have atleast seven XS heads that require some filling in certain critcal areas to increase port velocity. This is more of a passion reflecting perfection,rather than concerns of how much money has been lost...........Good Luck on your adventure............................Jack

royfisk · Posted: November 12, 2007, 5:14 pm Post subject: Re: Head work for a 750 job

Hi Jack
never did hear from you on the heads you asked about. I have been to busy to go forward with anything yet. Are you looking for someone to weld Jack? Is that what I am reading? I thought you did your own work. Anyhow if so give Stan Lynde from Lynde motorsports a call, Hes done some pretty remarkable heliarch work for me in the past and specialises with motorcycle engine cases, as well as heads of the american made variaty. His phone number is 1-802-254-8554 .

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Hey Roy.............Sorry I never got back with ya on the head as Griz gave a 71 for my experimental long rod motor using a quench chamber head,in fact I need to box it back up for re-flowing. The#s for the quench on the intakes where stable with no loses,even with shrouding the valves,forgot to port the exhaust but they gained 10% not ported,so I went back in there Wink

All welding is done in house just mearly pointed out what's need atleast in my opinion from what I've learned from porting the XS head............Jack

royfisk · Posted: November 12, 2007, 7:40 pm Post subject: Re: Head work for a 750 job

Jack is there particular years of heads better siuited for rework? Hate to sell a head that is better suited for rework then one that isnt. I have xs-1 heads xs-2 heads, tx-650 heads and several specials heads. I have heard rummoured that the early heads had more to work with but as I said rummoured.

Shannon60 · Posted: November 13, 2007, 1:09 am Post subject: Re: Head work for a 750 job

Hi Jack, yeah I,ve welded these heads before particularly in the short turn area but it is only helpful when you raise the roof then you gain the big low lift numbers

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Hey Shannon............... forgot to welcome you aboard Wink

but anyway,I "ve tried several attempts to raise the floor and roof on the intakes and all attempts to boost low #s were a failure,so I just basically work the intake ports to reduce resistance and to convert them to my semi high velocity port. My best #s to date for the intakes are 54 cfms at 100 and peak at 104 at 480,exhaust 100 44 cfms and 480 91 cfms, can pick up the intakes #s an additional 10% with some mods on the intakes but that'll depend on what's available in the S/T.

When ya get time shoot me a PM on what you'd charge to open the seats for 2mm oversized valves..................Jack

xsjohn · Posted: November 14, 2007, 8:33 pm Post subject: Re: Head work for a 750 job

I have never ported mine......guess years ago I did plenty of 2-strokes.....totally different.........

Question....after reading all the above posts........on a stock 80 engine with nicely richened carbs with stock or quiet mufflers....and without having to rev it to death......would polishing the intakes and working the exhausts be of any benefit for mid revs say 2500 to 4500 or so........I do lots of expressway crusing as say 65 at 3700rpm and always looking for something new to play with.........hope these quesions aren't to dumb....

Posted this pic below I found for those like me who barely even understand the terminology.........

John

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