Anybody out there milling the heads on their RD350's

[Fastash]

Just wondering how much material you are removing for street running pump premium gas ? .10 .20 .30 etc...

[Dvsrd]

I guess that depends......Just removing some material from the gasket surface may not be the best way. I suggest you contact Chuck "Supertune" for this info, or even better, have him machine your heads.

I am about to modify some RD250D heads for my 350A, using my lathe instead of a milling machine. Since the RD heads have a central spark plug, that is the most used method.

[Hardy]

I do recall Chuck posting on the old forum the what was required to machine a 350 and 400 head in a lathe to gain the correct squish bands, unfortunately I didn't record this info.

[RD7]

I saved a lot of info for my own use before the site went down. Apologies to the original posters no plagiarism  intended as I say it was for my own use.
Re: rd350 cykinder head machining

i have my 3rd rd. it is a 1973 rd350 stock engine. 5k original miles. it's been a while since i milled the the heads on my other rd. i can't remember how many thousands to take off for medium comp ratio.
chime in,
thanks,
mark

Re: rd350 cykinder head machining
« Reply #1 on: May 24, 2013, 12:52:33 PM »
Basically, you want your squish to be between .030 and .035.

Mill whatever it takes to get to that figure.

If you want to raise compression more than that will do for you (after cc'ing the heads and performing calcs of course, you'll have to mill more and then have somebody do your chambers for you and get you a 15 degree squish angle.

Simple milling will get your squish better and raise compression a tad - both good for your engine.

« Reply #3 on: May 24, 2013, 08:01:17 PM »
Thanks Drew for the compliments!
The main issue with RD350's is you can't get the squish under .045 without milling the cylinders.
RD350's come with horrible huge tolerance about .075-.085.
The easy way out is mill tops of cylinders and convert to the RD400 headgaskets as I'm doing for Drew's RD350 cylinders, then mill the heads to get to the correct squish.
The 2 main reasons this works better is:
1. The RD400 headgasket is .020 thick and the stock RD350 ring headgasket is .040, twice the thickness. This alone gets you .020 of the squish problem.
2. The RD350 ring headgaskets are prone to leakage due to being narrow and recessed and causes the head to warp under torquing. RD400 headgaskets are much wider and cover all of the deck surface instead of just partial sealing area around the bore and this prevents head warp that causes leakage.
Your second choice is to deck and O-ring the cylinder this then gets you another .020 over the RD400 headgasket and a full .040 over the stock RD350 ring headgasket.
Then mill heads to adjust final squish and compression ratio by CC' ing the head chambers with a buret.
If you look here you will see some of my machining pictures of a RD350 build doing this.
http://imageevent.com/supertune/rd350enginebuildpics

Chuck
Team Scream Racing

RD250 with RD350 top end questions..
« on: November 25, 2017, 09:01:41 PM »
I'm looking to doing a few 'might as wells' when I convert my 250 to a 350. I just wanted to confirm a couple things and ask a couple questions.

-It seems the consensus is it's a good idea to mill the top of the cylinders flat to use a RD400 gasket. I was planning on doing that unless convinced otherwise.
-It is worth it to mill the bottom of the cylinders to bump the compression and quench more (in addition to changing port timing a tad)? If so, how far do people go?

-I was planning on using detabbed Pro-X Banshee pistons unless convinced otherwise.

-Is it really worth the trouble to clean up the ports? I'm not sure but it looks like someone may have cleaned up the intake on mine. I wasn't going to try any real porting myself..
-I have thought about sending the cylinders out to have them done. Any recommendations for a company to send them to?

This is a for a street bike but I truly don't mind a high and tight powerband.

Any other recommendations are welcome.

Thanks in advance and sorry for pounding a dead horse.

Reply #1 on: November 25, 2017, 10:13:55 PM »
I would send your heads to SCR and have him mill them and cut them for o-rings and forget about using RD400 gaskets.

Yes it helps to clean up the ports if you know what you are doing and match them. If not leave them alone.

