Port/Polish XRL Head

I am considering porting my head when i do a hi comp piston. Ive read alot on the subject and feel confident in doing so now. I rebuilt my old 22R and did this on it with mild improvements. Although now after researching, i found i only half finished that port job!

My question is, has any one used XR'S Only for this service? If so, what was the cost? What was the improvement?

Now i realize a couple key points are,

1: Smoothing the short side radius.

2: keeping a semi rough wall surface(INT.), and mirror finish(EXH.).

3: Dont port match the EXH. port.

4: Smoothing the guide boss.

How do i add "Swirl" to this head? Any other thoughts?

There's one thing that you can still do to compliment that head porting.A lot of guys here recommend grinding off the excess weld from the headers ports too smooth the flow.Don't know if that's what you're reffering to in #3.

There's one thing that you can still do to compliment that head porting.A lot of guys here recommend grinding off the excess weld from the headers ports too smooth the flow.Don't know if that's what you're reffering to in #3.

yes ive done that mod. what im referring to is you want to keep the smaller opening on the head side of the exh. port. if you had equal opening sizes(exh port matched to the header) then exhaust gas IN the exhaust header could easily re-enter the combustion chamber, creating a EGR situation. not good for the next incoming intake charge. it would actually dilute the intake charge for the next combustion cycle.

Check these guys out. They just did some work for me and the price was great and the work was perfect. I know you will have to ship it a little further but I think the price will make it worth while.

http://www.mototricks.com/

Check these guys out. They just did some work for me and the price was great and the work was perfect. I know you will have to ship it a little further but I think the price will make it worth while.

http://www.mototricks.com/

did you have porting done on your XRL? What power range did you have them port for?

How do i add "Swirl" to this head? Any other thoughts?

martinfan,

Its worth remembering that you will get a swirl effect form the radial valve arrangement of the RFVC so you almost have that built into the head from the word go. Myself and the guy who ground my race cam pondered having phased inlet valve opening (ie one inlet valve opens before the other by grinding the cam with an offset) but he thought it wouldnt be worthwhile on the Honda head. This idea, he used to great effect on Yamaha R1 race motors for example as it gives better swirl...more midrange and top end!

From what Ive read/bene told about a 1mm step out form the exh port into the header is ideal, plus more on the bottom of the port if you have it welded and D shape the exit.

It may be worth you grinding the inlet valve guide right down if you want more flow.

Try and port the intake so that the gas flow uses al the head of the valve, what I mean is that dont angle the gas flow across the head of the valve but make sure it meets it as straight as possible.

Other than that - dont go too mad with the porting. The head flows well as std based on advice Ive had from guys who raced XBR/XR motors in their heyday.

HTH

In this tread i Fullraceporting a xr650 head to the limit of what is possible.

I have bin doing this in 17 years now so this is my newest porting skol.

If you doing this JB weld thing i am.... You "dont" lose some power anywhere in the powerband! just moooore!!

The Porting on this head is complite in a few days...I now the swedis can be hard to understand,He,He Just lok at the pictures .... Dynorun on the toppjobb is coming soon... I hoping for 7-10%

Follow the red Head Just! Side 30-

http://www.sporthoj.com/forum/showthread.php?t=171292&page=30

In this tread i Fullraceporting a xr650 head to the limit of what is possible.

I have bin doing this in 17 years now so this is my newest porting skol.

If you doing this JB weld thing i am.... You "dont" lose some power anywhere in the powerband! just moooore!!

The Porting on this head is complite in a few days...I now the swedis can be hard to understand,He,He Just lok at the pictures .... Dynorun on the toppjobb is coming soon... I hoping for 7-10%

Follow the red Head Just! Side 30-

http://www.sporthoj.com/forum/showthread.php?t=171292&page=30

WOW! That's some serious porting there! I dont want to go that extreme. That's an R head also.

Crmc33, thank you for the info. What is this i hear about using epoxy? Is that done instead of welding?

Also, how do you differentiate between Top end porting and bottom-mid range porting?

Is the old intake ports welded solid and a new straighter intake port done more for mid-top?

That is a long story.........The groundteory in my portings you can find here http://www.mototuneusa.com/think_fast.htm

I have test his teory in some 1-cylinder smokers and i am not so inpresst wiht the 65% teory!! in high reving 4cyll it prob is god? Just not!! take it so far in big 1-cyl. I Grind the rof and streated the ports and then Jb epoxy the lost Aluminium powder from the grinding. And ther you hav it no lost gasflowspeed and god lowend/mid/topp power...I can speak 2 days in this Theory .. We can take little more when i have fix a lexicon in inglirsdggjhgjh ..He,he

That is a long story.........The groundteory in my portings you can find here http://www.mototuneusa.com/think_fast.htm

I have test his teory in some 1-cylinder smokers and i am not so inpresst wiht the 65% teory!! in high reving 4cyll it prob is god? Just not!! take it so far in big 1-cyl. I Grind the rof and streated the ports and then Jb epoxy the lost Aluminium powder from the grinding. And ther you hav it no lost gasflowspeed and god lowend/mid/topp power...I can speak 2 days in this Theory .. We can take little more when i have fix a lexicon in inglirsdggjhgjh ..He,he

OK, good. I appreciate your help boost3. I have a little trouble understanding, you grind the roof, and streated the ports? I understand the roof part... I still dont understand where JB weld is applied?

