Author Topic: '94 500 bullet carb tips/reviews  (Read 617 times)

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winsun-enfield

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on: April 02, 2021, 08:35:00 am
Hello internet,
Besides my enfield with winsun diesel i overhauled a '94 500 bullet.
The carb which came with it was utter crap so i decided to get a pwk-clone. May folks on the German enfield forum get one cheap (40-50 euro's) and seem happy with it.

Okay, cool.. There are some reports about quality issues with the cheaper ones (logic i think) so i got the most expensive of the cloneb i could find; a 28mm Polini PWK.

Alas, after many efforts, i can not get it adjusted right, it really behaves like a 2 stroke carb and -only- an other needle won't fix that.(there's more difference in a carb in this)

so, i made a bet on the wrong horse..
Now i could trt a pwk clone again(but which to be sure it works out?)

Besides that, a German dealer offers Dellorto PHBH30mm for the bullet 500.
Is there any expereince here with those?

Further i would be interested in setting/which intestines a -japanese- and which type mikuni should have.

At last i would like to know how the JRC carbs are getting along..


viczena

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Reply #1 on: April 02, 2021, 08:42:39 am
I dont understand that. Carbs should be easy to install and adjust. And run great ever after without fault.

Enough of pro Carb propaganda.

Withstand the temptation to use a racing carb with too much diameter. They will give you more hp on full throttle but they are not drivable in lower rpm.

Dellortos are prone to not beeing consistently adjustable. Mikuni are great carbs. Use an O2 sensor to adjust your carb through all rpm. Everything else is just guesswork.
« Last Edit: April 02, 2021, 09:25:38 am by viczena »
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winsun-enfield

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Reply #2 on: April 02, 2021, 11:30:23 am
A 2 stroke carb differs in more things then just the needle, the polini pwk is apparantly solely a 2 stroke carb. Some other pwk clones apparantly are 'universal'?

Are there people here who have tried JRC carbs? These are 'made from'pwk's, Íve read some complaints about the glued on flange that loosens, restrictive fuel intake and sticking slides..


ddavidv

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Reply #3 on: April 02, 2021, 01:02:18 pm
Mine came with a PWK on it already. I believe these were sold by Classic Motorworks when they were the importer. No idea what model it is but I can tell you it works flawlessly.

You could always stick an Amal on it. Plenty of knowledge out there on those and it would be 'original' to what these came with back in the day.
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cyrusb

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Reply #4 on: April 02, 2021, 02:20:32 pm
My PWK 30 with a glued on flange has operated perfectly for the last 15 years. As an aside, what is the difference between a 2 stoke carb and a 4 stroke carb that you guys speak of?
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Adrian II

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Reply #5 on: April 02, 2021, 02:27:04 pm
@ ddavidv and cyrusb

So what jets/needle settings are on your PWK?

@ viczena,

Quote
Withstand the temptation to use a racing carb with too much diameter. They will give you more hp on full throttle but they are not drivable in lower rpm.

Here's Bullet Whisperer on a 500 Fury fitted with a 38mm Amal Mk2 on a mix of country lanes and main road, it looks pretty drivable to me!

https://www.youtube.com/watch?v=p-Q11n9D4A8

@winsun-enfield

40 to 50 Euros? THAT much???

https://www.ebay.co.uk/itm/30mm-Universal-Motorcycle-30-PWK-30mm-Carburetor-For-Keihin-OKO-Fit-Race-Scoo-BE/174368669640?hash=item28992ebfc8:g:KWcAAOSwdMhefPrE

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


cyrusb

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Reply #6 on: April 02, 2021, 02:44:03 pm
Exact size I don't remember (15 years is a long time), but I do remember it came with 2 extra jets 1 larger and 1 smaller than the one installed. After trying all three it ran perfect with the middle as shipped jets. And of course thats with cone filter and free flowing bottle exhaust.
2005E Fixed and or Replaced: ignition, fenders,chainguard,wires,carb,headlight,seat,tailight,sprockets,chain,shocks,fork springs, exhaust system, horn,shifter,clutch arm, trafficators,crankcase vent.


ace.cafe

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Reply #7 on: April 02, 2021, 03:12:17 pm
Most, if not all, of these fake PWK carbs are from OKO in Taiwan. They used to be on Ebay for around 20 bucks or so.
The problem with these carbs, besides being so cheap that people can sell them and make profit at $20, is that it is very hard to get proper jets and needles for them.

