Help with R75/7

[puccini]

I own a really clean R75/7.
Mileage is around 45,000 from all I can tell.

It starts right up when cold and does not smoke.
Oil consumption is normal or better.

I adjusted the valves correctly at the beginning of last summer and did not ride more than1500 miles.

Carbs are good and balance out well.

The problem is that it idles rough till it really warms up and then occationally still idles rough.
It has dual plugs and a dyna ignition. Timing is ok and the mark doesnt fluctuate at high rpm.

Guys I ride with say it smokes under hard accelleration.

I'm looking at new rings,
am I on the right track?
Gerry

[20774]

Did you do the carb balance with the engine warmed after a 10-15 minute ride? Sounds like the balance is not quite right if it idles rough.

As for the smoke, can you do a leakdown test or at least a compression test? The leakdown will confirm if rings are the problem. For me, if it performed well, got reasonable gas mileage and doesn't burn oil excessively, I'd live with it. Maybe ease off on the right wrist ;) and nobody will be telling you things you don't want to hear!! :laugh

[puccini]

Yes,
I used the electronic carb balancer.

I got a feeling that one cylinder has lower compression.

I guess I'll have to do the leakdown test and check the heads.

Gerry

[PGlaves]

I would head straight to the carburetors and make sure the jets and idle air passages are clean and not gummed up. I would verify that the fuel level in the bowls is perfect. Then I would verify that the spark plugs are crisp and properly gapped. Finally, I would adjust the idle mixture screws by the book to obtain smooth idle and no hesitation transitioning to the needle jet. After that - if it still idled poorly I would recheck the valve adjustment. If still a bit lumpy I would check compression and if compression is low when checked with carbs off the spigots, then I would do a leakdown test.

[puccini]

With the dyna ignition,
whats the suggested or recommended gap for the dual plugs.
And whats the latest gap for the valves.
Everyone has their own ideas.

Gerry

[20774]

With the dyna ignition,
whats the suggested or recommended gap for the dual plugs.
And whats the latest gap for the valves.


I've not heard of any changes for gaps on plugs or clearances for valves due to dual plugging...I'd go stock. About the only thing I've heard is adjustments in static timing and trying to control when full advance is reached. It's a bit of a compromise but there are some considerations for this in order to make the bike work reasonably in all situations.

[puccini]

I already know about the timing mark position change.
OT mark at top of the hole.

But I was tols that the plug gaps need to be larger for the dual plugs with the Dyna coil.

And, what are the recommended gaps for the valves.
I have 2 books with 2 different setting suggestions.
Gerry

[tkpinsc]

What rpm are you trying to set the idle at?

I'd keep the heads on and the rings in place until all the other options with carbs, valves and ignition are fully explored. Also make sure you do the compression and leakdown test before you pull the heads or this information will be lost. Lots of good advice already I'd add check for vacum leaks in the air tubes, etc.

[20774]

And, what are the recommended gaps for the valves.
I have 2 books with 2 different setting suggestions.

I use 0.15mm intake and 0.20mm exhaust. You might find 0.10mm intake, but a little looser doesn't hurt.

[flash412]

If you have OEM Beru metal (crap) spark plug caps, get rid of them. Replace them with NGK.