CB 360 tuning, carb, jets/pods questions.....

M

Moglix

cb360....
so i have a bunch of questions regarding http://www.dotheton.com/forum/index.php?topic=20960.0

I have been pretty slack on updating progress but have finished it with the good help of my bro in law...

Its had larger jets put in, new diaphrams, pods, re wired most of the bike, and also drilled out old coils and rewired. Since rewiring the coils a massive improvment in spark.... Did the tappets, set point etc. New fuel etc etc
This hasn't been ridden in over a year, but started bout 7th kick, sounded amazing...

HOWEVER problem when I went to ride was that it lost power when under exceleration, and ran like a bag of shit. We pulled plugs out and looks like under load it has poorer spark. It basically just ran really poorly. they weren't fouled up so straight away thought it must be air intake.
haven't checked compression but will do but wondering about some insight into what it could be, is it the pods etc?
I spoke to an old honda dude here in chch, NZ ,who used to race cb350's he told me pods are a nightmare on these, and that i should run velocity stacks? would that be worse or better??

I have searched through to look at other posts etc, and crazypj seems like the man! I'm new to all this so have no really concrete idea as to what now? there could be a number of different things from what I've read..

Any help woukld be greatly appreciated, I'll also add some photos to the other thread soon..
 
What size jets were fitted?
Fit 110~112 secondary main jets, set float level to 21mm.
DO NOT shim needles or drill air lift holes in slide.
It will still be rich mid-range but better than what you have now
Sending them to me for mods isn't practical from NZ
Post a pic of exhaust system
Did it go flat around 4,500~5,000 rpm? that's where they get real rich, you can see on my dyno print out on the lower graph (fuel/air ratio 9~10:1)
 
Thanks for the reply PJ! I'll double check the size, was told by the guy how installed the jets they were next size up from standard.
4500-5000 sounds about right for flating out, spluttering from pipes etc too.
Question, would it be better to run pods or stacks? The guy I've been speaking to swears thats stacks will be way better, said he can make some, tune the bike up really nice for a few beers. Would stacks be better han pods, and stop it from being rich in the mid range?
This is the exhaust system thus far, an old photo but thats whats on now as ipurchased the bike..
DSC_0003.jpg
 
The exhaust is about right length to work.
Stacks should smooth airflow but won't really do much for the mid-range rich problem, that's caused by change in induction length and different airflow characteristics..
You could probably use 107.5 or 110 instead of 112.
I think that if it was possible to drop the needles about 1mm it would really help mid range but as they are fixed it's going to be difficult.
I haven't modified seat in slide, if it gets screwed up new slides are real expensive (I'll experiment with most things eventually)
I bought some carbs off eBay so may try counter boring needle seat 0.5mm (still cost me $160.00 with shipping :o )
If your former racer thinks he can do it, go for it.
You will get increased engine wear without filters though.
Maybe you could find a filer that would fit over the end of stack?
 
awesome info!! I'm dropping to my man tomorrow for some stacks and tuning, hoping that this sorts it. If not will go back to plan b, go through the tuning of the carbs to pods.. Will update
 
picked up the bike the other day.... is running better, stacks made... I dont think that it was re jetted at all, just the stacks added.
Pj, would the above info for jets etc still be the same for these? It was starting to want to dye when slowing to a stop, this would mean to rich??
not sure wether i need to adjust the pull throttle, air/fuel mix jets or re jet carbs... any help would be appreciated...!thanks
P6010852.jpg
 
Moglix said:
Pj, would the above info for jets etc still be the same for these?
Click to expand...

Your probably going to need around 105~115 secondary mains and raise float level to 21mm
Did we go through the air jet thing? (screw in vs press in?)
I will be making a few this week
 
Finally got round to it, the weather here has been soooo shit recently..
Pj your a legend, put in 110's, set floats to 21mm and boom, no crackle, back fire etc. runs noticable better and stronger.
Thanks for your help!
 
Righto, so Pj i hope your out there :)
So bike has/ had been running sweet for awhile, the other day when i went to ride home bike wouldn't start. Eventually got it home, running on one, thought might have been one of the carbs that I didn't use gasket sealer on when rejetting.
So pulled carbs of, checked jets etc to make sure not blocked, sealed, put back on...
Kicked over and still on one, after mucking round for a bit bought two new plugs and then was fine.
However, plugs after quick 40 sec ride were blackened a bit, dry. Does this mean I'm overfueling, therefore should go done in Jet and set the float level a little higher? Also I never looked at size of primary jets, what should they be? or more so, what would be ideal for what I currently have set up?
Any help would be great!
 
Primary mains are #68
You may need 107.5 secondaries, at least they are easy to get hold of
Don't set float higher than 21mm
 
Anyone got a link to a good online stores for jets?? Weird question maybe but here in NZ the local here want $30 for 2... hey cant e worth that much?? Cant find the specific ones on ebay so any help would be great!
 
http://www.jetsrus.com/
If they won't ship direct to NZ let me know and I can forward them
 
PJ,
Would you say there is any difference between genuine jets or OEM equivalent jets on that site? I have been getting most of my jets from http://mikesxs.com, but they only have Mikuni jets. I am used to paying about $3/jet.
 
Jetsrus has option for OEM or aftermarket.
I use aftermarket, they are not the same as OEM but close enough not to matter.
I think if was critical for EPA/emissions things would be a bit different but even then it would mean finding a mm/letter or number drill inbetween sizes
 
Pj sending you an email re jets as I sorted, been away from computer for a while...

So i still have a problem. My bike seems to be running rich. Floats are at 21mm, have tried jets of 110, now 108. Plugs still fouling and getting dirty (dry). I have replaced points etc, set timing, replaced condensors. Spark is good.
Seems to run fine but then fouls when at idel or low revs, when revs are up is sweet, have full power etc, so it seems more of a bottom range issue?

So any thoughts as to is this purely jetting, or would there be anything to do with carb balence/intake? I have some 105's to chuck in too, but before i do that is there anything else it could be? Wrong plugs...???

I'm lost
 
Was reading someone elses post about running stacks. They suggest running bigger secondaries. wouldn't that mean if its runnig rich now at 108's putting in say a 115 would be overfueling it massively....
Fuck, so confused... been riding to work and cleaning plugs on the way at least 2-3 times.... it's not even a far ride :)
 
re carbs synced properly?
Where are mixture screw set?
Try setting them at 3/4 turn out (leans up idle) go out 1/4 turn and test ride
Fit a rear brace to prevent carbs tilting, as they droop bike gets rich (see Trek97's mod)
 
Mixture screw is turned out 1 and a half turns. Carbs aren't synced/ balanced properly, have tried but not sure if i have right...... That still needs doing...
Would these alone make it foul up?
Thanks again, will check Treks mod too...
 
Valves need to be adjusted correctly and timing needs to be set before carb sync
Try screwing mixture screws in 1/4 turn and see what difference it makes
 
hey pj i figured you might be the guy to ask
i am syncing carbs and at idle my manometer says their even, although i can feel exhaust pressure isnt the same from both and then as i open the throttle the right one tends to suck in more air. what could cause this?
 
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