Keihin PE28 Baseline Jetting (yx160)

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KtmJono_777

KtmJono_777

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Jul 13, 2011
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Location
Shellharbour, NSW
I have a PE28 Carby that has stock jets 125MJ 40PJ but has a JFQ needle. Its on a stock yx160. Could someone who is running a PE28 on a yx150/160 give me some direction for a baseline jet setup? I need to go and buy some new jets because the stock 125/40 is way rich. Bike only starts with throttle open, dies when the choke is pulled and won't idle. Also sounds like sh!te when running. (think big wet farts, its horrid) :action-smiley-003:

It was meant to have a 120MJ 30PJ installed when I purchased it, but that didn't happen. Would 120/30 be too lean? I have looked online and I have seen some threads of people running 120/35-38 on daytona 150 engines so 30 seems too lean. But I have no idea and don't want to order $80 worth of jets from showandgo to find a baseline. :bigcry:

Any help? I will be riding in a few weeks and this should have been sorted already. Grrrrrr. Thanks all.

Jono.
 
30 is likely to be too lean, and unavailable(my mixup), thus the installed baseline.

I'll Express the smaller jets 35/38. I'd intended to send with the shock, but that went to Hell.. Sorry.
 
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I'm gueing your at Sea level.. If it a genuine Keihin start with 38 pilot and a 102 main jets, (genuine Hex style) middle clip on the needle and 2.5 turns out on the air screw.
Go from there and see how it goes, Works for me and others on stock yx160's.
 
yeah Pete's sounds a little lean on the main. i can only give some input on a daytona 150 and 160 engine. i ran a 38 - 42 pilot and 118 main that was dyno'd and had a pretty consistent 13:1 air fuel readout.
 
Thanks everyone. 102 main does sound very lean. Is that with a JFQ needle Barnesd? 118 seems like it would be a good drop from 125. I have a 118 here too, might give it a crack. Hopefully I can combine that with the 35 or 38 from Terry and find a good setup. I'll double check my float height as well. Thanks again I appreciate all the info! Legends.
 
Barnesd09 said:
I'm gueing your at Sea level.. If it a genuine Keihin start with 38 pilot and a 102 main jets, (genuine Hex style) middle clip on the needle and 2.5 turns out on the air screw.
Go from there and see how it goes, Works for me and others on stock yx160's.
Click to expand...

Yes sea level, sorry forgot to ad that.
 
i ran a 38 in my DOHC daytona 160cc setup and the pipe would glow red in about 40sec at night. too lean for me. but i imagine this range would be good for your engine. all im saying is maybe test it in the dark so you can see if it runs lean. just a thought.

also i remember i ran my ported 2v daytona 160cc with a 125 main and it seemed to run ok. the plug said it was a little rich though. when dyno'd with the DOHC head, it asked for a 118 to be right on the money but i ran a 120 at night just to give the engine some loving.

hope this gives you some reference points.

also have a look around the net for pages and pics on how to read a 4 stroke plug color.
 
i might also add that main jet size has a lot to do with cam and valve springs.

stock yx160 will float the valves early so it doesnt need nor can it use a big main jet.
 
i run 38/120 on the 184 and it's good enough to tune with the air screw to all altitudes

i ran the same on the 26mm on the 175 that was sweet to

i'd go 38 pilot and somewhere between 102-112 main i'm not sure of the heihn size between there
 
The_GDFP said:
Ten mains, 100-122, on the way.
Click to expand...

Got those mains today. Cheers Terry :thumbup:
I also ordered a 102 and 108 Keihin plus a 38PJ from showandgo here in aus just in case yours didn't get here before chrissy. That would have been upsetting. lol. Hopefully I can get it sorted asap now.
 
sean01 said:
38/102 should be a pretty spot on starting point..

118 in a stock yx160 is miles to big..
Click to expand...

coolmodee01 said:
i run 38/120 on the 184 and it's good enough to tune with the air screw to all altitudes

i ran the same on the 26mm on the 175 that was sweet to

i'd go 38 pilot and somewhere between 102-112 main i'm not sure of the heihn size between there
Click to expand...


Ok so I have put in a 38/102 combo and no go. Still won't start without open throttle and sounds like a running turd. However once started it will idle now.

I have the air screw at 4 turns now to try and get more air in there. I'm pretty sure its mega rich. Plug is soaked and black, and like I said won't start without throttle cracked open about 1/4.

I noticed that during all the kicking it was leaking petrol out the overflow so I attempted to check the float level. I found it hard to get a measurement seeing as the floats are boxy but have a slight bulge on half of the lower surface, so I measure from the bulge.. who knows if that was right!?

Also it seemed like the float height was at 17mm and according the keihin website it should have been 14mm. I attempted to bend the tab to correct it but 14mm gives the float very little room before the flaot hits the roof of the carby. It seemed wrong. I also thought that if it was leaking then the float should have been less that 14mm, so thats confused me.. Its still leaking now so I have no idea what to do with that.

