R1 Carbs (lots of pics)

[Sudden]

Hi guys, been Lurking this thread for WAY too long. always wanted a datto on bike carbs, couldn't get a datto but I've got bike carbs :blush:. I'm currently trying to diagnose a problem where I would sometimes put my foot right down and it would run perfect (rich by narrowband standerds), but if i released throttle and slow down and do it again it sometimes randomly decides to go full lean :(, also at around 5200 and higher rpms the engine feels like its bucking a bit?

 

P.S. @ Vintage Rice, what a sexy engine bay <3

       @ holdmybeerandwatchthis - excellent post :D

 

car - EP82 starlet

Carbs - Mikuni BS36 off a yamaha fj1100 <- gravity feed model

HKT electric fuel pump with a T fitting at the pump outlet to drop pressure to carbs by sending the excess to the return line to the gas tank. 1/4inch fuel hose all round

 

 

 

[VintageRice]

Hrmmmmmm  wish I could help more but what a different setup.  Pump on gravity feed carbs. Running overrich? Floats made to seal under pressure?  How do you know the "T" fitting setup is working?  I'd make sure my fuel is right first. Clean carbs VERY well, and put a gravity feed tank(pop bottle) over the engine and giver a go.  Start with basic troubleshooting too, Thats all I got for now......

 

Oh.........post a pic and welcome.

[datzenmike]

... also at around 5200 and higher rpms the engine feels like its bucking a bit?

 

 

 

 

I worry that this may be pre ignition. Leaning out. 12:1 full throttle would be better.

[Sudden]

:D glad to spark the thread again!. Without the extra t fitting to return excess fuel to the tank the carbs were flooding and spitting fuel out the front or just running rich constantly, I had ordered a kit with the float needles for the younger pump model but i got the wrong kit. Carbs were cleaned and bench sync'd while i was fixing other problems with the engine

 

When my Lean/Rich gauge says im leaning out my engine won't ever reach past 4500. I had problems with pinking before. I was running 12 degrees ignition timing at idle and i would pink as soon as i reached 4000 rpms. I pulled timing to 9 degrees, it no longer does a one wheel peel but the engine is smoother and revs much more freely. With the way I have the carbs mounted ( will take a pic as soon as i finish typing ) I wonder if my carbs are bouncing up and down causing the throttle cable( which is mounted on a bracket to the engine head ) is opening and closing the throttle as they vibrate?

 

My current setup is a prototype to decide which direction to go with my 1.5 build, High compression (1.3 pistons into 1.5 block at 10.6:1 or 11.2 cr depending on which head i use) or stock compression at 9.4:1. not knowing pump octane really is a pain. 

 

Fairly large photos trying to squeeze as much as i can out of the cell camera

 

http://img593.imageshack.us/img593/1179/p1612120955.jpg <- only thing holding the carbs to the engine are sillicone couplers and hose clamps, fairly sturdy. Final version of this will be brought closer to engine (have to bend dipstick out of the way) and may be braced from underneath with brace for the efi intake manifold

 

http://img266.imageshack.us/img266/645/p1612120956.jpg < fuel line routing and return line T  fitting to drop the pump pressure

 

http://img844.imageshack.us/img844/8945/p161212095601.jpg <- restrictive exhaust and cat? 

 

http://img254.imageshack.us/img254/1598/p1612120959.jpg <- prototype vacuum plenum, not sure which of the 2 outlets on the distributor vacuum thingy I should be using for off throttle vacuum advance. Also run to an incar vacuum gauge to monitor it. Fuel injector seals silliconed into head, barb fittings screwed into seals, 1/4 inch fuel line and t fittings. :) will be used later to sync carbs when i get a carb sync for 4 carbs. current bench sync is pretty spot on though.

 

EDIT:  thought I'd clear something up, my problem with running lean happens as soon as i give it more than half throttle. but the problem is random, one minute i can put my foot down and the engine screams for more, staying rich and pulling strong all the way never missing a beat (ignoring the higher rpm bucking thingy for a bit ) randomly if i were to release the throttle, slow down and put my foot down again, the instant i go full throttle the engine would just say 'no' full lean condition and no power at all. the instant i see my narrowband read lean I'm instinctively off the throttle. <- previous testing done in 2nd gear.

