Running problems?

[Wolfie24]

Hi folks,

I'm currently preping my 99' suzuki dr650SE for an african tour. The main things which are bothering me at the moment is the fact the bike does not start first time and when finally running it spits and splutters as if its missing every other firing, and similarly anything below 3rd gear at slow speed and the bikes feels very ropey. Being a novice to the world of mechanics and motorbikes in general I am guessing it could be due to the carb??

I've recently fitted the 4.9IMS tank and due to the new petcock arrangement had to fit a cap on the vacuum hose outlet, could this be affecting the running?

Also how easy is it to change the steering head berings since these have also seen their last days.

Any help would be much appreciated,

cheers

[beddhist]

If this problem is new since you fitted the big tank then check that the carb is getting enough fuel. There is a little sieve filter in the inlet pipe of the carb.

Replacing the bearings is the same as on most other bikes. Quite a job, if you've never done it before. Getting the race of the stem is the hard part. I've had some poor quality bearings recently, probably made in China. Make sure you get good quality bearings from Japan or Europe. If in doubt stick with the genuine Suzi parts.

[Wolfie24]

Cheers beddhist,

Since posting last things have subsequently got worse, the bike has problems starting and when I finally manage to get her going it cuts out immediately when given any throttle.

I'm going to assess the way in which the vacuum hose has been plugged, possibly drain and flush the carb and check the inlet filter, and clean the spark plugs. I can't think of what else to do?

I've seen quite a few posts regarding the reserve level not being completely used after fitting the IMS tank, could this be due to the amount of pressure decreasing above the fuel line and so not delivering the fuel without the vacuum pump? Becasue of the close proximity of the new petcock with the carb the fuel hose between the two forms something resembling an upturned U-bend, again this could be a problem in the delivery of the fuel but can't really be changed since the carb inlet extends upwards above the horizontal petcock outlet?

Similarly when the engine cuts out or is switched off it does so with a clunk, should this be a concern? :confused1:

[beddhist]

You raise several issues here:

The problem with reserve in this case is most likely either the upended U bend or the fact that the bottom of the tank is too low for fuel to flow into the carb voluntarily. I have similar problems, but only when the fuel level is low. I take it you have problems even with a full tank?

There is no vacuum pump, there is a vacuum operated fuel tap on the stock tank. When the engine stops there is no vacuum and the tap closes via a spring-loaded membrane.

The clunk: have you checked your bike for the "engine grenade" problem? See separate topic on this deadly issue. If your bike is first registered in 99 then it may be a 98 model and they are ALL concerned, as far as I know.

Interestingly, my former gf's DR had a lound clunk when starting or stopping the engine. The noise sounds horrendous, as if the engine was about to explode, especially if the bike doesn't want to start. Mine didn't have this problem and neither bike has the engine grenade parts. Through a process of elimination I have narrowed the cause down to the starter clutch. I can't see anything wrong with it, but hers lets go a little before engaging when you turn it by hand. The proof came when I swapped it into my bike: I now have the noise and she doesn't. My bike now has well over 140000 km on the clock and the starter clutch has done even more. It still makes this noise every other time I stop the engine. I'm no longer worried about it. (Famous last words... )

[Hooli]

an upturned U-bend in the fuel line is the perfect way to cause a vapourlock & make the bike run crap. what happens is the heat from the engine causes the petrol to vapourise & rise. this petrol gas effectively blocks the fuel line so you bike suffers fuel starvation. i'd reroute that line in a flatter manner, even if you have to make it longer to do so.

[Frank Warner]

IMS tanks are known to have small plastic particals - unless cleaned out before installation these block the inlet filter on the carby. If that has already been removed then you may have blocked jets inside the carby.

There is no vacum pump on a DR. The vacum line from the carb goes to the standard fuel cock to turn it on .. it does not in any way pump the fuel.