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Euro-style dual TM38 flatslide carb installation

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: dazthebiker » Mon Feb 25, 2019 5:12 am

https://www.ebay.co.uk/itm/Yamaha-XV-Vi ... 2749.l2649

Really helpful guys, talked to them about the setup before i ordered. Currently have 190 mains, im guessing they will be too rich but im leaving them in for now until its up and running then i will adjust from there depending on the plugs.

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Mon Feb 25, 2019 5:59 am

Yup, I run about 175s (-ish) in mine, when sucking through the frame, but basically just a K&N attached to it. (Legal thing as I pointed out a few pages ago...)

Please let me know, which needle they used, as I just installed the slightly richer 6FJ41 needle from the two-stroke version as I couldn't get rid of a lean spot in the midrange) or even better all the jetting. Can't beat a bit of corporate espionage. :bg:

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

http://greasygreg.blogspot.co.at (My blog - Greasygreg.blogspot.co.at)
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: dazthebiker » Mon Feb 25, 2019 10:48 am

When i open the carbs up to sort the cables out i will have a look at the needles and let you know

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Mon Feb 25, 2019 12:35 pm

Thx, much appreciated!
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: Justheman80 » Thu Mar 14, 2019 5:40 pm

Dazthebiker - Any update on what was in your carbs?

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: Hellgate » Sat Mar 16, 2019 11:41 am

dazthebiker wrote:https://www.ebay.co.uk/itm/Yamaha-XV-Virago-750-920-1100-Mikuni-Twin-TM38-Flatslide-Carburetor-Kit/173584620229?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Really helpful guys, talked to them about the setup before i ordered. Currently have 190 mains, im guessing they will be too rich but im leaving them in for now until its up and running then i will adjust from there depending on the plugs.
Just saw this. That is great look kit. How do you like?
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: dazthebiker » Sun Mar 17, 2019 11:52 am

nanno wrote:Yup, I run about 175s (-ish) in mine, when sucking through the frame, but basically just a K&N attached to it. (Legal thing as I pointed out a few pages ago...)

Please let me know, which needle they used, as I just installed the slightly richer 6FJ41 needle from the two-stroke version as I couldn't get rid of a lean spot in the midrange) or even better all the jetting. Can't beat a bit of corporate espionage. :bg:

Cheers,
Greg


Been meaning to post for a while, main needle is a 6FJ40, comes with a 190 main and a choice of 180 or 200 to go up or down a bit.

haven't opened up the bottom of the carbs so dont know what the other jets are

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Sun Mar 17, 2019 3:11 pm

Thx, the 6FJ40 is an interesting choice. Please keep us updated!
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: dazthebiker » Mon Mar 18, 2019 2:24 pm

well shes up and running now! short video in my build post, ticks over pretty well, went to play with the air screws and one of them is missing! Doesn't seem to be having much effect on tickover, but still, will need to get a new one.

What do you have yours set at?

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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Mon Mar 18, 2019 2:42 pm

I haven't got my notes with me at home, but I think 1.5 turns out sounds about right. I had some issues with setting up midrange with the 6FJ40 as it was leaning out there.
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Tue May 21, 2019 2:22 am

Update from my end, as I already have done about 500-600mls with the 6FJ40 needle on mine and it is PERFECT.

The midrange is finally perfectly rich enough, so much that a slightly smaller pilot-jet is one of the next things, I'll have a go at, simply to see if that would lower fuel consumption, as the bike is now a bit rich at idle (starts without choke), even with the air-screw 3 turns out.

(Also I am currently not sure, if I have #20 or #17.5 pilots installed, but I need the bike on a daily basis at the moment... if it's still the #20 pilot installed that would explain everything.)

The last time I managed (including some rather spirited riding and multiple attempts to find out about the topspeed on the German Autobahn) 6.84L/100km, which is rather close to what I achieved with the VM38s (around 6.5 to 6.6L/100km), so all the jetting seems to be pretty good.

The other thing is that the bike is thermally absolutely stable after installing the richer needle. So I had some detonation issues late last Summer and generally running relatively high engine temps. This has now settled to reasonable levels somewhere between 90 and 100 degrees oiltemp. (Admittedly with the improved squish I can get away with less ignition advance than last season as well, so it might be a combination of both.)
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: jgyuen » Wed May 22, 2019 1:56 am

Just to clarify, you’ve gone back to the 6FJ40 and managed to get rid of your lean spot? Earlier you mentioned changing out to the 6FJ41.

I just put these on my 1000, looking forward to the first ride this season!
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Wed May 22, 2019 3:28 am

No, 6FJ40 is the richer (2-stroke) needle. The Mikuni enumeration on needles is (at its best) very confusing.

At the moment playing around with a #15 pilot jet and less air-screw to squeeze out the last bits of efficiency on the carbs. Once it dries up in the coming weeks, I will do some more in-depth tuning with a wideband setup.
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Sun May 26, 2019 12:37 pm

Noteworthy: TM38 carbs that can be bought nowadays, run the same floats as a TMX 38 where the two individual floats have the spare part numbers: 859-52020, 859-52021

Those carbs can also be converted back to the old style floats VM24/236 as fitted to the VM38s, but these floats can then fall out of the carb, when the float bowl is removed. BUT it does work to get you out of a pickle, because these floats are literally available everywhere (and cheap), whereas the specific TMX floats are not as easy to be found. The float-level stays the same (or at least close enough so the carbs run just fine.)

Background: one of the carbs started to overflow lately and as I have to order my Mikuni spares from Germany that'll take a few days. Also a lot of the spare parts catalogues are wrong on the floats and only show the older style floats, instead of the new ones.
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: jgyuen » Thu Jun 06, 2019 11:05 pm

Running the Mikuni OZ kit on my 1000, starts beautifully, idles great. (2.5 turns out on mix screw)

If I try to snap the throttle from 0-100 it just lets out a puff of backfire.

If I roll the throttle from 0-1/2 and then to 100 it has no issues.

What’s my bike trying to tell me.
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Fri Jun 07, 2019 3:02 am

What you describe sounds like it is running VERY rich down low.
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: jgyuen » Thu Jun 13, 2019 9:42 pm

What are you guys doing with the overflow tubes? Mine actually put out a tiny bit of fuel every time I lean it over on the kickstand which is slightly annoying.

Debating if it’s detrimental to cap them off
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: nanno » Fri Jun 14, 2019 12:50 pm

Sounds like your floats are set up a bit high. I only run the outer overflow tubes as there's not enough room to fit the inner ones. You can't cap them off or your float bowls won't be ventilated anymore.
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: Euro-style dual TM38 flatslide carb installation

PostAuthor: jgyuen » Fri Jun 14, 2019 3:23 pm

The kickstand has been shortened so the bike leans a little bit more than it should, I ended up routing the lines so they go upward a little bit before coming back down.. I'll see if the bike doesn't like that arrangement.

For anyone that buys the OZ kit, mine came with a 190 Main, 12.5 Pilot and 6FJ40 needle set on the middle clip.. I raised the needle (clip moved to the bottom groove) and changed out the pilot for a 15.. Haven't taken it on a long ride with the new settings but it's definitely happier on my farm road.
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Re: Euro-style dual TM38 flatslide carb installation

PostAuthor: Ita » Fri Aug 23, 2019 10:11 am

Awesome info lads...

I'll order the Mikuni Oz TM38 kit this week.

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