350LC Exhaust Shoot out
NOTES: Exhausts on Test Standard Yamaha 4L0 (350 ones) Allspeeds (small can) TSA (Two Stroke Addicts) Kunda Arrow Harris Lomas (80’s style) Swarbricks TZ 350G Dyno Set Up DynoStar 4th gear at 6000rpm set point. Rotation Calibration is 56 Basic Yamaha Factory Spec Yamaha quoted BHP at crank = 47bhp Rear Wheel = 47bhp minus 10% to 15% = 39.95bhp to 42.30bhp Base Line Data Baselined BHP at rear wheel = 41.5bhp, torque = 26.6ft-‐lbs Acceleration time = 8.5secs to max power from 10bhp start point (3000rpm) Testing Criteria All tests conducted on same bike (without taking it off the dyno as this affects calibration) Same operator on dyno controls, same rider on bike, all tests are full throttle from 3000rpm up to maximum revs before power starts to drop off, 5 runs per test No adjustments to the bike in anyway during the tests. Baselining The bike was strapped down to the dyno and then calibrated using the data above, so 4th gear, 6000 rpm Some initial runs of the bike where done before it was set so that it was running slightly rich in case some of the exhausts caused it to run weak.
Write Up The recent resurgence of the old skool LC’s and RD’s in general has also reignited the many long running debates about what works and what doesn’t on the old 2 stokes. As many will no doubt testify, the usual bragging rights in the pub and at bike meets are very rarely if ever backed up with fact, so I decided to set about seeing how much truth there was in the various long running debates. The obvious one to address first is the exhaust debate, therefore the first step was to decide how best to achieve this, use a standard motor, or a tuned one. In the end I decided to take a more “real world” approach and do what 95% of Joe public do which is to buy a set of exhausts and just bolt them on in the belief that all of the sales hype is true. To this end I decided the test had to be done on a completely stock engine, using my own bike which is a completely stock engine in the sense that the barrels have not been ported, the head has not been skimmed and the crank is just standard, everything else about the engine is also as Mr. Yamaha kicked out of his factory back in the 80’s. The only differences from stock on my bike is the carburation side of things, it has a set of 28mm PWK carb’s, 10mm reed spacers, some fibre reeds and the air box lid removed to allow better breathing (subject of another set of tests I did some time back) Next was sorting out the various exhausts to test, finding suitable candidates and the most popular brands was of course the ideal scenario, one which on balance proved harder to do than I initially thought, having been unsuccessful in securing a set of Microns or Nikon’s for the test, but then getting my hands on a very rare set of Harris pipes seemed to make up for that ! The tests also had to be completely identical and therefore some basics had to be adhered to in order that the test was fair. The ground rules agreed upon with John Warrington who owns the dyno, these where; 1. The bike would remain on the dyno throughout the test, therefore once calibrated it would remain the same for all tests 2. No tweaking or changes to the bike in anyway, this would also help reflect what a lot of people do when they buy/fit exhausts 3. John would work the dyno, I would ride the bike
4. All tests would be the best of 5 runs and all done from 3000rpm (approx 10bhp on average) to maximum power, no matter where ever that might be 5. Air Fuel Ratios would be recorded, but no adjustments made, this was mainly to safe guard the engine from depositing lots of molten metal into my crank should it run really weak at some point. The initial run up for base lining was nothing unusual, checking the Air Fuel ratios etc and making sure we was getting consistent results. After a few runs and adjusting the carburation so that it ran slightly rich, it was finally base lined with the stock pipes making 41.5bhp, which is pretty much where it was expected to be. The Test The bike on the dyno with standard exhausts fitted after the initial set up.
Allspeeds First up was the ever popular Allspeeds, the ones on test where original 30+yr old small cans, which sound just perfect and transport you immediately back to the 80’s, especially when a touch of Castrol R is added to the mix !
The bike runs nice with these on and the throttle response is good, it feels crisp overhaul and rev’s nicely round to 9k rpm before the power begins to tail off and the bike runs out of steam and is unwilling to rev much harder or higher.
TSA’s TSA’s where up next, these are a modern sculptured pipe and have had very good reports of improvements. The first thing you notice is how loud they are, the carbon end cans probably add to this, but they sound nice all the same ! The bike is responsive, although feels a little flatter initially compared to the Allspeeds, the air fuel ratio shows them to be running really rich low down which explains the initial flat feeling. They come on pipe around 5750rpm at which point the bike begins to take off like a scolded cat, before we know it, the bike is well into the redline and still going ! After the second run we decide it would be prudent to put some ear defenders on before we go deaf, the pipes sound great, if a little loud and the bike is serving up some impressive figures. Kunda Next up are the Kunda pipes, mainly because I’d never heard of them and was interested to see what they could do.