If you want to have them ported by a pro there are lots of places you can send them. Chuck "Supertune" Quenzler here on the forum, Ed Erlenbach, also here on the forum, SCR, Spec II. There are a few others but they are some of the best in the business.

A "high and tight" powerband may seem like fun but it is a PITA on the street. You will like it a lot more if you build it to have a more broad and lower to mid powerband. That's just my 2 cents though.

Reply #2 on: November 25, 2017, 10:33:26 PM »
Well, you just stepped into my wheelhouse!
So doing the RD400 headgasket conversion on the RD350 is one I do a lot. Mill the cylinders to 4.030 and lap the deck face on the 350 heads and your ready to go. Make sure you install the 400 headgaskets upside down or you need to grind off the pips on the 400 gasket if you try to install with pips down.
No need to mill the bottom of the cylinders, just by milling the RD350 cylinders and going to the 400 gasket will gain you plenty of compression for today's pump fuel.
No problem using the de-tabbed Pro-X pistons!
Cleaning up the ports are a good thing as the 350's are horrible compared the the 400's. I offer a update porting for $125 that works well for todays pump gas setups and takes care of the crappy ports from the factory.

This is What I do, only a few of us are still at porting cylinders, Gary at SpecII, Ron Black at RB design,  Scott at SCR, Ed at ERLENBACH RACING and myself are the major hitters on the RD specific engines...

Chuck 'SUPERTUNE' Quenzler III

[RD7]

and more
Re: Bore and piston pics of cylinders after run in
« Reply #30 on: September 16, 2017, 11:40:58 PM »
Ok, I got back online today!! GOODBY IRMA...
I can see your pics really well on my 27" monitor.
I do agree with slinger,mk and t jim. I think the bore looks really bad for the time that's on it.
My RD400 F-500 race cylinders w/2 full race seasons on them look way better. (And a AHRMA national #1 plate)
Yes, I do use the Wisecos and yes they collapse and need to be changed out every 4 race weekends, like in a AHRMA race weekend, 4-5 track outings on friday practice, and 2 classes on Saturday and 2 on Sunday. I have the pistons skirt coated and ceramic top coated to insure I protect the cylinder bores and have reliable track performance.
Just from what I see those pistons are way too short on the skirts and rock way too much. The measurements you posted for sizing are way excessive. 
My advice...Deck the tops of the cylinder in a squaring jig, then use 400 headgaskets, bore to 65mm to ensure a perfect straight and round bore to do your .002 thousandths for finish hone.
For a road racer, vertex for cast and wiseco or wossner for forged.
I would use forged pistons, no risk of piston breakage from a missed gear.
After boring these RD for over 30 years I have found that there's not that many shops that compete with high quality bore work. Bill @Bore tech is one...
I use Sunnen Honing equipment, they are the pioneers in honing technology and tooling IMO.
I use special stones that are made to hone industrial keyway bores, they have double stone shoe and double hone guide on each mandrel. This ensures a very precision finish bore.

