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**Yoshimura Carb Thread** (tuning, tips, setups, discussion)

18K views 39 replies 14 participants last post by  Gromotra 
#1 · (Edited)
Im getting a good deal on a Yoshi carb so in going to sell off my tuner and make the leap back in time

Ive already built a setup and went carb for a little bit just for shits so I only have a couple questions right off the bat for the couple of people who've done the Yoshi carb

If you didn't buy the conversion kit..
1: what throttle cable did you use? A normal off the shelf slide cable? What length?

2: where are you getting jets? I haven't searched yet for this but thought maybe someone has already found a good source
EDIT: Thank you GSX, the jets are shared with Keihin hex's, mains can be found here http://jetsrus.com/a_jets_by_carburetor_type/jets_keihin_99101-357_main_Hex_25-xxx.htm

3: where can you get parts? I'm going to want to get a second velocity stack and mod it to run in the airbox
EDIT: jumped on webike and searched the carb, still no jet kits but found this.. The filter adapter is up my ally since I'd like to retain the airbox
http://japan.webike.net/ps/Yoshimura+YD-MJN28/#!search&p.k=Yoshimura+YD-MJN28

EDIT: just found this on YouTube, a step by step process of installing the full yoshi carb kit, I didn't realized how much was actually involved, they really took their time setting up a nice kit.. I wish I read Japanese and was able to translate but even from the video you see where they retain the TPS which is pretty interesting and explains why the conversion kit is so pricey


I know a couple guys have made the jump so if you could post pics of your setup, your engine mods and your overall opinion of it that would be awesome
 
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#5 ·
Yeah, as far as getting it to run you just remove all the sensors from the tb but leave them plugged in, remove the injector but leave it plugged it (you can remove the fuel line if you want) and depin 2 wires, I don't remember which but I can reference back, this allows your fuel gauge to work without the fuel pump turning on, T into the J shaped hose which is the low pressure side of the pump and that T is your fuel feed to the carb

the bike starts and runs like normal and won't trip the CEL, also note IIRC the PGMFI uses the fuel system to limit revs, so by eliminating the efi you will no longer have a rev limiter which can be dangerous if you aren't careful or set up to over rev
 
#12 ·
The carb uses Keikin Hex Jets. My Finbro 183 ended up with a 112 main jet and the richest needle. The needle is a compromise. It is not like a conventional needle. It is like a spray bar. The carb worked ok, but I would have preferred a standard needle. It was rich down low and just a little rich on 3/4 throttle.
 
#25 ·
The question is what is your time worth, the yoshi carb has proven to be a fantastic one but not everyone can or cares to fiddle with them especially when the bike comes efi standard

You'll always have the efi vs carb debate and while I think a slide carb will produce a higher peak number compared to a throttle body of the same size only because of the intake port is nearly completely open vs having a butterfly fly in there to turbulate the air, efi will beat in about every real world driving category

In the end it's all about preference, efi is the ideal solution in 99% of riding scenarios
 
#26 ·
yep once you get up in the higher elevation you will wish you had F/I. I rode from Sunnyvale Ca to Reno with a carb motorcycle and once I started getting above 4000-5000 ft elevation my engine started to lose power, lack of air/fuel mixture at the right elevation causing loss of power. F/I system takes care of that. EZ to adjust and tune vers changing jets
 
#27 ·
After putting a timing light on the bike, I found out that you have to use a tps with the carb setup. Otherwise, it throws the timing off. One is supplied with the Yoshimura Grom conversion kit. I have the Takegawa 4 valve kit now. This thing screams now. I had the Finbro 183 kit before and there's no comparison.
 
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