Just purchased a GS450A for my girlfriend to learn on. Great bike for a beginner. Test rode it of course and it seemed ok, after all its like new with 3500 miles on it. Got it home and the lessons began in our cul-de-sac. After awhile I decided to take it out and see what she can do? I was surprised that her top speed was only 55. Went online to look up some info and found that it should do 80mph easily. Checked the bike over, seemed to be running fine, was a little low on oil though. Changed the oil and put in a good motorcycle synthetic. Put in some new plugs and took her out again. Only a little improvement, got her to 60mph. In low there was a bigger improvement. Before the oil change and plugs, she struggled at 35. After the oil and plugs she went to 50mph, but still only 60mph in high.
Any information or advice would be greatly appreciated. I am a little reluctant to take it into a shop since its a pretty rare bike and I don't expect many techs have had experience with the GS450A.
Obviously not enough oomph coming from the engine to push top gear to your desired speed. So...
Try seeing how fast you can go in the next gear down. Won't necessarily solve a mechanic problem but will give you an idea if the slightly lower gear, which is easier on the engine, can push the bike faster.
Have you done a compression test?
Do you know for sure it is running on both cylinders?
Did you drain the gas and put in fresh gas?
Checked the valves?
Cleaned the carbs?
Have you looked to see if an after market fuel filter has been installed? Some fuel filters not meant for bikes but used on bikes reduce fuel flow.
Michael
Thanks for your response.
No compression test yet. Bike has 3500 miles looks like new.
It is running very smooth on both cylinders.
Has fresh gas.
Have not checked valves or cleaned carbs, She starts and runs like a top.
I am suspecting the problem lies in the transmission. This is a 2 gear automatic bike.
Pete
Quote from: wyobuck on November 25, 2011, 01:40:30 PM
I am suspecting the problem lies in the transmission. This is a 2 gear automatic bike.
Pete
Ah, thought it was the 6 speed GS450. That'll teach me for not reading more accurately.
Ok, so you have the 450A with torque converter and two speed transmission. So, when you do your test runs you are putting into High Range aren't you? Yep, reread your post... big improvement in low, 60 tops in High. Hmmm... when you go into High are you sure you are in high? Cause struggling to do 60 is kind of what you'd expect if it was stuck in low. And if you're accelerating and try to get it into high, your asking the torque converter to suddenly stop supplying power and the change could be real hard to do - CLUNK, if it works, nothing if it doesn't. In which case you'd be better accelerating slow or putting it in high gear at 30 or something less demanding on the torque converter and the change to high would be easier - this would be to rule out False High as acceleration from 30 in high would be pretty poor.
With only small miles on it I'd not imagine the impeller blades are messed up or the torque converter for that matter (not that I'm a mechanic) cause you'd think if it's working fine to reach 60 there should be no real reason for it to not reach its 80mph speed.
Is there any way you can test the oil pressure in the TC? Cause if you're not getting enough pressure... transmission won't work properly either. Less top speed.
Most motorcycle techs might know diddley about the 450A, but a torque converter is a torque converter. They all work on the same principle. If you think the problem is related to that, then a little digging into torque converters might find you an answer - you might find a TC issue that mirrors your experiences. :dunno_black:
Michael
Tried going into high at 30, no change. Still 60 is the top.
Thanks again
Pete
My first new car was a 60 VW Beetle. It took a long time to work it up to the advertised top speed of 72 mph and if you had to slow a bit it took a long time again to get it back up there. Decades later I got an almost new 81 CM400A and it immediately reminded me of that VW. The CM400A was quick off the line, I always started in low and shifted to high around 30 mph or so, and it pulled surprisingly strong in high from 30-50 and then flattened out quite a bit after that. Riding about the suburbs and nearby secondary roads was fun up to maybe 55-65 mph but on an expressway it was not so much fun. It took a lot of time to work it up to 75 mph and I don't remember if I ever got it over that, probably not.
Your GS450A should go 80 mph but it might take a good long stretch to get it there. Those old Hondamatics without tachs had 1 and 2 marked on the speedos to indicate the intended redlines in gears, my CM400A was redlined at 50 mph in low and around 80 mph in high. It was easy enough to get to 50 mph in low but I never got it up to the mark in high. That's just the way they were. I wouldn't suspect the tranny to be your problem, that rugged 2 speed with converter never gave me any problems and I bought the bike with 2k miles on it and gave it to a friend at 98k miles and it had over 100k miles on it last time I saw it.
http://www.vjmc.com/
Someone in there will have the answers you are looking for.
Hi wyobuck,
I saw your post and have a few thoughts about it...
You say the bike "looks like new" and only has 3500 miles on it.
You say you changed the fuel and that it starts and runs fine.
But then you say that it won't go very fast and get up to speed.
But you didn't remove the carbs and clean all the tiny fuel passages.
