Vibration

[jay]

Took me 65 for a nice bimble over the Kirkstone pass in Cumbria yesterday.luvverly ride with sprog (pictured) on the back,wife was on her street triple R. ...anyhoo,on the way back,hit 80mph on a bit of dual carriageway, and BIG vibration.First time i've taken it to 80.....70 is as sweet as a nut,so wondering what it could be....when i got the bike,it had apparently had a full carb service,and all i've done is replace the inlet rubbers.I would have thought any fuelling problems or carb imbalance would affect running all the time......don't remember this kind of vibration on my last 65 (27 years ago) any ideas??

[Barry]

They all seem to have a band of vibration usually around 5000 rpm  give or take a few hundred. Normally this equates to a bit less than 80mph though.

Any idea what the revs were ?

Does it vibrate at the same revs in a lower gear?  

That would confirm if it is engine speed related or road speed related as in the drive train/wheel balance.  

[jay]

Hiya Barry.....would have been around 5000 ish.......didn't want to take it any further in case of damage....may well have cleared if i had kept going.Seeing as you're in Cheshire,could always meet up so you could have a play,and give me your opinion.  Jay

[Barry]

Hi Jay

I hadn't noticed you were in Accrington. I have a brother and a sister in the Helmshore/Rawtenstall area so I'll let you know next time I'm up that way.

While they all vibrate around 5000 rpm it's not usually a cause for concern just a rough patch compared to the smooth running at lower and higher revs. Nothing compared to say an old British twin.  Even though the carbs have been overhauled it might still be worth checking the balance. A 1/4 turn or less on the cable adjuster is enough to make a difference to smooth running. If you don't have a manometer to do the balancing it would do no harm to put a reference mark on one of the throttle cable adjusters and then try a 1/4 turn in either direction to see what difference that makes.

[Lucky_Lou]

Mine sometimes vibrates at about 4500/5000 i tune the carbs regularly which improves this alot to the point of being barely noticeable. My daughter lives in Longridge i often come home on the A56 M66 if you come over the hill let me know.
Lou

[montmil]

A possibility being the throttle cables are imbalanced at higher rpms; one cylinder pumping out more power than the other can lead to a buzzy situation.

The El Cheapo Grande manometer can help ascertain that things are in balance. There is a proper sequence to follow.

Go throughthe above suggestions first, then "we'll talk".

Monte

[Rob Valdez 79 R65]

Duane Ausherman suggests leaving the left cable adjuster's locknut loose, so you can reach down and adjust it on the fly.  Not something this 54 YO wants to do at 80 MPH!  
But you should be able to duplicate the situation in 4th or 3rd gear, and be traveling slower.  Find a deserted road.  Let your wife know where you are.

I saw one guy that has dual throttle cables at the handlebar, and installed a cable adjuster on one of them, so he can do it from the top.  I don't have the luxury of a lot of room with the dash panel and low bars.

I always found that my bike ran best at around 85mph, back in it's prime (and I was getting a lot of tickets...).
Then I got my GPSr and found out how slow I was really going at 85! lol!
But my first engine would willingly go to (an indicated) 100 (and I weighed 30lbs less).  I don't really remember trying it after installing engine #2 in 1997 or so.  Every year I get older, it seems I go slower.  

According to a chart I ran a few years ago, 80 mph might be 6500 rpm, depending on a few variables like tire size, FD ratio, etc.  I don't know of anything at that speed.

Just how bad was this vibration?  I figure it must have been pretty severe to make you back off.  Not just an increased buzz, right?  Because that is what the "famous R65 vibe" is like, to me, at least.
I keep buying them.

Your bike is beautiful!  I love that colour!

But what is up with your kid's leg?  Did you photoshop him in there?

[Bob_Roller]

Seems like some bikes are more affected by this than others .

I think a real good carb synchronization will lessen it, but it won't go away completely .

On my '81 R65, it was like a switch was turned on at 4200 rpm and then it would gradually go away with increased or decreased rpm's .

After 84,000 miles, I can't detect it anymore, I don't know if the engine finally 'broke in', or maybe I'm just numb to it now !!!!

[jay]

Thanks for all the replies peeps.....not had to mess with carb balance for a lot of years after gsx1400's and our present Triumph Street Triple "R"s.Cant see anywhere to plug in vacuum gauges,so must be this "manometer" thingy.Will pm lucky-lou and barry my phone number.Right,dentist,then we're out on the Triumphs for the day in the sun...Up to Hawes i think.

[Lucky_Lou]

Thanks for all the replies peeps.....not had to mess with carb balance for a lot of years after gsx1400's and our present Triumph Street Triple "R"s.Cant see anywhere to plug in vacuum gauges,so must be this "manometer" thingy.Will pm lucky-lou and barry my phone number.Right,dentist,then we're out on the Triumphs for the day in the sun...Up to Hawes i think.

Hoping to be in Hawes on Saturday 25th September(weather permitting) will be travelling down from Croft on Tees via Buttertubs with a pal, may go out to Devils bridge if we get time i got your number i will give you a bell nearer the time if you want to meet up. I have the Mark 3 Texas carb balancer(see photo) if your coming over to Squires call at my workshop for a tune up.
Lou
ps its the "Texas" balancer cos its bigger and better than all the rest..... [smiley=beehive.gif]

[Barry]

Jay

Tried to call you today and PM'd my phone numbers. Have a version of the balancer too if your ever out this way. The ingenuity that's gone on all around the world constructing the famous 3$ manometer is amazing and they are all different.

...and before anyone ticks me off for having the bike on the side stand "I've done me back in". It's not stopping me riding every day though. I'm just giving the old back a rest from the mighty heave off the centre stand.  Strangely its not smoking on the left pot at start up ....at least not when I remember to look behind.

[Rob Valdez 79 R65]

Vacuum port.  Click for larger picture.

[Barry]

Just got off the phone talking to Jay and said I would post a picture of the Carb vacuum take off points.  Rob read our minds across the pond and has already done that.

If you don't have a manometer here is the other mechanical method we talked about.

Take a pair of your partners finest and lightest knitting needles and bend as shown (if your brave enough). Pierce them through a couple of short lengths of stiff rubber tube pushed on to the inner ends of the throttle spindles.

The idea is you now have very sensitive indicators which amplify the slightest movement of the throttle spindles so stood over the tank operating the throttle you can see if one moves before the other. Not a complete substitute for a manometer but very quick to do and surprisingly accurate. You can get the balance very close this way.

[Lucky_Lou]

Nice one Barry.... Heath and Robinson spring to mind
Lou

[Rob Valdez 79 R65]

Anne Robinson?

Yes Barry, I like that!!!