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Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: 920Steveeeve » Mon Sep 25, 2017 2:33 pm

Like the subject says, I'm trying to figure out which route to go. I've gone back a few pages & haven't really found this same question, so as far as I can tell my choices are:

Oh yeah, they're the Hitachi carbs, if it matters. Reason I'm going through it is because it sat in a barn for a couple years & even though I got it running yesterday well enough to drive on the road, it's clearly not right.

1) Buy a rebuild kit (2) and attempt to rebuild them
2) Go on ebay & find someone selling freshly rebuilt Hitachi carbs
3) Go on ebay & find someone who rebuilds them
4) Purchase the dual 34mm Mikuni carbs
5) Figure out the 2 to 1 conversion, which sounds good and bad. Good because of the perks like no syncing, better low end, whatever. Bad because I don't want the air cleaner sticking out the side.

So if anyone has any input, I'd appreciate it!
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: SBG71 » Mon Sep 25, 2017 5:44 pm

If you don't want single out the side, that's one to cross off the list. That's what I have on mine and it's been great. I personally like the carb sticking out, gives it a different look. You can buy a rebuild kit fairly cheap and it's pretty easy to do if you have minimal skills and minimal tools, just keep track of what came out of where. I don't have any experience with the mikuni so can't offer any help there. I also have never had to sync my hitachis since I went single from the get go. Try the rebuild yourself, if it fails, then you can take them to someone. Good luck.

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: jeepme79 » Tue May 08, 2018 9:57 am

SBG71 wrote:If you don't want single out the side, that's one to cross off the list. That's what I have on mine and it's been great. I personally like the carb sticking out, gives it a different look. You can buy a rebuild kit fairly cheap and it's pretty easy to do if you have minimal skills and minimal tools, just keep track of what came out of where. I don't have any experience with the mikuni so can't offer any help there. I also have never had to sync my hitachis since I went single from the get go. Try the rebuild yourself, if it fails, then you can take them to someone. Good luck.


I am pondering the same question now. What route did you go with for the single setup? I noticed a few options ranging from $120 for just the intake all the way up to $700 for a full setup, but have seen mixed reviews for all of them.

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: bstig60 » Tue May 08, 2018 2:24 pm

If you are going to keep the Hitachi's send them out to be rebuilt and cleaned properly. Check out www.viragocarb.com and ask for joe..
If you want to go single carb, The KJS kit is the way to go, it is expensive, but you get a brand new Mikuni carb with the kit that is set up for your bike..... In the long run its worth the extra money if a single is what you decide on.
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: jeepme79 » Tue May 08, 2018 3:37 pm

Right now i'm looking at $60 for carb kits for my Hitachi's, or possibly spending $400 on the upgraded dual Mikuni setup. There are a few reasons i'm leaning toward the dual Mikuni setup:
1) pull cable vs vacuum operated
2) simple design that should be easier to manage vs stock
3) still sits inside the V and doesn't stick out (my build will be a narrow build)

What i'm looking for are the pro's and con's of the Mikuni setup. I'm not sure I want to spend the time and money rebuilding and tuning the stock carbs if i don't end up going that route in the future

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: mark75 » Tue May 08, 2018 4:17 pm

Hitachis in 'brand-new' state are quite adequate, but it's hard to find parts for them [more so down the road]

JMO - Mikunis are a better choice for that reason [parts are plentiful, easy to find, and will be for awhile]

JMO: as far as single --- before Ken retired and sold KJS, there wasn't a better one on the planet [may still be so] but I have not had any personal contact with the new owner.
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Hellgate » Tue May 08, 2018 6:55 pm

I'm running dual Hitachis on an XVS1100 hybrid motor, 10.6:1 compression, full porting, cams, 2:1 header, Cone Engineering muffler. Makes 75hp or so on a stingy Factory Pro dyno. That's with a stock airbox and an OEM paper filter. Runs great.

Syncing crabs is easy, just buy a meter and turn one screw no more than 1/2 a turn. Easy.

I've got some modern Mikuni CVs and VMs in a box. Someday I'll try them out.

For pure hp the VMs might get a few more, for rideability the CVs win hands down.

My last project was a Gen2 starter motor conversation, C5 ignition next, then carbs? With the testing I've done, the ignition is the limiting factor not the intake system. In otherwords, I don't see the value in the effort to upgrade over stock carbs at this point. Tuning the cards will work fine for pretty much any stock configuration.

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: jeepme79 » Wed May 09, 2018 8:47 am

I finished rebuilding the stock carbs last night. Had to make my own bowl gasket but so far it's holding. After that and a new set of plugs she fired right up. Hopefully tonight I'll get some tuning done and take it for a spin. The carbs were dirty but overall in good shape. Someone prior to me stripped some of the jets, so that made it interesting.

My plan is to get the bike tuned and running well, then ride it for a month or two before tearing it down for a custom build. Part of my thinking on the Mikuni setup is for simplicity. I'd like to strip as much wiring and vacuum lines as i can for the final results

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Flyingdog » Wed May 09, 2018 2:49 pm

Hellgate wrote:I'm running dual Hitachis on an XVS1100 hybrid motor.. with a stock airbox and an OEM paper filter. Runs great.

:touchit: Yea...why poke the monkey!!
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: nanno » Thu May 10, 2018 12:41 am

Hellgate wrote:For pure hp the VMs might get a few more, for rideability the CVs win hands down.


Just to add another opinion: Once jetted and synced correctly, the VMs are no less rideable than the stock carbs. Beware, we're not talking about the 34s here, but the correct-size 38s. The 34mm-kit is just there to make money on the back of unknowledgeable folk.