The first thing you notice is how flat they are from 3000rpm and they take until 6000rpm before they even start to make anymore power from the 3000rpm starting point, a total of 7 seconds has elapsed before anything happens. Then the power starts to climb and looks like a fairly steep curve, but that’s down mainly to making no power before that, once they get into their stride they start to make good power, but the bike is still climbing at 10,000 rpm and I am beginning to think about my crank ! The bike finally tops out at 11000rpm, max power is looking to be in the range of 10,500 rpm, so on the next two runs we take the bike to 11,500 rpm to be sure, that’s 2000 rpm into the redline, at which point I am thinking my crank will be making an appearance anytime soon ! The power figures are good, but the high rev’s required leave us thinking these are more race pipes than road pipes. Arrow Arrow pipes are known for producing very good 4 stroke pipes, although they have mixed reviews in the 2 stroke community. Compared to the Kunda’s they start to make power pretty much straight away, its not huge amounts, but it’s noticeable and the bike feels reasonably responsive. They start to come on pipe just after 6000rpm and keep pulling until well into 10,000+rpm, although power is beginning to tail off by then, the final figures are good, but not the best so far. Harris The Harris pipes are fitted and there is no expectation of what these may or may not do, they sound nice, Allspeed(ish) and the bike feels good on tick over as we just flick the throttle to check everything. The first run turns up some surprises, noticeably that the bike starts to make power immediately from 3000rpom onwards, the power curve is nice and the throttle response is crisp. This is a very impressive mid-‐range, however, by 8500 rpm the pipes are done and the power drops off dramatically as the bike refuses to rev much past 9000rpm. 80’s Lomas These are a popular pipe, which is evident why on the first run, from 4000 to 5000rpm they make an impressive 10bhp and then have a little dip which would be possible to dial out with some carburetor adjustments. The bike pulls strongly and feels good, max power peaks around 9200rpm, but the bike is revved to over 10,500rpm as the engine is willing and the pipes don’t
seem to be causing too much restriction, but they fail to produce any more power beyond the 9200rpm limit. They rev freely and quickly reaching max power in around 9 secs, with the last 25bhp being made in just over 5 secs. Swarbricks Another popular pipe, its evident from the initial run that these are not happy with the current carburetion set up as they feel exactly like the Kundra pipes, very flat until they come on pipe at 5500rpm. Once on pipe they have a nice power curve and climb nicely, although they take an age to start to come on song, these where the slowest to get into the power band and the bike required some coaxing to get it to go, again it would be possible to improve this with carburetion adjustments, but to what extent is hard to say. Max power peaks around 8750rpm and they are done just after 9000rpm, though we push them to around 9750rpm before the bike starts to give up. TZ350G Now these are a pure race pipe, its what the Yamaha racing teams use to use, so we are expecting pretty much nothing until around 7000rpm and then for them to go like stink. True to form they hit 6500rpm and the bike starts to accelerate quickly, going from nothing to peak power at 9750rpm in approx 5 secs, the bike rev’s cleanly through to 11000rpm and wants to keep going, but I take mercy on the engine and shut off. No doubt with a tuned motor these pipes will deliver large dollops of power at the higher rev range, as regards them being practical for the road, that would have to be a definite no even with the fuelling set to match the pipes, they are just too peaky. Micron’s Unfortunately I was unable to get my hands on a set for the test day, but these have been tested in the past, albeit to be fair, not in the exact same conditions as the rest. The results for these pipes are from a test when my bike was set up to run as best it could with them on. The bike was reasonably responsive up to 5750rpm at which point the pipes begin to do their stuff, they have a nice power curve and pulls strongly up to its peak power at 8500rpm, although the bike wasn’t revved any harder beyond this, it was evident that they had stopped producing any more power.
