I picked up the 2KR from the shop today - *insert big grin here*. <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s --> Brett managed to tune out most of the top-end richness, but there is still some work to do as can be seen from the dyno chart below......basically, he fitted all the o-rings supplied by Blair - huge thanks to Blair for supplying these <!-- s:cheers: --><img src="{SMILIES_PATH}/th_Cheers.gif" alt=":cheers:" title="cheers" /><!-- s:cheers: --> . The carbies were out of balance and the jetting took quite a bit to sort out - and at this point probably needs some more work. This will happen over the next couple of months....... A number of dyno runs were undertaken to get to this point - but Brett had some issues with both the battery (Motobatt) and the airbox which had been modified......too much. The battery was simply not up to the job (wouldn't even start the bike) and this can be seen in the stuttering right up in the top of the rpm range. A new battery should help sort this out but this won't be fixed until the next dyno session. Brett also had some issues with the airbox mods flowing far too much air. The front section of the screw-in lid had been cut right out, not a good mod at all. So some 'repairs' were undertaken to fix this - but I will be looking to buy an unmolested airbox lid at some point, if anyone has one that they would like to sell, could you please send me a pm ? I have entered this bike in Period 6 250 Production with the PCRA, Rd 1 is this weekend. Will post up a race report next week - but given the improvements made on the dyno over the last few days, I am hoping it will go OK. What I really like is a 10 hp increase and no big flat spot in the mid-range (probably due to the dodgy airbox mod...) Initial dyno figures: Base power run - 25.56hp Max torque - 10.56 ft-lb Tuned Base power 36.46hp Max torque - 15.70 ft-lb watch this space for updates <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s --> and finally - a huge thanks to Blair for his help in getting this bike up and tuned. Brett was really impressed with the quality of the o-rings in the kit and said they would have helped a lot. At least we are now working from a good consistent baseline as far as the carbs are concerned...... <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->
Re: 3LN1 dyno and tune-up results Great work Dave! That's a 50% improvement in horsepower. It is good to see someone doing things the right way, and it sounds like you have a good mechanic who knows his stuff. O-rings and seals are not that critical on most carbs but the Mikuni BST/BDST are completely different to most. All the best for your first race and keep up the good work. cheers Blair
Re: 3LN1 dyno and tune-up results That's a good result. If you add about 25% more to account for the transmission losses you end up with close to 45hp which is factory spec.
Re: 3LN1 dyno and tune-up results I expect that once the breaking down at the top end problem is overcome the final output would be close to the mark. What is redline on these models and does this model have an electronic rev limiter? I have never been a fan of total loss. If you lose 1 volt at the battery you lose a huge amount at the spark plug. Small race alternators weigh next to nothing and keep everything running sharp at peak revs. cheers Blair
Re: 3LN1 dyno and tune-up results Run the stock alternator with one wire disconnected. Reduced drag on the crank, enormously reduced load on the VRR (with the lights gone that thing is dumping a LOT of power) while maintaining the ability to pull to redline. Blair - the 3LN1/3/5 models redline at 18500 revs, and I THINK the TCI chops the spark at 19500.
Re: 3LN1 dyno and tune-up results thanks all - here is a bit more info about the racing from last weekend Brett worked on the bike for some considerable time - there had been a dodgy mod done to the airbox lid which meant that the carbs were getting far too much air. Brett sorted this and the bike was given a number of runs on the dyno to get it *just right*. The ragged response up high, is due to a couple of things - the airbox lid had not been entirely closed up as Brett was experimenting with the amount of mods to the lid to get it breathing right......but the main issue was the battery. It is an old Motobatt and its basically fuxxored. I changed the battery for a normal wet-cell Yuasa for the weekends racing - and it helped considerably. The response of the bike is now heaps better - Brett did a carb balance as well, this is crucial on these small motors. The bike started instantly and felt so much better than the previous track days. Its way off the pace in its class - P6 250 Production - but that is because its designed for 45kg jap jockeys that can hide entirely behind the fairing screen - not fat-arse 115kg aussie man-mountains <!-- s:-? --><img src="{SMILIES_PATH}/icon_Eyecrazy.gif" alt=":-?" title="Eye Crazy" /><!-- s:-? --> There are some pretty quick CBR250RR's running around in P6 250 proddie racing, these bikes have been developed over a number of years. The little fizzer was way off the pace but it finished all the practice, qualifying and racing legs. I just need to get more used to how it works, get much better starts and start using that massive front brake.......this will come over the course of the year. Next race is the June long weekend, back up in Sydney at the smaller south-circuit of Eastern Creek. .......and apparently what happens in the pits goes straight onto the forums <!-- s:wink: --><img src="{SMILIES_PATH}/icon_wink.gif" alt=":wink:" title="Wink" /><!-- s:wink: --> The bike itself is a heap of fun to ride and its good to have a second bike for racing, it makes the entry fees a lot more palatable. All I will be doing to this little jigger now, is a new cam-chain and CCT, a paint job and a decent muffler. That will be it for the rest of the year. Don - that mod to the alternator wiring sounds interesting - how does removing 1 wire reduce the drag on the crank ? I am guessing it is just one of the feed wires to the reg/rec, so doesn't really matter which one is disconnected ? I don't want to run a total-loss system on this bike - but would be really interested to know if anyone has had any success using a battery eliminator on this model ? The redline on the tacho on this bike redlines at 17000rpm. <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->
Re: 3LN1 dyno and tune-up results Excellent work, I have a FZR250 and the carb's are my issue too. I have it running but it floods when cold so you have to be real nice to it. Once it's warmed up it goes ok, but it's almost like there is lag from openeing the throttle to accelleration. I have a CBR250RR that is my main race bike so the FZR has not received attention in the last 2 years. We have about 10-15 cbr250rr's racing up here, it would be great to have a few southners come up for the qld champs or something. Is there anyone I can contact to see if they want to get a group together to come up?