Guess i will read that site you gave me.

Thanks. Rich.

did you have porting done on your XRL? What power range did you have them port for?

No, I just had them do my cylinder for a new piston.

OK, good. I appreciate your help boost3. I have a little trouble understanding, you grind the roof, and streated the ports? I understand the roof part... I still dont understand where JB weld is applied?

Guess i will read that site you gave me.

Thanks. Rich.

i wouldnt apply JB weld to anything myself LOL Heck NO. Why not get an extra head from ebay and try it yourself? I wanna do this for the womans 400ex but just havent yet. when i do im gonna just start by smoothing out a bit and see what gains that has. Read some pretty indepth articles referring to porting and its a bid science for sure. All the talk about flow and how bad flowing heads can actually have the fuel/air mixture collect on the intake runners and form drips and just run down the runners. Very involved part of an engine for sure. Most the reading was about V8 engines but the principal is the same for all engines.

You can weld/epoxy the intake port floor to raise it and grind the top of the intake tract till it breaks thru into the cam area. Then weld/epoxy the hole up.

Devcon make some good alumium epoxy that you can use to get a better shape. It needs a good key onto the intake tract, best to have a nice rough clean surface for it to stick, and even better if you can drill and pin the intake before putting on the epoxy. VERY inlvolved tho. Welding is better in the long term!

There shouldnt be a need to weld the port up completely but it would help.

utimately the skys the limit for porting but tends to be a process of diminishing returns. If I were you martinfan I would concentrate on;

-match the valve seats to valve port castings

-smooth the inlet valve guide down a little

-knife edge the splitter btwn the intake ports

-polish exh port and possible D shape (f you know/are a good welder)

- recut the valve seats

-grind valve heads to give more flow (additional angle cut on the gas washed surface of the head reduces restriction)

-smooth out casting marks on the comb. chamber (sharp corners where the valve seats start and around the s/plug for example)

You can do a lot more but will take a lot of time and/or money with not a great deal of extra power.

I know you wont want to take the E-starter off, but to be honest, this makes a huge difference to response on the XRL engine. more noticeable than porting mods. Would be wild on the loose stuff tho!! You can imagine how my 675 picks up with no starter or gen rotor! picks up like a KTM! I love it.

Anyway, I digress, I dont think youd be disaponited if you stuck loosely to what I said above for the porting.

HTH

Thanks a bunch for your knowledge/advise on this subject! I will do your suggestions to my head when i get it off. I will probably bug you some more when it comes time!

Any suggestions on porting tools i will need?

just a good mix of small and large rotary burrs, suitable drill (slim cable driven one I use) and the small emery paper bobbins are usefull for finishing. Some hand rifle files are useful (but slow) for careful work such as around valve seats and knife edging the intake web.

Hey guys, Use a set of old valves when you grind the conbustion chamber. so you dont jackup the valve seats.The more heads you do the better your set of old valves become for grinding the combustion chamber. For a die grinder I like to use a air diegrinder that has the long neck. also if you use sand paper rolls get a mandrel that is about 4 to 5 inches long. You can use your other hand to stablize the mandrel for more control. But I like to start out with a flat tipped carbide bit half inch in diameter and about an inch cutting length. looks like a cylinder. Use bees wax to keep the bit from filling up. dychem the valve seats and lap in the valves you are going to use, LIGHTLY. Or until you get an even mark all around the seat. that way you can sneak up on the seat its self. I have use of a valve seat cutting machine so I like to take the valve guides out to port the intake. But you guys can do it the hard way. If you pound the valve guides out you have to re cut the seat. On the valve guide I like to take about .100 of an inch off and put a nice radius surrounding the tip.

Dychem, is that the blue spray used to coat a part to make sure you get and even machine job on it? Where is it avail.?

Thanks for all the tips.

Stepho, you dont use a "d" shaped exhaust port? I've also read some about changing the intake port shape by welding and raising. I'm not sure i want to go that far. Your thoughts? No need to shave the exh. guide boss?

martinfan30, how much of a gain do you think porting the head will net you?

martinfan30, how much of a gain do you think porting the head will net you?

I hate to guess and be wrong later, but IF i dont make any mistakes....

With my cam, piston, etc., i'm hoping to see and addtl' 3-5 HP. I think that will be easily attainable with the porting plans i'm making.

On top of that, i really enjoy doing stuff like this!

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