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XT350 heads

PostAuthor: DGA » Wed Jul 23, 2014 9:04 pm

Has anyone ever looked into using a 4 valve head on an XV750 or larger? The XT350 head comes to mind, similar bore I would imagine, looks like a similar bolt pattern too.
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Re: XT350 heads

PostAuthor: Hollywoodmx » Sat Jul 26, 2014 3:40 pm

Being on of the few that adventure into high end performance of the xv's not sure what you are looking to gain by doing this. To me there are better places to spend the money. A good mod for a 750 is to swap in 1000 engine probly best bang for the buck if you are after hp.
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Re: XT350 heads

PostAuthor: Hellgate » Sat Jul 26, 2014 5:47 pm

Hummm... I like that idea. It would really help the top end I assume. I'll admit I don't know anything about that head/motor.

A lot would depend on how well designed the combustion area and squish area is to begin with.

I'll admit, the more I think about it I like the idea. I wish I'd thought of it 18 months ago. Too late for me now.
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Re: XT350 heads

PostAuthor: DGA » Sat Jul 26, 2014 8:43 pm

Was just a thought, not really after anything, maybe a novelty or something, but often manufacturers use similar engineering for similar products so I wondered if the XT350 might be close. Looking at one on Ebay, it has small valves so might not be a huge improvement. The XR Honda heads would be nice but have an odd twisted stud pattern because of the RFVC mechanism. But got to be air cooled, and single cam preferred.
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Re: XT350 heads

PostAuthor: Marvelicious » Sat Jul 26, 2014 9:45 pm

neale666 and I were having a PM conversation at one point about trying this with XT600 jugs and heads and pistons. Same bore as the 1100 Virago, but 4 valve heads. I don't know if he ever got around to taking a serious look at it, but maybe he'll chime in.
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Re: XT350 heads

PostAuthor: Hellgate » Sat Jul 26, 2014 9:50 pm

I looked at fiche and I think it is doable. The trick would be making new motor mounts, not big deal.

I wonder if the Germans have tried this?
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Re: XT350 heads

PostAuthor: DGA » Sun Jul 27, 2014 12:01 am

Nice to use the XT600 cylinders as well, then adapt the cylinder to the crankcase, I guess whichever is easiest. Engine mounts are a simple steel fabrication. Often it's quick to just compare head and base gaskets to find something that is close. The 600 would have much bigger valves. Could get crazy TL1000R type power out of a setup like that.
'81 XV750, clip ons, 18" rear wheel, lowered 920 forks with twin discs and 1.5" spring spacers, 1100 brake master cylinder with CNC billet cap, -3 braided brake lines, lowered instruments and headlight, CNC billet mirror mounts, small billet turn signals with running lights, Koso tach/ speedo, stainless 2 into 1 stepped headers with reverse cone muffler, starter heat shield, 4 guage starter cables, rear exhaust heat shield, 4" round open air filter with billet CNC mount, TM38 flat slide Mikuni carbs, XV700 ported heads, BT-C05 cams, colder BP8ES NGK plugs, stiffened swingarm, polished engine side covers, polished rear peg mounts with carbon cover panels, single horn relocated, Sparto tail light with 3D printed lens, BSA tank kneepads, one off carbon fiber cafe seat with brown cover, fork gaiters, KDX200 rear shock, single tach/speedo with carbon fiber dash, red LED under tank and seat lights, black pearl paint with silver accents.
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Re: XT350 heads

PostAuthor: Marvelicious » Sun Jul 27, 2014 1:42 am

Neale's pic, but I doubt he'll mind. Virago on the right...

Image

The studs are definitely not in the same locations, but they aren't far away. Still, there's not a lot of meat on the virago case for moving this stuff around. I don't think you could make it work without adding some material in a couple locations. Fine if you've got the welding skills, but I'd hate to think what it would cost to pay someone else. Skilled aluminum welders don't grow on trees.

The other obstacles that comes to mind are valvetrain related. Whether the cam chain will line up (potential deal breaker I would think), having to have a backward cam ground since one cylinder will be running opposite a normal XT600...
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Re: XT350 heads

PostAuthor: neale666 » Sun Jul 27, 2014 4:27 am

Yeah, no prob Marv.

As to whether I looked into it seriously thought, yeah, I've looked into it, but it's one of those "after I win big money" projects as it'll take stupid money to pull it off properly. Yes, the original mounting bolt holes in the case will need to be filled and new ones drilled, along with other adjustments, I'm sure. I have a line on a guy over here who did magic on a trashed/holed panhead case for a mate, and makes his own cases for harley drag engines, so when I've got the money behind me to go crazy I'll be chasing him up, while I'm at it I'd be seeing whether the XVS1300 crank can be made to work, to get the stroke about right for the XT600 cylinders (83mm against 84mm), try and get some strengthening ribs added (as someone else was saying that the racing XV750s in the '80s were getting case flex when they were pumping hard), oh, and I'd LOVE to find a way to shoehorn an XTZ1200 6 speed into it ;^) But just getting the case adjusted to mount the cylinders would be at least a couple of grand, I'm sure.

On the issue of engine mounts, the XT600 hangs off the head, as well, so that shouldn't be an issue. Probably a bigger issue would be working out how to shoehorn a couple of 2 barrel carbs into the space between the heads, or build a custom 4 port injector setup (my inclination is injection, as I have a set of 4 Leadwing injectors here now, and I'd love to add Nitrous, which would be easier with injection ;^), as the XT600 heads have 2 intake, as well as 2 exhaust, ports.

