Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => 350 Talk => Topic started by: husker on January 17, 2017, 10:09:32 AM
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The magazine tests back in the day had the A7's as the fastest of the 350's. In October I went on a 100 mile ride in the Omaha area and my brother went too on his A7. Well much to my disappointment he was able to pull away from me! And my GTR has a 40 tooth rear sprocket. A little more fine tuning is called for.......Rod
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Maybe the magazines were right? By the way , I've read that there is an early avenger engine and a later avenger engine. Apparently, Kawasaki spent R&D money for two engines .
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My brothers is a 71 model with 28mm carbs and cdi ignition. Thought the non stock gearing might even the two bikes out. My GTR is still running a little on the rich side and the ignition timing needs to be checked but then the A7 might not be in the best state of tune either...........Rod
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Rod, You sound just like the guys back in the day, love it ! ;D The few years between the machines could make a big difference. How do the claimed HPs compare? 28mm should be better than our 26mm carbs, there's 16% more throat area !!.
There was a power race going on, back then with rapid development in 2S technology. Every maker wanted the fastest bike on the market. Let's face it, despite BS claims, the GTR is a tourer first and a sports bike second.
Brian.
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Between the GTR and the A7 the GTR is definitely the choice for longer distances. New rear shocks on the A7 would be a big improvement as the originals springs are too stiff. A7s were rated at 42hp.
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There ya go, on paper, he has 5 more gg's than you ;D ;D ;D and the GTR does need to rev cleanly to 7500 rpm to get anywhere near it's claimed 37hp. The 40hp sometimes shown was poetic licence, just sounds better and sells more bikes ? Maybe get a Kawa 500, that'll show him. :o
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Interestingly..i built a standard 350 GTO engine for a friend that has his own Dynapro dyno.I built it carefully..but totally stock.. and it ran with standard pipes,carbs/filters and ignition.He sent me the Dyno sheet down after he'd run it and that bike gives 38bhp at the back wheel..at 7500rpm.
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Wow, that is surprising and pleasing. Even assuming 10% loss through the drive system, which is low, it suggests 42hp at the crank, 25% loss gives an unlikely 50hp !!
Japanese HPs were usually quoted at the crank because it's a higher number and they might have used smaller horses ;D ::) unlike the Italians who quoted at the rear wheel where it really mattered.
You must have done a brilliant job on that engine, I know who to come to in future !! ;D Brian
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Hey Rod. Looks like there is hope to kick your brother's A7's butt. Get tuning!
...bert
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I think the Kaw's CD ignition system had a power advantage. But, my GTR towed my buddie's A7 20 miles into Machinaw City in the same rain that fouled out his ignition system!
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When going on a ride with an A7 it's always a keep your fingers crossed hoping the CDI doesn't die on you. Another factor that makes the GTR a better road bike than an A7 is that A7's have this terrible pre ignition knock when you slightly let up on the throttle. They absolutely hammer. My brothers and mine both do it and it was mentioned in the Cycle World 350 comparison........Rod
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When was there a Cycle World comparison?
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When was there a Cycle World comparison?
It's in the "Download" section, or follow this quick link...
http://bridgestonemotorcycleparts.com/index.php?action=downloads;sa=view;down=65
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Back in the day I only ran into one A7. Had no trouble dusting him off. Plus next to the GTR the Kaw was butt ugly!
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Agree with that! My experience is that the GTR could out run RD350's in the straights at Del Ray Beach in the day. So I expect the A7 is at risk to a properly tuned GTR (go ahead and cheat Rod...no judges around). ;D ;) ;D
...bert
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Well i have a 1970 GTO and this last summer i was going for the ton ;D...... started too hammer down 8) got it up to about 70 and had some clutch slipping :o now the gto is up on the lift and i just put a new clutch pack in her 8) This summer i,m going for it again :P... Ton up boys... But i still don,t know if i,m a rocker , or the other one... here in the USA we don,t call ourselfs that... were just bikers
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Packrat.... No dispute, with a bike, You're a Rocker in the true sense of the word. Go for that 'burn up' and 'do the ton' then pull in the cafe for a
coffee and a 'bacon butty' 8)................ Don't you ever change what you are. That's a statement not a question ;D
The 'other ones' were 'Mods' , wore parka jackets or lounge suits! and rode scooters weighed down with mirrors and lights, don't think you qualify
as one of them.
We're all just bikers or motorcyclists here, now but the media still rake up 'Mods and Rockers' whenever a biking news item comes up. Brian
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Thanks,,,, One of my other bikes is a Yamaha TDM 850...... And that one halls ass... most folks in the USA never got that one... 2 year only.... ive run into blokes from your side of the pond,,,,, they knew what it was and were serpriced to see one... ;D,,,,,, and she will go past harleys like there stoped 8),,, and may be one day i,ll get to the T T,,,,,, there are only 2 things on my bucket list..... The T T and a vinsent ::)
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Regarding the speed of the GTR: About 1971 I took my GTR up to an indicated 110 mph on a straight stretch of I94. I have read some who felt 95 to 100 mph was tops which I found a puzzle. However, a British magazine Motorcycle Scooter & Three-Wheel Mechanic, April 1968 indicated a (tested) top speed of 108 mph. Perhaps a similar test of a 350 Kawasaki of that period would be a good comparision.
