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YADBS - Stage 6

yes so we figure its time to do something about the carbs and have some initial talks with ron. the idea is to go for something above 30mm and theoretically that should give us a good boost at higher rpms. of course at this point we are assuming that our gear shifting problems are pure history. anyway ron gives us an idea about the cost involved for the carb upgrade and we are a bit stumped. both me and tom are rather broke now and we ponder on what to do. but there is good news are jaggu offers to sponsor the carb project and we are back in action. jaggu had recently sold his esteem and so he promises to plonk in 12k soon. so we are moving now and soon we have our eyes
on something that ron offers for sale - a pair of mikuni vm34 roundslides. its something that ron have used on his dragbike and he assures us that its all setup and ready to be plugged in. so one fine day we take the bike over to rons place and its time for the carb transplantation.
meanwhile we had decided to add a pair of UNI filters as well to the shopping list so ron shows us the carbs and a fresh pair of UNIs and the stickers which come along. we waste no time in plugging in the big vm34s but on one side we find the carb rubbing against the aluminium side cover of the RD. ron solves that by using his grinder and the removes some metal from cover quickly. meanwhile i take a closer look at the
carbs and notice a curious tube exiting out of the float bowl and making its way into the carb venturi from near the top. ron explains that its a powerjet conversion kit
which he had installed sometime back. ok thats great since it means that we have an extra jet kicking in beyond a certian rpm. the idea is to ensure that we dont run lean at very high rpms. how powerjets work is quite simple - once rpms exceed a certian point, the airflow increases enough to create a low pressure inside the venturi which will suck fuel out of the bowl, through the tube, and through the power jets, which are around size 80, and into the carb venturi. right now we are jetted with around 260 mains and so once the powerjets kick in, we go upto 340 mains.

so we ride the bike around and fiddle a bit with the jetting and it takes some time to get it sorted. anyway soon thats done and the bike is parked away at my friends place near our testing strip.



now there are no news abt any drag happening soon and safe to say that we all lost interest a bit. still one weekend we gear up for some testing soon land up at our testing strip. the road is quite near the airport and the roar of planes landing and taking off kinda drowns the drag RD's scream and generally make us feel guilty of causing noise pollution. if i remember correctly, we did around 3 test sessions at this point of time, and each time something new went wrong and we had to roll the bike back.

i remember clearly the first of those sessions. also remember that we were running without oil in the gearbox since we wanted to try out the concept of "dry clutch". we reach the strip and i take it for a sanity run. the main difference i notice is the change in the powerband. the vm34s have a totally different character of their own. with the vm28s the powerband used to just explode out of nowhere, sharp and shrill. it was especially more striking because the bike was pretty weak outside the powerband. the vm34 felt more stronger even at lower rpms and you could really feel the powerband build. you could actually feel your arms being pulled more and more and you start getting pushed backwards slowly first then at an alarming rate and soon the front wheel slowly leaves the ground and then the slow rise turns into a rapid ascent and the wheel just shoots up once the powerband hits fully. these are some old pics from those sessions showing me and tom hanging on for dear life.
beyond the green wall there are the airport runways and our strip is almost parallel to them.

one could really make out that the topend had increased and that the redline had definitely moved up. the bike was almost touching 100kmph in 2nd gear and from one of the videos we got a performance number as well - 0 to 115kmph came in around 7 seconds, with the 3rd gear redlining.

that first session wasnt all smiles - soon there was a loud clunk from down below and the bike stuttered to a stop. and the clutch just went dead and we could make out that something mechanical had failed. we roll the bike back home and do some inspection, and we are horrified to see that the front sprocket had come loose cleanly. it came out of the shaft, hit the clutch mechanism and cleanly broke the clutch linkage which connects to one end of the clutch cable.
we went shopping for a new front sprocket washer, and fixed it in place tight and hard. meanwhile i go to a gas welding chap and beef up the clutch link. and so we are ready for more testing.