[FrankenDesmo]

Originally Posted by Mr Gazza

I use NGK DCPR8E spark plugs in my 900, I think those are the right ones. I also take care (now) to order the suffix type 4339, which are the version with the threaded terminal, so you can unscrew the ally nipple and use them bare threaded.

I had not heard of doing that before - is that just to remove any traces of resistance?
They seem to be the same plugs, heat range aside, except yours have a Projected insulator (whatever that means), and take a 16mm socket instead of 18mm.

It looks like you have exhausted all the avenues possible to avoid a carb strip and if the cooler and oil lines are spoiling the fun then it makes it even more justified. ( but could the lines be removed from the carbs and be safe to run with the tap turned off?)

True, I do appear to have enough access underneath to undo the inlet/outlet lines for the heater, which would be better than having to remove the whole battery & air box when the carbs need adjustment. Will see how possible that is.

Given what you say about an earlier conversion to the 900 engine makes me wonder if the carbs are right for the engine or maybe they have been played with?

I think the carbs are correct, but I have nothing to back this up with other than I would think that it was obtained as a whole unit, or they had an m900 donor of some kind, as the only piece that is still M600 (by the looks) is the frame (which is just the stamping on the tube, as we know the frame is no different). But aye, it could very well have been played with. The assumption is that it is a stock '93/94 900 lump & carbs, but there is no way for me to know until I crack things open.

I think it's well worth checking all the jet sizes and so forth... Blueprinting the carbs for want of a better expression.

The problems you are having in the lower rev range and lower throttle settings seem to indicate pilot jet problems. Unfortunately there is no pilot jet as such, it's just a drilling which blocks very easily with corrosion from standing and is somewhat harder to unblock! Ultra-sound cleaning is a good option.

You've been very patient and methodical so far. I think you stand a better chance of success with know clean carbs set to the base settings.

That's what I've been thinking - I need the carbs to be in a known state. An ultrasonic clean might not be a bad idea. I had been hoping to not have it off the road much longer, but it is still early in the year so a good time to put this sort of issue to bed properly. Once I've got them open I'll see if I should order some parts from factory pro (such as the emulsion tubes), if they need replacing. Might as well do it with good stuff - and he has a kit suited towards airbox lid chops, which is what I have.

Since you have got the electrical side sorted and new plugs fitted, I would suggest checking the valve clearances while you have the carbs and cooler and other gubbins out of the way. The valves and sparks should always be in perfect order before attempting tuning the carbs.

I had wondered if there could be an ignition issue, but I think I'd have problems all the way through the rev range, rather than part-throttle low revs - as that would seem to be firmly in the area of the pilots as you say.

Originally Posted by utopia

You said on the other thread that you drained the tank.
Did you inspect what came out and if so, was there any water in it ?
If there was, or maybe even if there wasn't, I wonder whether there is any water in the float bowls ...?
To be honest, I wouldn't bet on that being your problem but draining the float bowls might be one more thing that you could try before resorting to stripping the carbs.

Could definitely be worth a try - I'm guessing that water will tend to float on top and therefore stay there? Though I did run it dry with the tap off after draining the tank.