To fit VM38-9s, you also need VM38-200 inlet manifolds and a 2in1 throttle cable (which can be bought from most XS650 tuning shops). Additionally, if you want to continue sucking air through the frame, you need some turbo-intercooler bends in the right diameters.
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: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Crazy_Russian » Thu May 10, 2018 1:24 am

I just keep rebuilding my stock Hitachies, i have a tendency of letting my bike sit for a few years at a time. but after they are tuned, i've never experienced any issues with them. You can still find parts for them if you know how to google.

now please correct me if im wrong. but didnt latter model large XV's use Mikunis from the factory? are they worth a dang? is it a somewhat of a straight swap?
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: nanno » Thu May 10, 2018 1:50 am

Crazy_Russian wrote:I just keep rebuilding my stock Hitachies, i have a tendency of letting my bike sit for a few years at a time. but after they are tuned, i've never experienced any issues with them. You can still find parts for them if you know how to google.

now please correct me if im wrong. but didnt latter model large XV's use Mikunis from the factory? are they worth a dang? is it a somewhat of a straight swap?


Straight swap (even the throttle cable fits), but the slides are VERY heavy and as such the bike will react slower to throttle input. Also max. achievable power is somewhat decreased compared to a set of correctly dialed in Hitachis.

Cheers,
Greg
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: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Crazy_Russian » Thu May 10, 2018 3:33 am

nanno wrote:
Crazy_Russian wrote:I just keep rebuilding my stock Hitachies, i have a tendency of letting my bike sit for a few years at a time. but after they are tuned, i've never experienced any issues with them. You can still find parts for them if you know how to google.

now please correct me if im wrong. but didnt latter model large XV's use Mikunis from the factory? are they worth a dang? is it a somewhat of a straight swap?


Straight swap (even the throttle cable fits), but the slides are VERY heavy and as such the bike will react slower to throttle input. Also max. achievable power is somewhat decreased compared to a set of correctly dialed in Hitachis.

Cheers,
Greg

Thank's Greg,
so besides availability of components, i would consider it not worth it:)

one of these days (when im not slammed with school) Ill build my EFI setup :cl: :bg:
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Hellgate » Thu May 10, 2018 5:31 am

nanno wrote:
Hellgate wrote:For pure hp the VMs might get a few more, for rideability the CVs win hands down.


Just to add another opinion: Once jetted and synced correctly, the VMs are no less rideable than the stock carbs. Beware, we're not talking about the 34s here, but the correct-size 38s. The 34mm-kit is just there to make money on the back of unknowledgeable folk.

To fit VM38-9s, you also need VM38-200 inlet manifolds and a 2in1 throttle cable (which can be bought from most XS650 tuning shops). Additionally, if you want to continue sucking air through the frame, you need some turbo-intercooler bends in the right diameters.
Be ridable I meant with weather and altitude changes. VM are very nice once set up correctly.

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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: nanno » Thu May 10, 2018 6:18 am

Crazy_Russian wrote:so besides availability of components, i would consider it not worth it:)

one of these days (when im not slammed with school) Ill build my EFI setup :cl: :bg:


Yep, that's the gist of it really. I have IIRC two sets stashed away and only ever played around with one and really couldn't get them close to the performance of bone-stock Hitachis.

EFI is dead simple, you just have to find throttle bodies that fit. But with nowadays even MX-bikes being fitted with EFI you just have to have a look at one of those. Additionally you'll need a fuel pump and fuelpressure regulator and an EMU, such as Mega- or Microsquirt. Unfortunately they still can't cope with the stock triggering system so the ignition rotor out of a C5-ignition (as it bolts up to the camshaft), should be employed to do that. Basic EFI won't even need an AFR probe or anything like that, so should be really straightforward as such.

Hellgate wrote:]Be ridable I meant with weather and altitude changes. VM are very nice once set up correctly.


I've taken her to the Alps and yes she did lose some top-end at 10,000ft (my place is at around 1000ft altitude), but so did the Hitachis in the past, so no need to worry about that. (At least not more than with stock carbs...) But yes, they do require some tuning to get right.
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

http://greasygreg.blogspot.co.at (My blog - Greasygreg.blogspot.co.at)
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: mark75 » Thu May 10, 2018 3:03 pm

jeepme79 wrote:I finished rebuilding the stock carbs last night. Had to make my own bowl gasket but so far it's holding. After that and a new set of plugs she fired right up. Hopefully tonight I'll get some tuning done and take it for a spin. The carbs were dirty but overall in good shape. Someone prior to me stripped some of the jets, so that made it interesting.

My plan is to get the bike tuned and running well, then ride it for a month or two before tearing it down for a custom build. Part of my thinking on the Mikuni setup is for simplicity. I'd like to strip as much wiring and vacuum lines as i can for the final results



as far as vacuum lines, on a 700/750 you don't need any unless you have vac. petcock.

as for 1100 bare-bones wiring ... this may help ---> viewtopic.php?f=140&t=43018

couldn't find the one I wanted, but this is for 700/750 --->https://viragotechforum.com/viewtopic.php?f=140&t=35947
New Members Note- The site will allow full access (U/L, D/L, PM, etc) after your 5th post.
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Re: Carb choices: Rebuild, Rebuilt, Mikuni, single, double

PostAuthor: Jake » Thu May 10, 2018 3:16 pm

As an FYI, the OP last logged in on Oct. 19, 2017

He posted that he rebuilt his Hitachis. viewtopic.php?f=11&t=58652

Unless he logs in or otherwise visits the forum, he won’t get notifications of posts to this thread.
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