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1981 C70 Passport Shenanigans

Good news - the timesert worked like a charm.

I did keep the head on, and just went two or three turns at a time once the larger part of the tap hit the head, then pulled back and cleaned. Rinse and repeat until it was done.

Probably about 30 mins all together. It really is a brilliant concept.

Bad news - same symptoms.

I’m starting to think that the main jet might be a little too big and wetting the plug as I come to a stop? It doesn’t look obscenely rich when I pull it, but that is after a necessary idle (no clutch = no legit plug chops).

OEM 70cc is:

38 idle/88 main/11.1mm float
Idle screw 1-1/4 turns out
Mix screw 2-1/2-3 turns out

My 89cc is:
40 idle/92 main/15mm float
Idle screw 1-1/4 turn out
Mix screw 1/4 turn out

The idle circuit is acting rich, as it really “wants” to be fully close when sitting on the lift puttering away. If I put a 38 idle in, the plug comes out white and wants to die without choke, even 3-4 turns out.
 
Time sert kit came it a bit later than I was hoping, so fabbed up support brackets for a rear box.

Hoping this pushes it over the edge into “must have” for someone on Facebook marketplace come spring.

View attachment 41045

View attachment 41046
You can install 8) 6mm timeserts/female Helicoils into the top of the edge of the wood sides of the box for a hold-down lid, Lol. :oops:
:)
Although closed,someone could rip that box off of it thinking it's full of good stuff.
 
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Good news - the timesert worked like a charm.

I did keep the head on, and just went two or three turns at a time once the larger part of the tap hit the head, then pulled back and cleaned. Rinse and repeat until it was done.

Probably about 30 mins all together. It really is a brilliant concept.

Bad news - same symptoms.

I’m starting to think that the main jet might be a little too big and wetting the plug as I come to a stop? It doesn’t look obscenely rich when I pull it, but that is after a necessary idle (no clutch = no legit plug chops).

OEM 70cc is:

38 idle/88 main/11.1mm float
Idle screw 1-1/4 turns out
Mix screw 2-1/2-3 turns out

My 89cc is:
40 idle/92 main/15mm float
Idle screw 1-1/4 turn out
Mix screw 1/4 turn out

The idle circuit is acting rich, as it really “wants” to be fully close when sitting on the lift puttering away. If I put a 38 idle in, the plug comes out white and wants to die without choke, even 3-4 turns out.
I would be looking at the needle jet & needle,might be too rich.
Did you say you re-installed the OEM brass ?
 
You can install 8) 6mm timeserts/female Helicoils into the top of the edge of the wood sides of the box for a hold-down lid, Lol. :oops:
:)
Although closed,someone could rip that box off of it thinking it's full of good stuff.

Not sure I’m following… the box is always open on top.
I would be looking at the needle jet & needle,might be too rich.
Did you say you re-installed the OEM brass ?

So, it’s an aftermarket carb to give me adjustability on the idle jet (the OEM Keihin has a pressed in idle jet). It is the needle and needle seat that came with *that* carb.
 
Ed, an aftermarket carb can cause the running issues/problems you're experiencing.
They are built very quickly and In China and not jetted/tuned to that application/engine.
I know a new original is not available..
 
The sheng Wei carbs sold by dr atv are considered to be the “good” aftermarket carbs. I don’t think the original would be able to accommodate the big bore kit
 
The sheng Wei carbs sold by dr atv are considered to be the “good” aftermarket carbs. I don’t think the original would be able to accommodate the big bore kit
Don't under-estimate the performance of the stock carburetor.
These small engines are very sensitive to carb. changes.
I don't know the condition of your original including the non-removable pilot jet .. which can get reamed-out by mistake when someone is cleaning it w/ too harsh of a method.
The OEM carb may surprise you with it's good performance,even with the big bore kit.
I run a stock CB125S(124cc)carb(special 25mm spigot-type which came on 76-78' models)on my installed XL200R spec. engine,and even with the stock 76' CB125S headpipe & CB350 stock muffler,it works Great.
I could install an OEM XR200R carb. for quicker performance if I get the head ported and I drag raced it,but I'm running stop and go street conditions :OEM Keihin Rules (y) (y) imo.
The 'size of the valves' will only allow just so much flow,but the way your stock carb. has been designed by the OEM to nicely flow through that engine and atomize the fuel/air at all different rpms and load conditions works excellent,imo.
The size of the throat and slide may look too small.. don't let that turn you off to it's good performance.

You look at the inlet size to this carb. and it looks too small,but I installed it 9 years ago and wouldn't run any other;any time I see a used one on Ebay,I grab it for a spare,like this one.
Good all-around performance year-round.

Ed, you may find an old S90 engine,carb.,exh. some day to install into that 'Messenger Bike' and have a blast.
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Looking for an S90 carb might not be a bad idea at all
If you can port/match it to the size of your engine's manifold.

A CT90 manifold(using a S90 stock carb)may.. have enough of a bend to clear the frame,etc..
The intake port/cyl. head side of the CT90 manifold has a larger hole? but JBWeld can be used inside the larger hole to form a matching size port to your cyl. head using Prussian Blue,if the bolt pattern will fit.. only way to know is ask someone with a CT90/S90 to remove the manifold from their cyl. head and measure the bolt holes across.

You can also carefully open-up your stock 72cc manifold to accept the larger carb.
 
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Signs of life. swapped the original carb back on and played the jetting game for about two hours. It feels like it wants a 98 on the main, but with that I can't get it to idle - too rich. No float adjustment on the OEM carb. I might swap in an adjustable float, but that may also be getting too ridiculous with what's just meant to be a springtime sale so I can upgrade to something more reliable for every day transportation around the city.

Could also be a needle issue, I believe I'm using a "good" aftermarket one. No luck on ebay finding an OEM one, but hoping a buddy of mine that's into passports has a quality one. Will see when he's back from a trip.
 
Does anyone know what might cause a blinker to stay on solid?

The right side winks as normal, albeit with the low voltage at idle it gets about 4-5 winks and then goes solid. Picks up again once the engine revs up.

Left side will only blink when the engine is revving relatively hard. At idle it’s usually solid immediately unless I just came off a long high rev stretch.

I believe all the contacts are fine on both the front and back. A bit odd.
 
Does anyone know what might cause a blinker to stay on solid?

The right side winks as normal, albeit with the low voltage at idle it gets about 4-5 winks and then goes solid. Picks up again once the engine revs up.

Left side will only blink when the engine is revving relatively hard. At idle it’s usually solid immediately unless I just came off a long high rev stretch.

I believe all the contacts are fine on both the front and back. A bit odd.
The -Ground/earth path to each blinker;take a look to see if your main harness frame ground wires have solid continuity and the path which grounds the socket on each one of the blinker lights.
 
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Does anyone know what might cause a blinker to stay on solid?

The right side winks as normal, albeit with the low voltage at idle it gets about 4-5 winks and then goes solid. Picks up again once the engine revs up.

Left side will only blink when the engine is revving relatively hard. At idle it’s usually solid immediately unless I just came off a long high rev stretch.

I believe all the contacts are fine on both the front and back. A bit odd.
Check the grounds first as @bilbikek411 advised and then check the bullet connectors are all connected properly with no corrosion. Last thing and not likely is swap the bulbs from left to right and see if the problem moves to the other side just in case there is a problem with a bulb by some chance.
 
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