I'm wondering if this carby might have issues. Its not responding like it should to changes. Terry was this a new unit? I noticed the pilot jet that was in it had scratch marks on it and the scew driver notch was a bit mangled. Bot the jets that came in it were also dull in color not like new jets which are shiny and un marked. I'm sure it was a new unit, but I'm not having any luck with any of it right now.

Sorry for the long msg, just running out of answers. I'm riding in 4 days time and with Christmas on the weekend its looking like I won't be using this carby. :thumbdown:
 
Well, crap. Brand new carb, same one I have on my test bike. Jet marring was from swapping it.
Maybe you got some debris in the seat/needle, if it leaked. 4 turns is outside the adjustment range, typically. Air filter isn't over-oiled?
I have four PE28 and two PWK's on my stuff, and they all run great with 38/40 and 2 turns or so, 125-200+ builds. Nearly every video I post of a runner, is that carb.
Sorry for your grief, but some thing is amiss. VM26's leak a bit, but a Keihin should hold her liquor.
 
id be stripping the carb completely and give it a good blow out with compressed air..
re-do the float height to where it was previously.
replace or at least inspect all the inlet gaskets and rubber manifold adapter, make sure your pushing the carb right in the adapter as well..
also make sure there isnt any vacuum vent tubes on the carb left unsealed..

might pay to check your rocker clearances and make sure the exhaust gasket isn't leaking..

replace the spark plug and tune it with no air filter unless its too dusty where you are.
also make sure its not choking sitting in a locked up shed or something with no fresh air..
bad air temp makes it hard to tune..

i guessing this engine ran sweet with the last carby?
 
The_GDFP said:
Well, crap. Brand new carb, same one I have on my test bike. Jet marring was from swapping it.
Maybe you got some debris in the seat/needle, if it leaked. 4 turns is outside the adjustment range, typically. Air filter isn't over-oiled?
I have four PE28 and two PWK's on my stuff, and they all run great with 38/40 and 2 turns or so, 125-200+ builds. Nearly every video I post of a runner, is that carb.
Sorry for your grief, but some thing is amiss. VM26's leak a bit, but a Keihin should hold her liquor.
Click to expand...

sean01 said:
id be stripping the carb completely and give it a good blow out with compressed air..
re-do the float height to where it was previously.
replace or at least inspect all the inlet gaskets and rubber manifold adapter, make sure your pushing the carb right in the adapter as well..
also make sure there isnt any vacuum vent tubes on the carb left unsealed..

might pay to check your rocker clearances and make sure the exhaust gasket isn't leaking..

replace the spark plug and tune it with no air filter unless its too dusty where you are.
also make sure its not choking sitting in a locked up shed or something with no fresh air..
bad air temp makes it hard to tune..

i guessing this engine ran sweet with the last carby?
Click to expand...

Thanks fellas. So I have got it working! I went back and put the OE Molkt carby back on to ensure I hadn't f'ed up the valve adjustments and to isolate the problem. Bike started and ran after 3-5 kicks.

So then I pulled the PE apart. Removed all jets and the air screw. Blew through all hoses and pathways and blasted them with carby cleaner. I also gave the float back its 2-3mm so its at around 16mm now, even tho keihin calls for 14mm.

I then put it all back together very carefully. I set the AS to 2 turns out. wound up the idle adjuster to get more air in and put it on. I also spun and pushed at the rubber adapter (carb to intake manifold), but it really didn't look like it changed much. I also screwed that adapter clamp down like a biatch to make sure it wasn't leaking.

Then I started kicking. 10 kicks later and it fired up and went ballistic! Woah! Killswitch!!!! So I wound down the idle adjuster. 5 minutes of kicking later it fired again and I caught it with the throttle. It sounded friggen sweet and crisp, but would die immediately without riding the throttle a touch.

So I turned in the idle adjuster 2 turns. Walah! It was idling!!! So I quickly played with the AS and at 1 turn out it struggled but increased idle speed up to 3-3.5 turns out. I also dropped the idle adjuster a touch till it was just about spot on.

When the revs drop down after revving they fall below idle then climb back up. That is a sign of it being too rich yeah? Maybe I need to get a 35PJ in there?

Even revving it in the shed it feels and sounds more powerful then the Molkt! Its really crisp and strong. Like going from a garden hose to a pressure washer, just for a random analogy. Its totally horn!

I also noticed when revving hard that fuel mist was pushing back out the intake of the carby. Is that normal? Maybe just because the filter wasn't on?

Anyway when kicking its still leaking fuel like sieve, but maybe thats normal when being kicked for 5 minutes straight? Also I have no idea why its working now!! Maybe the rubber adapter was leaking air, and all the kicking was soaking the cylinder with unburnt fuel? But it still seems like its rich so hmmmm.. Thoughts?

Thanks so much for reading all this and helping. Sorry I've been a PITA Terry, thanks for not ignoring me! haha. I think this carby is going to be a weapon.. Pretty stoked now :)
 
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