krusty

I have a single disc setup, using the strange looking pivoting caliper, the one with wedge shaped pads!!!, this is my first experience of this type of caliper and I'm not sure I want to continue using the god awful thing. It appears a previous owner has rebuilt the caliper with new seals and the master cylinder looks clean enough, I have bled new fluid into the system but the effort required to give even a small amount of braking effect is crazy. The brake line is still the rubber original but I'm not convinced changing it will give significantly better performance. Is there a direct bolt on upgrade from a newer machine or have I got it all wrong about this oddball caliper. I have had olde japper-neese bikes before and I know the braking performance is nothing like a modern bike, but it would nice to have something a little stronger.

Time for a little update, I have had a play with my carbs and the following steps have been taken so far: firstly I set the carbs to standard 250 specs and tried a couple of runs, general low speed running was ok, the biggest problems were lack of midrange, real bad vibes over 4k revs, a hot stalling problem when at idle and popping thru the exhaust when throttling off. I then tried adjusting the pilot air screws and found I have lost all but a small amount of exhaust pop and the idle is much smoother(screws set at 4 turns out), then I raised the needles to the 4th notch, this leaves one more if I need it, and this has improved the overall running, reduced vibes and exceleration is stronger. The hot stalling is still evident and when getting into full throttle the main jets are struggling to keep up, theres a big flat spot. My next move has been to order up some jets, I have order two sets of pilot jets and two sets of mains. Pilot: current size 17.5, ordered 35 and 40 two of each Main: curent size is 110, ordered 117.5 and 122.5 two of each The pilot jets seem a little on the large size but they are actually quite a few steps down on standard 400 sizes and some further adjustment of the pilot circuit should make them work, I'm hoping these will help the hot stalling issue. The mains are even further down on stock 400 sizes in relation to the pilot jets due to the carbs smaller 32mm bore, I am really only looking for midrange flexability and not out right power so this would seam about right. When these turn up I will have a further play and report back. In the mean time please give me some feedback from personal experience on rejetting techniques, as stated previously I am still in the early stages with carb tuning and any advice would be greatly apreciated. One thing I would like to know is, Why do US spec bikes run different jet sizes on left and right cylinders??? All the UK specs are for same size jets left and right, Guessing it's something to do with the EGR circuit???

I have never played about with jetting, so I wouldn't know where to start. I figure trying standard 400 size jets might be a starting point but I don't want go spending money on jets that won't work properly, I really need a starting point to work from, I'm guessing that running the carbs with standard 250 jets will give lean running, but again I don't know for sure. I can see that the 250 carbs wil not give me full power but for normal loads and general pottering about I'm hoping they will work ok. Really need some old school know how on this one... Krusty. And my local Yam dealers are not interested in talking to the likes of me with my old bike, 'cos it's not making them a tonne of cash. So thats not really an option I'm afraid.

I have just collected an '82 XS400 SE 4G5(UK spec), It was bought as a non runner, but after delving into the bike a little bit, it seems it has the BS32 carbs from an XS250, has anyone used these carbs succesfuly with this engine and if so could they recommend some jet sizes. It appears the carbs have standard XS250 jets and the only change I have found from standard is that the needle has been raised to the 4th notch(2nd notch is standard for XS250). I can't wait to get the bike up and running, as it's in generaly very nice condition and I'm sure will be fun to ride. I'll try and get some pics up when it's back in one piece. Cheers... Krusty.