Scoring on plungers

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Miles
zxr400 oc member
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Posts: 466
Joined: Wed Apr 30, 2008 11:00 pm
My Bike: ZXR 400 L3
Location: Bangor, Northern Ireland

Scoring on plungers

Post by Miles » Wed Jun 28, 2017 12:37 am

Hello folks, may have written off two sets of carbs here but I had them both vapour blasted.

Upon rebuild, all with new seals and build to factory spec , the bike ran perfectly and the carbs looked great. The following morning however I had to use choke to start the bike, then the choke Jammed open.

After removing the carbs and stripping them down I had to pull the plungers out from their bores.

They were very badly scored. I rubbed them down and put the plungers back in. The bike has ran horrible ever since ie hanging revs, can't get any sort of vacuum reading on the sliders in my carb tune etc.

I then put other carbs on that I had cleaned and low and behold the choke plungers jammed open on.

I put good plungers in the carbs and they don't jam anymore but now I can't get the bike to run.

Is it possible that the blast medium has scored the carb bodies themselves and allowing air through ?

Has vapour blasting ruined two sets of carbs?

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banner001
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Re: Scoring on plungers

Post by banner001 » Wed Jun 28, 2017 9:40 am

i would think thats unlikely, obviously it depends on the media they used for blasting as it can range from plastic, to minerals, to metals, vapour blasting is pretty gentle, any damage was most likely there previously, how were they before you had them blasted?
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

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Miles
zxr400 oc member
zxr400 oc member
Posts: 466
Joined: Wed Apr 30, 2008 11:00 pm
My Bike: ZXR 400 L3
Location: Bangor, Northern Ireland

Re: Scoring on plungers

Post by Miles » Wed Jun 28, 2017 11:58 am

No problems before I had them cleaned. The scoring occurred from me having to remove the plungers as they were jammed solid inside the carb.

Only started after I had them cleaned so I think the was still medium stuck within the carb bodies. Both sets of carbs have the exact same problem and give the same running issue.

Only other thing that's changed is the adj cams but they were failed in to give the real tdc of my engine. (Kwak were a few degrees out but I'm assuming their mark is a one size fits all)

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