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Remember though that most of the GTRs tested in the magazines and on the road were improperly jetted. That makes a big difference in their performance. Even with that there were still some differences from one bike to the next within the same models. My brother and I both had GTRs. Both were overhauled by the same mechanic over the same winter and mine was always a bit faster.
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Coulda been the rider too! ;D
...bert
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The Dec 1970 Cycle 350 comparison had the A7 at only 52.81mph at an indicated 60 with the GTR not much better at 54.60. No idea how consistent the speedometers were from bike to bike. My brother bought a 1970 A7SS new and he said it would run up to an indicated 110....Rod
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We're supposed to grow out of this 'who's got the fastest bike thing' , when does that kick in ? ;D :D ;D You've got me at it now !! ::)
UK tests were likely done with 140 mains and factory oil pump setting. The claimed 108 max in MM is unreliable. Text doesn't mention it. Had they actually hit 108 on a timed track, I'm sure it would have been shouted long and loud.
Pictures were taken near Bill Smiths shop in and around Chester, his and my home town. Where was test run, local bypass? Had they gone out to nearby Oulton Park race track , surely there would be a picture. Would also have cost. I think the speed figures were supplied by Smith, the importer, looking to encourage more dealerships and sales. Where's Graham Weeks when we need him. RIP
Having said that, Richard of this site, stated in an early post that, 'some GTRs were noticeably better/faster than others' but not why.
There is some other critical factor on our engines/bikes that significantly affects and varies performance, bike to bike. 37hp should be good for 100mph on the road, just. Many race bikes achieve it on far less (low frontal area and fairing). Our tall bike and high bars don't help.
Optimum state of tune should be reproducible but doesn't always give expected performance result, from experience. (it does, however, smooth out the engine, which will run like a turbine when you get it right as attested in the Cycle World comparison).
Production tolerances another factor but where? ........... I would put forward, piston fit and barrel clearance, more critical on a 2S and will pay close attention on next engine rebuild.
Any other suggestions, you racers ? Disc valve fit or seal ? Brian.
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The Dec 1970 Cycle 350 comparison had the A7 at only 52.81mph at an indicated 60 with the GTR not much better at 54.60. No idea how consistent the speedometers were from bike to bike. My brother bought a 1970 A7SS new and he said it would run up to an indicated 110....Rod
It was pretty common for speedos from that era to be pretty optimistic, not just bikes, but cars, too. My 350 shows an indicated 100 mph at somewhere around 75 mph. That's with a NOS replacement speedometer I purchased from Richard several years ago. I replaced the original because it was wildly optimistic, the NOS one is just as bad (although much nicer looking). These days, it's easy to get an accurate speed, just carry a GPS unit or an app on your phone. I actually put a digital bicycle speedometer on mine. It works at normal highway speeds, but seems a little flaky at high speed. They only cost $10-$15, though.
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I won't say how I obtained the information, but police radar of the early seventies put the top speed of a certain GTR at 104mph.
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That pretty closely matches my 101 in the traps at Del Ray. ;D
...bert
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102 (per speedo) on my GTO back in 1971 on I-90 heading to Sturgis... ;D
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Aaaaawwwhhh ! Go on DL tell us ;D ::) gowon, gowon, gowon. ::)
Never saw more than 90 on my speedo but did seem to be moving quick............ Had 140 jets and factory pump setting, didn't clear properly to 7500, fluffed out at maybe 6500. 130s never came to UK, didn't have the know-how to mess with the pump.
Can't wait to get GTO nicely run-in and see what she can do, now I have the knowledge.............. Might kill myself but go out with a big grin on my face. What could be better ;D :D ;D 8) :o..................Whooooa, take it easy, Brian. :(
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Well back in the day ;D ;D ;D june of 1968 :o :o :o one dame week out of highshool ??? i get my draft notice.....SHIT.... got pissed... comeing home from my now x..... i,m on my 175 DT that the folks over in Rockford had played with... light goes green... i hammer down.. going threw the gears... i didnt see the cop till i was hitten the ton..... got busted for 60 over the limet :P and went to jail that nite..... And yes ;D i did have the fastest bike in school 8)
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Well Brian, if you must know, it involved handcuffs and not in a fun way.
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Almost....too much information, dude! ;D
...bert
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Cheers, DL, lets leave it at that. Bad luck. Was that the same high number bike that you have today. Brian.
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I don't have that bike today. I bought that one new in '70 and traded it in on a T500
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DL and Srpackrat wouldn't happen to still have those tickets. Could start a new tread (Traffic tickets received while riding a Bridgestone!)
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That ticket question needs to be posted, so all our members could see it and respond.