mikuni vs keihin carb reliability

[dieselr3]

ok Ive had enuff trying to get this F#$king POS going.
Ive now gone thru my mikunis and replaced everything it ran awesome for 1 week,then spent 2 weeks out of action after spending hundreds on a new shock then its back to running like crap again.These mikunis just wont stay in tune.All seals execpt carb to head and carb to airbox rubbers have been replaced with stock jets and internals,new float valves and set to 14.5mm,the carb rubbers on order are the last straw if it dosnt fix it!

Tell me guys are the keihins more reliable than the mikunis? becouse this bike is on the verge of being set alight,all other common faults have been looked at,ie 3 nology coils,ignition ignitor,new plugs,new cam chain,valve clearance all done/replaced,this bike is the most frustrating bike Ive ever owned.I put new float vales and o rings in and it went awesome for 1 week then out of the blue back to shit,WTF?,its backfiring thru the exhaust,CV rubbers new,no amount of tuning will sort it out,are the keihins more bullet proof/less trouble?,cheers

[JetdocX]

Carbs are the reason we invented fuel injection.  I feel your pain.  It seems I need to tear my Keihin carbs down once or twice a year do to some errant POS in an oriface somewhere causing a new and different problem every time.

Think how good you'll  get at doing them, though. :lol:

[dieselr3]

LOL,yea its like that unfortunatly I use my bikes as transport and cant justify taking carbs apart every few months for cleaning or fixing carbs!,they must be better than this surely,

[Bixxer Bob]

I don't have a lot of carb experience, and have never owned a Steamer, although it's basically the same engine as I had in my 900 Trident.

Anyway, for what it's worth, if there's crap getting in, it's only coming from one of two places - the airflow (so is your filter properly seated with no leaks and no leaks on the adjoining rubbers?) or the fuel (is the float bowl clean, is the fuel filter blocked or holed, is it up to the job or do you need to fit an in-line filter).

Oh, and another thing, do you maybe have water in your fuel? Don't ask me how I know that, I just suffered a blocked filler cap drain on my Girly.... :oops:  I drained the tank into a plastic container and found about a cupfull of water in the bottom.

[dieselr3]

cheers for replies,no water in the fuel.All fuel filters are good brand new fuel tap too.Not sure about the carb boots they are the one thing I havnt done,have sprayed carb cleaner around them but had no result,but beside that Ive pulled the trigger and going to put keihins on and rejet as per the forum recomendations.Also seems a few folk on the RAT forum change over too with better results,its worth a go before I torch the bike!might look at plug leads too,they also havnt been replaced,coils are nologys and not very old.The keihins look more robust 4 screws on the carb top and bowls,no float o rings,etc too leak around.

[MtheTiger]

I found out whilst overhauling my Tigger that the tank was full of gunk diluted in the gas. the gas looked white as milk when I poured it out :shock:  :shock:
This same stuff had stuffed up my reserve fuelfilter and mad it useless. before I put on the new petcock I rinsed my tank thrice with petrol and two time the white gunk kept coming out. After the rinsing no more problems apart from the new petcock that has begun leaking (dripping) again  :twisted:


Nice link for Mikuni replacement stuff:
http://www.mikuni-topham.de/

[NeilD]

I've got Mikunis on the Tiger and kehins on the TBS... Tiger had new diaphrams fitted just before I bought it end of last year and I've not touched then since (about 8000 miles on)... TBS I've had for 4 years/18000 miles and never touched the carbs except balance them last year  - I think I may need to finally delve in to them this winter as the enrichers arent working properly... only benefit of the Kehins are they seem to be more economical..  doesnt help you, but just trying to say that I dont think either are particularly unreliable, so wonder if your problem is actually outside the carbs on the supply side, or electrical?

[Mustang]

... only benefit of the Kehins are they seem to be more economical..  doesnt help you, but just trying to say that I dont think either are particularly unreliable, so wonder if your problem is actually outside the carbs on the supply side, or electrical?

I agree completely neither is better than the other , the keihins came jetted lean from the factory and need to be tweaked a bit
the mikunis are gas hogs but have a sweet midrange

I have a set of 15 year old ones on the 95 that were never touched until this year , they finally needed a cleaning after sitting all last winter .

The mikunis are more prone to needing a good flogging (read that as run the piss out of it for 10 miles or so )in the springtime to get the cobwebs out after sitting a while

[dieselr3]

cool,thanks guys for the input.Yea Im not sure if it is carbs or not,as Ive replaced the ignition sensor,and all 3 coils with nologys a year ago.I spose the last thing left would be plug leads,again this could be the root cause,and also carb manifold rubbers which are on order.Just very frustating when it ran awesome for a week,then for no reason back to pile of crap!

[pKp]

Probably not the case, but I can tell you from experience the K carbs are VERY picky about the gas quality. Just this weekend I went out to start 'er up for a ride - idled fine, ran OK. Then suddenly she would not take gas. I mean nothing. Twist the throttle - tries to die. Idled fine though.

Went through the same process as you in my head - coils, wires, etc - then remembered a post where someone said "drain the float bowls first!" So I drained all three float bowls - cranked her up - took off like a rocket...

[D-Fuzz]

When you talk about fuel quality, do you mean a preference for fresh gas versus stale gas? Or do you mean in regards to the octane/ethanol content of the gas?  It seems like it doesn't take long these days for gas to go bad and start gumming stuff up.

[pKp]

I think it's either way - old vs new or bad vs good. I can tell you that the gas that came out of the float bowls looked fine to my eye - certainly no water visible. Maybe a touch cloudy...

I'm putting on an in-line filter tonight...