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Post by RoadKone on May 21, 2008 18:59:59 GMT -5
I dont really know where else to post this so here is my emergency. I was running down the road doing about 65-70 when the bike just started slowing down. I pulled over and it was idleing fine. So I took off again.
Its hard to describe the noise it made when I hit 35-40. All I know is it wont accelerate after that mark. It sounds like something in the engine is bouncing around or whathaveyou and it won't accelerate without sputtering and making a "gagagagag' noise. I know its more than fixable because THE BIKE STILL RUNS! Harder to break than a rock.
The only thing I've done to it, really, is taken off the muffler and left only the down pipe. The first owner rejetted the carb for a Supertrapp and K&N Filter, and the second owner put the stock muffler back on without rejetting. So the bike was actually running better.
I know for sure its not the carb cuz i dumped the bowl. There is something in the engine.
Guys, I really need some help. I have a college kids budget and am deathly afraid of creating a basketcase bike. HELP!
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Post by canucksr on May 21, 2008 20:27:43 GMT -5
Is there an obstruction in the air-box / intake?
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Post by RoadKone on May 21, 2008 20:37:52 GMT -5
Nada. Whatever it is, its in the jug. I'm just too much of a puss too just take it apart and hope something falls out. But that looks like the only answer.
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Post by wotavidone on May 21, 2008 20:41:47 GMT -5
Can't quite follow your post. It reads that you have no muffler. Have you actually got a muffler on the bike now? Running straight out front pipe only would probably help create a lean condition, with resulting hot spots, pinging, etc. If you have really only got the downpipe, put a muffler on it before you burn an exhaust valve or something.
If you have actually got a full system on there, then consider the following.
Longterm readers of this forum might roll their eyes, because I beat this drum a lot, but take a look at the octane rating of your fuel.
The symptoms you describe are not all that different from the way my bike behaved when I got it. The cure after many fruitless hours checking carbs, jetting, ignition timing, plugs, etc, was to fill the tank with 98 Octane fuel. That's Australian Octane rating of 98. Which I'm not sure if USA uses the same system. Plenty people on this forum could clear that point up for us.
Mick
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Post by RoadKone on May 21, 2008 21:01:04 GMT -5
Well, I took the pipe off and it has been off for about two or three weeks. So I might have already done the damage. Yeah we have 98 octane. At $4.25 a gallon. (you do the conversion)
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Post by stevec5000 on May 21, 2008 21:24:00 GMT -5
Regular fuel, whatever is cheapest, works fine for me. If it sounds like something inside the cylinder you can take the spark plug out and look down inside there with a spot light and see if it looks OK inside while you turn it over by hand. You can take the valve covers off and turn it over while you check the valves to see if they are operating OK. I would also use a timing light and check the timing while it's running, check if the advance works properly, you have steady spark and so on.
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Post by solo2racr on May 21, 2008 21:29:58 GMT -5
I am assuming that this came on suddenly. If that is correct, I wouldn't think it would be an octane but a mechanical issue. If it is not detonating, using a higher octane will have no effect. Be prepared to remove the engine and start tearing it down. I would try to do a compression test before you removed the engine to maybe get an idea as to what may be going on. It is really hard to say what may be wrong without riding it or listening to it ourselves. Before you start spinning wrenches, get a manual for it. For you budget, the Haynes manual will get you by. Read it BEFORE you start to tear into the engine so you will have an idea what to look for as you go. If anything looks questionable or not sure what somethings are or mean.....ask away.
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Post by RoadKone on May 21, 2008 21:39:55 GMT -5
I was lucky enough to inherit the Clymer and Yamaha manuals from the previous owners. What are the symptoms of an unseated or burned valve?
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Post by colinjay on May 21, 2008 21:53:50 GMT -5
Normally a burnt, bent or poor sealing valve will give give the opposit effect, i.e. the bike will be hard to start, and run poorly, cough and backfire etc at low revs, then run a bit better as the revs increase.
TThere is a high speed pickup coil for the ignition system, if this fails the bike will normally start and run ok at low revs the just stop reving and sometimes start to cough and backfire etc as it tries to change to the high speed pick up. It might be worth having a look at the resistance and condition of this pickup coil. A spark plug or ingition coil breaking down under load can also give a sinilar effect.
CJ
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Post by solo2racr on May 21, 2008 22:20:44 GMT -5
There is a high speed pickup coil for the ignition system, if this fails the bike will normally start and run ok at low revs the just stop reving and sometimes start to cough and backfire etc as it tries to change to the high speed pick up. It might be worth having a look at the resistance and condition of this pickup coil. A spark plug or ingition coil breaking down under load can also give a similar effect. CJ I agree. This would be a good place to start. And doesn't require removing the engine. |
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Post by wotavidone on May 21, 2008 22:56:04 GMT -5
Lesseee. $4.25 per gallon (3.8 litres per gallon) = $1.12 per litre. EXchange rate = 0.95. So that's $1.12/0.95 = $1.18 Australian per litre.
Geez you guys get cheap fuel. Its about $1.60 per litre here.
If I wuz you, I'd put the muffler back on it before I did anything else. Then put a timing light on it and see if it advances as the revs pick up.
mick
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Post by canucksr on May 22, 2008 15:23:44 GMT -5
Do a compression test before you tear apart too much.
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Post by fenz on May 22, 2008 19:48:30 GMT -5
Head gasket is another posability as they can make some weird noises when they let go.
Bike will still run but will be down on power and when you try to give it the beans usually get a weird flapping/clacking sound.
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