RG500 carburation

[Lorenzo]

Hallo to everybody,
In order to qualify for vintage bike status, I need to restore the bike to the original condition ( so away the 170 x 17 tire, the jolly moto's, the USD forks and so on...);
After removing the jolly pipes, I took apart the carbies, expecting them to be overjetted for the original pipes but much to my astonishment, the main, pilot and needle where the original sizes, even though the outfit has been crisp all over the range;
having refitted the original pipes & silencers, the bike is somewhat difficult to start from cold, unless I do remove the air cleaner outlet pods, chocke the venturis (whith cloth or paper) to which the bike busts into life. It strikes me as "quirky" behaviour, in that if I have to restrict the air passages on starting, I would at least expect a lean plug, instead I got a rich one, which I am managing to correct via the air screw and throttle stop screw settings, plus a consistent spurt of oil from the lower pipes amidst a cloud of smoke...
If I accelerate whithin the 1/8 twist range, the noise become deaf, once past it, is all OK (apart from the smoke and oil);
the motor does not appear to consume tranny oil;
Whath do You make of it??

[Lorenzo]

Could it possibly be a sticking ring (I am referring to the fact that the carburetors inlets have to be effectively sealed, in order for the bike to start)?
This could also explain the splatter from the pipe...?
New smaller pilot jets have been ordered in the meantime (22.5 instead of 25);

By the way, am I in the wrong board, in that I have a Suzuki, I have a stroker, but I seem to get no answer... you know the feeling when you feel deliberatly avoided..?!

[Craig380]

Hi Lorenzo, I must have missed your earlier post ....

If the bike runs clean when it is warm, it sounds to me like the choke mechanism (or cold-start enrichment jets) is not working correctly on the carbs.

Does the bike have the factory air filter and intakes fitted?

[Lorenzo]

Hello Craig, the bike is on the original everithing, as I am bringing it back to factory specs in order for it to comply with certified vintage status (being a stroker, is the only way to use it on a everyday basis around town, for an otherwise banned class-of-emission vehicle);

The fact that in order to start it, I need to remove the intake thrunks and effectively seal the carburetors intakes, made me think about a sticking ring, not sealing enough, so unable to exert a vigourous suction;

But, on the other hand, it should just start on three cylinders.....

So what's left , in my limited and shy knowledge, is a worn out crank seal, for which I am rigging up a vacuum test;

[Craig380]

I agree, sticking rings on just ONE piston would not cause this problem.

But I would also say that ALL the disc valve housings (I think these make the seal on the RG) would have to be worn to cause the problem. The housings have some sort of material (like cork) which seals the disc valve, I understand that this can get damaged and pieces can break off.

This may be a silly question, does the bike have a vacuum-operated fuel tap? If so, do you use the 'prime' setting when starting the bike the first time from cold?

[Lorenzo]

No the carbs are gravity fed;

To start it from cold I just use the fuel enrichener (a.k.a. choke)

[Lorenzo]

I just changed the pilot jets from the original 25 to 22.5;

It seems a little crispier on the 1/8 range and now the n. 4 pipe, which was sputtering the oily substance does not smoke at all, instead n. 1 & 3 cyl. (the left side one) are;

The two pipes run very hot -while n.1 & 4 are cool- the plugs on n. 1 & 3 showing a lean condition;

I have put some additive to the transmission oil, supposed to mellow the seals, but I think is too early to ripe the benefits;

It makes me think of a flowed/ported engine (the full history of which, I do not know) that was giving the best with the tuned chambers, and now with the original one's is bogging down a little;

Any ideas much appreciated;

Here a sound file, listen from seconds 7 , 20 and 36;



http://s39.beta.photobucket.com/user/za ... 1.mp4.html

[Lorenzo]

Well, I removed the exhaust gaskets, put back the original #25 pilot jets, cleaned the air screws (a bit of grime and two of them are pitted, so they are going to be replaced asap), fiddled with the exaust valve front right casing, where the clatter seemed to come from, reseated and retightened the starter plunger, and the crackling sound is back as well the pull from tickover, with no spatter coming out and not particularly smokey;

This is how it sounds now...

http://s39.beta.photobucket.com/user/za ... k.mp4.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[Craig380]

Does it start from cold without you needing to block the intakes? Sounds sweet!

[Lorenzo]

Yes and apart from the hexaust valve (sticking?) problem it must have had air sucked in from somewere it was not supposed to;

thanks