Chuck 'SUPERTUNE' Quenzler III


Reply #33 on: September 17, 2017, 07:00:45 AM »
Chuck,
   Those bores look very nice! You do good work and it shows.
My advice...Deck the tops of the cylinder in a squaring jig, then use 400 headgaskets, bore to 65mm to ensure a perfect straight and round bore to do your .002 thousandths for finish hone.
I have seen where people have decked the tops of the cylinders, and used RD400 single head gaskets, and they went to that design for a reason... the RD400 head gasket gave superior sealing, and then the O-ring mods were for the very high compression race motors.
Yes, I do use the Wisecos and yes they collapse and need to be changed out every 4 race weekends, like in a AHRMA race weekend, 4-5 track outings on friday practice, and 2 classes on Saturday and 2 on Sunday. I have the pistons skirt coated and ceramic top coated to insure I protect the cylinder bores and have reliable track performance.
When you change out your pistons, do you have to bore the cylinder, or do anything to it for ring seating after the 4 race weekends? Also, I have a set of cast pistons (I am thinking they are cast for the price) that are ceramic coated, with a coating on the skirts that wears into the metal, instead of wearing off the metal. I have thrashed on them pretty good, and they seem to have held up well. As you know, occasional missed shifts aren't uncommon on these old motors lol, especially on the race track...
I use Sunnen Honing equipment, they are the pioneers in honing technology and tooling IMO.
The family at PR Racing up here in Toledo have a Sunnen machine, they have been boring and porting cylinders for 30 years, and their dirt bike engines have won numerous races. They have (what they said) a $10,000 boring bar, and that allows them to get the precision you are talking about. The only problem is, they don't do a lot of machine work any more, as they are into eBay and their website sales. I wish Jeff would take the time to do my cylinders, but that probably isn't going to happen, unless I get them to him on a good day lol... then wait 3 months for him to complete them.

Since I have my motor apart here's some pics of the Wiseco pistons that have about 5 hours track time and 1500 hooligan street miles. They started at .003 clearance and have about .005 now. They seem to have done ok by me. I was careful to allow warm up before full throttle. You can still see the "ribs" on the skirts all the way down. There was a touch of wear in the cylinder below the intake port. I think 20:1 fuel mix helps. I may try the Wossners next.
MK, those pistons look good. I have a question about the hole above the intake ports, is that stock from WIseco, and if so, is that for the boost port? My pistons have never had this oval hole, and is it necessary? Also, those appear to be RD400 pistons, or are they for the Banshee, or RZ350?

I need a reliable motor, as the endurance racing is coming back to Nelson Ledges next year, and I would like to run the RD350 in the 3 hour endurance race. So, I would sacrifice HP for reliability, and as Scott Clough's original RD350 back in the '70's had over 4,000 race miles on it, and still held up with 1970's era pistons, it should be possible to do so now, on an amateur racer budget. (Read not a lot of bucks here lol). I do enjoy competition, and I am not into the bling, just want a good, reliable motor, with good handling chassis., which I do have a good handling bike right now. I appreciate all the knowledge and experience each of you have, and I know that we are all here to help and encourage each other in our passion. Thanks you all, and God bless you all!
Charlie

Reply #37 on: September 17, 2017, 08:42:44 AM »
Charlie,

I have seen where people have decked the tops of the cylinders, and used RD400 single head gaskets, and they went to that design for a reason... the RD400 head gasket gave superior sealing, and then the O-ring mods were for the very high compression race motors.

On a budget builds just do the 400 gasket, in most cases you don't have to re-machine the heads when not going all the way to o-ringing mods.
Here's pics of me machining RD cylinders in my squaring jig and then cutting the o-ring groove.
Quote from: charlie h. on September 17, 2017, 09:07:57 AM
Chuck,
   I am wondering if even forged pistons would have withstood the full power shift from 3rd gear to 2nd lol... I figure you were turning at least 9500rpm when you shift, and then thinking you were in 4th, added about 2500rpm's to the 9500, and man, you got at least 12k on the piston. At least the Pro X piston carnage spelled it's trademark on top of the piston, as the parts spell out an 'X' lol.
The machining looks nice! You are a qualified machinist, I see. Well, if I just use the RD400 head gasket, can I use it with the stock tops of the cylinders?
Charlie
No, you machine the tops of the cylinder to remove the step to be able to use the flat 400 gasket.
My # on deck height is 4.030 on RD350's and 4.380 on the 400's.
Another benefit is able to torque up to 21 ft-lbs on the headbolt studs, this prevents pretty much any blown headgasket failures, + adds reliability.   
« Last Edit: September 17, 2017, 09:19:19 AM by SUPERTUNE1 »
Logged
Racegas + Lots of oil = HORSEPOWER
2 time Daytona AHRMA Formula-500 winner '06
'78 RD400E
TEAM SCREAM RACING
RD machine work, boring, porting, cranks and engine building.
New email: cqsupertune@tampabay.rr.com

one for the machinists..
« on: October 27, 2016, 04:02:52 PM »
both pro and tinkerers alike. I have 2 questions:  oh, first off you should probably know that i'm kind of a novice on the lathe so don't roll your eyes too hard if you can help it.   

