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-   -   Cheap Chinese replacement carb.. (review) (http://www.gasgasrider.org/forum/showthread.php?t=25768)

JAD 12-05-2021 10:59 AM

Cheap Chinese replacement carb.. (review)
 
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Hi all, I have been struggling for weeks with the carb setup on my 2007 EC250... (UK) I have read everything and tried everything...literally!
I managed to improve things but I was beset with inconsistent results and erratic idle and just....well just... not good...

Anyway, I decided to buy a PWK 38 from China... despite some misgivings it was a final attempt at resolving the issues.

It cost ?28 and arrived within 2 weeks. My first impression was poor as the idle jet broke when I tried to remove it but a small "easy out" removed it and I installed all the genuine Keihin parts that I had bought in an attempt to cure the old carb.

So, everything (jets, needle etc) was transferred to the Chinese copy, fitted to the bike, pilot screw out 1.5 turns fuel on, (short prayer)..... starts 1st kick with a fast idle. The idle screw actually works now and turning it out slowed the idle speed and she just sat there with a beautiful steady idle... be still my beating heart :).

I let it idle as I refitted the seat and took it for a run. Absolute bloody perfection... I am a fussy bugger when it comes to bikes and this little bike felt like it had a new engine. Everything about it is improved. The response is clean and linear throughout the rev range, the idle is perfect, the spooge has all but disappeared and she starts 1st or 2nd prod hot or cold.

Needless to say I am delighted!

I do wonder what was wrong with my old carb as I had replaced everything that could be replaced except the jet block gasket. I may get some security Torx bits and remove it tomorrow to see if that was a problem but I guess it was just old and worn like me.

Anyway, my advice to anyone with an old well worn EC250 with fueling problems is just spend a few quid on a new carb. It will save hours and hours of grief.

Happy days.. I just need the weather to improve a bit in the north of England now....

JAD 12-06-2021 01:56 AM

A couple of people have pm'd me for details... this is it... (38mm)

https://www.aliexpress.com/item/3285...6b214c4dl6vmgZ

JAD 12-06-2021 06:45 AM

I removed the jet block and the gasket looks in a poor sate. Some evidence of leakage.
This may have been the issue but not sure... https://uploads.tapatalk-cdn.com/202...8ac4851811.jpghttps://uploads.tapatalk-cdn.com/202...ce47f30440.jpghttps://uploads.tapatalk-cdn.com/202...c40ec675f8.jpg

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SS109 12-06-2021 08:10 AM

The jet block gasket is a known issue in old carbs or ones that have been cleaned by soaking in solvent or had brake parts cleaner used on them. Jets-R-Us has new replacements available.

I'll give you another little tip that I didn't see anyone else post about a PWK carb. Set your float height to 18mm and not the factory setting. It will make dialing in the jetting that much easier and without little weird running issues. A lot of people don't realize how much float height affects the running of the engine.

JAD 12-06-2021 10:13 AM

Thanks SS.. good to know.

I have to say 2T carbs are a "black art" but I have enjoyed learning about them. I think my old (2007) carb had a range of issues relating to old age and wear and tear! I am convinced I had some tiny air leaks somewhere which messed everything up. I was even toying with taking the engine apart to check the various seals...glad I didn't because the new carb has resolved all of the issues and it runs as sweet as a nut now.

swazi_matt 12-06-2021 01:25 PM

Quote:

Originally Posted by JAD (Post 199320)
Thanks SS.. good to know.

I have to say 2T carbs are a "black art" but I have enjoyed learning about them. I think my old (2007) carb had a range of issues relating to old age and wear and tear! I am convinced I had some tiny air leaks somewhere which messed everything up. I was even toying with taking the engine apart to check the various seals...glad I didn't because the new carb has resolved all of the issues and it runs as sweet as a nut now.

wait till you start delving into the suspension valving LOL

(F5) 12-06-2021 06:02 PM

For giggles look down the brass jet in the block. The needle can wear it oval. Magnification and light help.

JAD 12-07-2021 04:21 AM

I will have a look... the carb setup seems to be a common issue for people..it is very frustrating to keep mauling with it and not getting consistent results.

I have been for a couple of rides (tarmac) with the new carb and it has genuinely transformed the bike.

It pulls cleanly without a big "hit" (I think the new needle helps here), has plenty of power, lifts the wheel in the first 3 gears, nice steady cruise, pulls well from ridiculously low revs, no excessive spooge, no smoke when warmed up and best of all has a clean and steady idle!

All for a few pounds and 5 mins to setup.... bliss!

JAD 12-07-2021 05:25 AM

1 Attachment(s)
Forgot to mention another issue I discovered.. The throttle cable was frayed and probably causing a bit of friction .. Impossible to detect unless it was removed.
Another age related problem! :)

JAD 12-09-2021 06:30 AM

Just checked mpg with new carb and about 15% improvement..

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