s900t8v

so I threw on the 28mm flatslide mikuni I had on a while before doing all the head mods etc... I could never get the jetting right from 1/3-3/4 because even on the leanest needle clip it was still boggy, if I went down a main jet it ended up too lean at WOT. but I found a few atomisers in the shed !!! woop. so I mounted it back up! the pilot jet was too lean at 30 so upped to 40. main jet 170 - needs to go up to 175, 180 is too rich at WOT peak rpm which is about 10-11k before it comes off the pipe. the atomiser was a 175 series Q4 which is very rich, I substituted it for a P8 which is WAY better, still too rich but no bog. I'm thinking a P4 or O8 would be good to try. O8 is about the middle in terms of atomisers or needle jets needle middle position but I will drop this leaner and see if I can pick up the performance in this range. I've got the jetting way better with the leaner atomiser, the thing rips and you really notice the throttle response difference of the flatslide carb, it just jerks (and slips the clutch like mad) Always thinking about how to grab a few more ponies with this bike. I have to take a bunch of measurements before I go any further with port adjustments. I've got a 34mm flatslide carb in line to try And now I picked up a banshee reed cage wit boyesens an te rubber intake boot or $15! there will be some extensive work required to make this work. The boot has the spigot for a boost bottle an this just stretches large enough to fit the monster 34mm flatslide I bought for this bike! The rubber mount has stuffers which is good too. I am going to epoxy around the inlet and fins and see if I can fit the banshee cage it's 9mm wider than the DT175 cage I have in there. Originally it was the super tiny ct cage! The banshee cage is about 20% bigger an with a bit of modification should flow really well. I am going to widen the boost port a bit and re angle the transfers flat acros te crown they're aimed up as is the old style. I've hydroformed a few chambers for another project and have a laser cut template ready as an upgrade of te current chamber I'm running. Once all this is done I'll probably look at cutting down the combustion chamber even just a bit smaller. I bought the later DT style piston to replace the ct piston with the much larger piston windows I still gotta fit it when I get a chance. I want to be happy with the state of tune and porting and fuelling cos I'll have to break in the new rings. My cylinder has a bit of wear probably needs a bore oversize but Inwont borer in case i kill the cylinder with a mod or porting idea. I still have to plug the decomp hole above the exhaust port. Finally figured out my end game to sort the clutch - New OEM CT springs - shimmed 2mm - New steels + frictions will install this with the CT3 gearset I have with the evenly spaced gear ratios. I need a CT shift drum if anyone has one lying around they're willing to sell for cheaps i'd be interested. cheers ed

hey blackhat I'm going to try blasting some used steels and use them with used good frictions within spec. I guess blasting them without warping may be a bit tricky. lever pull is ok! I am getting new levers cos the current clutch one is heavily worn. I used this stator/rotor kit - see it uses the same stator plate as the points ignition ct/at/early dt series The AG series CDI is interesting, it used a single stage coil setup with pulser mounted on top of source coil to trigger the CDI unit which makes it look similar to the 2 stage DT CDI... and the CDI box is a 4 wire static timing box like found on the RX100 series, however the RX100 use a pulsar coil mounted in a different location as well despite having the static box which I find weird. The AG series CDi seems to make use of the early CT/DT100 stator plate with the opposed coils whereas the later DT CDI uses the V shaped CDI setup. The AG uses 130mm stator - the same as AT,CT, DT100 The 78 and later DT125/175 uses 120mm stator Here is a DT175 stator setup with pulsar coil, 2 stage CDI coil and lighting/charging coil - the two stage coil is meant to be better for higher RPM. Here is comparison of the variable timing and fixed timing boxes e= here is the 4 wire cdi (RX50,100, AG100,175) vs the later 6 7 wire cdi (IT175, DT175 mX etc) you can see the 4 wire has fixed timing, the 6 and 7 wire has a variable timing curve. I am looking to see if I can adapt a variable timing box to suit. I'd love to be able to computer tune the CDI

