Apologies Mr Green ... I did get your email ... Ive just been slack in answering ...... I hadnt read that one before, good find .... ! Sounds like its a 'common problem' ..... pity he didnt continue to post to see if he resolved it. Im waiting on yours to arrive and be installed
So am I - still showing as awaiting delivery to partzilla and the wait is killing me Some time ago, whilst I was searching part sources, the TDM 850 uses the same floats, I came across this post - the first answer is a really good one - the mention of random behaviour is the best part http://answers.yahoo.com/question/index?qid=20080215072326AAep4Bs
i think i MAY have a break through , six sigma racing on ebay make a jet kit containing mods you may allready know this , but why is it so good i asked and what are these mods and can anyone really do them here is 6 sigmas responce Drilling Slide and Clipping Slide Spring When you quickly open the throttle in the carb, a large increase in airflow passes through the carb to match the throttle position. This creates an extreme lean condition momentarily because the fuel delivery system has not been able to keep up with the rapid increase in airflow. The CV carb, does not allow the slide to open quickly enough to stop this lean condition due to the slide NOT being directly connected to the throttle, and instead relies on a change in pressure to lift the slide. this process takes a moment in which it is lean . -DRILLING THE SLIDE- One of the ways in which to reduce the amount of time for the atmospheric pressure to equalize is to increase the size of the holes through which it passes. This is a balance between to large of holes equals no vacuum, andto little equals slow throttle response. The second way in which to increase throttle (slide) speed is to reduce the pressure placed upon the slide by the spring. This is referred to as "clipping the spring” and involves cutting 1-2 coils off of the spring. The reason behind this is that the reduced spring rate will allow quicker opening resulting in sharper throttle response. Kit Includes: Main Jets, Needle Adjusters, Nylon Spacers, Drill Bits, Slide Hole mod (with CV carb), Idle Mixture mod, Slide Spring Mod (with CV carb), Carb Schematic, Specifications, Carb Sync Tool build, Carb Cleaning Procedure, Proper Tuning Techniques, and step by step instructions with photos. The pilot jet is not included. The needle adjusters and idle mixture circuit adjustment solve the requirement for pilot jet replacement. The pilot jet controls 100% of the engine idle and 25% of the transition onto the needle. 6 Sigma has found that the engine will idle with the standard pilot jet, with or without the air-box and with the slide and needle removed from the carburetor; therefore 6 Sigma does not change the pilot jet. Doing so is proof that the other circuits are not used correctly. Idle and off idle is controlled by the mixture screw and the float level which have the most positive effect below 4000 rpm.
how are your slides grey do they lift and slide quite easy or no ? myn are a little sticky im thinking though i did my best to clean and reseat them well after a full carb strip and clean/ viton seel kit the bike on the road has improved , though i do still have the flooding problem im going to order this jet kit and have a race performance mechanic do the mods and my shims also check this bs with the float level im hoping the combo of the jet kit and shims fix my problem
dont be sorry by all means elaborate , i assume you know of these kits then do you advise against trimming the spring or the drill bit mod any info on them would be helpfull
this part is backwards - the benefit of a CV carb is that the time taken to lift the slide is matched with the time taken for fuel to make it's way via the needle jet and they rise in unison. Before the slide rises, there is flow restriction, because the slide is in the lower position, there is an increase in vacuum potential with the butterfly open and by the time the slide vacuum is sufficient to begin lifting it, the fuel is higher in the jet needle system and ready to be delivered. The downside to CV carbs is the not quite instantaneous throttle response because of the time this process takes. Consider carbed cars - they have accelerator pumps, I've had to repair a few over the years. Bogging off idle usually meant the accelerator pump plunger was gone. Easy inspection - remove the air filter pull the throttle cable, if it was working you'd see a spurt of fuel down the throat. This was to avoid a lean condition during the time taken for the other fuel circuits to come online. Crude but effective. The CV carb does a similar thing in a different way, controlling the airflow momentarily till the fuel becomes available for delivery via the jet needle circuit... This line below is bogus - the other fuelling circuits are simply not in use below a certain engine speed & load. Curiously the other part about the idle circuit is 100% correct. Yesterday for kicks I had mine running -> getting up to temp, the fuel tap was turned off and on for brief periods to make certain the carbs wouldn't run dry. Anyway with it up to temp I then sat it at about 4-5K RPM for say 60 seconds - with the fuel tap turned on the whole time, hoping that I would have it flood one me. It didn't... However when I returned it to idle and the idle circuit came back into play it flooded immediately and started chugging. I immediately turned the fuel tap off -> I then used the above technique from fzrarchives of flipping the slides up and blipping the throttle to get it back to normal quickly. But riding it with the, seat & tank unbolted and the airbox screws removed and a screwdriver handy just isn't quite practical... Unfortunately my carb parts aren't due to arrive at partzilla till next Monday -> then shipping to me, so conclusive proof is still a little ways off peace out Glenn
This page is a good description http://www.400greybike.com/forum/viewtopic.php?f=35&t=12571 When I first got the bike I was intrigued by the CV carbs working principles so did some reading, I can't however find the reference which detailed the slide operation principles to control the lean condition as the throttle is opened I'm with Blair on this one - they're selling hot air, overpriced hot air at that...