 

EDIT2: did some more thorough testing this evening. 1st gear full throttle, rich and perfect, will rev to a million if I weren't afraid of breaking it(or feels that way :P) 2nd gear is iffy, it may or may not lean out if accelerating hard, but will run spike to lean at exactly 5000 rpms o.O, scary ( I should have moved my rich lean gauge to a spot within my line of sight to notice this before. 3rd gear, waste of time will lean out at around 3500rpms. I have no idea where to start with this problem. :(

[ssnapz]

ok after a day and a half of reading 44 pages, i want r1 carbs. i want to turbo my napz, but to make my holley blow through will cost $400. i could do the r1s for half that. so 4 bills to run 1 holley or 2 bills to run 4 mikunis, im sold. any advice on turbo with them? i only seen one turbo set up in this thread and i dont know how he ran 10psi with no boost ref reg. im more looking for pluming ideas and jetting. should i do a plenum or a reversed header. and should i go bigger jets then non boost or will the pitot tube handle the fuel. i do plan on making the r1s work before i start.the.turbo swap. dont want to chase a turbo prob when its carbs. i also plan on this taking a while, still doing suspinsion i cant afford. but great thread. hard to believe 44 pages and not 1 worth skipping.

[72240z]

I would do efi for turbo. Carb blow through is difficult at best with common tried and true dcoe's but with bike carbs your just compounding it even more lol. I was thinking of doing an old school blow through on my z since I already have triples but its just not worth it. 

Small update on my end I ordered 2 sets of gsxr tbs for 160 shipped lol. I also sourced a place to fab the adapters I will need for dcoe bolt pattern as well for maybe 250. I need to find the cheapest msns way possible now and some coils etc... 

[spudly13]

ok after a day and a half of reading 44 pages, i want r1 carbs. i want to turbo my napz, but to make my holley blow through will cost $400. i could do the r1s for half that. so 4 bills to run 1 holley or 2 bills to run 4 mikunis, im sold. any advice on turbo with them? i only seen one turbo set up in this thread and i dont know how he ran 10psi with no boost ref reg. im more looking for pluming ideas and jetting. should i do a plenum or a reversed header. and should i go bigger jets then non boost or will the pitot tube handle the fuel. i do plan on making the r1s work before i start.the.turbo swap. dont want to chase a turbo prob when its carbs. i also plan on this taking a while, still doing suspinsion i cant afford. but great thread. hard to believe 44 pages and not 1 worth skipping.

 im running a 1.6 jet on my l20, as long as your pitot tube is sized right you can ALMOST just tune it na and hook it all up, some other things to think about that have already been somewhat disscussed, the plastic t's are junk, you will have to make you own metal ones like i did, and i have heard that the caps on the carbs will only hold 10 pounds, so if you were planning on more, might wanna look for billet caps

 

and as far as never running a reg, i never bothered cause i rarely ever hit fuel cut. i could pull 4 gears up to 90 before id hit fuel cut, and ive never needed to pull for any longer then that

[ssnapz]

im planing 8psi, and i dont want efi, to much clutter with wires and payne to tune. carbs are simple and cheap

[72240z]

Ok everyone knows everything lol gl 

[spudly13]

Ok everyone knows everything lol gl

Lol For the record when I do it again megasquirt is in my plans, after talking to icehouse a few times he's got me pretty convinced but for now the r1 turbo setup works just fine, and really is pretty easy to tune

[ssnapz]

plus the r1s look cool

[VintageRice]

I say if its a toy car and not a daily driver go for it. I know people on here are scared of bike carbs but these are so simple its sick. And theres TONS of people who have turbo'd them with great reliability........but on snowmobiles.   The 2003, 2004, 2005 yamaha RX1 snowmobile used the same carbs only a diff angle and everybody and their mom turbo'd those sleds out west. But......if it sucks and you hate it not my fault..........   :D

 

 

 

 

 

EFI would be more reliable and less headaches but c'mon.......everybody has EFI where's the fun in that! !    :confused:  :P

[VintageRice]

Do some reserch.  See, so many people turbo these carbs that a company makes these.

 

Billet "T" fittings, and I think there's billet carb caps too.                             EDIT yerp here they are.  Yikes hope its $185 for four and not one !!  