So the first stage of converting to CDI is done! SUCCESS! :woop: Bike started first kick, I checked the spark before I kicked it over and it barely requires any effort to kick! revs out well! wont know until I ride it if its helped the top end at all (8500-9000) rpm. I cant believe I had some plastic 6 terminal conncetors and crimp on spades in my utilux kit that actually were the same as the OEM yamaha ones. I just had to change the pin layout on the stator plate to match my pre CDI wiring loom, very simple took about 10 minutes. its a 4 wire CDI box red/white - cdi input from stator black/red - ignition kill orange - trigger to coil black - earth to chassis stator is a pulserless CDI stator - I just matched the colours up! yellow - ac lighting red white - CDI coil output green/red - nighttime charging green - daytime charging blue - neutral light Once I convert to 12v I'll be throwing an electronic tach on and EGT/CHT probes. Just waiting on the 12v regulator and flasher units, then have to go globe shopping then It'll be ready to test. The biggest downside of this CDI stator plate is that its not adjustable, it doesnt have slotted holes, I might have to pay a machinist to slot them for me so I can adjust the ignition timing! its set at 2mm I think or slightly less, very retarded for my setup. Once I do boost ports through the piston I might even be able to advance it up to 3mm without increasing crown temps too far.

adjusted the timing to 2.5mm the other day, - filed the points they were sitting at about 2.5ohms resistance closed, got it down to 0.5ohms which is factory spec acceptable. after about 1000km of riding. still putting the bike back together after doing a heap of servicing ordered a bunch of new parts - new piston kit $35 - new levers chrome $16 - new handlebar grips $4 - new rear shocks $100 - new wiring loom insulation $5 - 12v regulator/rectifier $3 - 12v flasher relay $3 going to convert to 12v and at the same time trial one of the early style pulserless CDI units from a later model yamaha ag175 it used the 4 wire CDI box also found on RXS100, will be interesting to see what it runs like if it runs at all. hopefully pretty straight forward wiring wise! I dont know if this CDI box works but I watched a cool video on youtube showing how to service them! Note: BBcode and smileys are still usable. 1976 Yamaha rAG175

considering my bike doesnt have a reg, I assume the lighting coil is too weak, it runs the headlight, taillight, and instrument bulb... I think I might have got it figured! The non CDI stator plates have 2 coils, left = lighting right = charging. the lighting coil is a lower output coil and is unregulated so wont do 12v I have a CDI stator plate here with me, the left coil is lighting/charging and the right is CDI. the CDI models have the rectifier for charging circuit and regulator for lighting circuit like NE0 meaning that it will do the 12v conversion. I will just swap the left coil onto my pre CDI stator plate. It means I can get rid of the right hand coil as the left hand coil does both! then I just do the 12v conversion like everyone else. I am still umming and arring about CDI as well. maybe I should try it.

hey I am looking at doing this conversion my ct 175 has 2 coils, lighting/charging coil and a selenium rectifier, 2 wires red/white, no sign of a regulator on the bike. I am wanting to go 12v because my 6v battery died and the selenium rectifier has failed. (open circuit both directions), I want to run a 12v tacho and 12v egt/cht probes - I am not particularly fussed abought lighting thats just a perk. also I am guessing 12v will provide a better spark - do I need to change the coil? did you guys put a ballast resistor in line? the cheapest selenium rectifier for 6v I can get is $25 I can get a 12v regulator/rectifier for $3 from ebay flasher unit 12v $3 ebay bulbs a whole of $10 Cheap 12v 2a-4a battery $20 sounds good I just need to know what I should think about regarding spark etc considering my bike doesnt have a reg, I assume the lighting coil is too weak, it runs the headlight, taillight, and instrument bulb, I am thinking perhaps I could leave this at 6v and convert the charging circuit to 12v?

took it for another spin today! its great! I've got the stock 24mm carb on again, I am looking at making a custom stubby flange for a 34mm flatslide instead of just using the 28mm flatslide. rechecked the squish, set at 0.7mm which is fine. the bike is just nothing like it used to be. the clutch is slipping like mad after the upgrade haha so I will have to throw another new clutch pack in. think I will buy a set of new OEM springs and shim them up, and maybe even add a 6th plate in to the pack to try and lock it down for good! I am running points, I am thinking about trying a transistor ignition pack to see if it will improve engine performance, basically turns the points into a switch, so they dont wear out, and also eliminates problems associated with points bounce or coil lag at high rpm. be interesting to see if it would help top rpm. I think now the limiting factor is probably the carb! to do list is now - throw in a b8es plug and check the jetting is ok - reset the timing think probably around 2.5mm btdc - throw in new OEM frictions/steel pack - grab a new piston kit - the bigger windows will be beneficial, and I will shorten the piston a bit as well to lighten it up. - install the lighter flywheel I have and examine the advance mechanism on it. I think its actually a start retard system but could potentially be reversed to retard at higher rpm (with a heavier spring) could be an idea! - install transistor ignition module after I knock over most of these mods I think I'll dyno the bike and see where I am at power wise. after that I think I will be going silly with even more porting! I probably really need to pull the engine and open up the transfer bases in the crankcase.