how to you fixture your heads? assuming the spark plug hole is concentric with the chamber and parallel with the sealing surface, do you just thread a mandrel m14x1.25 and stick it in a 3 jaw? or make a more involved fixture mounted on a faceplate or flat plate and4 jaw chuck using the head bolts?

what tool do you use to turn the radius on a combustion chamber dome? facing the gasket surface and widening a squish band are easy, but how to maintain a radius while opening up the chamber to increase the volume isn't making sense to me. i don't have a ball turner, and won't be getting one. i have some ideas but none of them are making me happy.

the goal is to "detune" a yz250 head closer to the yz250x specs. tighter squish, more volume. from this



Reply #3 on: October 27, 2016, 04:40:33 PM »
My Kaw H2 heads turn fine when held by the spark plug hole.  For the bowl, I just make a full-radius cutter from a 1/2" square tool bit and work it carefully.  You can make a cardboard template if you want to, then cut to that, a little at a time.  You end up working the X and Y almost like a wood turning lathe.

I've also been adjusting the volume for no head gasket, and adding a groove for a Viton O-ring.  They work beautifully.

Reply #6 on: October 27, 2016, 05:47:33 PM »
You need the cutter radius to be smaller than the smallest radius in the bowl.  That way you don't ever get a wide contact area to make it chatter.  Not sure if you've ever used a wood lathe, but it's really similar.  You kind of cut by feel, even though you're turning the dials and not holding the tool by hand.  You don't plunge in, but rather sweep around the bowl, taking shallow cuts.  I usually use the carriage crank and not the compound slide.  You could practice on a scrap head, or just a scrap of aluminum, to get the feel.  I don't need to have the spindle speed terribly slow for this method

Reply #11 on: October 27, 2016, 09:28:11 PM »
I don't have all the pic's I thought...
So on a RD head with a centered sparkplug 14mm hole I have a threaded mandrel to screw head onto in the lathe.
Make sure you are indicated as perfect as you can get...I like .0005 tenths.
Before doing this you want to lap the heads on 220 grit wet n dry to make sure they're flat, then lay flat on a granite plate or other flat surface and measure from the sparkplug seat down through the plug hole to the surface. Write this # down for each head.
All stock RD head's will never be the same.
Next I set them in a mill and spotface the plug seats, starting with the shorter of the two.
Most heads will clean up about .006-.008
Mill both to the same height.

Next mount on arbor in lathe, just a strong hand tight and to 600-750 rpms spindle speed.
I cut about .015 a pass with a air spray coolant.
Once done with cutting deck surface, set the tool post at the desired angled degrees for cutting the squish band.
I cut at .005 at a time and this is done by hand on crank handle feed.
Pay careful attention to your final O.D. for the size of bore your using and the depth for piston to head clearance.
I use a pair of digital calipers and measure the top of the piston head and cut the squish band on the head .015 bigger for alignment fit and piston rock for some setups that have a closer positive deck height.

[Fastash]

Thanks for the information. I'm officially confused on what direction to go now. Lol !

[RD7]

So was I to start with, finally decided to  flycut the barrels flat and cut an O ring groove in them. If you flycut the recess off the top you can use RD 400 gaskets and later on if you want to you can O ring them.

[m in sc]

thats what i have on my lightweight. cut jugs and (was) rd400 gaskets, now o-ringed heads. 

[Greaser Greg]

Does all this apply to r5 heads as well? How much will I notice this work on an otherwise stock engine?  Is it s.o.p. to mill heads for any rebuild, like a car, in some of your "books"?

[Fastash]

Speaking of R5 cylinder heads will they interchange with RD? Any notable differences or benefits?