I even wonder what you mean when you say it has clean fuel. Did you DRAIN all the old fuel from the tank and hoses and carbs or did you just dump some fresh fuel into the tank?
My feeling is that the carbs and fuel jets are obstructed from sitting for so long. The bike has low miles, has hardly been ridden and the fuel has been sitting and getting gunky for decades.
That's where I'd start to look.
You can't know what is up here without a baseline and that means spotlessly clean carbs and jets and fuel passages.
Then replace the spark plugs.
Charge the battery completely.
Make sure every ground connection and wire is properly connected and clean.
Check all fluid levels -- is the transmission fluid at the correct level? I would even change all the fluids.
Only then can you begin evaluating what the problem is, though by doing all the above I would bet that you'd fix the problem.
I hope this helps.
Best wishes,
Trwhouse :)
Quote from: gsJack on November 25, 2011, 05:41:01 PM
My first new car was a 60 VW Beetle. It took a long time to work it up to the advertised top speed of 72 mph and if you had to slow a bit it took a long time again to get it back up there. Decades later I got an almost new 81 CM400A and it immediately reminded me of that VW. The 400A was quick off the line, I always started in low and shifted to high around 30 mph or so, and it pulled surprisingly strong in high from 30-50 and then flattened out quite a bit after that. Riding about the suburbs and nearby secondary roads was fun up to maybe 55-65 mph but on an expressway it was not so much fun. It took a lot of time to work it up to 75 mph and I don't remember if I ever got it over that, probably not.
Your 450A should go up to 80 mph but it'll take a good long stretch to get it there. Those old Hondamatics without tachs had 1 and 2 marked on the speedos to indicate the intended redlines in gears, my 400A was redlined at 50 mph in low and around 80 mph in high. It was easy enough to get to 50 mph in low but I never got it up to the mark in high. That's just the way they were. I wouldn't suspect the tranny to be your problem, that rugged 2 speed with converter never gave me any problems and I bought the bike with 2k miles on it and gave it to a friend at 98k miles and it had over 100k miles on it last time I saw it.
Thanks for your input Jack,
I am not sure that is the problem though. In another forum I was given a performance article and it stated that the GS450A had the same time in a 1/4 mile as the original Datsun 240Z. Seems like it would get to 80 before going the 1/4. The person that supplied the info was also a GS450A owner, infact he had 3 of them. He reached 80mph on his with no problems and believes top speed on a well broken in perfectly running bike is 94mph. He thinks I have a definate problem.
Pete
Quote from: Trwhouse on November 26, 2011, 09:14:28 AM
Hi wyobuck,
I saw your post and have a few thoughts about it...
You say the bike "looks like new" and only has 3500 miles on it.
You say you changed the fuel and that it starts and runs fine.
But then you say that it won't go very fast and get up to speed.
But you didn't remove the carbs and clean all the tiny fuel passages.
I even wonder what you mean when you say it has clean fuel. Did you DRAIN all the old fuel from the tank and hoses and carbs or did you just dump some fresh fuel into the tank?
My feeling is that the carbs and fuel jets are obstructed from sitting for so long. The bike has low miles, has hardly been ridden and the fuel has been sitting and getting gunky for decades.
That's where I'd start to look.
You can't know what is up here without a baseline and that means spotlessly clean carbs and jets and fuel passages.
Then replace the spark plugs.
Charge the battery completely.
Make sure every ground connection and wire is properly connected and clean.
Check all fluid levels -- is the transmission fluid at the correct level? I would even change all the fluids.
Only then can you begin evaluating what the problem is, though by doing all the above I would bet that you'd fix the problem.
I hope this helps.
Best wishes,
Trwhouse :)
Thanks Trwhouse,
Don't think its that simple. The bike was stored for awhile but with gas removed. The carbs were rebuilt at 2200 miles. I can't believe the motor would run as smooth as it does if it has anything clogged in the carbs. I have a 1984 V65 Sabre that has a bit of a stumble when you gas it occasionally, but I have been running Bell's Marine MXO though it and it has improved immensly. I will probably get the carbs rebuilt eventually, but I want to see how far the carb cleaner will take it.
There is no transmission fluid in the GS, the motor oil serves both engine and tranny.
Thanks Again
Pete
Forgive me if I'm talking absolute rubbish, but does it have chain drive? (I don't know the model at all) If so, maybe someone has messed around with the gearing?
Quote from: bryan88 on November 26, 2011, 11:59:31 AM
Forgive me if I'm talking absolute rubbish, but does it have chain drive? (I don't know the model at all) If so, maybe someone has messed around with the gearing?
Thanks, but it is shaft drive.
Pete
no it should be a shaft drive setup. Now thats something else to look into see how gummed up the gear lube in the rear end looks with it not being driven very much it could be very thick and not letting the gears turn the way they should.
