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Chinese 27mm Pumper Carb;

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I am contemplating trying one of these pumper carbs on the ol' XR200R.

 

It looks like you can dial in when the pumper actually works and the duration. 

 

Any thoughts on from an application stand point. 

 

TeamRude, have you ever tried one of these out by chance ???

 

Had one on my old KLX 331 and loved it (Mikuni TM33). 

 

http://www.ebay.com/itm/321309022955?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Michael 

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Thanks VortecVPI,

 

However not enough detail to make any sort of determination. 

 

The stock one performs extremely well, however there are times when lugging the motor, those pumpers come in handy. 

 

I am throwing out the 27mm pumper carb option for a stock motor with an opened up exhaust.

 

If I had a 218, then a 30mm pumper would sound like a viable option.

 

I have been following some the AJP PR4 write ups and it comes with a 30mm pumper carb running a Chinese Honda CRF230F semi copy motor. 

 

It is a Keihin/Deni PZ30 w/ accelerator pump, aka "pumper carb".

 

AJP puts in a lot of R&D time and would not put on a pumper carb if it did work. 

 

Things are kind of light lately on the 200R improvements, so I thought I would stimulate some conversation.

 

Michael 

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you will need a split cable,two ends to carb,one for pump,one for slide. I have this carb sitting in garage for 2 years! Couldn't get a cable to work,and the carb sellers don't offer one,at least they didn't when I was looking,i asked them. Ended up with stock carb on big bore xr200 with an xrs only headpipe pipe and wr250f muffler,runs well like this. Let us know if you get cable for it,would still like to try it! Could probably get a cable for small twin carb bike and modify it,i didn't try that.

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Chuck just mentioned in the CRF230 forum he will be trying a Keihin PWK28 on his XR218.  We have a few guys using these on CRF230s and they are raving about them.  I will be trying one soon as well.

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That'll work! Nice thread

 

But these pumper carbs would be bolt on and cheap; IMO could be a cheap and easy  improvement over stock carb for a modded engine. Based on my experience with the pumper carb on my CRF250X a  pumper carb on a XR should really improve throttle response. Might be better than a PWK28.  :thinking:  Tuning required. :(

 

I have a PWK28 ready to go onto my 218, just a few loose ends: Need to mod a manifold I built for the BSR 31 or build a new one. Install a larger XR250R air boot to the air box. Buy a different slide. And machine a carb bell to air boot adapter. Prob won't start that until the end of April. Because of this thread a PZ30 is tempting because what a AP would do for throttle response.

 

I am looking for a junk 86+ XR200R frame to use as a mock up. Just need enough of an engine bay so I can install a mock up engine (I have old parts),  the coil and CDI module,  and enough air box area to mount an air box.  Anyone have one?

 

So as I sit here in AZ  I've been researching doing several EFI projects for two XR218s and a CRF250X. Mostly out of frustration with tuning the CRF250X carb, but also because of other functions that can be done with a programmable EFI system like Microsquirt or Ecotron. One being programmable 3D ignition control which I would like for the 218s.  Besides all of the hardware issues a lot of tuning time will be required. 👎 As appealing as the project is I don't want to loose too much riding time. 🤦

Edited by Chuck.
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From what I can see it looks like a "dead rip off" of our stock XR 200 R Keihin carburetors with an accelerator pump. 

 

You could tune it to come in at any time, i.e, late in the bottom end, early in the mid range, mid range, early WOT, whatever you want. 

 

Duration can be controlled with the spring tension and or length. I used an old ball point spring on my TM33 that worked great. 

 

Yes, would definitely take some tinkering to dial it in. 

 

My only concern would be how does it effect starting after a get off, or a tip over (it happens). 

 

Would the cylinder have to much excess fuel to restart, other than than that, looks good, just need seat time and patience. 

 

I do not have the bung setup and A/F ratio meter that you have Chuck, so would have to rely on the old butt dyno. 

 

As I am rebuilding my 02 KTM 520 EXC, I still will go over and start the ol' 200R I still ask myself how can you make this better within a certain cost point. 

 

I did see one post way back, where someone put a Chinese pumper carb on and loved it, but I think it was a 30mm vs. a 27mm. 

 

Given I still have the stock set up a 27mm would be a better fit, as I think with some headwork a 30mm would be better and perhaps more compression as well. 

 

Dunno, just kicking around ideas. Still to cold and rainy to go riding on the trails, so doing a little bench racing. 

 

Chuck you getting into EFI is intriguing on the XR218R, but see a better fit for the CRF250X.

