I found the promblem!!! Not good

holy fcr! sux man. hope you can pull it off..

$hit, not good is there much damage, or have you found it in time.

Any chance of a few pictures of the offending item and the results.

Has anybody heard of this before ? because it's a new one on me.

Neil. :thumbsup::thumbsup::confused:

I have heard that the vacuum release plate can crack on older models. Was it the vacuum release plate, item 21 on the linked diagram?


where did the carb come from?

For any of you following my other thread http://www.thumpertalk.com/forum/showthread.php?t=359191&page=1&pp=10

I found the promblem. The Slide on the FCR carb was comming apart and shooting metal flakes in the cylinder. It was holding the valve open causing the fluxuation in the compression readings, and the poor running! son of a bitch!!!

Damn...That was my next guess! j/k :thumbsup:

In his garage it says the carb is from a '98 yz400f.

They had a problem with the vacuum release plate, correct?

metal flakes in cyclinder, low compression and valves held open :thumbsup: sounds really expensive, how is the slide coming apart??? don't really understand, some inligthening me!

This probably has nothing to do with your problem but the Suzuki manual shows that diagram with the plate upside down from the suddco diagram???????

I cant remember but I think it is the manual that shows it wrong. I ran into this when i rejetted by bike, when I put the carb together the slide kept getting hung up and tight. I dont know if the bike would have ran that way or not but it for sure would have ground away at the slide.

They may have corrected the manual. I have an earlier DR-Z400/E (brown cover) 3rd edition, February 2002 Part No. 99500-43022-01E manual.

****IF you have this maunal be careful and compare to the suddco diagram. You will see they are 180deg different.

98 yzf definately had the slide plate breaking issue.

I have heard that the vacuum release plate can crack on older models. Was it the vacuum release plate, item 21 on the linked diagram?


Yep it was item 21. I bought thae carb on E-bay about 2yrs ago. It has worked great up untill now! Once I got everything apart there wasnt really much damage. the cylinder was still good. the valves and head were good. From the looks of it I can just replace that plate, and o-ring. then put a new piston in and reassemble. Is there anything else I sould look at? I will try to get a few pic up

Is there anything else I sould look at?

I'm not sure if the problem is only with the yzf carbs, but I've heard here that those are more susceptible. Hopefully Burned will have some info on this.

I think that it's something that I am going to put on my annual check up, if the vacuum release plate looks worn, replace it! I bought a new one recently when I was working on an old carb and the parts look identical. Maybe the newer carb bodies have been changed so they don't wear the plate so badly.

In his garage it says the carb is from a '98 yz400f.

They had a problem with the vacuum release plate, correct?

Now that's what you get for putting Yamaha parts on your DRZ :thumbsup::confused: Wow sorry to hear that, I hope the damage is not too bad. Just when you thnk about stator bolts stripping, cam chains, valves, tensioners, countershaft nut etc. something like this happens :thumbsup:

I had a slide plate break in my 41mm on my SV650 cost me 2 wins and 280 in entry fees....I made one out of stainless cause it was on backorder.WORKED GREAT

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