cobrabc1993 Posted April 15, 2010 Report Share Posted April 15, 2010 I have a fresh built 421 cub, sheerer small bore inframes, .... Has vforce reeds, boss intake,and like new 34mm mikuni flatslides..... The problem is, I cant seem to get the mid range "bogg"out of this thing, which is a flatslide characteristic..... This thing screams from 3/4 to wide open throttle, but tryn to stab the throttle at low rpms, this thing spits sputtters, falls on its face, till it gets the rpms to hit the powerband.. And, if you try to ride this thing just cruising with the throttle at half throttle, it acts way rich, and just sputters out the pipes, like it s way fatt... Im running 370mains, needle on 3rd clip, in the middle spot, and 50pilots....... My question is, does any one have a motor setup like mine with Mikunis, and if you do, what are your settings, and how does your bike respond at different rpm ranges..?? Im at 1000ft elevation, and run 50/50race,pumpfuel..... Quote Link to comment Share on other sites More sharing options...
cobrabc1993 Posted April 15, 2010 Author Report Share Posted April 15, 2010 Also, im goin to try and play with my needle clip settings, but these worked perfect on my last engine, in the middle spot.. and I was also told, i may need to try a different needle or needle seat?? Hopefully someone out there has tried these carbs on a 421..... Almost everyone runs the keihns on these setups, but i was hoping to make these Mikunis work........ Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted April 15, 2010 Report Share Posted April 15, 2010 I have a set of 28mm Mikuni TM's bored to 30mm on my uncles 460cc cub motor. You need to make sure you have the correct nozzles, needles, slide cutouts, and neddle/seat for a banshee installed in them. You should be close on the main, but those other components are crucial. Info is on the HQ for the other specs. Quote Link to comment Share on other sites More sharing options...
cobrabc1993 Posted April 16, 2010 Author Report Share Posted April 16, 2010 ok, thanks, yes, these carbs are set up for a banshee....and the slides and needles are banshee specific...... I moved the needle clip to 2nd notch from the top to lean out the mid, and that made a huge difference...... Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted April 16, 2010 Report Share Posted April 16, 2010 So your carbs are set up with these internals? Slide: 2.5 Needle: 5L1 2nd from top Pilot jet: 30 Main jet: around 380-390 Float height: 22mm Nozzle: 175 (P4) Air screw: 2-2.5 turns out Needle seat: 2.5 Quote Link to comment Share on other sites More sharing options...
cobrabc1993 Posted April 16, 2010 Author Report Share Posted April 16, 2010 Dang, your gona make me pull those carbs back apart.... The mains are at 380, pilots are 50s with air screw 2turns out, and the needles are a 5L sumthn, on the second clip, i didnt write it down...... Are the slides usually marked? From what ive seen, i could have a 3.0 or 3.5 slide..... I will pull one out and look for numbers, or would it be best to try and measure the amount of cutaway on the slide....? Also, you mentioned there is "specs" for the Mikuni Flat slides on here, you dont by chance, remember where you found those???? Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted April 16, 2010 Report Share Posted April 16, 2010 Those are the specs, I posted them on here. Those are for mikuni 28mm carbs, but should be some what close. You can also llok in the pinned jetting setup thread at the top of this forum page. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted April 16, 2010 Report Share Posted April 16, 2010 The TM 32-34 are different than the 28's, if you try to use a 175 series needle jet it won't work. The 34's come with a 5FP-17 needle and 389 Q2 needle jet out of the box. Those settings should be close. Probably end up with the needle on the 4th or 5th clip. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted April 16, 2010 Report Share Posted April 16, 2010 Well there you go, some direct input on the 34mm. Just verify your setup and adjust away. Quote Link to comment Share on other sites More sharing options...
springer Posted April 17, 2010 Report Share Posted April 17, 2010 i'm trying to get my 34's dialed in as well. i had done some searching before and there was quit a bit of info from a few years ago. shouldn't really change i suppose. i remember reading that the Q-2 is very rich and it was recommended to drop to like a P-8 or P-6 for them to run very good. any input about that wildcard? i was thinking about trying a different needle jet. edit: figured i would post this link since it takes me 15 mins to find it every time i look for it. http://www.mikunipower.com/Catalog/MikuniCatalog18-19.htm might help someone out. Quote Link to comment Share on other sites More sharing options...
cobrabc1993 Posted April 17, 2010 Author Report Share Posted April 17, 2010 Thanks, Snopczynski and Wildcard, for the input....... I think i have them pretty close now, but i am Wondering, like " Springer" Mentioned, should We try a different Needle jet tube?? He says the Q2 may be a bit on the fat side? Just curious, i had heard that from another member, that i should try another needle jet tube?? Quote Link to comment Share on other sites More sharing options...
springer Posted April 22, 2010 Report Share Posted April 22, 2010 anyone have any input on the needle jet tube topic?? Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted April 22, 2010 Report Share Posted April 22, 2010 A 389 Q0 needle jet would be the next leaner....010" smaller bore. If you do install one you will want to start tuning with the needle in the 4th or 5th clip position. Where are you at on your pilot air screw adjustment? You may still be rich on the pilot circuit affecting the other jetting circuits. Those carbs came with a vm22/210 #50 pilot from Mikuni, what size is in there now? -Brandon Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted April 22, 2010 Report Share Posted April 22, 2010 Also....It is more likely that your slide is a 4.0, that is the only slide available for those carbs these days and should work fine with your application. Quote Link to comment Share on other sites More sharing options...
cobrabc1993 Posted April 23, 2010 Author Report Share Posted April 23, 2010 Im running the factory #50pilot, with the air screws two turns out....... Seems the best right there..... still a little bog in the mid range, but not \ as bad as it was..... Im starting to wonder if its not my shearer pipes that are killing my low to mid performance.... From mid on up it screams... Im on a 390main jet, and it acts like it wants even more on the topend..... Anyways, do you sell the different needle jets for those carbs, or where do you purchase them.... Thanks for your help Brandon........ Quote Link to comment Share on other sites More sharing options...
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