hey thanks blackhat ! opened up the reed cage a bit more, about 15% should flow a little better at peak RPM I actually put the 24mm carb back on while I order a bunch of spare parts for the 28mm flatslide. the 24mm carb setup retains the boost bottle setup which I think does really improve on/off throttle! I never did get the 28mmm jetting right, the needle jet is the wrong type and too rich, it bogs at mid throttle, probably also to do with the throttle slide cutaway as well. I took it for a spin today! holy cow the bike just shreds the clutch again and it pulls hard and quick despite a lot of slip! prior to the new head i';d got the clutch to a point of non slippage with a 6 disc pack, and shimmed springs! now ive upped the power it cant handle it! just shreds. plan now is to throw in the set of new clutch plates and steels I was keeping for a rainy day. it may just be that the ratios are too short and I should lengthen them to reduce the slippage... but should be able to get the clutch to hold irrespective of gear ratios. heres a comparison of the windows on the piston CT (mine) DT!!!! probably gonna throw one of these kits in soon http://www.ebay.com.au/itm/181864922535?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

finally cut a high comp squish band head for the yam, took 1.5mm -1.7mm off, squish set at 50% and 0.5-0.7mm havent putit on but it should rip! MINTY fresh also did a bit more porting work, cut down the transfers and reangled the boost port, chamferered the transfers a bit more

hey mate check your pms

second that on the spray cans original color - dings filled with 2k body filler tank primed painted an cleared with $10 acrylic paints (cheapest you can get here) then wetsanded with p1200 after 10 mins of drill mounted wool buff pad meguiars 105 fine foam pad meguiars 205 I would definitely use 2k clear for the tank, I used acrylic so if you dont wash it off straight away it marrs the paint and you hve to rebuff it. Beware with 2k the isocyanates can cause severe respiratory reactions in some people and cause permanent sensitisation which means any future small exposure can trigger acute respiratory distress syndrome (like anaphylaxis) spray it only with good ventilation and try not to kill the neighbours kids. the only isocyanate safe mask is a Sundstrom with P3 particle filter and ABE or ABEK filters. I use one and recommend it. A lot of people dont bother and are fine, then you google and read the stories of people sensitized to iso's. good luck!

havent done much on the bike lately put type F ATF in and the clutch is slipping a lot less haven't bothered replacing that stuff yet made a new fuel tap gasket out of nitrile bonded cork sheet (10 bucks for A4 sheet) - no longer leaky fuel tap carb bleeds fuel out overflows when on side stand, have to turn tap off to prevent this. will have to fabricate a more straight side stand (It does lean way over as its an ag bike stand) still waiting to modify the head.

hard run in every time use mineral oil, get it warm, thrash it briefly heavy load med-high throttle, let cool by cruising for short time, repeat - drain oil after first few runs. so many cars and motorcycles are run to their peak rpm/load on the dyno, this does most of the ring bed in, the fluids are often dumped and refilled. the take it easy is more of a thing to ensure suspension or other components aren't faulty - the 1000km service is meant to have a thorough once over for loose fasteners, faulty suspension etc anything that could have been done incorrectly at the factory that could cause catastrophic failure - this is my opinion but if you look at car factory vids and engine building stuff most of the bed in is in the first-second time the motor runs. i've known people with drag cars to bed the rings in on the strip.

I'm wondering if its actually rich not lean, it has a 175 series P8 atomiser in it which is for 4 strokes and supossedly works ok with reed valves, but I'm thinking I might put a 169 p0 atomiser in - the 2 stroke guys say the difference is obvious even with reed induction... it seems to be lean at partial throttle with the 170 despite needle position, I need to plug chop the 170 main, I tried a 180 but the bottom end is far too rich then an now i'm wondering if the atomiser will solve the bottom end and 180 is in fact the right jet. i'm using a dt175 rubber boot, the 28mm mikuni is only 33mm flange so same as the standard DT carb as far as I know. I am looking for a boot to buy that has the port for the boost bottle as I would like to retain that feature on the bike.. because i've changed carb I cant readily tell if I've lost performance as a result of removing it. are the later dt 175 intake boots the same sizing as the earlier ones?