Mikuni 38's on a 78SE!?

adi1974

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Hi there, my 78SE appears to have Mikuni 34's (AMEND) on it when it would originally have had 38's (AMEND. I'm in the process of getting it running after about a year and a half.

Basically I wondered if its worth me sticking with the 38's and getting them sorted and tuned or whether I'd be better off with 38s (AMEND) in the first place?

Some background..... It has aftermarket exhaust (cocktail shakers) and K+N filters, not much else modified. There rest is cosmetics really. Last summer I realized the carbs were flooding and opened them up, cleaned what I could and replaced o rings that were perished and letting fuel flood into the float bowls. I set the ignition timing also and recently adjusted the valve clearances (although I therefore think I need to do the timing again). Put fresh fuel in and it started pretty easily on the choke. Dies when I kill the choke after 5mins or so. The new plugs were quite blackened (from only being on choke?). I did notice that fuel through the filter was a bit slow so will replace that at the weekend. I've not had it on the road since I bought it 2 / 3 years ago (started a family in the meantime)so I dont know how well the carbs were performing prior to my ownership.

So, yeah, basically, am I likely to be able to get these 34's (AMEND) working well or should I start looking for replacements to get me off to a better start?

Thanks in advance
 
Last edited:
SORRY MY MISTAKE! Tired, long day. I got it the wrong way around they're 34's on it when it should have 38's! (Doh!!!)
 
Yes, you can make them work well on your '78. They are, in fact, better carbs - newer and a more modern design, also lighter so less strain on the boots if running pods. Sounds like you need to clean them again or better. Sounds like your pilot circuit is plugged. That's why it stalls when you take the choke off. You shouldn't need the choke for much longer than a minute or so in warm weather. I can flick mine off in 10 or 15 seconds. It needs it to start when cold but can be shut off almost immediately.
 
Not a problem, we all make mistakes.
I think the BS34's have a slight edge on driveability. Smoother responce across the rpm range.
Fix what you have.
Leo
 
Thanks guys, that sets my mind (the tired one) at rest. I'll try and get time to pull them off and have a look, clean em up and see if there's anything amiss. Obviously there's lots of variables I've yet to dial in so I'm not surprised its not spot on but its good to know I'm not starting off on the wrong foot. Cheers!
 
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