JRC uses a OKO and glues a manifold stub on it.

Why don't you do yourself a favor and buy a real carburetor?
A VM32 Mikuni is only about $100, and a manifold from Sudco is about $25. All parts are readily available, and so are tuning instructions.

If you stick to the cheap stuff, you will never get out of your vicious circle of poor carbs.
My 2 cents.
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winsun-enfield

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Reply #8 on: April 02, 2021, 03:55:42 pm
I would like a good mikuni,. but what slide, neelde, jetting?
An enfield dealer sells dellorto phbh's for an enfield.. also revieuws about hard to adjust.


ace.cafe

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Reply #9 on: April 02, 2021, 04:02:45 pm
I would like a good mikuni,. but what slide, neelde, jetting?
An enfield dealer sells dellorto phbh's for an enfield.. also revieuws about hard to adjust.

There are many example of Mikuni jetting and tuning for VM32 or TM32 on this forum in the archives. Use the search function.
It is likely that you could get it very close to correct on your first try, if you read what others have done.

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AzCal Retred

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Reply #10 on: April 02, 2021, 04:40:11 pm
ACE @ # 7: a hearty +1 to not buying more cheap unsupported crap.

Get the pre-sorted Mikuni or the Amal, or simply make the MikCarb work with Hitchcocks jetting chart. Carbs are just so stories, once dialed they work well. You can pull a lot of hair out becoming a carb tuner, or you can get the sorted model and enjoy riding the bike. Fine tuning is one thing, starting from scratch is another.

Two-strokes are completely different engines, the intake mix gets gargled through the carb more than a 4-stroke does. The needle jets are different for one thing, often they hade "shields" on them. Without ready access to a box of tuning bits specific to your exact carb, there's a lot of guesswork involved. IF you can find another fellow that has a 28mm PWK on a Bullet AND has tuned it to run well AND has recorded in detail the exact internal bits used, you yourself can spend a large block of time rediscovering the wheel.

A new OEM MikCarb is about $100, the tuning path is well trodden, parts are readily available from H's to compensate for intake & exhaust mods. Both of mine work well. Unless you are running a forged piston, steel rod & needle bearing con rod and routinely winding to 6,000 RPM striving for HP, the 28mm MikCarb is good enough. For about $200 you can get the Amal, already sorted, well supported, with maybe a better choke system. The Mikuni is the same story but with better parts. I'd sort the MikCarb and go riding.

https://accessories.hitchcocksmotorcycles.com/accessory-shop/carburettor-kits/38529
PART No. 90086 ; CARBURETTOR KIT, MIKUNI 32mm (1989 - 2007 500 Bullet) ; £249.00
This is a genuine Japanese made 32mm Mikuni carburettor with all the necessary parts to fit the 500cc Bullet. It will give improved performance over the standard carburettor. The kit comprises of a Mikuni carburettor, special manifold, S&B air filter throttle cable and spare jets etc.


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viczena

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Reply #11 on: April 02, 2021, 05:29:52 pm
Is it painted blue?
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Stanley

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Reply #12 on: April 02, 2021, 06:27:16 pm
I was wary of the Chinese-made copy of a Taiwanese copy of a Keihin, so I went with JRC's Taiwanese copy. They offered me the jets to tune it but I got them on eBay from one of many suppliers. My bike ran fine after fettling with a main change and needle adjustment. The JRC bolts right on and negates the need for a leak-prone rubber hose.
I would avoid any PWK sold for $20.

 


AzCal Retred

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Reply #13 on: April 02, 2021, 06:54:22 pm
@ #11: It worked again!!  ;D  "Like a tuna to the bait..." Roy Latimer, 1986

@ #12: Stanley - Do you have the JRC Carb & jet numbers you used? It'd save a lot of trial & error. I like the bolt-on approach also. Any links to share?
« Last Edit: April 02, 2021, 06:58:02 pm by AzCal Retred »
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Stanley

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Reply #14 on: April 02, 2021, 07:07:26 pm
I'm afraid my notebook went to the new owner, but JRC was helpful with jetting.