Suzuki DRZ400E Update

Published on 1 May 2023 at 09:45

Just a brief update on my Suzuki DRZ400E with the flat slide carb - I was having trouble getting the thing running after a couple of years of slumber. I had got it so it was running quite well at high throttle settings but it just did not want to play ball at tick over - a pretty clear indication of a blocked idle circuit. I had stripped the carb -  KeiHin 39mm FCR - and cleaned the idle jet but when I tried to squirt cleaner through the idle circuit none was getting in to the venturi - it was clearly solidly blocked. I took the whole carb off and gave it a good go in the ultrasonic cleaner at 55 degrees. Even 45 minutes of that brutal treatment did nothing and the circuit remained blocked so I decided to strip the whole carb. it was then that disaster struck and I managed to break the casting of the body while attempting to remove a stick screw. Yes, the most sub optimal of possible scenarios  - the carb was now useless. I did look at a new Kei Hin replacement at about 650 quid but quickly decided I would never get my money back so I looked in to used items instead. They were coming back at 350 quid with no certainty that I wouldn't have the same problem again. In my research I came across a few videos where people had used Chinese copies with great success, the price was about 150 quid. I was sceptical at first but after the 5th or 6th video I though it was worth a go. I have to say I was incredibly impressed with about 90 per cent of it - pretty annoyed with the last 10 per cent - let me explain.

Firstly the delivery time was excellent, I had expected  month long wait, I got it inside of a week. In that time I had several updates from the seller, I could not fault them - perfect.

I inspected the item carefully, the quality of the casting was absolutely top notch, all of the dimensions were spot on, here were even a couple of mods that made the carb better than the original, the removable inlet throat being one such thing - it would make it very easy to machine or replace to fit different sized inlet rubbers.

it was when I came to fit the thing that it went slightly  pear shaped as the throttle cable bracket was wrong and I could not fit my cable without the throttle being pulled half open at minimum throttle opening. I did not want to replace the nearly new throttle cables so I had to modify the bracket instead. Sorry, I did not take a photo as I was in a hurry, I wanted to take the bike to an auto jumble in the hope of selling it. Anyway, I modded the bracket and it now worked perfectly except for one other problem. I found I could not adjust the tickover as the anti rattle spring on the adjuster was too long. I had to cut off about 3mm from he spring length to allow it to adjust to the correct position.

The carb came with a bag full of various tickover and main jets but the supplier said it was jetted as standard so I thought I would give it a whirl as is. I have to say it definitely seems about right, the thing really moves and throttle response is amazing.

Overall I am very impressed, I suspect some piddling about with the jets may unleash another hp or two but I think it's fine as is. I would definitely recommend this solution to others, usual caveats about me not recommending any particular supplier apply.

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