760 single carb.....lean rear cyl

[Dazz]

B1 Frankensomethin 760......61X cases with 760 barrels
ported
single carb 48mm riva power bomb....
.
had a riva red pipe and i'm just changing over to a Mod pipe
.
rear cylinder was lean and melted a bit
.
is there anything inherent or unbalanced with these single inlet manifolds and with tuning
is there more load on rear cylinder....???
plug reads seem a little unbalanced..

.
.
just about to put it back into the water with new pistons and pipe
i've done a bit of a single carb rear lean search on the site...
any idea's ??
or any tips

 

[Matt_E]

I'd be looking real close at the rear crank seals with an air leak in mind.

 

[ryan]

what stator you running? what matt said is very possable.

 

[Dazz]

thanks i'll check that crank seal
.
stock stator i think.....why?

 

[ryan]

if your running the 760 stuff that is whats wrong. thats all. or the crank is off a few degrees.

 

[Dazz]

spoke to a mate with a ported 701, single 44 who just put on the mod pipe a couple of months back
leaned out a couple of rear pistons..
and now tunes and plug chops of the rear plug only....with front a little rich
checked cases and crank seals all good, new-as
......same sort of unbalanced thing through single intake manifold
.

 

[kevbo]

Its the 48mm carb. They have a way of slowly getting leaner at full throttle until one of the pistons melt. If long full throttle runs are important then use the stock 44. That 48 should only be for short bursts of WOT. I learned that the hard way along with many others, big singles are for freestyle only.

 

[ryan]

hum good to know.i may be testing that out real soon.

 

[Dazz]

http://www.x-h2o.com/threads/19403&page=2

geez...i hope not
want my cake and eat-it ......
surf machine and i'll be in the Sports Class CC course......fully pinned

 

[ryan]

i run my stuff wide open all day long.