Bonneville America Forums Forums Technical Forums General Tech Need some help.. Have a rattle at hwy speed

When my 04 speedmaster is at hwy speed. When I open up the throttle I hear a rattle. It makes the rattle only when I open the throttle goes away when I back off of throttle. No noise at slower speeds or at idle. I have looked for any loose points and have found nothing. Could it be in the carbs? If so what could be loose. I have 22,000 miles on bike have inspected the chain and sprokets ,do not have much wear on either. This has only started this spring not sure where to go so any help would be appreciated.
Thanks

Put some higher octane gas in it and see if it goes away.

I run premiun which is around 91 octane. Could be left over stable that was in the bike for winter storage? I have ran a number of tanks of gas through bike so I thought all of that would be gone.

So, it's an engine rattle, not a vibration rattle?

I think it is an engine rattle. Cant really hear where it is coming from.

shouldn't happen at 22,000 but it was common on the old Triumphs to get a carb rattle when the slides got worn in the old Amals. I would look for something loose and get some fresh gas in there.

Process of elimination :

At what RPM does it rattle ?
Will it do it at that RPM in neutral ?
Is the rattle symptomatic of a certain gear ?
Is it a high frequency metallic rattle ( valvetrain )
It takes a refined ear , but you can think and hear your way to the problem most times .

Another good way to find the source is if you can get the rattle to happen while the bike is on the kickstand take a long screwdriver and put the handle against your ear and put the blade against different parts of the engine. It will act like a stethescope and help pin point the sound. It will be loudest through the driver when it is touched closest to the noise.

Could be an exhaust leak...

having the snorkel out, wot will cause a vibration that may rattle something. ensure the air box is tight. The rear bolts specifically and the top air box cover (the one you remove to service the filter). Make sure the harness cover is fastened too. The faux air covers and the holders.
Check: Where you exhaust headers bolt to the jugs, where the slip-ons bolt to the header pipes and check the rear peg hangers. Check the cross over clamp.

Back when you had 15K on bike you had asked about chain replacement. Now you are at 22K and no longer worried about it. imh experience, 20K is it. A worn chain will make it feel like you are on a dip laden road when you are actually on a smooth road. The chain will make a rough tumbling noise too. usually, when hard accelerating, you are driving the chain with increasing force, keeping it taunt, and the chain noise will lessen. Can you pull the chain off of the rear sprocket? 'Rattle' is hard to pin down.


what does all this mean for your problem? dunno. cept the part about checking for loose stuff.

My bike has rattled when the headlight bucket isn't correctly seated.
The dash console also vibrates and makes an odd sound at times. One screw is stripped, but I don't think the tab is wide enough for a helicoil, etc. Not sure what to do about that one.

I could not get the rattle to duplacate on stand. Maybe the chain as Moe said. I will order one from fasteddy today and see if that gets the problem fixed. I was wondering about the front sprocket,17,18 or 19 what is the diff on these 3.

Just throwing out some ideas.

What about chain alignment/rear wheel alignment? Loose/cracked chain guard? Loose drive sprocket?

You probably have a 16 tooth front sprocket on an early Speedmaster. I'm running an 18 tooth on my 03 America. For my kind of riding, it's fine but you will have to try for yourself.

I did not think that the chain was the issue but after my first long ride I had to adjust it quite a bit, so maybe the problem. I am going to go over it tonight and recheck all that has been suggested here. any and all thoughts are welcome.STILL just learning the ends and outs.slow learner here

here is another dumb question..... I was rechecking bike and the chain is slack again after a 10 mile ride. the adjustment screws are where I set them. Can the chain get that far out that quick? Or am I missing something.Yes i did tighten the axle bolt....

Are you checking slack at several spots?

IT was out to about 1.5 inches from 1 inch.Readjusted to 1 inch.

I was under the impression to go to the slackest point but could have missed it.

What I meant was checking it several times, rolling bike forward a little each time. Or if its on a stand, rotate rear wheel a little, checking it about 4 different spots. If its too tight anywhere, it could ruin countershaft bearing. It wouldn't loosen up in only 10 miles.

I looked at the chain and 1/2ed it I have 2 very tight spots when marks are at sprockets and loose spots when marks are mid way to sprockets. new chain on its way. Hope this works. I am going to loosen chain in the tight areas so I can ride. That should be ok as long as I dont ride like a banche (right).

always ALWAYS adjust the chain at the tightest spot. if you have a stand, lift the rear then spin the tire. look at the chain in relation to the swing arm. you will be able to see when the chain is tight. find that tight spot - the tightest spot if more than one - then set bike down and adjust. the service manual says 20 to 30 mm deflection. i say just until the chain barely touches the swing arm when pushing up on the lower loop of the chain. speaking of chains, vera lynn is on her side stand waiting for me to whip one on her. was riding cinnamon girl and guess what, yup she is going to need one soon. 18000 miles happens real quick. dangit. chains and tires. i could only imagine the cost if i had a couple of triples

regarding the rattle at wot, be sure to check all your exhaust connections.

when i say replace the chain
what i mean is
chain kit: chain, front sprocket and rear sprocket.

If your chain is getting stretched that quickly, it is shot. It will continue to need adjustments after just about every ride unless you replace it and the sprockets. I love the 18 tooth front sprocket on my America, offers a much more relaxed cruising RPM. I can't imagine living with the stock 16 tooth Speedy front sprocket. I ordered everything from Fast Eddy.

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I looked at the chain and 1/2ed it I have 2 very tight spots when marks are at sprockets and loose spots when marks are mid way to sprockets. new chain on its way. Hope this works. I am going to loosen chain in the tight areas so I can ride. That should be ok as long as I dont ride like a banche (right).

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I ordered the Kit from Fast Eddy last night. Thanks for the help .