 

http://turboaddictionparts.com/catalog/rx1-billet-carb-float-bowl-tee-pair.html

 

[VintageRice]

Lookie here!  A RX1 intercooler! !  Wonder if the carb spacing in the same from the bike to the sled.......snot sure on that one........the motors are the same except the sled motor has no gearbox like the bike does........hrmmmmm I dunno....  either way its $1,395.00  YIKES !

 

[VintageRice]

Couple good threads on snowest.

 

 

 "RX1 carb referencing question" <-----------info on how to hook up reference lines for fuel compensation

http://www.snowestonline.com/forum/showthread.php?t=173815&highlight=RX1

 

Old school RX1 Turbo tuning

http://www.snowestonline.com/forum/showthread.php?t=226866&highlight=RX1

 

 

I think you have to become a free member of snowest forum to view...........gay.....a few years back they turned the forum into a pay site with premium members so you have a bunch of stupid restrictions..........I know ratsun would NEVER go there.....EVER........its evil....

[ssnapz]

i grew up on bikes so bike carbs are simple for me. and efi is for smog and if your scared to think outside the box

[72240z]

Talking so much shit lol efi is for people scared to think outside the box? This swap isnt outside the box it IS the box. How hard is it to hack a manifold and no hub it to a set of carbs, wow that's some macgyver type innovation.... It's so easy and played out even honda kids consider it an easy go to. 

EFI is more efficient and provides better control as well as consistency. Three things that are important when pushing boost. 

I like carbs and efi equal in their own right but keeps shit real. Carbs are easier and been done for like a century. Nothing original there... 

[spudly13]

Talking so much shit lol efi is for people scared to think outside the box? This swap isnt outside the box it IS the box. How hard is it to hack a manifold and no hub it to a set of carbs, wow that's some macgyver type innovation.... It's so easy and played out even honda kids consider it an easy go to. 

 

EFI is more efficient and provides better control as well as consistency. Three things that are important when pushing boost. 

 

I like carbs and efi equal in their own right but keeps hit real. Carbs are easier and been done for like a century. Nothing original there... 

 

Its true, if your going bike carbs cause they look cool....well... anyone who knows anything about datsuns will think fuel injection is just as cool, and while i have no idea the qaulity of work your capable of, again 72240z is right, its really easy to hack together a carb setup (just look at my car closely lol)

 

and... cold starts with these carbs sucks, terriable, full choke and gotta let it warm up for like 4 min before you can even move it... if this is for a dd i would re consider efi, but at the same time if your set on the carbs it works just fine.

 

another thing to consider, i dont know jack about the napz motor your using, but if its anything like my l20... stock l motors dont last long with boost, the cast pistons break, valve guides and seals go pretty quick and if your gunna do it, do it right, low comp, rebuilt head, good pistons etc

 

just my opinions

[spudly13]

Do some reserch.  See, so many people turbo these carbs that a company makes these.

 

Billet "T" fittings, and I think there's billet carb caps too.                             EDIT yerp here they are.  Yikes hope its $185 for four and not one !!  

 

http://turboaddictionparts.com/catalog/rx1-billet-carb-float-bowl-tee-pair.html

 

50 bucks lol ill stick to my homemade ones, they were free and look just as good haha

[72240z]

Ya that price seems a bit extreme to me lol. Bike parts always are though. I was looking at velocity stacks and they want BUKU bucks for a decent set of metal ones. I'm just going to snatch a bunch of the rubber sets, F that. Even though I'll have to buy 3 air boxes to get 6 matching lol. They want more for 1 set of velocity stacks then I paid for 2 sets of tb's.

I have trouble sometimes with my triples and cold starts. Dont have enrichment circuits hooked up though so that doesnt help lol. 

[ssnapz]

anyone play with the kawi kein carbs, i found a set for free.

[72240z]

Do you mean keihin?

[ssnapz]

yes i did

[72240z]

I have only done some basic cleaning and maint on them. They have a good rep. Other then that regarding your plans idk. 

[spudly13]

i havent messed with kawi keihin specifically, but keihin carbs were all i ran on my 2-stroke quads, (probally some differences and similarities) and they were very simple, easy to tune etc