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-   -   Yamaha XT 600 single carb + KTM shock - How it was made (https://www.horizonsunlimited.com/hubb/yamaha-tech/yamaha-xt-600-single-carb-77386)

Svaneberg 18 Aug 2014 07:15

I'm not using the temp sensor, but a suggestion would be to Mount it on the oil bolt on the right side Engine cover :)


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nickargas 18 Aug 2014 10:15

I.just put mine on the hangar below the bolt for the oil, on the frame... via heat transfer it shows me the engines temp... p.s. still can't believe this is an xt... it sure goes like a Duke 2 man!! Thank you for the inspiration jakob! Single Carb works wonders...will take some photos and I will upload them on dropbox or imageshack for you as promised man! Would be very happy if we ride together once!

xtrock 18 Aug 2014 10:43

so what you have on 0-100km/h?

nickargas 18 Aug 2014 11:30

Don't know xtrock... haven't timed it or dyno it... I will make a new video for u as promised wearing the head band so u can check the vapor tacho for the speed and the time... what mechanical mods have u done to yours xtrock?

xtrock 18 Aug 2014 11:40

Quote:

Originally Posted by nickargas (Post 476722)
Don't know xtrock... haven't timed it or dyno it... I will make a new video for u as promised wearing the head band so u can check the vapor tacho for the speed and the time... what mechanical mods have u done to yours xtrock?

So far i only have the KN filter, new exhaust all the way, dynojet kit stage 2. It runs perfect all the way, no missfire and pulls very good on all gears. Have standard 15/45 i have tried the 14 but didint like it, to short on 1gear.

nickargas 18 Aug 2014 19:22

Had the same on mine prior to the conversion.. plus my exhaust is custom made with a bigger fmf powerbomb... the.difference is staggering... I took a video for u but camera was tilted a bit high... will try again for u tomorrow man...

xtrock 18 Aug 2014 20:07

Quote:

Originally Posted by nickargas (Post 476771)
Had the same on mine prior to the conversion.. plus my exhaust is custom made with a bigger fmf powerbomb... the.difference is staggering... I took a video for u but camera was tilted a bit high... will try again for u tomorrow man...

Sounds great, i guess you now have the xtra power we all want.. What is the cheapest carb for this?

Svaneberg 18 Aug 2014 20:12

The easiest and cheapest Way is to use the carbs from a raptor (2 parallel carb setup). The Best single carb is IMHO a keihin FCR 39/41. Alt. A mikuni TM 40.


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xtrock 18 Aug 2014 20:48

Quote:

Originally Posted by Svaneberg (Post 476778)
The easiest and cheapest Way is to use the carbs from a raptor (2 parallel carb setup). The Best single carb is IMHO a keihin FCR 39/41. Alt. A mikuni TM 40.


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Ok thanks, the difference from stock is that you get two carbs and not the vacuum slide?

Svaneberg 18 Aug 2014 20:54

Well. If you Go for the raptor setup you'll actually get 2 parallel working cv carbs (vacuum slide) instead of the oem 1 mechanical/1 vacuum. The single option Can be both vacuum (bst 40) or mechanical (fcr/tm/PHM). The fcr and tm will incorporate a accelerator pump. Jakob


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xtrock 18 Aug 2014 21:02

Quote:

Originally Posted by Svaneberg (Post 476785)
Well. If you Go for the raptor setup you'll actually get 2 parallel working cv carbs (vacuum slide) instead of the oem 1 mechanical/1 vacuum. The single option Can be both vacuum (bst 40) or mechanical (fcr/tm/PHM). The fcr and tm will incorporate a accelerator pump. Jakob


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Yes i see now on pic that raptor have 2 slide, why will these give more power than original?

Svaneberg 18 Aug 2014 21:08

Well because the work parallel as oposed to the oem which only work the left carb up to approx. 1/3 to1/2 throttle thus only letting fuel mixture in through the left intake valve. With the parallel setup you get fuel mixture in through both valves from idle on.


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xtrock 18 Aug 2014 21:27

How about the handling of the bike with this new carb in like winter/ offroad where you need a gentle steady low rpm? iam thinking thats why they made the bike with this second carb when rpm is rising? http://www.tenere.co.uk/forum/viewtopic.php?f=14&t=1126

Svaneberg 18 Aug 2014 21:38

Mine is handling very Well due to the slide being only partly open under low rev. For an explanation of the oem vs single setup see Here:

The general issue is that the smaller carb areal, the better low end torgue. Thats why Yamaha designed the dual carb on the XT. Running to approx. 1/3 throttle only activates the 1st carb for better low end as the air vacuum in the manifold is low and therefore, it cannot draw from a, let's say 39mm carb as the vacuum is too low and the engine will bog. As the throttle is opened more and RPM and therefore vacuum increases, the second carb (vacuum controlled), is activated, thus giving more air/fuel mixture to the engine.
This setup has definately it's advantages, however also some disadvantages: When running up to 1/3 throttle (only 1st carb engaged) only the left intake valve is getting air/fuel mixture thus getting cooled by fuel. The right intake valve is running "dry" making it extremely hot. Furthermore you don't have the advantage of 2 valves at up to 1/3 throttle.
With the single carb (in my case FCR39) you have the slide acting as a variable sqare areal so you will get the same function as with the original dual setup. However when you do WOT or close from almost closed throttle/low engine rpm, the wacuum in the manifold isn't high enough to draw the extra air/ful mix needed and the engine will bog. That's why the carb needs an accelerator pump to give an extra squirt of fuel when WOT. The original dual carb doesn't need that as the 2nd carb is a vacuum controlled carb and therefore the slide won't lift until the vacuum is high enough. Conclusion - using a single AP carb will utilize both intake valves from engine start and also won't need to "wait" for vacuum to build up. Result is much quicker respons.

Br
Jakob


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xtrock 18 Aug 2014 21:59

Is the raptor 660 carb bolt on for the 3TB?


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