 

If anyone can do it, your the Guy, you are somewhere between passionate and obsessed, I like that !!!  :ride:

 

Michael 

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My only concern would be how does it effect starting after a get off, or a tip over (it happens).

I did notice a lack of vents on the upper float bowl of the PZ carbs, unlike all of the vents on the PD and FCR carbs.  I had a tip over flooding problem with the BSR 31 carb because of the lack of vents. The castings were there so I drilled them so it was vented like the PDs. And the biggest shortcoming of CV carbs is no way to flood clear them. 👎

 

old butt dyno

Works just fine🤣 and is faster than AFR meters or dynos.

 

I think with some headwork a 30mm would be better and perhaps more compression as well.

My thoughts, but I thought I would start with just blending to the manifold.

 

EFI is intriguing on the XR218R, but see a better fit for the CRF250X.

Throttle bodies are easier to find for the X, but there are some 26-28mm scooter TBs out there.  I really wanted a 30 for the XR.

If the TB is too large the throttle response will be too sudden. KTM uses a linkage system at the carb to soften the  off idle throttle opening rate, which I will consider for the X. Would also like it for the XR.

My friends Montesa 4RT has a Keihin no battery EFI and the throttle response is instant, you can hear it in the exhaust note, and it can be difficult to ride when you are tired.  Fortunately the engine doesn't have much power. It is faster than a XR200R but not my 218. 

What intrigues me about  aftermarket EFI controllers is you can fine tune power and throttle response via the fuel and ignition tables, and have a handle bar switch(es) to switch to alternate fuel  and/or ignition tables.

 

you are somewhere between passionate and obsessed,

Just lots of free time for an idled mind. :ride:

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Just so you guys know, Chinese rate carb different. Not ACTUAL carb size but size where it bolts to manifold, The "30" is actually a 26 and should work well on 200. Also they tend to jet these on lean side so be prepared to swap main and possible pilot.

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Teamrude,

 

Can you elaborate on a specific carburetor, or is it intellectual property knowledge ???

 

Working for a Metal Finishing Company, we don't tell Customers squat.

 

They ask and we give them generalizations, but absolutely no specifics. 

 

Michael

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I compared the dimensions shown in one of the PZ30 ebay ads to my PD97 dimensions and it seems to have the same outside dimensions but with a 2mm larger outlet ID. So it will fit the manifold and air boot but will mismatch to the manifold ID.

 

I  agree with Terry about jetting, all newer carbs seem to be jetted lean, which hurts performance.

 

With an accelerator pump jetting can be leaner and still provide good, or better, throttle response than a rich jetted non AP carb.  A case in point in my XR218 (w/ a PD97 carb) compared to my CRF250X (w/ a FCR pumper); the X has much more power and very much better throttle response than the XR, and gets the same or better mileage on the same trails. 🤦

 

The Xs are jetted notoriously lean from the factory, rejetting increases power AND throttle response.

 

 So the 30 is pretty much a bolt on with an accelerator pump :banana:

I suspect jetting could be an issue as I don't know if the jets are Keihin or unmarked knockoffs 👎

 

I'm waiting for someone to post results of a PZ30 project. 

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I compared the dimensions shown in one of the PZ30 ebay ads to my PD97 dimensions and it seems to have the same outside dimensions but with a 2mm larger outlet ID. So it will fit the manifold and air boot but will mismatch to the manifold ID

Does this mean that the PZ27 is the stock fit, or close to it ???

 

 

Item Description

27mm PZ-27, Choke cable version w/accelerator pump

Specifications:

  Intake Diameter: 27mm

  Air Filter Mount Diameter: 38mm

  Mounting Holes: 48mm (eye to eye center)

  Height: 165mm

  Depth: 80mm

  Accelerator Pump

Michael

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I found one listing for the PZ27 that showed the inlet bell at 39mm so smaller than the 44mm bells on the PZ30 and PD97.

 

As Terry pointed out the Chinese nominal size is the carb outlet ID rather than the venturi size that others use.

 

What we don't know is the venturi size of the Chinese carbs, but close examination of photos indicate they are oval shaped like the PDs.

The PD97 uses a 24mm slide, the venturi measures: 22.2w x 28.6h = 635mm2 which an area of a 28mm circle.  The outlet ID is 30mm.

Edited by Chuck.

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Yep, looks like the PZ30 is the way to go vs. the PZ27 and yes Chuck you are correct on the overflow, it's not there,

 

checking the photo's it appears there is spot for one, but the accelerator mechanism would be in the way.

 

This could be a problem on a tip over, hence making starting more difficult, if not very difficult.

 

The #1 reason I love the lil 200 is it is extremely easy to start even after a get off, or a tip over. 

 

Michael 

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