At the moment I'm scraping to try an make a Yamaha Stryker tripletree and XTZ600 forks & disk work on the XV1000, until I can get the XVS1100 lowers and new springs, disks etc to do the job properly.

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Re: XT350 heads

PostAuthor: Hollywoodmx » Sun Jul 27, 2014 9:59 pm

I doubt we would see tlr1000 power in any Virgo custom configuration.
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Re: XT350 heads

PostAuthor: nanno » Tue Jul 29, 2014 3:13 pm

Hellgate wrote:I looked at fiche and I think it is doable. The trick would be making new motor mounts, not big deal.

I wonder if the Germans have tried this?


No, because the racing series, that fuels development, doesn't allow 4-valve engines from Japan...

There's a 2into1 inlet manifold fitted to the Grizzly 600, which also sometimes used on XTs, to get rid of the dual barrel carbs!

Cheers
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Re: XT350 heads

PostAuthor: DGA » Sat Aug 02, 2014 10:03 am

The XT350 has a single inlet port, was also one of my requirements for this, too complex and not enough room between the heads for four inlet ports and carbs, and too many people on here whine constantly about carb problems so imagine running four carbs! Can't imagine there is room for 2 1 into 2 manifolds there either. LOL, you could run a single carb onto a complex fabricated manifold, or sit a Holley 4 barrel out the side.
'81 XV750, clip ons, 18" rear wheel, lowered 920 forks with twin discs and 1.5" spring spacers, 1100 brake master cylinder with CNC billet cap, -3 braided brake lines, lowered instruments and headlight, CNC billet mirror mounts, small billet turn signals with running lights, Koso tach/ speedo, stainless 2 into 1 stepped headers with reverse cone muffler, starter heat shield, 4 guage starter cables, rear exhaust heat shield, 4" round open air filter with billet CNC mount, TM38 flat slide Mikuni carbs, XV700 ported heads, BT-C05 cams, colder BP8ES NGK plugs, stiffened swingarm, polished engine side covers, polished rear peg mounts with carbon cover panels, single horn relocated, Sparto tail light with 3D printed lens, BSA tank kneepads, one off carbon fiber cafe seat with brown cover, fork gaiters, KDX200 rear shock, single tach/speedo with carbon fiber dash, red LED under tank and seat lights, black pearl paint with silver accents.
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Re: XT350 heads

PostAuthor: neale666 » Sat Aug 02, 2014 11:33 am

nanno wrote:There's a 2into1 inlet manifold fitted to the Grizzly 600, which also sometimes used on XTs, to get rid of the dual barrel carbs!

Cheers
Greg


The factory 2 into 1 is actually rather long and usually requires a relocation of the upper shock mount on the XT600 to work (have one here to use on my XT600 mods), at least one guy has hacked that up to make a shorter one that will fit the stock frame. ( Hence my comment that fuel injection would be my preference for induction)

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Re: XT350 heads

PostAuthor: nanno » Mon Aug 04, 2014 10:50 am

Neale,

would you happen to have a link for the XT600 mods? Sounds mighty interesting to me...

Cheers,
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http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

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Re: XT350 heads

PostAuthor: faffi » Fri Aug 28, 2015 4:02 am

Bringing this back to life. Considering that people have made 5-cyclinder Kawasaki two-strokes from two triples, a V12 CBX as well as a Kawasaki Z1300 cum 2300, a 48-cylinder Kawa two-stroke and more, making a 4-valve Virago should not be out of the question.

I would presume that one should either look into fitting the barrels and heads off an XT600 - or perhaps XT660 for L/C and fuel injection - or design a new cylinder head from scratch, but using standard items like cam and valves from let's say an XT600. Krauser did that when making a 4-valve head for the old airheads. You will need a new piston to fit the new head. If you are lucky, the piston pin diameter will be the same for the XT as for the XV, or more mods must be made.

While this is miles above my skills, it would be interesting to learn if someone ever decided to go ahead with such a project.
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Re: XT350 heads

PostAuthor: turbodog » Fri Aug 28, 2015 6:13 am

I have idly pondered how to do a 4-valve XV head for years (decades?). I looked fondly at the Vstar950 engine (until I saw how lacking the aftermarket performance options are) as a perfect 4-valve successor to the XV920. Now I own a BMW R1100S... probably a reasonably close approximation to what might be achieved from a HP (100@crank,85+RWHP) and torque (65RWTQ) point of view. What I can say is that I miss the low end grunt of the XV920 more than I appreciate the extra ponies at redline. But, I'm an old fart. Younger/more aggressive riders might feel differently.
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Re: XT350 heads

PostAuthor: Hollywoodmx » Sun Oct 11, 2015 5:50 pm

Watch in 5 min of research as I destroy hopes of such a mod. This doesn't even account for alignment of the cam chain either. Heads nor the cylinders are compatible. Such attempt would be a giant waste of money and effort in which a turbo, nos, or fuel injection will out shadow in returns for a fraction of the effort.

Not to mention you can barely fit 2 carbs under a virago.


Xt600 vs tr1/xv1000.

Head and base comparison.

[attachment=0:2tctci0t]38o34.jpg[/attachment:2tctci0t][attachment=1:2tctci0t]140.jpg[/attachment:2tctci0t]


[attachment=3:2tctci0t]10054378.jpg[/attachment:2tctci0t]
[attachment=2:2tctci0t]mtFnYxje0SLsubdagssMmDA.jpg[/attachment:2tctci0t]
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Re: XT350 heads

PostAuthor: Sami_Timonen » Tue Apr 18, 2017 5:59 am

Any new information about this ?

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