Mikuni & raceback

[-JC-1]

When using a race back adapter on a Mikuni 48, is it necessary to use the 1/4" manifold spacer when attaching to a G manifold?
Or can I mount the Mikuni and race back directly to the G manifold with no I'll effect?
Tia

Joe

[dynaglide]

It'll clear the cylinders no problem w/just the raceback adapter.

[-JC-1]

Yes it does, just to clarify- I've already done it with, but I'm still not quite clearing the tank, even with a 3/8 washer under the rear gas tank mount, so I'm thinking that eliminating the 1/4 spacer- might just give me enough room.

my concern is removing that 1/4" of insulation between the manifold and the race back,

?

thanks,

joe

[dynaglide]

removing the 1/4" will have no effect on the carb, but don't know if it'll do the trick w/the tank, I have no experience about that.
What kind of bike?  Maybe lifting the front of the tank instead of the rear might work better...?

[-JC-1]

04 electra glide, I don't see an easy way to lift tank front?

[Admiral Akbar]

The 1/4 spacer is supposed to reduce carb heating from the intake manifold on a G carb.. On a 48, the should be some rubber seal between the adapter and the carb.. I'm not familiar with the race back but if it allows too much heat from the manifold to flow from the to the carb there may be issues..   You can do is use an Ultima manifold which is nothing more than one that is like a stock CV manifold with the rubber.. Since you have the race back I'd give it a try.. One thing that I've noticed is that the needle jet on the 48 is way too small.. You get a bad lean cough at cruise..

Max

[Tattoo]

I used a 1/4 spacer under the rear tank mount on my 2006 FLHX, it cleared my 48 Mikuni with the race back. I raised the stock needle one groove and seeems to be ok...

[hrdtail78]

I have seen some problems not running the insulator spacer.  But I do know of one out there without it.  He says he has no problems without it.  The raceback will tranfer the heat to the carb.

[dynaglide]

What's the issue with heat transfer to a Mik?  Is it specific to the 48s?  I run a Mik 45 with a racerback adapter on an "E" manifold, and haven't noticed any problem - but then again, I may not know what I'm missing...

[hrdtail78]

I saw inconstancy's with A/F as the engine heated up.  Carb body got heated with cylinder heads.  Infrared showed heat.  I don't think this is only 48's, and it could just be their crappy float bowl design.

[Admiral Akbar]

I saw inconstancy's with A/F as the engine heated up.  Carb body got heated with cylinder heads.  Infrared showed heat.  I don't think this is only 48's, and it could just be their crappy float bowl design.

Amen to that.. Some one needs to come up with a better after market one..

Max

[hrdtail78]

Make me one Max, and I will try it on my 48.  I don't even want it for free.

[fergy1940]

hrdtail78 I'm thinking of using the 48 Mikuni what is the problem with bowl? TIA
Fergy

[Tattoo]

I have had no issues with mine....

[tmwmoose]

I used a spigot manifold from Rivera eng 48mikuni kit no tank issue's

[hrdtail78]

hrdtail78 I'm thinking of using the 48 Mikuni what is the problem with bowl? TIA
Fergy

It's small.  So it has difficulties holding float level consistant.  A baffle would help.  Still a great carb.

[Admiral Akbar]

That brings up a point.. Anyone running a fuel pump? Where is a good place to get one?

Max

[-JC-1]

I used a spigot manifold from Rivera eng 48mikuni kit no tank issue's

Yup, a spigot manifold would pull mine in closer to the motor, but I just got it all back together last nite with the 1/4" spacer, and I tweaked the spool a touch to get 1/8" clearance under the tank. Alls good now and I'm gonna leave it that way.

For a while


Joe

[tmwmoose]

Don't forget the rubber mount motor mounts "shaky shaky" hope 1/8" is enough