You have worn parts that's all. If you do plan to replace the choke plungers, you might as well just rebuild the carbs seeming everything will be out of the bike at that point. I replaced the rubber (yammy still sells them) between the carbs and intake, as well as the ones between the airbox and carbs. Nothing was seating anymore and had some noticeable leaks. Took apart the carbs next to see what was going on and found worn choke plungers, emulsion tubes + needles (53000km bike), hard as hockey puck gaskets and the paper fuel filter that had started to throw bits into the carbs themselves.
Mistake #1
I will start by saying I poked the bear and put in a cheap ebay carb jetting kit and payed the price. Everything was suppose to be spec for MK1 with stock sizes but the kit was horrible with the exception of fresh gaskets. I spent two weeks #$@ing playing with the new needle settings and mixture screw. It was always lean and pinged after warming up. Started to run 94 octane just so I didn't destroy the motor trying to sort this out. Under a 10x microscope you could see all the holes for the pilots and mains were way off and that the build quality was what you would expect for cheap knockoffs.
The proper approach:
Very carefully took all the gaskets and plastic parts and cleaned with a little dawn handsoap and some water (except the CV slide and diaphragm, leave them alone). Patted them dry with a clean rag and put off to the side till assembly. Took all the old mikuni jetting and clean them (ultrasonic and blown through with air) I did the same with the carb bodies and check that all passages were clear. Ordered a factory pro kit for new tubes and needles. Installed the old jets and then put in my replacement factory pro emulsion tubes + needles. **** Checked the float height **** and one was 13mm if measured from the highest point of the float to the where the gasket rests against the body. The other was 15.26mm which is near the 15mm stock setting. Fixed the float height, threw it all back together and resynced the carbs.
I never like cleaning plastic or rubber with solvents because they will likely dry them out and make for more issues later. A good hand soup and water will keep them from being damaged.
Current settings for my 92 TDM 850 3VD are:
Pilot jet: #37.5 (stock)
Needles: #1175i-90q-70r-45t_ti (Factory Pro titanium is just the _ti part of the number)
Needle clip pos: 3rd/middle position
Float height: 15mm
Main jet: #142.5 ( aftermarket GPR single exhaust)
mixture screws: 2.5 turns ( stock is 3) & FP recommends 2
Bike starts and idles much better. I also changed the CV springs in hopes to help part throttle response, but some minor tuning is still needed. I have a flatspot around 4k, but that's an easy fix. The plated emulsion tubes and titanium needles are overkill, but my aim is for me not to do anymore serious carb work on this bike for at least 10 years.
Edited by Phracker, 04 June 2016 - 02:21 pm.