Adding to what Ruckus said there is also some info about drilling the slides on the VFR400 that you can find on the greybike forum. That comes from the HRC kit information as I recall. The drilling operation probably had its roots, at least partially if not all, in the kits and supplements that were made available for various models. As an example if you go to my FZR400 3TJ1 page, at the bottom is a race kit manual that can be downloaded. Page 4 gives instructions for drilling the existing two holes to a diameter of 3mm. This is all meant to be part of the factory kit and not a standalone modification. You have to also consider that racing engines spend most of their life with the throttle wide open. Not easing away from the traffic light. I have no doubt that it might be possible to improve the performance/response of an existing set of carburettors but it will require a lot of testing and work. I seriously doubt that 'Sigma' have obtained all of the models of motorcycle that they sell 'kits' for, ensured that all these motorcycles are in perfect mechanical condition, then performed extensive work on a brake dyno (not dynojet or rolling road) to ensure that these kits work. How many FZR250s have they tested in the USA where they claim to be based. What is their address? It sounds like a great way to make money though, 4 main jets, 4 nylon washers, a drill bit and a piece of paper for a bundle of cash. cheers
The only circumstances under which I would drill the slides is if I already had a perfect spare set, which I don't and prices for the diaphragms, which tend to include the slides and vice versa - are around $130 - each. this is an interesting read, deals with CV carbs though related specifically big twins - the principles are well explained however.
What did I do to my bike today? .... RODE THE BASTARD! Same ol shite at low revs but it cruised along well enough to get in a 160k round trip ..... Happy bloody new year to me
How did that happen Mr Grey? I thought it would conk out and then do the chugging thing once it was warm.
Well I think its just spooked. The original original problem of it dying then not starting when warm until u gave it time to cool (?) seems to have been replaced with just the low revs/idle/flooding conk out thing ..... which happens warm , cold or anything inbetween Maybe I fixed one problem and created another. A couple of times when it did that I could smell fuel pretty badly. The other thing is its churning thru the fuel at a fast rate from my observations. Its also running 10,000RPM at 100kmh .... I changed the gearing from stock but dont know if thats a problem. Not sure whats more unpredictable ... bikes or women
From my experience, women, because bikes will stop misbehaving once you truly know the source of the problem...
OH and just so I can salvage myself from the nice little sexist hole I've thrown myself into, the above statement says nothing about women in general and everything about my past choices in women specifically - it's all been my fault - always
Dunno, this bike seems very much like a woman. You can never seem to find the "source" of the problem. And when you solve one, another issue from the opposite direction crops up. This then gives the response of (being that it is coming from the polar opposite direction) "WHAT THE F@&$? WHERE DID THAT COME FROM?"
Just had a thought, if your problem is that the carbs are flooding, can you hang the overflow tubes that clip up onto the back of the air box, down so that they are lower or so that the excess fuel flows out rather than into the inlet. Run them down into a catch tank/bottle rather than onto the road in front of the rear tyre. I can't see how these so called breather tubes allow the fuel to escape, maybe they aren't, EPA regs, so they just flood the cylinders. In the good old days before computers & greenies the overflows were just holes in the sides of the carbies & you knew straight away when the needle wasn't holding. Just a thought, hope it helps, I'm going to try it.
If you check this diagram you'll see that the lowest point for fuel to overflow is the pilot air system, #6 & #7 in the diag, so when the needle & seat plays up the fuel goes into the inlet manifold -> straight downwards On any other bike with the carbs in the vertical position and overflow tubes at the top of the float bowl section it will spill out of them. peace out