Quote from: joshr08 on November 26, 2011, 10:37:59 AM
i love when people ask for help then know more then everyone that posts a reply to there question.
Glad I can make you happy!
now from what i have been reading theres a one way clutch that is supposed to let the stator spin once its up to a certain speed so that its not robbing power. Kinda sounds like thats supposed to happen around 40-50 mph so that maybe where your problem sits. It maybe gummed up and not spinning freely. You can take this info with all the rest.
There's an owners manual you can download here:
http://www.suzukicycles.org/GS-series/GS450GA_owners-manual.shtml (http://www.suzukicycles.org/GS-series/GS450GA_owners-manual.shtml)
Quote from: joshr08 on November 26, 2011, 12:27:51 PM
now from what i have been reading theres a one way clutch that is supposed to let the stator spin once its up to a certain speed so that its not robbing power. Kinda sounds like thats supposed to happen around 40-50 mph so that maybe where your problem sits. It maybe gummed up and not spinning freely. You can take this info with all the rest.
Ok drained the oil, opened up the case and everything looks clean as a whistle. Thought that could have been it, no luck.
Thanks for your suggestion.
Pete
You will get some well meaning suggestions but serously....I doubt anyone in here has ever seen inside one let alone be able solve the problem....asuming it is related to the centrifugal clutch and transmission.
You need to ask the question in a forum more suited to owners of this sort of machine :dunno_white:
Quote from: wyobuck on November 26, 2011, 09:24:13 AM
.....................In another forum I was given a performance article and it stated that the GS450A had the same time in a 1/4 mile as the original Datsun 240Z. Seems like it would get to 80 before going the 1/4. The person that supplied the info was also a GS450A owner, infact he had 3 of them. He reached 80mph on his with no problems ........................
Pete
Well he ought to know and I never rode a GS450A but I put a lot of time/miles in on my old CM400A, same type of bike. A quick check shows the RX7 and 280ZX quarter mile times to be about 17 sec. I have a copy of a road test of my CM400A from the July 81 issue of Cycle magazine and they show a 17.8 sec @ 73.95 mph quarter but don't spec a top speed. They comment that their Suzuki GS250T beat that by 2.2 sec and their CB400T(6 speed) was 3.67 sec and 16 mph faster than the 400A in the quarter. My first bike was a CB400T that I put 6 months and 6k miles on before trading it on a CB750K that I put 80k miles on and when I got that CM400A I was still very impressed with it's torque at moderate speeds. Builds speed fast off the line but just poops out before it gets to the end of the quarter. :icon_lol: That's the point I was trying to make above and of course we all expect your Suzuki GS450A to be faster than the Honda CM400/450A were, your GS450A has the same basic engine our GS500s have. :thumb:
Thanks for your research! I took it out on the interstate today, got on right before a downhill stretch. I shifted into high at 30 as recomended. She seemed to be accelerating a little faster and went up to 65 in about 1/4 mile. Then as I got down the hill and started a very slight incline, she went back to 60 then to 55. :dunno_black:. Still running without any bumps, stumbles, backfires etc...
Thanks again
Pete
Those bikes were choked down by cam and carb changes to maxamize mid range performance but yours is running out of breath even sooner than it should, could it be something as simple as a very dirty air cleaner element or a stuck choke?
OK, carbs were cleaned at 2200 miles, and it has 3500 now?
If you haven't been through the carbs yourself, you can't be assured that they were done, or done right. The fact that your top speed's increasing the more you ride makes me think you're cleaning the carb as you're riding. If you don't want to tear down, run a tank or two with Sea Foam and see if that helps.
Compression. Check it. Valves. Check your clearances. You should be doing this on any new-to-you bike (the compression, esp., before you buy it.)
Interesting that your top speed picked up after changing the oil. I wonder if the crankcase was filled with automotive oil with friction modifiers that messed with the bike's clutch. I don't know how these "automatics" work... car auto transmissions are full of clutch packs that do the decoupling. Running a couple of crankcases worth of "real" MC oil may help if this is the case.
To be honest, friction modifiers shouldn't do anything to the top speed. If it's not the carbs, then one thing I can think of is that the lock up clutch in the torque converter isn't working, but I don't know if the bike even has a lock up clutch to begin with.
Thanks for all the responses. Removed air filter and found it to be pretty clean, so cleaning it did nothing. I am running Bell's Marine MXO as I do with all my bikes every third tank. Found to be the best by a bunch of VMax owners here in FL. Think ACE Hardware carries it. One half ounce to 5 gallons. As I said in the beginning bought this for my girlfriend to learn on and the lack of top speed is not a big issue now. Will run it for a few months before I get real serious about finding the problem, maybe take it to a shop. Just thought someone here had firsthand experience with this bike.