Re: 3LN1 dyno and tune-up results The alternator has 3 windings, each of which puts out its share of the power. The way the winding are connected means that removing / disconnecting one wire takes two of those windings out of the circuit. If you label the wires A, B, and C, your windings are AB, AC, & BC. Disconnecting wire A takes AB and AC out of the game, and you now have 1/3 of the nominal power being generated. This also means that the absorbed power at the crank is also reduced by about the same (not enormous, but with a 250 every bit helps) and you've also reduced the heat load on the voltage regulator enormously. The alternator output is fixed - it makes what it makes - and any generated but unused power has to be dissipated by the VRR. Race bikes, without all those silly headlights and tail lights and horns (and and and) have MUCH smaller power requirements compared to a streetbike. By reducing the total power going to the VRR by 2/3, the power dissipated is going to fall off, probably to almost nothing. The battery eliminator is just a big capacitor. Unless you plan on push-starting your bike, stick with the battery - there are several racers building incredibly light 4-cell LiFePo batteries that are FAR safer, more stable, and more convenient that the older Li-ion batteries. If your tach has a painted redline of 17000, I'm going to say that instrument is from a 3LN6 or 7. Is your oil filter internal (above the headers) or external, next to the side stand?
Re: 3LN1 dyno and tune-up results Hi Simon - you should get in touch with Blair (maelstrom) and get some new o-rings for your FZR carbies. From the sounds of things you probably need to do the valve clearances as well - I know mine will need doing as well as a cam-chain and CCT replacement. There are a couple of very quick CBR250RR punters in the PCRA, running around in P6 250 proddie class - not sure how many you would get in a group, I think there were 3 entered for Rd 1 ? Maybe if you contacted the PCRA something could be organised ? thanks for the tips about the electrics Don - will have a look at that on the weekend. If I can release a couple more ponies every little bit helps <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s --> I couldn't see any external oil filter near the sidestand, the build date is 1989 - redline is definitely 17k, the tacho markings are in 2000rpm increments, the last numbered rpm point is 18k and there is 1 more mark after that to indicate 19k. Not sure if that helps or not ? <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->
Re: 3LN1 dyno and tune-up results good work mate, good to see the amount of horsepower you got out of it! you should ask your mechanic for the specs he used (float height, jet sizes etc) might be handy on this forum
Re: 3LN1 dyno and tune-up results Just had a look though my old photos and the 2KR has a red line at 17,000.. The later 3LN series had the 18,500 red line.
Re: 3LN1 dyno and tune-up results thanks Dave - yes I think it is the 2KR and not the 3LN1 - better change the heading for this topic ! <!-- s --><img src="{SMILIES_PATH}/icon_redface.gif" alt="" title="Embarassed" /><!-- s --> I'll check with the dyno dude and see if he can remember what he eventually used - the bike spent a considerable amount of time on the dyno getting it just right. I do recall he said that the carbie balance was out a fair bit and this makes a big difference on these little motors. The bike starts now immediately on the choke when cold and settles down to to a good idle quickly. I also was lucky enough to get a good replacement muffler for the stock unit. One of the boys on the local forum with a 3LN1 was selling a Delkevic Titanium muffler and engine pipe for $50 <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s --> so this was a bargain. This exhaust pretty much bolted straight on after a slight mod to the mid-pipe - but the sound is heaps better. Can't wait to get the bike out onto the track again to hear what it sounds like with the new pipe on. I reckon its about 1/3 the weight of the stock muffler. <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->
