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Replace Hitachi's to Mikuni slide carbs

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Replace Hitachi's to Mikuni slide carbs

PostAuthor: matthijsH » Thu Jan 09, 2020 6:07 am

Hi there, I'm Matthijs form the Netherlands.

I could not get my XV750 running without hiccups. We found out that my Hitachi HSC40 carbs were worn out. Now i want to replace them with the Mikuni VM slide carbs. I want to go with a Dual carb setup. But i'm not sure wich size to chose: the Mikuni VM34 or the VM36.

I've seen a offer of a Mikuni vm34 kit with inlet adapters in America, but it cost a lot to ship it to my country, The Netherlands. The VM36's would be easier the fit in because of the measurements of the housing (then i could use the inletboots of a Yamaha BT1100).

Does one of you guys know if a dual setup with mikuni VM36's would be overkill for a XV750? Would the airflow in the venturi of the VM36's be to slow in comparison to the VM34's?

Thanks a lot in advance!
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Re: Replace Hitachi's to Mikuni slide carbs

PostAuthor: nanno » Thu Jan 09, 2020 9:41 am

Vm38s has been done a few times. The BT1100 rubbers look like they would fit the VM36 and (one version of) TM38s, but the carbs will not go in all the way. All the roundslide and flatslide Mikunis with 43mm outside-diameter on the engine side fit into VM38-200 rubbers. (And these are available for VERY reasonable money.) Cables are available via Heidentuning in the Netherlands. I am not sure, but I think he's also selling the VM38-200 inlet rubbers.

Cheers,
Greg (from Austria, so basically the same problem as you have)
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

*Look to my profile for a link to my blog*
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Bike year & model: 1981 Yamaha TR1
1982 Yamaha TR1 Turbo
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1979 RD250/R5/DS7-hodgepodge (in bits)
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Re: Replace Hitachi's to Mikuni slide carbs

PostAuthor: matthijsH » Mon Jan 13, 2020 2:28 pm

Ah thanks a lot for the hint
So the dual setup with the mikuni vm36's is not overkill for 750cc?
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Re: Replace Hitachi's to Mikuni slide carbs

PostAuthor: nanno » Tue Jan 14, 2020 7:36 am

36s? Definitely not. I'd go for VM38s though as you can benefit from my work jetting them*, plus a few guys on the German TR1-Forum are using them as well. If you want to go with a 36mm carb, you may want to go with a 36mm Dellorto, because that's what some guys use on the German forum.

*There's at least one jetting thread on this forum, where people posted their setups, so you can use that as a baseline and save yourself from quite some work.
As this forum's search doesn't seem to work very well, use google or any other search-engine of choice to find the post.
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

*Look to my profile for a link to my blog*
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nanno
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Bike year & model: 1981 Yamaha TR1
1982 Yamaha TR1 Turbo
1977 XS 750 Sidecar
1984 XT500 4Valve (Austrian Tax saving edition)
1979 RD250/R5/DS7-hodgepodge (in bits)
Sex: Male



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