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Discussion Starter #1
Hello all! If anyone has some suggestions that would be awesome.

Bought the bike as a commuter bike, I'm fairly new to cycling and wasn't looking for a project bike. Turns out I got a small project on my hands. :/

It runs awesome for the most part, except it seems to overheat when I take it up past 60 or so and hold it. If I hold the throttle down for a while it will run for a few miles, and then eventually start losing power on and off, shuttering (like its not getting fuel or air consistently). I pull off asap and let it cool down, and it runs fine again for a few miles back home. If I try to start it before it cools down, it won't go.

Its one other issue which might help debugging is that it very occasionally stalls from idling once I open the throttle to go. May be unrelated.

I'm in Denver, CO, so I may need to adjust the carbs, but haven't done so and am unaware if the prior owner has done so. I pulled the old spark plugs and they looked back from carbon and not oil, based solely on some pictures I've looked at online; I could very well be wrong. I'm not sure if the oil radiator is clogged, it gets hot but not as hot as the crankcase.

I've taken a good deal of the bike apart, cleaned the carbs, changed the oil, etc, and am still having problems. I'm no mechanic, but I've learned a lot in the past few days. (Yikes). Tips are very much appropriated from the pros.
 

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If I hold the throttle down for a while it will run for a few miles, and then eventually start losing power on and off, shuttering (like its not getting fuel or air consistently).
This problem sounds very much like a plugged tank vent; the resulting vacuum in the tank cuts off the fuel flow.
Next time it happens, pop the fuel cap and see if it won't start back up immediately. Having a spare key helps with this test.

As for the stalling off idle, give it a double dose of a good carb cleaner in the gas......and be sure that you idle speed isn't too low.
Are the pipes and air filter still stock ??
 

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Discussion Starter #3
This problem sounds very much like a plugged tank vent; the resulting vacuum in the tank cuts off the fuel flow.
Next time it happens, pop the fuel cap and see if it won't start back up immediately. Having a spare key helps with this test.
I will check this for sure next time it happens. Awesome thanks.

As for the stalling off idle, give it a double dose of a good carb cleaner in the gas......and be sure that you idle speed isn't too low.


After I cleaned the carbs I set the idle speed, so hopefully its good (I will verify). I can add some cleaner to the gas and try that too. This problem hasn't happened for a while so cleaning them may have done it, I just didn't know if it would help with the bigger picture.

Are the pipes and air filter still stock ??
Yes all is stock. I ordered a replacement (stock) air filter, current looked old and dirty. Haven't received replacement yet.

Thanks much.
 

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I agree with Easy- most likely a fuel flow problem, such as the above mentioned vent, or a kinked fuel line, or something simple like that. As an air-cooled bike, there is very little that can go wrong to cause overheating other than a lean condition, and the bike should cool better as you go faster and have more airflow. So a fuel delivery problem is by far the most likley cause.

Can you post a pic of your ride? I have not seen a 450ga since there was one in the local Suzuki dealership showroom back in 1982. Japanese bikes with automatic transmissions were a very short lived fad, and the Honda outsold the Suzuki about 10 to 1, so I am tickled that you still have a rare Suzukimatic on the road.
 

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Discussion Starter #6
Sure :) other than this and some cosmetic stuff works great.

So it did it again on the way home from work in 92? ish weather. To work just fine in the morning. I took the cap off and didn't hear a whoosh, but I had my helmet on so if it was quiet I could have missed. I cleaned the gas cap just in case.

When it first did this i thought it might be bad old fuel so I installed an after market fuel filter, hopefully I didn't ruin it. :madd: It was doing it before.

I did also notice the prime position of the petcock doest work, but I see gas flowing when it's on on and the engine is cranking. Cleaned petcock out with spray earlier, but that didn't fix it either, clearly.

IMG_20130819_213526.jpg
 

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I did also notice the prime position of the petcock doest work, but I see gas flowing when it's on on and the engine is cranking.
That is a pretty clear indication that something in the petcock is screwed up because PRIme should flow when nothing else does.
Is it possible that you don't have the lever positions figured out right ??

Did cracking the cap make it restart any easier ??
 

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Discussion Starter #8 (Edited)
Is it possible that you don't have the lever positions figured out right ??

LOL, possible, but they have it labeled for noobs like me. Maybe I'm not turning it far enough? The labeling is Reserve left, On down, Prime right. Through my new clear fuel filter, I can see it flowing when set to on when the engine is idling, and nothing when on prime. Didn't try res. When I dissembled it, I tried putting the vacuum spring on the other side of the diaphragm for fun, and then all three worked and flowed like prime. Its currently installed in the correct position.

Did cracking the cap make it restart any easier ??
I was able to get it started again (faster) before it cooled down, but I had to use the choke to do it. I hadn't thought to try choking it before, and this time it stalled in a bad spot to experiment.

Tonight I'll have more time to do some serious work on it, so I'll be looking at all this stuff. Thanks for all the feedback guys.
 
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