Points to Note and the Facts It is very evident that some pipes are better served on a tuned motor than on a stock one, it is also relevant to consider not only the maximum BHP a pipe will make, but also how long it takes to get there and whereabouts that power is made. Too often, the focus is purely on the maximum BHP figure, paying little regard to the acceleration curve/characteristics of the pipes, in reality for road use a pipe that has a good spread of power is the better option, whereas peaky pipes are better served on the track. If power is delivered in the mid-‐range in a smooth and consistent manner it allows for a faster and smoother ride on the road, pipes that deliver peaky power are difficult to ride on the road as they need to be kept constantly in the power band, which generally equals having to ride closer to the limit and changing gears frequently. Results So is there a clear all round winner, well yes and no, it all depends on what you want, if talking purely max BHP then the TSA pipes are clear winners, however some of the other pipes are very good for lower down gains. The table below shows the results of the test, which includes the max BHP, max Torque and also the time taken to reach max BHP. Note: All timings and figures are from the starting position of 3000 rpm Exhaust BHP@REVS Torque@REVS Time (ft-lbs) (secs) Standard Exhausts 41.5@8466 26.6@7419 8.3 Allspeeds 46.1@8999 28.4@7311 8.8 Arrow 46.2@9595 27.0@8625 13.0 Harris 39.8@8569 26.7@6973 8.9 Kunda 48.2@10302 27.3@8043 13.5 Lomas 44.3@9322 27.5@7944 8.8 Micron* 46.9@8036 28.6@7636 9.1 Swarbricks** 43.5@8768 28.5@7827 9.8 (32) Two Stroke Addict (TSA) 50.3@9863 28.9@7752 11.2 TZ350 48.3@9704 27.6@8839 10.0 * Micron Exhaust test results are from an earlier test run on the same bike and settings
** Swarbricks took an initial 32 seconds to hit peak power, after some coaxing with the throttle, e.g. not pulling the throttle hard back, they did perform much better, but required feathering of the throttle to make them work low down The graph below shows how they all compare to each other in respect of BHP, the standard pipes have been left off
The acceleration graph shows a very different story and this should always be considered on how well an exhaust performs as this directly affects how the bike rides/pulls when being ridden on the road.
As can be seen the Swarbricks took a very long time to come on pipe, this could be tuned out to some degree by changing the carburetion which was affecting these badly. The graph without the Swarbricks is easier to see the differences between the exhausts, this graph has the standard pipes on to show how they all compare to a standard pipe in respect of acceleration.
So which pipe is best, well, I’ve opted to fit a set of TSA’s on my bike as they work so well on the whole. There are 3 pipes that are probably best avoided for road use, namely Arrow, Kunda and TZ350, the reasons being; Arrows because they take a long time to reach peak power and it’s at very high RPM. Kunda because they make power so high up that your engine is unlikely to last very long ! TZ350 pipes as these are purely race pipes and are designed to work with a highly tuned engine, on a standard motor they do release some power, but this is high into the rev range.
If you opt to fit a set of Swarbricks, then factoring time on the dyno and some careful setting up would no doubt improve them significantly, but just bolting them is unlikely to be a good idea. Summary What is clear from the test is that each and every exhaust will require some setting up in respect of carburetion and possibly in some cases engine tuning in the form of porting, head skimming etc. The thrust of this test was all about just bolting them onto a bike, which is what most people tend to do, the value of investing time on a dyno to set them up to suit the bike is evident. After the test was completed, the TSA exhausts where fitted back onto the bike to improve the fueling, the graph below shows what results can be gained in just an hours work on the dyno.
Compared to the initial test, the max BHP has increased from 50.3bhp to 53.1hp, and max torque has gone up from 28.9ft-‐lbs to 30.3ft-‐lbs.
The blue line shows the power after adjusting the main jet size only, max BHP is now at 51.8bhp The yellow line shows the power after adjusting the pilot jet size, max BHP is now at 53.1bhp. Further gains are still possible as the engine was still running a little lean in the mid range and rich at the higher revs, another hour or so on the dyno would probably yield a further 1bhp to 2bhp and possibly another 1 ft-‐lb of torque. The graph also shows how the mid range dip has been made significantly better and further adjustments should see this improve even further. Finally, the gains are clear to see when compared to the stock pipe, this is even more evident on the first test ride, the bike pulls strongly and leaning forward over the tank is mandatory in 1st and 2nd gear if you want to keep the front wheel down.
The end result is an impressive BHP gain of 11.8bhp (28%) over stock pipes and torque up 3.7ft-‐lbs (14%), if you tried to achieve similar % gains on a modern sports bike you would have to invest a significant amount of money ! The bike with a set of TSA’s fitted after being set up on the dyno
Special thanks to; John Warrington Motorcycles (Tel: 01653 698258) for allowing me to fill his dyno room up with 2 stroke smoke for a day Mick Greary for collecting all of the exhausts and bringing them to the test Norbo Lea for the loan of 7 sets of the exhausts Andy Graham for the loan of his TSA’s Brian Harrington for the loan of the Harris pipes Written by Dave Whattam, Sept 2013