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Hi Everyone, does anyone else's 350 vibrate really badly at about 70mph/6500 revs (all figures pure guessimations due to vagliar clocks ). Mine is so bad i could not maintain that speed and had to slow down, tried to speed up but got unbearable. Does anyone else suffer from this or do i need to start looking into it? Thanks Tony

Mine is smoother at that speed than 50 but it's not bad at any speed getting smoother at higher speeds.
The carb balance makes a big difference at lower speeds but could be worth a look also engine mount
bolts.

Mine is MUCH smoother at high revs. In fact, I've hit 85mph on the little beast and it doesn't vibrate at all. Something is up.

Ooops.

Ralph wrote:...could be worth a look also engine mount
bolts.

This!

Stainless engine bolts in particular seem to work loose.

Some engines are more vibratory than others. It's worth checking the timing on the rear cylinder, but you'll have to transfer a timing mark to do so.

My 350K vibrated like a very vibratory thing when I first got it, buzzing like crazy at around 70mph. The vibes were, if I remember rightly, one of the reasons the previous owner sold the bike.

There was no one thing wrong, but lots of little tweaks over the next few months calmed things down to the point where the riding experience is now unrecognisable. It's not glassy smooth like a modern Japanese four, but it's not intrusively buzzy either.

Stuff I did:
Adjusted the tappets - they were quite a bit out, and different between heads.
Cleaned and then balanced the carbs really carefully, at tickeover *and* with an open throttle - they were also a fair bit out of adjustment.
Checked the timing with a strobe (it was fine).
Loosened and re-tightened the engine bolts.
Tightened lots of other loose bolts.

Fitted sticky Renthall grips so that I didn't have to cling on to the bars quite so tightly.
Removed various bits of chorme trim from the horn - this was adding to the impression of vibration by rattling noisily.
Tidied up the wiring in the headlight and stuck a couple of strips of duct tape inside so that it wasn't rattling.

The first five are probably the most important, the last three probably did more to reduce the impression of vibration.

Thanks for all the advice everyone. I've checked my engine mounting bolts and they weren't loose, but did need a little bit of torquing. I think i need to spend a little time at the weekend tinkering, checking and adjusting everything to see if just a general service may sort it out! As mentioned in a previous post i have problems with keeping my carbs in balance as my cables are too short and do not allow me to have the lock nut on the top of the carb, so i think that may be the first thing to check. Maybe a new set of correctly fitting cables might be worth investing in.

On a similar note does anyone know were i can buy a set of wire feeler gauges to check my tappet clearance correctly. A google search has drawn a blank, so just wondered if anyone knows of anyone who stocks them. Thanks

Reprofile the rocker tips.



http://www.ebay.co.uk/itm/EZE-LAP-Diamo ... 519f063801

Having control cables so short there's no adjustment cannot help.The slides may well be hanging and the throttle may operate when you turn the handlebars from lock to lock.

Has anyone had any experiences (good or bad) with Venhill cables? So they fit ok? or am i best sticking with NLM?

NLM stock Venhill cables. I've had quite a few problems, mostly with clutch cables, which led me to making my own. I had the cast on nipple pull off one cable, so a good job it wasn't a brake! Throttle cables are more or less OK, but tend to be a bit long (too long cables still fit, too short ones don't). The inner cable is a bit thick too.

The twistgrips vary on how deep the cable sits in the cable block and can be too taught on the shallow ones. Drilling out the block to sit the cable deeper can result in destroying the block if you're not careful (not available as as spare as far as I know).

Only the clutch cable, the first Venhill one wore through on the engine guide but
to give it a little lee way it was a slightly longer one supplied by MLN by I take it
mistake, it's done about 10000 mile ordered the correct one Wed night direct and it
arrived Thurs morning I have to say it is very light and smooth but only time will tell.

mgelder wrote:Loosened and re-tightened the engine bolts.

This is a worthwhile task. It is a good idea to (slightly) loosen and re-tighten bolts holding the engine, perhaps also the exhaust system every few years. Things change a little over. Letting the components find their best clearances sometimes helps.

Mine as never been bad but fitting vibration dampers from a Suzuki makes a noticeable difference.